Node / markqvist / reticulum-cpp.git / files / src / Cryptography / PKCS7.h

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#pragma once

#include "../Bytes.h"

//#include "../Log.h"

#include <stdexcept>

namespace RNS { namespace Cryptography {

class PKCS7 {

public:

static const size_t BLOCKSIZE = 16;

static inline const Bytes pad(const Bytes& data, size_t bs = BLOCKSIZE) {

Bytes padded(data);

inplace_pad(padded, bs);

return padded;

}

static inline const Bytes unpad(const Bytes& data, size_t bs = BLOCKSIZE) {

Bytes unpadded(data);

inplace_unpad(unpadded, bs);

return unpadded;

}

// updates passed buffer

static inline void inplace_pad(Bytes& data, size_t bs = BLOCKSIZE) {

size_t len = data.size();

//debug("PKCS7::pad: len: " + std::to_string(len));

size_t padlen = bs - (len % bs);

//debug("PKCS7::pad: pad len: " + std::to_string(padlen));

// create zero-filled byte padding array of size padlen

//p v = bytes([padlen])

//uint8_t pad[padlen] = {0};

uint8_t pad[padlen];

memset(pad, 0, padlen);

// set last byte of padding array to size of padding

pad[padlen-1] = (uint8_t)padlen;

// concatenate data with padding

//p return data+v*padlen

data.append(pad, padlen);

//debug("PKCS7::pad: data size: " + std::to_string(data.size()));

}

// updates passed buffer

static inline void inplace_unpad(Bytes& data, size_t bs = BLOCKSIZE) {

size_t len = data.size();

//debug("PKCS7::unpad: len: " + std::to_string(len));

// read last byte which is pad length

//pad = data[-1]

size_t padlen = (size_t)data.data()[data.size()-1];

//debug("PKCS7::unpad: pad len: " + std::to_string(padlen));

if (padlen > bs) {

throw std::runtime_error("Cannot unpad, invalid padding length of " + std::to_string(padlen) + " bytes");

}

// truncate data to strip padding

//return data[:len-padlen]

data.resize(len - padlen);

//debug("PKCS7::unpad: data size: " + std::to_string(data.size()));

}

};

} }