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<title>Symmetric-key algorithm</title>

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<span id="openzim-page-title" class="mw-page-title-main"><span class="mw-page-title-main">Symmetric-key algorithm</span></span>

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<p><b>Symmetric-key algorithms</b><sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>a<span class="cite-bracket">]</span></a></sup> are <a href="Algorithm" title="Algorithm">algorithms</a> for <a href="Cryptography" title="Cryptography">cryptography</a> that use the same <a href="Key_(cryptography)" title="Key (cryptography)">cryptographic keys</a> for both the encryption of <a href="Plaintext" title="Plaintext">plaintext</a> and the decryption of <a href="Ciphertext" title="Ciphertext">ciphertext</a>. The keys may be identical, or there may be a simple transformation to go between the two keys.<sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> The keys, in practice, represent a <a href="Shared_secret" title="Shared secret">shared secret</a> between two or more parties that can be used to maintain a private information link.<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> The requirement that both parties have access to the secret key is one of the main drawbacks of <a href="Symmetric" class="mw-redirect" title="Symmetric">symmetric</a>-key encryption, in comparison to <a href="Public_key_encryption" class="mw-redirect" title="Public key encryption">public-key encryption</a> (also known as asymmetric-key encryption).<sup id="cite_ref-4" class="reference"><a href="#cite_note-4"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> However, symmetric-key encryption algorithms are usually better for bulk encryption. With exception of the <a href="One-time_pad" title="One-time pad">one-time pad</a> they have a smaller key size, which means less storage space and faster transmission. Due to this, asymmetric-key encryption is often used to exchange the secret key for symmetric-key encryption.<sup id="cite_ref-6" class="reference"><a href="#cite_note-6"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup>

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

<p>Symmetric-key encryption can use either <a href="Stream_cipher" title="Stream cipher">stream ciphers</a> or <a href="Block_cipher" title="Block cipher">block ciphers</a>.<sup id="cite_ref-9" class="reference"><a href="#cite_note-9"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup>

</p><p>Stream ciphers encrypt the digits (typically <a href="Byte" title="Byte">bytes</a>), or letters (in substitution ciphers) of a message one at a time. An example is <a href="ChaCha20" class="mw-redirect" title="ChaCha20">ChaCha20</a>. <a href="Substitution_cipher" title="Substitution cipher">Substitution ciphers</a> are well-known ciphers, but can be easily decrypted using a <a href="Frequency_table" class="mw-redirect" title="Frequency table">frequency table</a>.<sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup>

</p><p>Block ciphers take a number of bits and encrypt them in a single unit, padding the plaintext to achieve a multiple of the block size. The <a href="Advanced_Encryption_Standard" title="Advanced Encryption Standard">Advanced Encryption Standard</a> (AES) algorithm, approved by <a href="NIST" class="mw-redirect" title="NIST">NIST</a> in December 2001, uses 128-bit blocks.

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

<p>Examples of popular symmetric-key algorithms include <a href="Twofish" title="Twofish">Twofish</a>, <a href="Serpent_(cipher)" title="Serpent (cipher)">Serpent</a>, <a href="Advanced_Encryption_Standard" title="Advanced Encryption Standard">AES</a> (Rijndael), <a href="Camellia_(cipher)" title="Camellia (cipher)">Camellia</a>, <a href="Salsa20" title="Salsa20">Salsa20</a>, <a href="ChaCha20" class="mw-redirect" title="ChaCha20">ChaCha20</a>, <a href="Blowfish_(cipher)" title="Blowfish (cipher)">Blowfish</a>, <a href="CAST5" class="mw-redirect" title="CAST5">CAST5</a>, <a href="Kuznyechik" title="Kuznyechik">Kuznyechik</a>, <a href="RC4" title="RC4">RC4</a>, <a href="Data_Encryption_Standard" title="Data Encryption Standard">DES</a>, <a href="Triple_DES" title="Triple DES">3DES</a>, <a href="Skipjack_(cipher)" title="Skipjack (cipher)">Skipjack</a>, <a href="Secure_and_Fast_Encryption_Routine" title="Secure and Fast Encryption Routine">Safer</a>, and <a href="International_Data_Encryption_Algorithm" title="International Data Encryption Algorithm">IDEA</a>.<sup id="cite_ref-11" class="reference"><a href="#cite_note-11"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup>

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<div class="mw-heading mw-heading2"><h2 id="Use_as_a_cryptographic_primitive">Use as a cryptographic primitive</h2></div>

<p>Symmetric ciphers are commonly used to achieve other <a href="Cryptographic_primitive" title="Cryptographic primitive">cryptographic primitives</a> than just encryption.

</p><p>Encrypting a message does not guarantee that it will remain unchanged while encrypted. Hence, often a <a href="Message_authentication_code" title="Message authentication code">message authentication code</a> is added to a ciphertext to ensure that changes to the ciphertext will be noted by the receiver. Message authentication codes can be constructed from an <a href="AEAD" class="mw-redirect" title="AEAD">AEAD</a> cipher (e.g. <a href="AES-GCM" class="mw-redirect" title="AES-GCM">AES-GCM</a>).

</p><p>However, symmetric ciphers cannot be used for <a href="Non-repudiation" title="Non-repudiation">non-repudiation</a> purposes except by involving additional parties.<sup id="cite_ref-12" class="reference"><a href="#cite_note-12"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> See the <a rel="nofollow" class="external text" href="http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=44736">ISO/IEC 13888-2 standard</a>.

</p><p>Another application is to build <a href="Hash_function" title="Hash function">hash functions</a> from block ciphers. See <a href="One-way_compression_function" title="One-way compression function">one-way compression function</a> for descriptions of several such methods.

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<div class="mw-heading mw-heading2"><h2 id="Construction_of_symmetric_ciphers">Construction of symmetric ciphers</h2></div>

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</style><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="Feistel_cipher" title="Feistel cipher">Feistel cipher</a></div>

<p>Many modern block ciphers are based on a construction proposed by <a href="Horst_Feistel" title="Horst Feistel">Horst Feistel</a>. Feistel's construction makes it possible to build invertible functions from other functions that are themselves not invertible.

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<div class="mw-heading mw-heading2"><h2 id="Security_of_symmetric_ciphers">Security of symmetric ciphers</h2></div>

<p>Symmetric ciphers have historically been susceptible to <a href="Known-plaintext_attack" title="Known-plaintext attack">known-plaintext attacks</a>, <a href="Chosen-plaintext_attack" title="Chosen-plaintext attack">chosen-plaintext attacks</a>, <a href="Differential_cryptanalysis" title="Differential cryptanalysis">differential cryptanalysis</a> and <a href="Linear_cryptanalysis" title="Linear cryptanalysis">linear cryptanalysis</a>. Careful construction of the functions for each <a href="Round_(cryptography)" title="Round (cryptography)">round</a> can greatly reduce the chances of a successful attack. It is also possible to increase the key length or the rounds in the encryption process to better protect against attack. This, however, tends to increase the processing power and decrease the speed at which the process runs due to the amount of operations the system needs to do.<sup id="cite_ref-13" class="reference"><a href="#cite_note-13"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup>

</p><p>Most modern symmetric-key algorithms appear to be resistant to the threat of <a href="Post-quantum_cryptography" title="Post-quantum cryptography">post-quantum cryptography</a>.<sup id="cite_ref-djb-intro_14-0" class="reference"><a href="#cite_note-djb-intro-14"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> <a href="Quantum_computing" title="Quantum computing">Quantum computers</a> would exponentially increase the speed at which these ciphers can be decoded; notably, <a href="Grover's_algorithm" title="Grover's algorithm">Grover's algorithm</a> would take the square-root of the time traditionally required for a <a href="Brute-force_attack" title="Brute-force attack">brute-force attack</a>, although these vulnerabilities can be compensated for by doubling key length.<sup id="cite_ref-djb-groverr_15-0" class="reference"><a href="#cite_note-djb-groverr-15"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> For example, a 128 bit AES cipher would not be secure against such an attack as it would reduce the time required to test all possible iterations from over 10 quintillion years to about six months. By contrast, it would still take a quantum computer the same amount of time to decode a 256 bit AES cipher as it would a conventional computer to decode a 128 bit AES cipher.<sup id="cite_ref-16" class="reference"><a href="#cite_note-16"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup> For this reason, AES-256 is believed to be "quantum resistant".<sup id="cite_ref-17" class="reference"><a href="#cite_note-17"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-18" class="reference"><a href="#cite_note-18"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup>

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<div class="mw-heading mw-heading2"><h2 id="Key_management">Key management</h2></div>

<div role="note" class="hatnote navigation-not-searchable">Main article: <a href="Key_Management_Interoperability_Protocol" title="Key Management Interoperability Protocol">Key Management Interoperability Protocol</a></div>

<div class="mw-heading mw-heading2"><h2 id="Key_establishment">Key establishment</h2></div>

<div role="note" class="hatnote navigation-not-searchable">Main article: <a href="Key_establishment" class="mw-redirect" title="Key establishment">Key establishment</a></div>

<p>Symmetric-key algorithms require both the sender and the recipient of a message to have the same secret key. All early cryptographic systems required either the sender or the recipient to somehow receive a copy of that secret key over a physically secure channel.

</p><p>Nearly all modern cryptographic systems still use symmetric-key algorithms internally to encrypt the bulk of the messages, but they eliminate the need for a physically secure channel by using <a href="Diffie%E2%80%93Hellman_key_exchange" title="Diffie–Hellman key exchange">Diffie–Hellman key exchange</a> or some other <a href="Public-key_cryptography" title="Public-key cryptography">public-key protocol</a> to securely come to agreement on a fresh new secret key for each session/conversation (forward secrecy).

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<div class="mw-heading mw-heading2"><h2 id="Key_generation">Key generation</h2></div>

<div role="note" class="hatnote navigation-not-searchable">Main article: <a href="Key_generation" title="Key generation">key generation</a></div>

<p>When used with asymmetric ciphers for key transfer, <a href="Cryptographically_secure_pseudorandom_number_generator" title="Cryptographically secure pseudorandom number generator">pseudorandom key generators</a> are nearly always used to generate the symmetric cipher session keys. However, lack of randomness in those generators or in their <a href="Initialization_vector" title="Initialization vector">initialization vectors</a> is disastrous and has led to cryptanalytic breaks in the past. Therefore, it is essential that an implementation use a source of high <a href="Entropy_(information_theory)" title="Entropy (information theory)">entropy</a> for its initialization.<sup id="cite_ref-19" class="reference"><a href="#cite_note-19"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-20" class="reference"><a href="#cite_note-20"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-21" class="reference"><a href="#cite_note-21"><span class="cite-bracket">[</span>20<span class="cite-bracket">]</span></a></sup>

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<div class="mw-heading mw-heading2"><h2 id="Reciprocal_cipher">Reciprocal cipher</h2></div>

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<p>A reciprocal cipher is a cipher where, just as one enters the <a href="Plaintext" title="Plaintext">plaintext</a> into the <a href="Cryptography" title="Cryptography">cryptography</a> system to get the <a href="Ciphertext" title="Ciphertext">ciphertext</a>, one could enter the ciphertext into the same place in the system to get the plaintext. A reciprocal cipher is also sometimes referred as <b>self-reciprocal cipher</b>.<sup id="cite_ref-22" class="reference"><a href="#cite_note-22"><span class="cite-bracket">[</span>21<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-23" class="reference"><a href="#cite_note-23"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup>

</p><p>Practically all mechanical cipher machines implement a reciprocal cipher, a <a href="Involution_(mathematics)" title="Involution (mathematics)">mathematical involution</a> on each typed-in letter.

Instead of designing two kinds of machines, one for encrypting and one for decrypting, all the machines can be identical and can be set up (keyed) the same way.<sup id="cite_ref-24" class="reference"><a href="#cite_note-24"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup>

</p><p>Examples of reciprocal ciphers include:

</p>

<ul><li><a href="Atbash" title="Atbash">Atbash</a></li>

<li><a href="Beaufort_cipher" title="Beaufort cipher">Beaufort cipher</a><sup id="cite_ref-25" class="reference"><a href="#cite_note-25"><span class="cite-bracket">[</span>24<span class="cite-bracket">]</span></a></sup></li>

<li><a href="Enigma_machine" title="Enigma machine">Enigma machine</a><sup id="cite_ref-26" class="reference"><a href="#cite_note-26"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup></li>

<li>Marie Antoinette and <a href="Axel_von_Fersen_the_Younger" title="Axel von Fersen the Younger">Axel von Fersen</a> communicated with a self-reciprocal cipher.<sup id="cite_ref-27" class="reference"><a href="#cite_note-27"><span class="cite-bracket">[</span>26<span class="cite-bracket">]</span></a></sup></li>

<li>the Porta polyalphabetic cipher is self-reciprocal.<sup id="cite_ref-28" class="reference"><a href="#cite_note-28"><span class="cite-bracket">[</span>27<span class="cite-bracket">]</span></a></sup></li>

<li><a href="Purple_cipher" class="mw-redirect" title="Purple cipher">Purple cipher</a><sup id="cite_ref-29" class="reference"><a href="#cite_note-29"><span class="cite-bracket">[</span>28<span class="cite-bracket">]</span></a></sup></li>

<li><a href="XOR_cipher" title="XOR cipher">XOR cipher</a></li>

<li><a href="Vatsyayana_cipher" class="mw-redirect" title="Vatsyayana cipher">Vatsyayana cipher</a></li></ul>

<p>The majority of all modern ciphers can be classified as either a <a href="Stream_cipher" title="Stream cipher">stream cipher</a>, most of which use a reciprocal <a href="XOR_cipher" title="XOR cipher">XOR cipher</a> combiner, or a <a href="Block_cipher" title="Block cipher">block cipher</a>, most of which use a <a href="Feistel_cipher" title="Feistel cipher">Feistel cipher</a> or <a href="Lai%E2%80%93Massey_scheme" title="Lai–Massey scheme">Lai–Massey scheme</a> with a reciprocal transformation in each round.

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

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<li id="cite_note-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-1">^</a></b></span> <span class="reference-text">Other terms for symmetric-key encryption are <i>secret-key</i>, <i>single-key</i>, <i>shared-key</i>, <i>one-key</i>, and <i>private-key</i> encryption. Use of the last and first terms can create ambiguity with similar terminology used in <a href="Public-key_cryptography" title="Public-key cryptography">public-key cryptography</a>. Symmetric-key cryptography is to be contrasted with <a href="Asymmetric-key_cryptography" class="mw-redirect" title="Asymmetric-key cryptography">asymmetric-key cryptography</a>.</span>

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

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</style><cite id="CITEREFKartit2016" class="citation journal cs1">Kartit, Zaid (February 2016). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=uEGFCwAAQBAJ&q=%22keys+may+be+identical%22&pg=PA147">"Applying Encryption Algorithms for Data Security in Cloud Storage, Kartit, et al"</a>. <i>Advances in Ubiquitous Networking: Proceedings of UNet15</i>: 147. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>9789812879905</bdi>.</cite></span>

</li>

<li id="cite_note-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-3">^</a></b></span> <span class="reference-text"><cite id="CITEREFDelfs,_HansKnebl,_Helmut2007" class="citation book cs1">Delfs, Hans; Knebl, Helmut (2007). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=Nnvhz_VqAS4C&pg=PA11">"Symmetric-key encryption"</a>. <i>Introduction to cryptography: principles and applications</i>. Springer. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>9783540492436</bdi>.</cite></span>

</li>

<li id="cite_note-4"><span class="mw-cite-backlink"><b><a href="#cite_ref-4">^</a></b></span> <span class="reference-text"><cite id="CITEREFMullen,_GaryMummert,_Carl2007" class="citation book cs1">Mullen, Gary; Mummert, Carl (2007). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=yDgWctqWL4wC&pg=PA112"><i>Finite fields and applications</i></a>. American Mathematical Society. p. 112. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>9780821844182</bdi>.</cite></span>

</li>

<li id="cite_note-5"><span class="mw-cite-backlink"><b><a href="#cite_ref-5">^</a></b></span> <span class="reference-text"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.geeksforgeeks.org/difference-between-symmetric-and-asymmetric-key-encryption/">"Demystifying symmetric and asymmetric methods of encryption"</a>. Geeks for Geeks. 2017-09-28.</cite></span>

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<cite id="CITEREFRistenpartYilek2010" class="citation web cs1">Ristenpart, Thomas; Yilek, Scott (2010). <a rel="nofollow" class="external text" href="https://www.ndss-symposium.org/wp-content/uploads/2017/09/rist.pdf">"When Good Randomness Goes Bad: Virtual Machine Reset Vulnerabilities and Hedging Deployed Cryptography"</a> <span class="cs1-format">(PDF)</span>. <i>NDSS Symposium 2010</i>. <q>Random number generators (RNGs) are consistently a weak link in the secure use of cryptography.</q></cite></span>

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

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</style></div><div role="navigation" class="navbox" aria-label="Navbox0" style="padding:3px"><table class="nowraplinks hlist navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><td colspan="2" class="navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><td colspan="2" class="navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><div id="Block_ciphers_(security_summary)197" style="font-size:114%;margin:0 4em"><a href="Block_cipher" title="Block cipher">Block ciphers</a> (<a href="Cipher_security_summary" title="Cipher security summary">security summary</a>)</div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">Common<br>algorithms</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<li><a href="Blowfish_(cipher)" title="Blowfish (cipher)">Blowfish</a></li>

<li><a href="Data_Encryption_Standard" title="Data Encryption Standard">DES</a> (<a href="DES_supplementary_material" title="DES supplementary material">internal mechanics</a>, <a href="Triple_DES" title="Triple DES">Triple DES</a>)</li>

<li><a href="Serpent_(cipher)" title="Serpent (cipher)">Serpent</a></li>

<li><a href="Twofish" title="Twofish">Twofish</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Less common<br>algorithms</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<li><a href="Camellia_(cipher)" title="Camellia (cipher)">Camellia</a></li>

<li><a href="Skipjack_(cipher)" title="Skipjack (cipher)">Skipjack</a></li>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Other<br>algorithms</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<li><a href="Adiantum_(cipher)" title="Adiantum (cipher)">Adiantum</a></li>

<li><a href="Akelarre_(cipher)" title="Akelarre (cipher)">Akelarre</a></li>

<li><a href="Anubis_(cipher)" title="Anubis (cipher)">Anubis</a></li>

<li><a href="Ascon_(cipher)" title="Ascon (cipher)">Ascon</a></li>

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

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

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

<li><a href="Chiasmus_(cipher)" title="Chiasmus (cipher)">Chiasmus</a></li>

<li><a href="CIPHERUNICORN-A" title="CIPHERUNICORN-A">CIPHERUNICORN-A</a></li>

<li><a href="CIPHERUNICORN-E" title="CIPHERUNICORN-E">CIPHERUNICORN-E</a></li>

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

<li><a href="Cobra_ciphers" title="Cobra ciphers">Cobra</a></li>

<li><a href="COCONUT98" title="COCONUT98">COCONUT98</a></li>

<li><a href="Cryptomeria_cipher" title="Cryptomeria cipher">Cryptomeria/C2</a></li>

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

<li><a href="CS-Cipher" title="CS-Cipher">CS-Cipher</a></li>

<li><a href="Grand_Cru_(cipher)" title="Grand Cru (cipher)">Grand Cru</a></li>

<li><a href="Hasty_Pudding_cipher" title="Hasty Pudding cipher">Hasty Pudding cipher</a></li>

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

<li><a href="Intel_Cascade_Cipher" title="Intel Cascade Cipher">Intel Cascade Cipher</a></li>

<li><a href="Iraqi_block_cipher" title="Iraqi block cipher">Iraqi</a></li>

<li><a href="Kalyna_(cipher)" title="Kalyna (cipher)">Kalyna</a></li>

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

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

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

<li><a href="Khufu_and_Khafre" title="Khufu and Khafre">Khufu and Khafre</a></li>

<li><a href="KN-Cipher" title="KN-Cipher">KN-Cipher</a></li>

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

<li><a href="Ladder-DES" title="Ladder-DES">Ladder-DES</a></li>

<li><a href="Lucifer_(cipher)" title="Lucifer (cipher)">Lucifer</a></li>

<li><a href="MacGuffin_(cipher)" title="MacGuffin (cipher)">MacGuffin</a></li>

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

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

<li><a href="Mercy_(cipher)" title="Mercy (cipher)">Mercy</a></li>

<li><a href="MISTY1" title="MISTY1">MISTY1</a></li>

<li><a href="MULTI2" title="MULTI2">MULTI2</a></li>

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

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

<li><a href="Nimbus_(cipher)" title="Nimbus (cipher)">Nimbus</a></li>

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

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

<li><a href="Prince_(cipher)" title="Prince (cipher)">Prince</a></li>

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

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

<li><a href="Secure_and_Fast_Encryption_Routine" title="Secure and Fast Encryption Routine">SAFER</a></li>

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

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

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

<li><a href="Simon_(cipher)" title="Simon (cipher)">Simon</a></li>

<li><a href="Speck_(cipher)" title="Speck (cipher)">Speck</a></li>

<li><a href="Spectr-H64" title="Spectr-H64">Spectr-H64</a></li>

<li><a href="Square_(cipher)" title="Square (cipher)">Square</a></li>

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

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

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

<li><a href="Zodiac_(cipher)" title="Zodiac (cipher)">Zodiac</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Design</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Feistel_cipher" title="Feistel cipher">Feistel network</a></li>

<li><a href="Key_schedule" title="Key schedule">Key schedule</a></li>

<li><a href="Lai%E2%80%93Massey_scheme" title="Lai–Massey scheme">Lai–Massey scheme</a></li>

<li><a href="Product_cipher" title="Product cipher">Product cipher</a></li>

<li><a href="Confusion_and_diffusion" title="Confusion and diffusion">Confusion and diffusion</a></li>

<li><a href="Round_(cryptography)" title="Round (cryptography)">Round</a></li>

<li><a href="Avalanche_effect" title="Avalanche effect">Avalanche effect</a></li>

<li><a href="Block_size_(cryptography)" title="Block size (cryptography)">Block size</a></li>

<li><a href="Key_whitening" title="Key whitening">Key whitening</a> (<a href="Whitening_transformation" title="Whitening transformation">Whitening transformation</a>)</li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Attack<br>(<a href="Cryptanalysis" title="Cryptanalysis">cryptanalysis</a>)</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Brute-force_attack" title="Brute-force attack">Brute-force</a> (<a href="EFF_DES_cracker" title="EFF DES cracker">EFF DES cracker</a>)</li>

<ul><li><a href="Biclique_attack" title="Biclique attack">Biclique attack</a></li>

<li><a href="3-subset_meet-in-the-middle_attack" title="3-subset meet-in-the-middle attack">3-subset MITM attack</a></li></ul></li>

<li><a href="Linear_cryptanalysis" title="Linear cryptanalysis">Linear</a> (<a href="Piling-up_lemma" title="Piling-up lemma">Piling-up lemma</a>)</li>

<li><a href="Differential_cryptanalysis" title="Differential cryptanalysis">Differential</a>

<ul><li><a href="Impossible_differential_cryptanalysis" title="Impossible differential cryptanalysis">Impossible</a></li>

<li><a href="Truncated_differential_cryptanalysis" title="Truncated differential cryptanalysis">Truncated</a></li>

<li><a href="Higher-order_differential_cryptanalysis" title="Higher-order differential cryptanalysis">Higher-order</a></li></ul></li>

<li><a href="Differential-linear_attack" title="Differential-linear attack">Differential-linear</a></li>

<li><a href="Distinguishing_attack" title="Distinguishing attack">Distinguishing</a> (<a href="Known-key_distinguishing_attack" title="Known-key distinguishing attack">Known-key</a>)</li>

<li><a href="Integral_cryptanalysis" title="Integral cryptanalysis">Integral/Square</a></li>

<li><a href="Boomerang_attack" title="Boomerang attack">Boomerang</a></li>

<li><a href="Related-key_attack" title="Related-key attack">Related-key</a></li>

<li><a href="Slide_attack" title="Slide attack">Slide</a></li>

<li><a href="Rotational_cryptanalysis" title="Rotational cryptanalysis">Rotational</a></li>

<li><a href="Side-channel_attack" title="Side-channel attack">Side-channel</a>

<ul><li><a href="Timing_attack" title="Timing attack">Timing</a></li>

<li><a href="Power_analysis" title="Power analysis">Power-monitoring</a></li>

<li><a href="Electromagnetic_attack" title="Electromagnetic attack">Electromagnetic</a></li>

<li><a href="Acoustic_cryptanalysis" title="Acoustic cryptanalysis">Acoustic</a></li>

<li><a href="Differential_fault_analysis" title="Differential fault analysis">Differential-fault</a></li></ul></li>

<li><a href="Interpolation_attack" title="Interpolation attack">Interpolation</a></li>

<li><a href="Partitioning_cryptanalysis" title="Partitioning cryptanalysis">Partitioning</a></li>

<li><a href="Rubber-hose_cryptanalysis" class="mw-redirect" title="Rubber-hose cryptanalysis">Rubber-hose</a></li>

<li><a href="Black-bag_cryptanalysis" title="Black-bag cryptanalysis">Black-bag</a></li>

<li><a href="Davies_attack" title="Davies attack">Davies</a></li>

<li><a href="Rebound_attack" title="Rebound attack">Rebound</a></li>

<li><a href="Chi-squared_test" title="Chi-squared test">Chi-square</a></li>

<li><a href="Time/memory/data_tradeoff_attack" title="Time/memory/data tradeoff attack">Time/memory/data tradeoff</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Standardization</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Advanced_Encryption_Standard_process" title="Advanced Encryption Standard process">AES process</a></li>

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

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

<li><a href="NSA_Suite_B_Cryptography" title="NSA Suite B Cryptography">NSA Suite B</a></li>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Utilization</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Initialization_vector" title="Initialization vector">Initialization vector</a></li>

<li><a href="Block_cipher_mode_of_operation" title="Block cipher mode of operation">Mode of operation</a></li>

<li><a href="Padding_(cryptography)" title="Padding (cryptography)">Padding</a></li></ul>

</div></td></tr></tbody></table><div></div></td></tr><tr><td colspan="2" class="navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><div id="Stream_ciphers94" style="font-size:114%;margin:0 4em"><a href="Stream_cipher" title="Stream cipher">Stream ciphers</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">Widely used ciphers</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<li><a href="Salsa20#ChaCha_variant" title="Salsa20">ChaCha</a></li>

<li><a href="Crypto-1" title="Crypto-1">Crypto-1</a></li>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="ESTREAM" title="ESTREAM">eSTREAM</a> Portfolio</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%">Software</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<li><a href="Rabbit_(cipher)" title="Rabbit (cipher)">Rabbit</a></li>

<li><a href="Salsa20" title="Salsa20">Salsa20</a></li>

<li><a href="SOSEMANUK" title="SOSEMANUK">SOSEMANUK</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Hardware</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Grain_(cipher)" title="Grain (cipher)">Grain</a></li>

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

<li><a href="Trivium_(cipher)" title="Trivium (cipher)">Trivium</a></li></ul>

</div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Other ciphers</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Achterbahn_(stream_cipher)" title="Achterbahn (stream cipher)">Achterbahn</a></li>

<li><a href="ISAAC_(cipher)" title="ISAAC (cipher)">ISAAC</a></li>

<li><a href="KCipher-2" title="KCipher-2">KCipher-2</a></li>

<li><a href="Panama_(cryptography)" title="Panama (cryptography)">Panama</a></li>

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

<li><a href="Scream_(cipher)" title="Scream (cipher)">Scream</a></li>

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

<li><a href="SOBER-128" title="SOBER-128">SOBER-128</a></li>

<li><a href="Spritz_(cipher)" class="mw-redirect" title="Spritz (cipher)">Spritz</a></li>

<li><a href="Turing_(cipher)" title="Turing (cipher)">Turing</a></li>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Generators</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Shrinking_generator" title="Shrinking generator">shrinking generator</a></li>

<li><a href="Self-shrinking_generator" title="Self-shrinking generator">self-shrinking generator</a></li>

<li><a href="Alternating_step_generator" title="Alternating step generator">alternating step generator</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Theory</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Block_cipher_mode_of_operation" title="Block cipher mode of operation">block ciphers in stream mode</a></li>

<li><a href="Shift_register" title="Shift register">shift register</a></li>

<li><a href="Nonlinear-feedback_shift_register" title="Nonlinear-feedback shift register">NLFSR</a></li>

<li><a href="T-function" title="T-function">T-function</a></li>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Attacks</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Correlation_attack" title="Correlation attack">correlation attack</a></li>

<li><a href="Correlation_immunity" title="Correlation immunity">correlation immunity</a></li>

<li><a href="Stream_cipher_attacks" title="Stream cipher attacks">stream cipher attacks</a></li></ul>

</div></td></tr></tbody></table><div></div></td></tr></tbody></table><div></div></td></tr><tr><td colspan="2" class="navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks mw-collapsible mw-collapsed navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><div id="Cryptography149" style="font-size:114%;margin:0 4em"><a href="Cryptography" title="Cryptography">Cryptography</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">General</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="History_of_cryptography" title="History of cryptography">History of cryptography</a></li>

<li><a href="Outline_of_cryptography" title="Outline of cryptography">Outline of cryptography</a></li>

<li><a href="Classical_cipher" title="Classical cipher">Classical cipher</a></li>

<li><a href="Cryptographic_protocol" title="Cryptographic protocol">Cryptographic protocol</a>

<ul><li><a href="Authentication_protocol" title="Authentication protocol">Authentication protocol</a></li></ul></li>

<li><a href="Cryptographic_primitive" title="Cryptographic primitive">Cryptographic primitive</a></li>

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

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

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

<li><a href="Cryptographic_nonce" title="Cryptographic nonce">Cryptographic nonce</a></li>

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

<li><a href="Hash_function" title="Hash function">Hash function</a>

<ul><li><a href="Cryptographic_hash_function" title="Cryptographic hash function">Cryptographic hash function</a></li>

<li><a href="Key_derivation_function" title="Key derivation function">Key derivation function</a></li>

<li><a href="Secure_Hash_Algorithms" title="Secure Hash Algorithms">Secure Hash Algorithms</a></li></ul></li>

<li><a href="Digital_signature" title="Digital signature">Digital signature</a></li>

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

<li><a href="Key_(cryptography)" title="Key (cryptography)">Key (cryptography)</a></li>

<li><a href="Key_exchange" title="Key exchange">Key exchange</a></li>

<li><a href="Key_generator" title="Key generator">Key generator</a></li>

<li><a href="Key_schedule" title="Key schedule">Key schedule</a></li>

<li><a href="Key_stretching" title="Key stretching">Key stretching</a></li>

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

<li>Machines</li>

<li><a href="Cryptojacking_malware" class="mw-redirect" title="Cryptojacking malware">Cryptojacking malware</a></li>

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

<li><a href="Random_number_generation" title="Random number generation">Random number generation</a>

<ul><li><a href="Cryptographically_secure_pseudorandom_number_generator" title="Cryptographically secure pseudorandom number generator">Cryptographically secure pseudorandom number generator</a> (CSPRNG)</li></ul></li>

<li><a href="Pseudorandom_noise" title="Pseudorandom noise">Pseudorandom noise</a> (PRN)</li>

<li><a href="Secure_channel" title="Secure channel">Secure channel</a></li>

<li><a href="Insecure_channel" class="mw-redirect" title="Insecure channel">Insecure channel</a></li>

<li><a href="Subliminal_channel" title="Subliminal channel">Subliminal channel</a></li>

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

<li><a href="Decryption" class="mw-redirect" title="Decryption">Decryption</a></li>

<li><a href="End-to-end_encryption" title="End-to-end encryption">End-to-end encryption</a></li>

<li><a href="Harvest_now%2C_decrypt_later" title="Harvest now, decrypt later">Harvest now, decrypt later</a></li>

<li><a href="Information-theoretic_security" title="Information-theoretic security">Information-theoretic security</a></li>

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

<li><a href="Codetext" class="mw-redirect" title="Codetext">Codetext</a></li>

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

<li><a href="Shared_secret" title="Shared secret">Shared secret</a></li>

<li><a href="Trapdoor_function" title="Trapdoor function">Trapdoor function</a></li>

<li><a href="Trusted_timestamping" title="Trusted timestamping">Trusted timestamping</a></li>

<li><a href="Key-based_routing" title="Key-based routing">Key-based routing</a></li>

<li><a href="Onion_routing" title="Onion routing">Onion routing</a></li>

<li><a href="Garlic_routing" title="Garlic routing">Garlic routing</a></li>

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

<li><a href="Mix_network" title="Mix network">Mix network</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Mathematics</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Cryptographic_hash_function" title="Cryptographic hash function">Cryptographic hash function</a></li>

<li><a href="Block_cipher" title="Block cipher">Block cipher</a></li>

<li><a href="Stream_cipher" title="Stream cipher">Stream cipher</a></li>

<li><a href="Authenticated_encryption" title="Authenticated encryption">Authenticated encryption</a></li>

<li><a href="Public-key_cryptography" title="Public-key cryptography">Public-key cryptography</a></li>

<li><a href="Quantum_key_distribution" title="Quantum key distribution">Quantum key distribution</a></li>

<li><a href="Quantum_cryptography" title="Quantum cryptography">Quantum cryptography</a></li>

<li><a href="Post-quantum_cryptography" title="Post-quantum cryptography">Post-quantum cryptography</a></li>

<li><a href="Message_authentication_code" title="Message authentication code">Message authentication code</a></li>

<li><a href="Cryptographically_secure_pseudorandom_number_generator" title="Cryptographically secure pseudorandom number generator">Random numbers</a></li>

<li><a href="Steganography" title="Steganography">Steganography</a></li></ul>

</div></td></tr><tr><td class="navbox-abovebelow" colspan="2"><div>

<ul><li><span class="noviewer" typeof="mw:File"><span title="Category"></span></span> Category</li></ul>

</div></td></tr></tbody></table><div></div></td></tr></tbody></table></div>

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This article is issued from <a class="external text" title="Last edited on 2025-06-19" href="https://en.wikipedia.org/wiki/?title=Symmetric-key_algorithm&oldid=1296410547">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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