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Password strength

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</style><div role="note" class="hatnote navigation-not-searchable">For organizational rules on passwords, see <a href="Password_policy" title="Password policy">Password policy</a>.</div>

Password strength is a measure of the effectiveness of a <a href="Password" title="Password">password</a> against guessing or <a href="Brute-force_attack" title="Brute-force attack">brute-force attacks</a>. In its usual form, it estimates how many trials an attacker who does not have direct access to the password would need, on average, to guess it correctly. The strength of a password is a function of length, complexity, and unpredictability.<a href="#cite_note-CERT-1">[1]</a>

Using strong passwords lowers the overall <a href="Risk" title="Risk">risk</a> of a security breach, but strong passwords do not replace the need for other effective <a href="Security_controls" title="Security controls">security controls</a>.<a href="#cite_note-2">[2]</a> The effectiveness of a password of a given strength is strongly determined by the design and implementation of the <a href="Authentication#Authentication_factors" title="Authentication">authentication factors</a> (knowledge, ownership, inherence). The first factor is the main focus of this article.

The rate at which an attacker can submit guessed passwords to the system is a key factor in determining system security. Some systems impose a time-out of several seconds after a small number (e.g. three) of failed password entry attempts. In the absence of other <a href="Vulnerability_(computer_security)" title="Vulnerability (computer security)">vulnerabilities</a>, such systems can be effectively secured with relatively simple passwords. However, systems store information about user passwords, and if that information is not secured and is stolen (say by breaching system security), user passwords can then be compromised irrespective of password strength.

In 2019, the United Kingdom's <a href="National_Cyber_Security_Centre_(United_Kingdom)" title="National Cyber Security Centre (United Kingdom)">NCSC</a> analyzed public databases of breached accounts to see which words, phrases, and strings people used. The most popular password on the list was 123456, appearing in more than 23 million passwords. The second-most popular string, 123456789, was not much harder to crack, while the top five included "<a href="Qwerty" class="mw-redirect" title="Qwerty">qwerty</a>", "password", and 1111111.<a href="#cite_note-3">[3]</a>

<div class="mw-heading mw-heading2"><h2 id="Password_creation">Password creation</h2></div>

Passwords are created either automatically (using randomizing equipment) or by a human; the latter case is more common. While the strength of randomly chosen passwords against a <a href="Brute-force_attack" title="Brute-force attack">brute-force attack</a> can be calculated with precision, determining the strength of human-generated passwords is difficult.

Typically, humans are asked to choose a password, sometimes guided by suggestions or restricted by a set of rules, when creating a new account for a computer system or internet website. Only rough estimates of strength are possible since humans tend to follow patterns in such tasks, and those patterns can usually assist an attacker.<a href="#cite_note-NIST-4">[4]</a> In addition, lists of commonly chosen passwords are widely available for use by password-guessing programs. Such lists include the numerous online dictionaries for various human languages, breached databases of <a href="Plaintext" title="Plaintext">plaintext</a> and <a href="Cryptographic_hash_function" title="Cryptographic hash function">hashed</a> passwords from various online business and social accounts, along with other common passwords. All items in such lists are considered weak, as are passwords that are simple modifications of them.

Although random password generation programs are available and are intended to be easy to use, they usually generate random, hard-to-remember passwords, often resulting in people preferring to choose their own. However, this is inherently insecure because the person's lifestyle, entertainment preferences, and other key individualistic qualities usually come into play to influence the choice of password, while the prevalence of online <a href="Social_media" title="Social media">social media</a> has made obtaining information about people much easier.

<div class="mw-heading mw-heading2"><h2 id="Password_guess_validation">Password guess validation</h2></div>

Systems that use passwords for <a href="Authentication" title="Authentication">authentication</a> must have some way to check any password entered to gain access. If the valid passwords are simply stored in a system file or database, an attacker who gains sufficient access to the system will obtain all user passwords, giving the attacker access to all accounts on the attacked system and possibly other systems where users employ the same or similar passwords. One way to reduce this risk is to store only a <a href="Cryptographic_hash" class="mw-redirect" title="Cryptographic hash">cryptographic hash</a> of each password instead of the password itself. Standard cryptographic hashes, such as the <a href="Secure_Hash_Algorithm_(disambiguation)" class="mw-redirect" title="Secure Hash Algorithm (disambiguation)">Secure Hash Algorithm</a> (SHA) series, are very hard to reverse, so an attacker who gets hold of the hash value cannot directly recover the password. However, knowledge of the hash value lets the attacker quickly test guesses offline. <a href="Password_cracking" title="Password cracking">Password cracking</a> programs are widely available that will test a large number of trial passwords against a purloined cryptographic hash.

Improvements in computing technology keep increasing the rate at which guessed passwords can be tested. For example, in 2010, the <a href="Georgia_Tech_Research_Institute" title="Georgia Tech Research Institute">Georgia Tech Research Institute</a> developed a method of using <a href="GPGPU" class="mw-redirect mw-disambig" title="GPGPU">GPGPU</a> to crack passwords much faster.<a href="#cite_note-gtri-5">[5]</a> <a href="Elcomsoft" class="mw-redirect" title="Elcomsoft">Elcomsoft</a> invented the usage of common graphic cards for quicker password recovery in August 2007 and soon filed a corresponding patent in the US.<a href="#cite_note-belenko-6">[6]</a> By 2011, commercial products were available that claimed the ability to test up to 112,000 passwords per second on a standard desktop computer, using a high-end graphics processor for that time.<a href="#cite_note-elcomsoft-7">[7]</a> Such a device will crack a six-letter single-case password in one day. The work can be distributed over many computers for an additional speedup proportional to the number of available computers with comparable GPUs. Special <a href="Key_stretching" title="Key stretching">key stretching</a> hashes are available that take a relatively long time to compute, reducing the rate at which guessing can take place. Although it is considered best practice to use key stretching, many common systems do not.

Another situation where quick guessing is possible is when the password is used to form a <a href="Cryptographic_key" class="mw-redirect" title="Cryptographic key">cryptographic key</a>. In such cases, an attacker can quickly check to see if a guessed password successfully decodes encrypted data. For example, one commercial product claims to test 103,000 <a href="Wi-Fi_Protected_Access" title="Wi-Fi Protected Access">WPA</a> PSK passwords per second.<a href="#cite_note-8">[8]</a>

If a password system only stores the hash of the password, an attacker can pre-compute hash values for common password variants and all passwords shorter than a certain length, allowing very rapid recovery of the password once its hash is obtained. Very long lists of pre-computed password hashes can be efficiently stored using <a href="Rainbow_tables" class="mw-redirect" title="Rainbow tables">rainbow tables</a>. This method of attack can be foiled by storing a random value, called a <a href="Cryptographic_salt" class="mw-redirect" title="Cryptographic salt">cryptographic salt</a>, along with the hash. The salt is combined with the password when computing the hash, so an attacker precomputing a rainbow table would have to store for each password its hash with every possible salt value. This becomes infeasible if the salt has a big enough range, say a 32-bit number. Many authentication systems in common use do not employ salts and rainbow tables are available on the Internet for several such systems.

<div class="mw-heading mw-heading3"><h3 id="Entropy_as_a_measure_of_password_strength">Entropy as a measure of password strength</h3></div>

Password strength is specified by the amount of <a href="Information_entropy" class="mw-redirect" title="Information entropy">information entropy</a>, which is measured in <a href="Shannon_(unit)" title="Shannon (unit)">shannon</a> (Sh) and is a concept from <a href="Information_theory" title="Information theory">information theory</a>. It can be regarded as the minimum number of <a href="Bit" title="Bit">bits</a> necessary to hold the information in a password of a given type. A related measure is the <a href="Binary_logarithm" title="Binary logarithm">base-2 logarithm</a> of the number of guesses needed to find the password with certainty, which is commonly referred to as the "bits of entropy".<a href="#cite_note-9">[9]</a> A password with 42 bits of entropy would be as strong as a string of 42 bits chosen randomly, for example by a <a href="Fair_coin" title="Fair coin">fair coin</a> toss. Put another way, a password with 42 bits of entropy would require 242 (4,398,046,511,104) attempts to exhaust all possibilities during a <a href="Brute_force_search" class="mw-redirect" title="Brute force search">brute force search</a>. Thus, increasing the entropy of the password by one bit doubles the number of guesses required, making an attacker's task twice as difficult. On average, an attacker will have to try half the possible number of passwords before finding the correct one.<a href="#cite_note-NIST-4">[4]</a>

<div class="mw-heading mw-heading3"><h3 id="Random_passwords">Random passwords</h3></div>

<div role="note" class="hatnote navigation-not-searchable">Main article: <a href="Random_password_generator" title="Random password generator">Random password generator</a></div>

Random passwords consist of a string of symbols of specified length taken from some set of symbols using a random selection process in which each symbol is equally likely to be selected. The symbols can be individual characters from a character set (e.g., the <a href="ASCII" title="ASCII">ASCII</a> character set), syllables designed to form pronounceable passwords or even words from a word list (thus forming a <a href="Passphrase" title="Passphrase">passphrase</a>).

The strength of random passwords depends on the actual entropy of the underlying number generator; however, these are often not truly random, but pseudorandom. Many publicly available password generators use random number generators found in programming libraries that offer limited entropy. However, most modern operating systems offer cryptographically strong random number generators that are suitable for password generation. It is also possible to use ordinary <a href="Dice" title="Dice">dice</a> to generate random passwords <style data-mw-deduplicate="TemplateStyles:r1033199720">

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</style>(see <a href="Random_password_generator#Stronger_methods" title="Random password generator">Random password generator § Stronger methods</a>). Random password programs often can ensure that the resulting password complies with a local <a href="Password_policy" title="Password policy">password policy</a>; for instance, by always producing a mix of letters, numbers, and special characters.

For passwords generated by a process that randomly selects a string of symbols of length, L, from a set of N possible symbols, the number of possible passwords can be found by raising the number of symbols to the power L, i.e. NL. Increasing either L or N will strengthen the generated password. The strength of a random password as measured by the <a href="Information_entropy" class="mw-redirect" title="Information entropy">information entropy</a> is just the <a href="Binary_logarithm" title="Binary logarithm">base-2 logarithm</a> or log2 of the number of possible passwords, assuming each symbol in the password is produced independently. Thus a random password's information entropy, H, is given by the formula:

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<annotation encoding="application/x-tex">{\displaystyle H=\log _{2}N^{L}=L\log _{2}N=L{\log N \over \log 2}}</annotation>

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</math><img src="./d30dfce3e0cd67b4fc5b4410cd7d0d5e89781f6d.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.338ex; width:35.535ex; height:5.843ex;" alt="{\displaystyle H=\log _{2}N^{L}=L\log _{2}N=L{\log N \over \log 2}}" loading="lazy">

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where N is the number of possible symbols and L is the number of symbols in the password. H is measured in <a href="Bit" title="Bit">bits</a>.<a href="#cite_note-NIST-4">[4]</a><a href="#cite_note-10">[10]</a> In the last expression, log can be to any <a href="Base_of_a_logarithm" class="mw-redirect" title="Base of a logarithm">base</a>.

A <a href="Binary_number" title="Binary number">binary</a> <a href="Byte" title="Byte">byte</a> is usually expressed using two hexadecimal characters.

To find the length, L, needed to achieve a desired strength H, with a password drawn randomly from a set of N symbols, one computes:

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<annotation encoding="application/x-tex">{\displaystyle L={\left\lceil {\frac {H}{\log _{2}N}}\right\rceil }}</annotation>

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</math><img src="./998d6b928d9677e34401e0c2599bf65f37573202.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.505ex; width:14.705ex; height:6.176ex;" alt="{\displaystyle L={\left\lceil {\frac {H}{\log _{2}N}}\right\rceil }}" loading="lazy">

where <math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \left\lceil \ \right\rceil }">

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<annotation encoding="application/x-tex">{\displaystyle \left\lceil \ \right\rceil }</annotation>

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</math><img src="./41cd14e9fa8645c07bb88437f88f8a2464451e5b.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:2.645ex; height:2.843ex;" alt="{\displaystyle \left\lceil \ \right\rceil }" loading="lazy"> denotes the mathematical <a href="Floor_and_ceiling_functions" title="Floor and ceiling functions">ceiling function</a>, i.e. rounding up to the next largest <a href="Natural_number" title="Natural number">whole number</a>.

<div class="mw-heading mw-heading3"><h3 id="Human-generated_passwords">Human-generated passwords</h3></div>

People are notoriously poor at achieving sufficient entropy to produce satisfactory passwords. According to one study involving half a million users, the average password entropy was estimated at 40.54 bits.<a href="#cite_note-11">[11]</a>

Thus, in one analysis of over 3 million eight-character passwords, the letter "e" was used over 1.5 million times, while the letter "f" was used only 250,000 times. A <a href="Uniform_distribution_(discrete)" class="mw-redirect" title="Uniform distribution (discrete)">uniform distribution</a> would have had each character being used about 900,000 times. The most common number used is "1", whereas the most common letters are a, e, o, and r.<a href="#cite_note-perfect-12">[12]</a>

Users rarely make full use of larger character sets in forming passwords. For example, hacking results obtained from a MySpace phishing scheme in 2006 revealed 34,000 passwords, of which only 8.3% used mixed case, numbers, and symbols.<a href="#cite_note-myspace-passwords-13">[13]</a>

The full strength associated with using the entire ASCII character set (numerals, mixed case letters, and special characters) is only achieved if each possible password is equally likely. This seems to suggest that all passwords must contain characters from each of several character classes, perhaps upper and lower-case letters, numbers, and non-alphanumeric characters. Such a requirement is a pattern in password choice and can be expected to reduce an attacker's "work factor" (in Claude Shannon's terms). This is a reduction in password "strength". A better requirement would be to require a password not to contain any word in an online dictionary, or list of names, or any license plate pattern from any state (in the US) or country (as in the EU). If patterned choices are required, humans are likely to use them in predictable ways, such as capitalizing a letter, adding one or two numbers, and a special character. This predictability means that the increase in password strength is minor when compared to random passwords.

Password Safety Awareness Projects

Google developed Interland teach the kid internet audience safety on internet. On the chapter called Tower Of Tresure it is advised to use unusual names paired with characters like (₺&@#%) with a game.<a href="#cite_note-14">[14]</a>

<div class="mw-heading mw-heading4"><h4 id="NIST_Special_Publication_800-63-2">NIST Special Publication 800-63-2</h4></div>

<a href="NIST" class="mw-redirect" title="NIST">NIST</a> Special Publication 800-63 of June 2004 (revision two) suggested a scheme to approximate the entropy of human-generated passwords:<a href="#cite_note-NIST-4">[4]</a>

Using this scheme, an eight-character human-selected password without uppercase characters and non-alphabetic characters OR with either but of the two character sets is estimated to have eighteen bits of entropy. The NIST publication concedes that at the time of development, little information was available on the real-world selection of passwords. Later research into human-selected password entropy using newly available real-world data has demonstrated that the NIST scheme does not provide a valid metric for entropy estimation of human-selected passwords.<a href="#cite_note-WeirEtAl-15">[15]</a> The June 2017 revision of SP 800-63 (Revision three) drops this approach.<a href="#cite_note-16">[16]</a>

<div class="mw-heading mw-heading3"><h3 id="Usability_and_implementation_considerations">Usability and implementation considerations</h3></div>

Because national keyboard implementations vary, not all 94 ASCII printable characters can be used everywhere. This can present a problem to an international traveler who wished to log into a remote system using a keyboard on a local computer (see article concerned with <a href="List_of_Latin-script_keyboard_layouts" title="List of Latin-script keyboard layouts">keyboard layouts</a>). Many handheld devices, such as <a href="Tablet_computer" title="Tablet computer">tablet computers</a> and <a href="Smart_phone" class="mw-redirect" title="Smart phone">smart phones</a>, require complex shift sequences or keyboard app swapping to enter special characters.

Authentication programs can vary as to the list of allowable password characters. Some do not recognize case differences (e.g., the upper-case "E" is considered equivalent to the lower-case "e"), and others prohibit some of the other symbols. In the past few decades, systems have permitted more characters in passwords, but limitations still exist. Systems also vary as to the maximum length of passwords allowed.

As a practical matter, passwords must be both reasonable and functional for the end user as well as strong enough for the intended purpose. Passwords that are too difficult to remember, an issue compounded by password complexity requirements, may be forgotten and so are more likely to be written on paper, which is a security risk if the paper is improperly secured.<a href="#cite_note-Gartner-17">[17]</a><a href="#cite_note-ACMInteractions2009-18">[18]</a><a href="#cite_note-SP800-63B-19">[19]</a> In contrast, <a href="Bruce_Schneier" title="Bruce Schneier">Bruce Schneier</a> argues that forcing users to remember passwords without assistance can only accommodate weak passwords, thus posing a greater security risk, and most people are good at securing their wallets or purses, which is a "great place" to store a written password.<a href="#cite_note-Schneier-writedown-20">[20]</a>

<div class="mw-heading mw-heading2"><h2 id="Required_bits_of_entropy">Required bits of entropy</h2></div>

The minimum number of bits of entropy needed for a password depends on the <a href="Threat_model" title="Threat model">threat model</a> for the given application. To limit the effectiveness of brute-force attacks, the <a href="National_Institute_of_Standards_and_Technology" title="National Institute of Standards and Technology">National Institute of Standards and Technology</a> recommends system administrators always store passwords with a <a href="Key_derivation_function" title="Key derivation function">key derivation function</a> that performs some <a href="Key_stretching" title="Key stretching">key stretching</a>, as opposed to in <a href="Plaintext" title="Plaintext">plaintext</a> or solely with a <a href="Cryptographic_hash_function" title="Cryptographic hash function">cryptographic hash function</a>.<a href="#cite_note-SP800-63B-19">[19]</a> Other implementation details, such as limiting the number of incorrect password attempts, provide additional protection.<a href="#cite_note-hotsec07-21">[21]</a> If such methods are not used, passwords with more entropy are needed. It also pays to bear in mind that since computing power continually grows, to prevent offline attacks the required number of bits of entropy should also increase over time.

RFC 4086, "Randomness Requirements for Security", published June 2005, presents some example threat models and how to calculate the entropy desired for each one.<a href="#cite_note-22">[22]</a> Their answers vary between 29 bits of entropy needed if only online attacks are expected, and up to 96 bits of entropy needed for important cryptographic keys used in applications like encryption where the password or key needs to be secure for a long period and stretching isn't applicable. A <a href="USENIX" title="USENIX">USENIX</a> conference paper from 2007 wrote that, with the proper safeguards in place, 20 bits of entropy is sufficient to protect against practical online threats.<a href="#cite_note-hotsec07-21">[21]</a> A 2010 <a href="Georgia_Tech_Research_Institute" title="Georgia Tech Research Institute">Georgia Tech Research Institute</a> study based on unstretched keys recommended 12 characters as a minimum length requirement for a random password.<a href="#cite_note-gtri-5">[5]</a><a href="#cite_note-msnbc-23">[23]</a>

The upper end of password entropy recommendations is related to the stringent requirements of choosing keys used in encryption. In 1999, <a href="EFF_DES_cracker" title="EFF DES cracker">an Electronic Frontier Foundation project</a> broke 56-bit <a href="Data_Encryption_Standard" title="Data Encryption Standard">DES</a> encryption in less than a day using specially designed hardware.<a href="#cite_note-EFF-deep-crack-24">[24]</a> In 2002, <a href="Distributed.net" title="Distributed.net">distributed.net</a> cracked a 64-bit key in 4 years, 9 months, and 23 days.<a href="#cite_note-distributed-25">[25]</a> As of October 12, 2011, distributed.net estimates that cracking a 72-bit key using current hardware will take about 45,579 days or 124.8 years.<a href="#cite_note-distributed-72-26">[26]</a> Due to currently understood limitations from fundamental physics, there is no expectation that any <a href="Digital_computer" class="mw-redirect" title="Digital computer">digital computer</a> (or combination) will be capable of breaking 256-bit encryption via a brute-force attack.<a href="#cite_note-schneier-cyptogram-27">[27]</a> Whether or not <a href="Quantum_computers" class="mw-redirect" title="Quantum computers">quantum computers</a> will be able to do so in practice is still unknown, though theoretical analysis suggests such possibilities.<a href="#cite_note-28">[28]</a>

<div class="mw-heading mw-heading2"><h2 id="Guidelines_for_strong_passwords">Guidelines for strong passwords</h2></div>

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<div class="mw-heading mw-heading3"><h3 id="Common_guidelines">Common guidelines</h3></div>

Guidelines for choosing good passwords are typically designed to make passwords harder to discover by intelligent guessing. Common guidelines advocated by proponents of software system security have included:<a href="#cite_note-29">[29]</a><a href="#cite_note-schneier07-30">[30]</a><a href="#cite_note-31">[31]</a><a href="#cite_note-UMD01-32">[32]</a><a href="#cite_note-Bidwell000-33">[33]</a>

<ul><li>Consider a minimum password length of 8<a href="#cite_note-34">[34]</a> characters as a general guide. Both the US and UK cyber security departments recommend long and easily memorable passwords over short complex ones.<a href="#cite_note-35">[35]</a><a href="#cite_note-36">[36]</a></li>

<li>Generate passwords randomly where feasible.</li>

<li>Avoid using the same password twice (e.g. across multiple user accounts and/or software systems).</li>

<li>Avoid character repetition, keyboard patterns, dictionary words, and sequential letters or numbers.</li>

<li>Avoid using information that is or might become publicly associated with the user or the account, such as the user name, ancestors' names, or dates.</li>

<li>Avoid using information that the user's colleagues and/or acquaintances might know to be associated with the user, such as relatives or pet names, romantic links (current or past), and biographical information (e.g. ID numbers, ancestors' names or dates).</li>

<li>Do not use passwords that consist wholly of any simple combination of the aforementioned weak components.</li></ul>

Forcing the inclusion of lowercase letters, uppercase letters, numbers, and symbols in passwords was a common policy but has been found to decrease security, by making it easier to crack. Research has shown how predictable the common use of such symbols are, and the US<a href="#cite_note-SP800-63B-19">[19]</a> and UK<a href="#cite_note-37">[37]</a> government cyber security departments advise against forcing their inclusion in password policy. Complex symbols also make remembering passwords much harder, which increases writing down, password resets, and password reuse, all of which lower rather than improve password security.<a href="#cite_note-ACMInteractions2009-18">[18]</a> The original author of password complexity rules, Bill Burr, has apologized and admits they decrease security, as research has found; this was widely reported in the media in 2017.<a href="#cite_note-tesla.tours-38">[38]</a> Online security researchers<a href="#cite_note-39">[39]</a> and consultants are also supportive of the change<a href="#cite_note-40">[40]</a> in best practice advice on passwords. Despite this, complexity requirements in password policies remain widespread: a 2023 study of 20,000 websites found that about 20% still require passwords to contain characters from at least one character class.<a href="#cite_note-41">[41]</a>

Some guidelines advise against writing passwords down, while others, noting the large numbers of password-protected systems users must access, encourage writing down passwords as long as the written password lists are kept in a safe place, not attached to a monitor or in an unlocked desk drawer.<a href="#cite_note-Schneier-writedown-20">[20]</a> Use of a <a href="Password_manager" title="Password manager">password manager</a> is recommended by the NCSC.<a href="#cite_note-National_Cyber_Security_Centre-42">[42]</a>

The possible character set for a password can be constrained by different websites or by the range of keyboards on which the password must be entered.<a href="#cite_note-43">[43]</a>

<div class="mw-heading mw-heading3"><h3 id="Examples_of_weak_passwords">Examples of weak passwords</h3></div>

<div role="note" class="hatnote navigation-not-searchable">See also: <a href="Password_cracking" title="Password cracking">Password cracking</a> and <a href="List_of_the_most_common_passwords" title="List of the most common passwords">List of the most common passwords</a></div>

As with any security measure, passwords vary in strength; some are weaker than others. For example, the difference in strength between a dictionary word and a word with obfuscation (e.g. letters in the password are substituted by, say, numbers‍—‍‌a common approach) may cost a password-cracking device a few more seconds; this adds little strength. The examples below illustrate various ways weak passwords might be constructed, all of which are based on simple patterns which result in extremely low entropy, allowing them to be tested automatically at high speeds:<a href="#cite_note-perfect-12">[12]</a><div class="paragraphbreak" style="margin-top:0.5em"></div>

<ul><li><a href="Default_password" title="Default password">Default passwords</a> (as supplied by the system vendor and meant to be changed at installation time): password, default, admin, guest, etc. Lists of default passwords are widely available on the internet.</li>

<li>Reused passwords: Passwords should be unique to a particular account. Altering reused passwords, such as changing a few letters or numbers, does not provide sufficient security.</li>

<li>Dictionary words: chameleon, RedSox, sandbags, bunnyhop!, IntenseCrabtree, etc., including words in non-English dictionaries.</li>

<li>Words with numbers appended: password1, deer2000, john1234, etc., can be easily tested automatically with little lost time.</li>

<li><a href="Munged_password" title="Munged password">Munged passwords</a> (words with simple obfuscation): p@ssw0rd, l33th4x0r, g0ldf1sh, etc., can be tested automatically with little additional effort. For example, a domain administrator password compromised in the <a href="DigiNotar" title="DigiNotar">DigiNotar</a> attack was reportedly Pr0d@dm1n.<a href="#cite_note-44">[44]</a></li>

<li>Doubled words: crabcrab, stopstop, treetree, passpass, etc.</li>

<li>Common sequences from a keyboard row: qwerty, 123456, asdfgh, etc. including diagonal or backward sequences (qazplm, ytrewq, etc).</li>

<li>Numeric sequences based on well known numbers such as 911 (<a href="9-1-1" class="mw-redirect" title="9-1-1">9-1-1</a>, <a href="September_11_attacks" title="September 11 attacks">9/11</a>), 314159... (<a href="Pi" title="Pi">pi</a>), 27182... (<a href="E_(mathematical_constant)" title="E (mathematical constant)">e</a>), 112 (<a href="112_(emergency_telephone_number)" title="112 (emergency telephone number)">1-1-2</a>), etc.</li>

<li>Identifiers: jsmith123, 1/1/1970, 555–1234, one's username, etc.</li>

<li>Weak passwords in non-English languages, such as contraseña (Spanish) and ji32k7au4a83 (bopomofo keyboard encoding from Chinese)<a href="#cite_note-45">[45]</a></li>

<li>Anything personally related to an individual: license plate number, Social Security number, current or past telephone numbers, student ID, current address, previous addresses, birthday, sports team, relative or pet names (or nicknames, birthdays, initials, etc.) can easily be tested automatically after a simple investigation of a person's details.</li>

<li>Dates: dates follow a pattern and make your password weak.</li>

<li>Names of well-known locations: New York, Texas, China, London, etc.</li>

<li>Names of brands, celebrities, sports teams, musical groups, TV shows, movies, etc.</li>

<li>Short passwords: Even if a password doesn't have any of the weaknesses listed above, if it is too short, it can be easily cracked.</li></ul>

There are many other ways a password can be weak,<a href="#cite_note-46">[46]</a> corresponding to the strengths of various attack schemes; the core principle is that a password should have high entropy (usually taken to be equivalent to randomness) and not be readily derivable by any "clever" pattern, nor should passwords be mixed with information identifying the user. Online services often provide a restore password function that a hacker can figure out and by doing so bypass a password.

<div class="mw-heading mw-heading3"><h3 id="Rethinking_password_change_guidelines">Rethinking password change guidelines</h3></div>

In the landscape of 2012, as delineated by <a href="William_Cheswick" title="William Cheswick">William Cheswick</a> in an article for ACM magazine, password security predominantly emphasized an alpha-numeric password of eight characters or more. Such a password, it was deduced, could resist ten million attempts per second for a duration of 252 days. However, with the assistance of contemporary GPUs at the time, this period was truncated to just about 9 hours, given a cracking rate of 7 billion attempts per second. A 13-character password was estimated to withstand GPU-computed attempts for over 900,000 years.<a href="#cite_note-47">[47]</a><a href="#cite_note-48">[48]</a>

In the context of 2023 hardware technology, the 2012 standard of an eight-character alpha-numeric password has become vulnerable, succumbing in a few hours. The time needed to crack a 13-character password is reduced to a few years. The current emphasis, thus, has shifted. Password strength is now gauged not just by its complexity but its length, with recommendations leaning towards passwords comprising at least 13-16 characters. This era has also seen the rise of Multi-Factor Authentication (MFA) as a crucial fortification measure. The advent and widespread adoption of password managers have further aided users in cultivating and maintaining an array of strong, unique passwords.<a href="#cite_note-49">[49]</a>

<div class="mw-heading mw-heading2"><h2 id="Password_policy">Password policy</h2></div>

<div role="note" class="hatnote navigation-not-searchable">Main article: <a href="Password_policy" title="Password policy">Password policy</a></div>

A password policy is a guide to choosing satisfactory passwords. It is intended to:

<ul><li>assist users in choosing strong passwords</li>

<li>ensure the passwords are suited to the target population</li>

<li>Provide recommendations for users concerning the handling of their passwords</li>

<li>impose a recommendation to change any password which has been lost or suspected of compromise</li>

<li>use a <a href="Blacklist_(computing)#Usernames_and_passwords" title="Blacklist (computing)">password blacklist</a> to block the use of weak or easily guessed passwords.</li></ul>

Previous password policies used to prescribe the characters which passwords must contain, such as numbers, symbols, or upper/lower case. While this is still in use, it has been debunked as less secure by university research,<a href="#cite_note-50">[50]</a> by the original instigator<a href="#cite_note-51">[51]</a> of this policy, and by the cyber security departments (and other related government security bodies<a href="#cite_note-52">[52]</a>) of USA<a href="#cite_note-SP800-63B-19">[19]</a> and UK.<a href="#cite_note-53">[53]</a> Password complexity rules of enforced symbols were previously used by major platforms such as Google<a href="#cite_note-54">[54]</a> and Facebook,<a href="#cite_note-55">[55]</a> but these have removed the requirement following the discovery that they actually reduced security. This is because the human element is a far greater risk than cracking, and enforced complexity leads most users to highly predictable patterns (number at the end, swap 3 for E, etc.) which helps crack passwords. So password simplicity and length (passphrases) are the new best practice and complexity is discouraged. Forced complexity rules also increase support costs, and user friction and discourage user signups.

Password expiration was in some older password policies but has been debunked<a href="#cite_note-tesla.tours-38">[38]</a> as best practice and is not supported by USA or UK governments, or Microsoft which removed<a href="#cite_note-56">[56]</a> the password expiry feature. Password expiration was previously trying to serve two purposes:<a href="#cite_note-LOPSA-57">[57]</a><div class="paragraphbreak" style="margin-top:0.5em"></div>

<ul><li>If the time to crack a password is estimated to be 100 days, password expiration times fewer than 100 days may help ensure insufficient time for an attacker.</li>

<li>If a password has been compromised, requiring it to be changed regularly may limit the access time for the attacker.</li></ul>

However, password expiration has its drawbacks:<a href="#cite_note-WEB-58">[58]</a><a href="#cite_note-CERIAS-59">[59]</a><div class="paragraphbreak" style="margin-top:0.5em"></div>

<ul><li>Asking users to change passwords frequently encourages simple, weak passwords.</li>

<li>If one has a truly strong password, there is little point in changing it. Changing passwords that are already strong introduces a risk that the new password may be less strong.</li>

<li>A compromised password is likely to be used immediately by an attacker to install a <a href="Backdoor_(computing)" title="Backdoor (computing)">backdoor</a>, often via <a href="Privilege_escalation" title="Privilege escalation">privilege escalation</a>. Once this is accomplished, password changes won't prevent future attackers from accessing them.</li>

<li>Moving from never changing one's password to changing the password on every authenticate attempt (pass or fail attempts) only doubles the number of attempts the attacker must make on average before guessing the password in a brute force attack. One gains much more security by just increasing the password length by one character than changing the password on every use.</li></ul>

<div class="mw-heading mw-heading3"><h3 id="Creating_and_handling_passwords">Creating and handling passwords</h3></div>

The hardest passwords to crack, for a given length and character set, are random character strings; if long enough they resist brute force attacks (because there are many characters) and guessing attacks (due to high entropy). However, such passwords are typically the hardest to remember. The imposition of a requirement for such passwords in a password policy may encourage users to write them down, store them in <a href="Mobile_device" title="Mobile device">mobile devices</a>, or share them with others as a safeguard against memory failure. While some people consider each of these user resorts to increase security risks, others suggest the absurdity of expecting users to remember distinct complex passwords for each of the dozens of accounts they access. For example, in 2005, security expert <a href="Bruce_Schneier" title="Bruce Schneier">Bruce Schneier</a> recommended writing down one's password:

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</style><blockquote class="templatequote">Simply, people can no longer remember passwords good enough to reliably defend against dictionary attacks, and are much more secure if they choose a password too complicated to remember and then write it down. We're all good at securing small pieces of paper. I recommend that people write their passwords down on a small piece of paper, and keep it with their other valuable small pieces of paper: in their wallet.<a href="#cite_note-Schneier-writedown-20">[20]</a></blockquote>

The following measures may increase acceptance of strong password requirements if carefully used:

<ul><li>a training program. Also, updated training for those who fail to follow the password policy (lost passwords, inadequate passwords, etc.).</li>

<li>rewarding strong password users by reducing the rate, or eliminating, the need for password changes (password expiration). The strength of user-chosen passwords can be estimated by automatic programs which inspect and evaluate proposed passwords when setting or changing a password.</li>

<li>displaying to each user the last login date and time in the hope that the user may notice unauthorized access, suggesting a compromised password.</li>

<li>allowing users to reset their passwords via an automatic system, which reduces help desk call volume. However, some systems are themselves insecure; for instance, easily guessed or researched answers to password reset questions bypass the advantages of a strong password system.</li>

<li>using randomly generated passwords that do not allow users to choose their passwords, or at least offering randomly generated passwords as an option.</li></ul>

<div class="mw-heading mw-heading3"><h3 id="Memory_techniques">Memory techniques</h3></div>

Password policies sometimes suggest <a href="Memory_improvement" title="Memory improvement">memory techniques</a> to assist remembering passwords:

<ul><li>mnemonic passwords: Some users develop <a href="Mnemonic" title="Mnemonic">mnemonic</a> phrases and use them to generate more or less random passwords which are nevertheless relatively easy for the user to remember. For instance, the first letter of each word in a memorable phrase. Research estimates the password strength of such passwords to be about 3.7 bits per character, compared to the 6.6 bits for random passwords from ASCII printable characters.<a href="#cite_note-60">[60]</a> Silly ones are possibly more memorable.<a href="#cite_note-61">[61]</a> Another way to make random-appearing passwords more memorable is to use random words (see: <a href="Diceware" title="Diceware">Diceware</a>) or syllables instead of randomly chosen letters.</li>

<li>after-the-fact mnemonics: After the password has been established, invent a mnemonic that fits.<a href="#cite_note-62">[62]</a> It does not have to be reasonable or sensible, only memorable. This allows passwords to be random.</li>

<li>visual representations of passwords: a password is memorized based on a sequence of keys pressed, not the values of the keys themselves, e.g. a sequence !qAsdE#2 represents a <a href="Rhomboid" title="Rhomboid">rhomboid</a> on a US keyboard. The method to produce such passwords is called PsychoPass.<a href="#cite_note-:10-63">[63]</a> Passwords produced by this method are much weaker than their length suggests, since successive keys are not independent and common keyboard sequences are included in password dictionaries. But some improvements can be made.<a href="#cite_note-64">[64]</a><a href="#cite_note-65">[65]</a></li>

<li>password patterns: Any pattern in a password makes guessing (automated or not) easier and reduces an attacker's work factor.

<ul><li>For example, passwords of the following case-insensitive form: consonant, vowel, consonant, consonant, vowel, consonant, number, number (for example pinray45) are called Environ passwords. The pattern of alternating vowel and consonant characters was intended to make passwords more likely to be pronounceable and thus more memorable. Such patterns severely reduce the password's <a href="Information_entropy" class="mw-redirect" title="Information entropy">information entropy</a>, making <a href="Brute_force_attack" class="mw-redirect" title="Brute force attack">brute force</a> password attacks considerably more efficient. In the UK in October 2005, employees of <a href="Departments_of_the_United_Kingdom_Government" class="mw-redirect" title="Departments of the United Kingdom Government">the British government</a> were advised to use passwords in this form.</li></ul></li></ul>

<div class="mw-heading mw-heading2"><h2 id="Password_managers">Password managers</h2></div>

<div role="note" class="hatnote navigation-not-searchable">Main article: <a href="Password_manager" title="Password manager">Password manager</a></div>

A reasonable compromise for using large numbers of passwords is to record them in a password manager program, which include stand-alone applications, web browser extensions, or a manager built into the operating system. A password manager allows the user to use hundreds of different passwords, and only have to remember a single password, the one which opens the encrypted password database.<a href="#cite_note-66">[66]</a> Needless to say, this single password should be strong and well-protected (not recorded anywhere). Most password managers can automatically create strong passwords using a cryptographically secure <a href="Random_password_generator" title="Random password generator">random password generator</a>, as well as calculating the entropy of the generated password. A good password manager will provide resistance against attacks such as <a href="Key_logging" class="mw-redirect" title="Key logging">key logging</a>, clipboard logging and various other memory spying techniques.

<ul><li><a href="Keystroke_logging" title="Keystroke logging">Keystroke logging</a></li>

<li><a href="Passphrase" title="Passphrase">Passphrase</a></li>

<li><a href="Phishing" title="Phishing">Phishing</a></li>

<li><a href="Vulnerability_(computing)" class="mw-redirect" title="Vulnerability (computing)">Vulnerability (computing)</a></li></ul>

<div class="mw-heading mw-heading2"><h2 id="References">References</h2></div>

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</style><div class="reflist">

/* start https://en.wikipedia.org/ */

.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("./mw/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("./mw/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("./mw/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("./mw/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}

/* end https://en.wikipedia.org/ */

</style><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.us-cert.gov/cas/tips/ST04-002.html">"Cyber Security Tip ST04-002"</a>. Choosing and Protecting Passwords. US CERT. 21 May 2009. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20090707141138/http://www.us-cert.gov/cas/tips/ST04-002.html">Archived</a> from the original on July 7, 2009. Retrieved June 20, 2009.</cite>

</li>

<li id="cite_note-2"><a href="#cite_ref-2">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.securityweek.com/why-user-names-and-passwords-are-not-enough">"Why User Names and Passwords Are Not Enough | SecurityWeek.Com"</a>. www.securityweek.com. 31 January 2019. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20201204204759/https://www.securityweek.com/why-user-names-and-passwords-are-not-enough">Archived</a> from the original on 2020-12-04. Retrieved 2020-10-31.</cite>

</li>

<li id="cite_note-3"><a href="#cite_ref-3">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.bbc.com/news/technology-47974583">"Millions using 123456 as password, security study finds"</a>. BBC News. 21 April 2019. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20250426235754/https://www.bbc.com/news/technology-47974583">Archived</a> from the original on 26 April 2025. Retrieved 24 April 2019.</cite>

</li>

<li id="cite_note-NIST-4">^ <a href="#cite_ref-NIST_4-0">a</a> <a href="#cite_ref-NIST_4-1">b</a> <a href="#cite_ref-NIST_4-2">c</a> <a href="#cite_ref-NIST_4-3">d</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20040712152833/http://csrc.nist.gov/publications/nistpubs/800-63/SP800-63v6_3_3.pdf">"SP 800-63 – Electronic Authentication Guideline"</a> (PDF). NIST. Archived from <a rel="nofollow" class="external text" href="http://csrc.nist.gov/publications/nistpubs/800-63/SP800-63v6_3_3.pdf">the original</a> (PDF) on July 12, 2004. Retrieved April 20, 2014.</cite>

</li>

<li id="cite_note-gtri-5">^ <a href="#cite_ref-gtri_5-0">a</a> <a href="#cite_ref-gtri_5-1">b</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.gtri.gatech.edu/casestudy/Teraflop-Troubles-Power-Graphics-Processing-Units-GPUs-Password-Security-System">"Teraflop Troubles: The Power of Graphics Processing Units May Threaten the World's Password Security System"</a>. <a href="Georgia_Tech_Research_Institute" title="Georgia Tech Research Institute">Georgia Tech Research Institute</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20101230063449/http://www.gtri.gatech.edu/casestudy/Teraflop-Troubles-Power-Graphics-Processing-Units-GPUs-Password-Security-System">Archived</a> from the original on 2010-12-30. Retrieved 2010-11-07.</cite>

</li>

/* start https://en.wikipedia.org/ */

.mw-parser-output .citation{word-wrap:break-word}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}

/* end https://en.wikipedia.org/ */

</style><a rel="nofollow" class="external text" href="https://worldwide.espacenet.com/textdoc?DB=EPODOC&IDX=US7929707">US patent 7929707</a>, Andrey V. Belenko, "Use of graphics processors as parallel math co-processors for password recovery", issued 2011-04-19, assigned to Elcomsoft Co. Ltd.<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Apatent&rft.number=7929707&rft.cc=US&rft.title=Use+of+graphics+processors+as+parallel+math+co-processors+for+password+recovery&rft.inventor=Andrey+V.+Belenko&rft.assignee=Elcomsoft+Co.+Ltd.&rft.date=2011-04-19">

</li>

<li id="cite_note-elcomsoft-7"><a href="#cite_ref-elcomsoft_7-0">^</a> <a rel="nofollow" class="external text" href="http://www.elcomsoft.com/eprb.html#gpu">Elcomsoft.com</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20061017173506/http://www.elcomsoft.com/eprb.html">Archived</a> 2006-10-17 at the <a href="Wayback_Machine" title="Wayback Machine">Wayback Machine</a>, <a href="ElcomSoft" title="ElcomSoft">ElcomSoft</a> Password Recovery Speed table, <a href="NTLM" title="NTLM">NTLM</a> passwords, <a href="Nvidia_Tesla" title="Nvidia Tesla">Nvidia Tesla</a> S1070 GPU, accessed 2011-02-01

</li>

<li id="cite_note-8"><a href="#cite_ref-8">^</a> <a rel="nofollow" class="external text" href="http://www.elcomsoft.com/ewsa.html">Elcomsoft Wireless Security Auditor, HD5970 GPU</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20110219131825/http://www.elcomsoft.com/ewsa.html">Archived</a> 2011-02-19 at the <a href="Wayback_Machine" title="Wayback Machine">Wayback Machine</a> accessed 2011-02-11

</li>

<li id="cite_note-9"><a href="#cite_ref-9">^</a> <cite id="CITEREFJames_Massey1994" class="citation conference cs1"><a href="James_Massey" title="James Massey">James Massey</a> (1994). <a rel="nofollow" class="external text" href="http://www.isiweb.ee.ethz.ch/archive/massey_pub/pdf/BI633.pdf">"Guessing and entropy"</a> (PDF). Proceedings of 1994 IEEE International Symposium on Information Theory. IEEE. p. 204. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20140101065020/http://www.isiweb.ee.ethz.ch/archive/massey_pub/pdf/BI633.pdf">Archived</a> (PDF) from the original on 2014-01-01. Retrieved 2019-07-12.</cite>

</li>

<li id="cite_note-10"><a href="#cite_ref-10">^</a> Schneier, B: Applied Cryptography, 2e, page 233 ff. John Wiley and Sons.

</li>

<li id="cite_note-11"><a href="#cite_ref-11">^</a> <cite id="ACM_978-1-59593-654-7/07/0005." class="citation book cs1">Florencio, Dinei; Herley, Cormac (May 8, 2007). <a rel="nofollow" class="external text" href="http://research.microsoft.com/pubs/74164/www2007.pdf">"A large-scale study of web password habits"</a> (PDF). Proceedings of the 16th international conference on World Wide Web. p. 657. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1145%2F1242572.1242661">10.1145/1242572.1242661</a>. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>9781595936547</bdi>. <a href="S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:10648989">10648989</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20150327031521/http://research.microsoft.com/pubs/74164/www2007.pdf">Archived</a> (PDF) from the original on March 27, 2015.</cite>

</li>

<li id="cite_note-perfect-12">^ <a href="#cite_ref-perfect_12-0">a</a> <a href="#cite_ref-perfect_12-1">b</a> <cite id="CITEREFBurnett2006" class="citation book cs1">Burnett, Mark (2006). <a href="Dave_Kleiman" title="Dave Kleiman">Kleiman, Dave</a> (ed.). Perfect Passwords. Rockland, Massachusetts: Syngress Publishing. p. 181. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>978-1-59749-041-2</bdi>.</cite>

</li>

<li id="cite_note-myspace-passwords-13"><a href="#cite_ref-myspace-passwords_13-0">^</a> <cite id="CITEREFBruce_Schneier2006" class="citation news cs1">Bruce Schneier (December 14, 2006). <a rel="nofollow" class="external text" href="http://archive.wired.com/politics/security/commentary/securitymatters/2006/12/72300?currentPage=all">"MySpace Passwords aren't so Dumb"</a>. Wired Magazine. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20140521031354/http://archive.wired.com/politics/security/commentary/securitymatters/2006/12/72300?currentPage=all">Archived</a> from the original on May 21, 2014. Retrieved April 11, 2008.</cite>

</li>

<li id="cite_note-14"><a href="#cite_ref-14">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://beinternetawesome.withgoogle.com/en_us/interland/">"Play Interland - Be Internet Awesome"</a>. Play Interland - Be Internet Awesome. Retrieved 2024-09-10.</cite>

</li>

<li id="cite_note-WeirEtAl-15"><a href="#cite_ref-WeirEtAl_15-0">^</a> <cite id="CITEREFMatt_WeirSusdhir_AggarwalMichael_CollinsHenry_Stern2010" class="citation web cs1">Matt Weir; Susdhir Aggarwal; Michael Collins; Henry Stern (7 October 2010). <a rel="nofollow" class="external text" href="http://reusablesec.blogspot.com/2010/10/new-paper-on-password-security-metrics.html">"Testing Metrics for Password Creation Policies by Attacking Large Sets of Revealed Passwords"</a> (PDF). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20120706124704/http://reusablesec.blogspot.com/2010/10/new-paper-on-password-security-metrics.html">Archived</a> from the original on July 6, 2012. Retrieved March 21, 2012.</cite>

</li>

<li id="cite_note-16"><a href="#cite_ref-16">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://pages.nist.gov/800-63-3">"SP 800-63-3 – Digital Identity Guidelines"</a> (PDF). NIST. June 2017. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20170806142240/https://pages.nist.gov/800-63-3/">Archived</a> from the original on August 6, 2017. Retrieved August 6, 2017.</cite>

</li>

<li id="cite_note-Gartner-17"><a href="#cite_ref-Gartner_17-0">^</a> <cite id="CITEREFA._Allan" class="citation web cs1">A. Allan. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20060427032938/http://www.indevis.de/dokumente/gartner_passwords_breakpoint.pdf">"Passwords are Near the Breaking Point"</a> (PDF). Gartner. Archived from <a rel="nofollow" class="external text" href="http://www.indevis.de/dokumente/gartner_passwords_breakpoint.pdf">the original</a> (PDF) on April 27, 2006. Retrieved April 10, 2008.</cite>

</li>

<li id="cite_note-ACMInteractions2009-18">^ <a href="#cite_ref-ACMInteractions2009_18-0">a</a> <a href="#cite_ref-ACMInteractions2009_18-1">b</a> <cite id="CITEREFNorman2009" class="citation journal cs1">Norman, Donald (2009-11-01). "When Security Gets in the Way". <a href="ACM_Interactions" title="ACM Interactions">ACM Interactions</a>. 16 (6): 60–63. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1145%2F1620693.1620708">10.1145/1620693.1620708</a>. <q>Passwords illustrate several of the difficulties with current methods of enforcing security. Passwords are the least expensive mechanism known for securing systems. But onerous password requirements reduce security and increase costs. They reduce security because many people either use trivial algorithms to generate memorable passwords or write down their passwords and store them in easily discoverable places. They increase costs because help desks must be staffed to handle the large number of users who have forgotten their passwords and can no longer log in. These requirements keep out the good guys without deterring the bad guys.</q></cite>

</li>

<li id="cite_note-SP800-63B-19">^ <a href="#cite_ref-SP800-63B_19-0">a</a> <a href="#cite_ref-SP800-63B_19-1">b</a> <a href="#cite_ref-SP800-63B_19-2">c</a> <a href="#cite_ref-SP800-63B_19-3">d</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://pages.nist.gov/800-63-3/sp800-63b.html#a3-complexity">"Special Publication 800-63B - Digital Identity Guidelines"</a>. <a href="National_Institute_for_Standards_and_Technology" class="mw-redirect" title="National Institute for Standards and Technology">National Institute for Standards and Technology</a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.6028%2FNIST.SP.800-63b">10.6028/NIST.SP.800-63b</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20170421121654/https://pages.nist.gov/800-63-3/sp800-63b.html#a3-complexity">Archived</a> from the original on 21 April 2017. Retrieved 17 May 2021.</cite>

</li>

<li id="cite_note-Schneier-writedown-20">^ <a href="#cite_ref-Schneier-writedown_20-0">a</a> <a href="#cite_ref-Schneier-writedown_20-1">b</a> <a href="#cite_ref-Schneier-writedown_20-2">c</a> <cite id="CITEREFBruce_Schneier2005" class="citation web cs1">Bruce Schneier (17 June 2005). <a rel="nofollow" class="external text" href="http://www.schneier.com/blog/archives/2005/06/write_down_your.html">"Schneier on Security"</a>. Write Down Your Password. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20080413032636/http://www.schneier.com/blog/archives/2005/06/write_down_your.html">Archived</a> from the original on April 13, 2008. Retrieved April 10, 2008.</cite>

</li>

<li id="cite_note-hotsec07-21">^ <a href="#cite_ref-hotsec07_21-0">a</a> <a href="#cite_ref-hotsec07_21-1">b</a> <cite id="CITEREFFlorêncioHerleyCoskun2007" class="citation conference cs1">Florêncio, Dinei; Herley, Cormac; Coskun, Baris (2007). <a rel="nofollow" class="external text" href="https://www.usenix.org/legacy/event/hotsec07/tech/full_papers/florencio/florencio.pdf">Do Strong Web Passwords Accomplish Anything?</a> (PDF). <a rel="nofollow" class="external text" href="https://www.usenix.org/legacy/events/hotsec07/">2nd USENIX Workshop on Hot Topics in Security</a>. Boston, Massachusetts.</cite>

</li>

<li id="cite_note-22"><a href="#cite_ref-22">^</a> <cite class="citation cs1"><a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc4086">Randomness Requirements for Security</a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.17487%2FRFC4086">10.17487/RFC4086</a>. <a href="Request_for_Comments" title="Request for Comments">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc4086">4086</a>.</cite>

</li>

<li id="cite_note-msnbc-23"><a href="#cite_ref-msnbc_23-0">^</a> <cite class="citation news cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20130711022009/http://www.nbcnews.com/id/38771772/">"Want to deter hackers? Make your password longer"</a>. <a href="NBC_News" title="NBC News">NBC News</a>. 2010-08-19. Archived from <a rel="nofollow" class="external text" href="http://www.nbcnews.com/id/38771772">the original</a> on July 11, 2013. Retrieved 2010-11-07.</cite>

</li>

<li id="cite_note-EFF-deep-crack-24"><a href="#cite_ref-EFF-deep-crack_24-0">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20100101001853/http://w2.eff.org/Privacy/Crypto/Crypto_misc/DESCracker/HTML/19980716_eff_descracker_pressrel.html">"EFF DES Cracker machine brings honesty to crypto debate"</a>. EFF. Archived from <a rel="nofollow" class="external text" href="https://w2.eff.org/Privacy/Crypto/Crypto_misc/DESCracker/HTML/19980716_eff_descracker_pressrel.html">the original</a> on January 1, 2010. Retrieved March 27, 2008.</cite>

</li>

<li id="cite_note-distributed-25"><a href="#cite_ref-distributed_25-0">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20130910051812/http://stats.distributed.net/projects.php?project_id=5">"64-bit key project status"</a>. Distributed.net. Archived from <a rel="nofollow" class="external text" href="http://stats.distributed.net/projects.php?project_id=5">the original</a> on September 10, 2013. Retrieved March 27, 2008.</cite>

</li>

<li id="cite_note-distributed-72-26"><a href="#cite_ref-distributed-72_26-0">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://stats.distributed.net/projects.php?project_id=8">"72-bit key project status"</a>. Distributed.net. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20181009090806/http://stats.distributed.net/projects.php?project_id=8">Archived</a> from the original on October 9, 2018. Retrieved October 12, 2011.</cite>

</li>

<li id="cite_note-schneier-cyptogram-27"><a href="#cite_ref-schneier-cyptogram_27-0">^</a> <cite id="CITEREFBruce_Schneier" class="citation web cs1">Bruce Schneier. <a rel="nofollow" class="external text" href="http://www.schneier.com/crypto-gram-9902.html">"Snakeoil: Warning Sign #5: Ridiculous key lengths"</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20080418225248/http://www.schneier.com/crypto-gram-9902.html">Archived</a> from the original on April 18, 2008. Retrieved March 27, 2008.</cite>

</li>

<li id="cite_note-28"><a href="#cite_ref-28">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://stackoverflow.com/questions/2768807/quantum-computing-and-encryption-breaking">"Quantum Computing and Encryption Breaking"</a>. Stack Overflow. 2011-05-27. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20130521043721/http://stackoverflow.com/questions/2768807/quantum-computing-and-encryption-breaking">Archived</a> from the original on 2013-05-21. Retrieved 2013-03-17.</cite>

</li>

<li id="cite_note-29"><a href="#cite_ref-29">^</a> Microsoft Corporation, <a rel="nofollow" class="external text" href="http://www.microsoft.com/protect/yourself/password/create.mspx">Strong passwords: How to create and use them</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20080101132156/http://www.microsoft.com/protect/yourself/password/create.mspx">Archived</a> 2008-01-01 at the <a href="Wayback_Machine" title="Wayback Machine">Wayback Machine</a>

</li>

<li id="cite_note-schneier07-30"><a href="#cite_ref-schneier07_30-0">^</a> Bruce Schneier, <a rel="nofollow" class="external text" href="http://www.schneier.com/blog/archives/2007/01/choosing_secure.html">Choosing Secure Passwords</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20080223002450/http://www.schneier.com/blog/archives/2007/01/choosing_secure.html">Archived</a> 2008-02-23 at the <a href="Wayback_Machine" title="Wayback Machine">Wayback Machine</a>

</li>

<li id="cite_note-31"><a href="#cite_ref-31">^</a> Google, Inc., <a rel="nofollow" class="external text" href="https://www.google.com/accounts/PasswordHelp">How safe is your password?</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20080222225549/https://www.google.com/accounts/PasswordHelp">Archived</a> 2008-02-22 at the <a href="Wayback_Machine" title="Wayback Machine">Wayback Machine</a>

</li>

<li id="cite_note-UMD01-32"><a href="#cite_ref-UMD01_32-0">^</a> University of Maryland, <a rel="nofollow" class="external text" href="http://www.cs.umd.edu/faq/Passwords.shtml">Choosing a Good Password</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20140614022254/http://www.cs.umd.edu/faq/Passwords.shtml">Archived</a> 2014-06-14 at the <a href="Wayback_Machine" title="Wayback Machine">Wayback Machine</a>

</li>

<li id="cite_note-Bidwell000-33"><a href="#cite_ref-Bidwell000_33-0">^</a> <cite id="CITEREFBidwell2002" class="citation book cs1">Bidwell, Teri (2002). <a rel="nofollow" class="external text" href="https://archive.org/details/hackproofingyour0000bidw">Hack Proofing Your Identity in the Information Age</a>. Syngress Publishing. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>978-1-931836-51-7</bdi>.</cite>

</li>

<li id="cite_note-34"><a href="#cite_ref-34">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://stealthbits.com/blog/nist-password-guidelines/#:~:text=NIST%20now%20requires%20that%20all,characters%20as%20a%20maximum%20length.">"NIST PASSWORD GUIDELINES IN 2020"</a>. Stealthbits. 18 August 2020. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20210517103234/https://stealthbits.com/blog/nist-password-guidelines/#:~:text=NIST%20now%20requires%20that%20all,characters%20as%20a%20maximum%20length.">Archived</a> from the original on 17 May 2021. Retrieved 17 May 2021.</cite>

</li>

<li id="cite_note-35"><a href="#cite_ref-35">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.ncsc.gov.uk/collection/passwords/updating-your-approach">"Password Policy - Updating your approach"</a>. UK National Cyber Security Centre. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20210517100330/https://www.ncsc.gov.uk/collection/passwords/updating-your-approach">Archived</a> from the original on 17 May 2021. Retrieved 17 May 2021.</cite>

</li>

<li id="cite_note-36"><a href="#cite_ref-36">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.cisa.gov/news-events/news/choosing-and-protecting-passwords">"Choosing and Protecting Passwords"</a>. US Cybersecurity & Infrastructure Security Agency (CISA). 2019-11-18. Retrieved 2023-10-10.</cite>

</li>

<li id="cite_note-37"><a href="#cite_ref-37">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.ncsc.gov.uk/collection/passwords/updating-your-approach">"Password administration for system owners"</a>. UK National Cyber Security Centre. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20210517100330/https://www.ncsc.gov.uk/collection/passwords/updating-your-approach">Archived</a> from the original on 17 May 2021. Retrieved 17 May 2021.</cite>

</li>

<li id="cite_note-tesla.tours-38">^ <a href="#cite_ref-tesla.tours_38-0">a</a> <a href="#cite_ref-tesla.tours_38-1">b</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.tesla.tours/campaigns/password-rules#h.8jxqtu8i7po2">"Password Rules - Founder of Password Complexity Says SORRY!"</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20210517094441/https://www.tesla.tours/campaigns/password-rules#h.8jxqtu8i7po2">Archived</a> from the original on 17 May 2021. Retrieved 17 May 2021.</cite>

</li>

<li id="cite_note-39"><a href="#cite_ref-39">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://cups.cs.cmu.edu/passwords.html">"CyLab Usable Privacy and Security Laboratory (CUPS)"</a>. Carnegie Mellon University (USA). Retrieved 17 May 2021.</cite>

</li>

<li id="cite_note-40"><a href="#cite_ref-40">^</a> <cite id="CITEREFBruce2017" class="citation web cs1">Bruce, Schneier (10 October 2017). <a rel="nofollow" class="external text" href="https://www.schneier.com/blog/archives/2017/10/changes_in_pass.html">"Changes in Password Best Practices"</a>. Schneier on Security. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20210513055046/https://www.schneier.com/blog/archives/2017/10/changes_in_pass.html">Archived</a> from the original on 13 May 2021. Retrieved 17 May 2021.</cite>

</li>

<li id="cite_note-41"><a href="#cite_ref-41">^</a> <cite id="CITEREFAlroomiLi2023" class="citation conference cs1">Alroomi, Suood; Li, Frank (2023). <a rel="nofollow" class="external text" href="https://arxiv.org/pdf/2309.03384">Measuring Website Password Creation Policies At Scale</a> (PDF). Proceedings of the 2023 ACM SIGSAC Conference on Computer and Communications Security. Association for Computing Machinery. pp. 3108–3122. <a href="ArXiv_(identifier)" class="mw-redirect" title="ArXiv (identifier)">arXiv</a>:<a rel="nofollow" class="external text" href="https://arxiv.org/abs/2309.03384">2309.03384</a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1145%2F3576915.3623156">10.1145/3576915.3623156</a>. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>9798400700507</bdi>.</cite>

</li>

<li id="cite_note-National_Cyber_Security_Centre-42"><a href="#cite_ref-National_Cyber_Security_Centre_42-0">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.ncsc.gov.uk/blog-post/what-does-ncsc-think-password-managers">"What does the NCSC think of password managers?"</a>. www.ncsc.gov.uk. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20190305053922/https://www.ncsc.gov.uk/blog-post/what-does-ncsc-think-password-managers">Archived</a> from the original on 2019-03-05.</cite>

</li>

<li id="cite_note-43"><a href="#cite_ref-43">^</a> e.g. for a keyboard with only 17 nonalphanumeric characters, see one for a BlackBerry phone in <a rel="nofollow" class="external text" href="http://www.hardwaresecrets.com/fullimage.php?image=18705">an enlarged image</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20110406121058/http://www.hardwaresecrets.com/fullimage.php?image=18705">Archived</a> 2011-04-06 at the <a href="Wayback_Machine" title="Wayback Machine">Wayback Machine</a> in support of <a rel="nofollow" class="external text" href="http://www.hardwaresecrets.com/article/795/2">Sandy Berger, BlackBerry Tour 9630 (Verizon) Cell Phone Review, in Hardware Secrets (August 31, 2009)</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20110406121111/http://www.hardwaresecrets.com/article/795/2">Archived</a> April 6, 2011, at the <a href="Wayback_Machine" title="Wayback Machine">Wayback Machine</a>, both as accessed January 19, 2010. That some websites don’t allow nonalphanumerics is indicated by <a rel="nofollow" class="external text" href="http://forums.theregister.co.uk/post/527230">Kanhef, Idiots, For Different Reasons (June 30, 2009) (topic post)</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20110406121058/http://forums.theregister.co.uk/post/527230">Archived</a> April 6, 2011, at the <a href="Wayback_Machine" title="Wayback Machine">Wayback Machine</a>, as accessed January 20, 2010.

</li>

<li id="cite_note-44"><a href="#cite_ref-44">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://thehackernews.com/2011/09/comodohacker-responsible-for-diginotar.html">"ComodoHacker responsible for DigiNotar Attack – Hacking News"</a>. Thehackernews.com. 2011-09-06. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20130517204022/http://thehackernews.com/2011/09/comodohacker-responsible-for-diginotar.html">Archived</a> from the original on 2013-05-17. Retrieved 2013-03-17.</cite>

</li>

<li id="cite_note-45"><a href="#cite_ref-45">^</a> <cite id="CITEREFDave_Basner2019" class="citation news cs1">Dave Basner (8 March 2019). <a rel="nofollow" class="external text" href="https://www.iheart.com/content/2019-03-08-heres-why-ji32k7au4a83-is-a-surprisingly-common-password/">"Here's Why 'ji32k7au4a83' Is A Surprisingly Common Password"</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20190325154357/https://www.iheart.com/content/2019-03-08-heres-why-ji32k7au4a83-is-a-surprisingly-common-password/">Archived</a> from the original on 25 March 2019. Retrieved 25 March 2019.</cite>

</li>

<li id="cite_note-46"><a href="#cite_ref-46">^</a> Bidwell, p. 87

</li>

<li id="cite_note-47"><a href="#cite_ref-47">^</a> <cite id="CITEREFWilliam2012" class="citation web cs1">William, Cheswick (2012-12-31). <a rel="nofollow" class="external text" href="https://queue.acm.org/detail.cfm?id=2422416">"HTML version - Rethinking Passwords"</a>. <a href="Association_for_Computing_Machinery" title="Association for Computing Machinery">Association for Computing Machinery</a> (ACM). <a rel="nofollow" class="external text" href="https://archive.today/20191103172648/https://queue.acm.org/detail.cfm?id=2422416">Archived</a> from the original on 2019-11-03. Retrieved 2019-11-03.</cite>

</li>

<li id="cite_note-48"><a href="#cite_ref-48">^</a> <cite id="CITEREFWilliam2012" class="citation journal cs1">William, Cheswick (2012-12-31). <a rel="nofollow" class="external text" href="https://doi.org/10.1145%2F2405116.2422416">"ACM Digital Library - Rethinking Passwords"</a>. Queue. 10 (12): 50–56. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1145%2F2405116.2422416">10.1145/2405116.2422416</a>.</cite>

</li>

<li id="cite_note-49"><a href="#cite_ref-49">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://bitwarden.com/resources/the-state-of-password-security/">"The State of Password Security 2023 Report | Bitwarden Resources"</a>. Bitwarden. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20231011012838/https://bitwarden.com/resources/the-state-of-password-security/">Archived</a> from the original on 2023-10-11. Retrieved 2023-09-24.</cite>

</li>

<li id="cite_note-50"><a href="#cite_ref-50">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.andrew.cmu.edu/user/nicolasc/publications/Tan-CCS20.pdf">"Practical Recommendations for Stronger, More Usable Passwords Combining Minimum-strength, Minimum-length, and Blocklist Requirements"</a> (PDF). Carnegie Mellon University. Retrieved 17 May 2021.</cite>

</li>

<li id="cite_note-51"><a href="#cite_ref-51">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.tesla.tours/campaigns/password-rules#h.8jxqtu8i7po2">"Bill Burr, Founder of Password complexity rules says SORRY!"</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20210517094441/https://www.tesla.tours/campaigns/password-rules#h.8jxqtu8i7po2">Archived</a> from the original on 17 May 2021. Retrieved 17 May 2021.</cite>

</li>

<li id="cite_note-52"><a href="#cite_ref-52">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20210504043052/https://ico.org.uk/for-organisations/guide-to-data-protection/guide-to-the-general-data-protection-regulation-gdpr/security/passwords-in-online-services/#whatrequirementsshould">"Passwords in online services"</a>. UK Information Commissioner's Office (ICO). Archived from <a rel="nofollow" class="external text" href="https://ico.org.uk/for-organisations/guide-to-data-protection/guide-to-the-general-data-protection-regulation-gdpr/security/passwords-in-online-services/#whatrequirementsshould">the original</a> on 4 May 2021. Retrieved 17 May 2021.</cite>

</li>

<li id="cite_note-53"><a href="#cite_ref-53">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/458857/Password_guidance_-_simplifying_your_approach.pdf">"Password guidance"</a> (PDF). Cyber Security, UK Government Communications Headquarters. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20210517094441/https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/458857/Password_guidance_-_simplifying_your_approach.pdf">Archived</a> (PDF) from the original on 17 May 2021. Retrieved 17 May 2021.</cite>

</li>

<li id="cite_note-54"><a href="#cite_ref-54">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://support.google.com/accounts/answer/32040?hl=en#:~:text=Meet%20password%20requirements,accented%20characters%20aren't%20supported.">"Create a Strong Password"</a>. Google Inc. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20210517094441/https://support.google.com/accounts/answer/32040?hl=en#:~:text=Meet%20password%20requirements,accented%20characters%20aren't%20supported.">Archived</a> from the original on 17 May 2021. Retrieved 17 May 2021.</cite>

</li>

<li id="cite_note-55"><a href="#cite_ref-55">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.facebook.com/help/1573156092981768/">"Login and Password Help"</a>. FaceBook Inc. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20210517094439/https://www.facebook.com/help/1573156092981768/">Archived</a> from the original on 17 May 2021. Retrieved 17 May 2021.</cite>

</li>

<li id="cite_note-56"><a href="#cite_ref-56">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://docs.microsoft.com/en-au/archive/blogs/secguide/security-baseline-final-for-windows-10-v1903-and-windows-server-v1903">"Security baseline (FINAL) for Windows 10 v1903 and Windows Server v1903"</a>. Microsoft. 23 May 2019. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20210517094440/https://docs.microsoft.com/en-au/archive/blogs/secguide/security-baseline-final-for-windows-10-v1903-and-windows-server-v1903">Archived</a> from the original on 17 May 2021. Retrieved 17 May 2021.</cite>

</li>

<li id="cite_note-LOPSA-57"><a href="#cite_ref-LOPSA_57-0">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20081012063918/http://lopsa.org/node/295">"In Defense of Password Expiration"</a>. League of Professional Systems Administrators. Archived from <a rel="nofollow" class="external text" href="http://lopsa.org/node/295">the original</a> on October 12, 2008. Retrieved April 14, 2008.</cite>

</li>

<cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20160817223701/https://www.cesg.gov.uk/articles/problems-forcing-regular-password-expiry">"The problems with forcing regular password expiry"</a>. IA Matters. CESG: the Information Security Arm of GCHQ. 15 April 2016. Archived from <a rel="nofollow" class="external text" href="https://www.cesg.gov.uk/articles/problems-forcing-regular-password-expiry">the original</a> on 17 August 2016. Retrieved 5 Aug 2016.</cite>

</li>

<li id="cite_note-CERIAS-59"><a href="#cite_ref-CERIAS_59-0">^</a> <cite id="CITEREFEugene_Spafford" class="citation web cs1">Eugene Spafford. <a rel="nofollow" class="external text" href="http://www.cerias.purdue.edu/weblogs/spaf/general/post-30/">"Security Myths and Passwords"</a>. The Center for Education and Research in Information Assurance and Security. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20080411123000/http://www.cerias.purdue.edu/weblogs/spaf/general/post-30/">Archived</a> from the original on April 11, 2008. Retrieved April 14, 2008.</cite>

</li>

<li id="cite_note-60"><a href="#cite_ref-60">^</a> <cite id="CITEREFJohannes_KieselBenno_SteinStefan_Lucks2017" class="citation conference cs1">Johannes Kiesel; Benno Stein; Stefan Lucks (2017). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20170330174637/https://www.internetsociety.org/sites/default/files/ndss2017_03A-4_Kiesel_paper.pdf">"A Large-scale Analysis of the Mnemonic Password Advice"</a> (PDF). Proceedings of the 24th Annual Network and Distributed System Security Symposium (NDSS 17). Internet Society. Archived from <a rel="nofollow" class="external text" href="https://www.internetsociety.org/sites/default/files/ndss2017_03A-4_Kiesel_paper.pdf">the original</a> (PDF) on 2017-03-30. Retrieved 2017-03-30.</cite>

</li>

<li id="cite_note-61"><a href="#cite_ref-61">^</a> <a rel="nofollow" class="external text" href="http://uc.iupui.edu/uploadedFiles/Learning_Center_Site/Mnemonic%20Devices.pdf">Mnemonic Devices (Indianapolis, Ind.: Bepko Learning Ctr., University College)</a>, as accessed January 19, 2010 <a rel="nofollow" class="external text" href="https://web.archive.org/web/20100610000727/http://uc.iupui.edu/uploadedFiles/Learning_Center_Site/Mnemonic%20Devices.pdf">Archived</a> June 10, 2010, at the <a href="Wayback_Machine" title="Wayback Machine">Wayback Machine</a>

</li>

<li id="cite_note-62"><a href="#cite_ref-62">^</a> <a rel="nofollow" class="external text" href="http://changingminds.org/techniques/memory/remembering_passwords.htm">Remembering Passwords (ChangingMinds.org)</a> <a rel="nofollow" class="external text" href="http://archive.wikiwix.com/cache/20100121181700/http://changingminds.org/techniques/memory/remembering_passwords.htm">Archived</a> 2010-01-21 at Wikiwix, as accessed January 19, 2010

</li>

<li id="cite_note-:10-63"><a href="#cite_ref-:10_63-0">^</a> <cite id="CITEREFCipressoGaggioliSerinoCipresso2012" class="citation journal cs1">Cipresso, P; Gaggioli, A; Serino, S; Cipresso, S; Riva, G (2012). <a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3846346">"How to Create Memorizable and Strong Passwords"</a>. J Med Internet Res. 14 (1): e10. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.2196%2Fjmir.1906">10.2196/jmir.1906</a>. <a href="PMC_(identifier)" class="mw-redirect" title="PMC (identifier)">PMC</a> <a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3846346">3846346</a>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/22233980">22233980</a>.</cite>

</li>

<li id="cite_note-64"><a href="#cite_ref-64">^</a> <cite id="CITEREFBrumenHeričkoRozmanHölbl2013" class="citation journal cs1">Brumen, B; Heričko, M; Rozman, I; Hölbl, M (2013). <a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3742392">"Security analysis and improvements to the PsychoPass method"</a>. J Med Internet Res. 15 (8): e161. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.2196%2Fjmir.2366">10.2196/jmir.2366</a>. <a href="PMC_(identifier)" class="mw-redirect" title="PMC (identifier)">PMC</a> <a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3742392">3742392</a>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/23942458">23942458</a>.</cite>

</li>

<li id="cite_note-65"><a href="#cite_ref-65">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://blogs.dropbox.com/tech/2012/04/zxcvbn-realistic-password-strength-estimation/">"zxcvbn: realistic password strength estimation"</a>. Dropbox Tech Blog. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20150405131234/https://blogs.dropbox.com/tech/2012/04/zxcvbn-realistic-password-strength-estimation/">Archived</a> from the original on 2015-04-05.</cite>

</li>

<li id="cite_note-66"><a href="#cite_ref-66">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www2.eecs.berkeley.edu/Pubs/TechRpts/2014/EECS-2014-138.html">"The Emperor's New Password Manager: Security Analysis of Web-based Password Managers | EECS at UC Berkeley"</a>. www2.eecs.berkeley.edu. Retrieved 2023-10-01.</cite>

</li>

</ol></div></div>

<div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2></div>

<ul><li><a rel="nofollow" class="external text" href="https://tools.ietf.org/html/rfc4086">RFC 4086: Randomness Requirements for Security</a></li>

<li><a rel="nofollow" class="external text" href="https://web.archive.org/web/20160416035311/http://www.architectingsecurity.com/2010/09/11/password-patterns/">Password Patterns:The next generation dictionary attacks</a></li></ul></div><div><div class="zim-footer">

This article is issued from <a class="external text" title="Last edited on 2025-08-07" href="https://en.wikipedia.org/wiki/?title=Password_strength&oldid=1304724053">Wikipedia</a>. The text is available under <a class="external text" href="https://creativecommons.org/licenses/by-sa/4.0/deed.en">Creative Commons Attribution-Share Alike 4.0</a> unless otherwise noted. Additional terms may apply for the media files.

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