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| -rw-r--r-- | md5.cc | 206 |
1 files changed, 206 insertions, 0 deletions
@@ -0,0 +1,206 @@ +/* Functions to compute MD5 message digest of memory blocks according to the + definition of MD5 in RFC 1321 from April 1992. + Copyright (C) 2020-2022 Antonio Diaz Diaz. + + This library is free software. Redistribution and use in source and + binary forms, with or without modification, are permitted provided + that the following conditions are met: + + 1. Redistributions of source code must retain the above copyright + notice, this list of conditions, and the following disclaimer. + + 2. Redistributions in binary form must reproduce the above copyright + notice, this list of conditions, and the following disclaimer in the + documentation and/or other materials provided with the distribution. + + This library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. +*/ + +#define _FILE_OFFSET_BITS 64 + +#include <cstring> +#include <stdint.h> + +#include "md5.h" + + +namespace { + +/* These are the four functions used in the four steps of the MD5 algorithm + as defined in RFC 1321. */ +#define F(x, y, z) ((x & y) | (~x & z)) +#define G(x, y, z) ((x & z) | (y & ~z)) +#define H(x, y, z) (x ^ y ^ z) +#define I(x, y, z) (y ^ (x | ~z)) + +/* Rotate x left n bits. + It is unfortunate that C++ does not provide an operator for rotation. + Hope the compiler is smart enough. */ +#define ROTATE_LEFT(x, n) (x = (x << n) | (x >> (32 - n))) + +// FF, GG, HH, and II transformations for rounds 1, 2, 3, and 4. +#define FF(a, b, c, d, x, s, ac) \ + { a += F(b, c, d) + x + ac; ROTATE_LEFT(a, s); a += b; } +#define GG(a, b, c, d, x, s, ac) \ + { a += G(b, c, d) + x + ac; ROTATE_LEFT(a, s); a += b; } +#define HH(a, b, c, d, x, s, ac) \ + { a += H(b, c, d) + x + ac; ROTATE_LEFT(a, s); a += b; } +#define II(a, b, c, d, x, s, ac) \ + { a += I(b, c, d) + x + ac; ROTATE_LEFT(a, s); a += b; } + +} // end namespace + + +void MD5SUM::md5_process_block( const uint8_t block[64] ) + { + uint32_t a = state[0], b = state[1], c = state[2], d = state[3], x[16]; + + for( int i = 0, j = 0; i < 16; ++i, j += 4 ) // fill x in little endian + x[i] = block[j] | (block[j+1] << 8) | (block[j+2] << 16) | (block[j+3] << 24); + + /* Round 1 */ + FF (a, b, c, d, x[ 0], 7, 0xD76AA478); // 1 + FF (d, a, b, c, x[ 1], 12, 0xE8C7B756); // 2 + FF (c, d, a, b, x[ 2], 17, 0x242070DB); // 3 + FF (b, c, d, a, x[ 3], 22, 0xC1BDCEEE); // 4 + FF (a, b, c, d, x[ 4], 7, 0xF57C0FAF); // 5 + FF (d, a, b, c, x[ 5], 12, 0x4787C62A); // 6 + FF (c, d, a, b, x[ 6], 17, 0xA8304613); // 7 + FF (b, c, d, a, x[ 7], 22, 0xFD469501); // 8 + FF (a, b, c, d, x[ 8], 7, 0x698098D8); // 9 + FF (d, a, b, c, x[ 9], 12, 0x8B44F7AF); // 10 + FF (c, d, a, b, x[10], 17, 0xFFFF5BB1); // 11 + FF (b, c, d, a, x[11], 22, 0x895CD7BE); // 12 + FF (a, b, c, d, x[12], 7, 0x6B901122); // 13 + FF (d, a, b, c, x[13], 12, 0xFD987193); // 14 + FF (c, d, a, b, x[14], 17, 0xA679438E); // 15 + FF (b, c, d, a, x[15], 22, 0x49B40821); // 16 + + /* Round 2 */ + GG (a, b, c, d, x[ 1], 5, 0xF61E2562); // 17 + GG (d, a, b, c, x[ 6], 9, 0xC040B340); // 18 + GG (c, d, a, b, x[11], 14, 0x265E5A51); // 19 + GG (b, c, d, a, x[ 0], 20, 0xE9B6C7AA); // 20 + GG (a, b, c, d, x[ 5], 5, 0xD62F105D); // 21 + GG (d, a, b, c, x[10], 9, 0x02441453); // 22 + GG (c, d, a, b, x[15], 14, 0xD8A1E681); // 23 + GG (b, c, d, a, x[ 4], 20, 0xE7D3FBC8); // 24 + GG (a, b, c, d, x[ 9], 5, 0x21E1CDE6); // 25 + GG (d, a, b, c, x[14], 9, 0xC33707D6); // 26 + GG (c, d, a, b, x[ 3], 14, 0xF4D50D87); // 27 + GG (b, c, d, a, x[ 8], 20, 0x455A14ED); // 28 + GG (a, b, c, d, x[13], 5, 0xA9E3E905); // 29 + GG (d, a, b, c, x[ 2], 9, 0xFCEFA3F8); // 30 + GG (c, d, a, b, x[ 7], 14, 0x676F02D9); // 31 + GG (b, c, d, a, x[12], 20, 0x8D2A4C8A); // 32 + + /* Round 3 */ + HH (a, b, c, d, x[ 5], 4, 0xFFFA3942); // 33 + HH (d, a, b, c, x[ 8], 11, 0x8771F681); // 34 + HH (c, d, a, b, x[11], 16, 0x6D9D6122); // 35 + HH (b, c, d, a, x[14], 23, 0xFDE5380C); // 36 + HH (a, b, c, d, x[ 1], 4, 0xA4BEEA44); // 37 + HH (d, a, b, c, x[ 4], 11, 0x4BDECFA9); // 38 + HH (c, d, a, b, x[ 7], 16, 0xF6BB4B60); // 39 + HH (b, c, d, a, x[10], 23, 0xBEBFBC70); // 40 + HH (a, b, c, d, x[13], 4, 0x289B7EC6); // 41 + HH (d, a, b, c, x[ 0], 11, 0xEAA127FA); // 42 + HH (c, d, a, b, x[ 3], 16, 0xD4EF3085); // 43 + HH (b, c, d, a, x[ 6], 23, 0x04881D05); // 44 + HH (a, b, c, d, x[ 9], 4, 0xD9D4D039); // 45 + HH (d, a, b, c, x[12], 11, 0xE6DB99E5); // 46 + HH (c, d, a, b, x[15], 16, 0x1FA27CF8); // 47 + HH (b, c, d, a, x[ 2], 23, 0xC4AC5665); // 48 + + /* Round 4 */ + II (a, b, c, d, x[ 0], 6, 0xF4292244); // 49 + II (d, a, b, c, x[ 7], 10, 0x432AFF97); // 50 + II (c, d, a, b, x[14], 15, 0xAB9423A7); // 51 + II (b, c, d, a, x[ 5], 21, 0xFC93A039); // 52 + II (a, b, c, d, x[12], 6, 0x655B59C3); // 53 + II (d, a, b, c, x[ 3], 10, 0x8F0CCC92); // 54 + II (c, d, a, b, x[10], 15, 0xFFEFF47D); // 55 + II (b, c, d, a, x[ 1], 21, 0x85845DD1); // 56 + II (a, b, c, d, x[ 8], 6, 0x6FA87E4F); // 57 + II (d, a, b, c, x[15], 10, 0xFE2CE6E0); // 58 + II (c, d, a, b, x[ 6], 15, 0xA3014314); // 59 + II (b, c, d, a, x[13], 21, 0x4E0811A1); // 60 + II (a, b, c, d, x[ 4], 6, 0xF7537E82); // 61 + II (d, a, b, c, x[11], 10, 0xBD3AF235); // 62 + II (c, d, a, b, x[ 2], 15, 0x2AD7D2BB); // 63 + II (b, c, d, a, x[ 9], 21, 0xEB86D391); // 64 + + // add the processed values to the context + state[0] += a; state[1] += b; state[2] += c; state[3] += d; + } + + +/* Update the context for the next 'len' bytes of 'buffer'. + 'len' does not need to be a multiple of 64. +*/ +void MD5SUM::md5_update( const uint8_t * const buffer, const unsigned long len ) + { + unsigned index = count & 0x3F; // data length in bytes mod 64 + count += len; // update data length + const unsigned rest = 64 - index; + unsigned long i; + + if( len >= rest ) // process as many bytes as possible + { + std::memcpy( ibuf + index, buffer, rest ); + md5_process_block( ibuf ); + for( i = rest; i + 63 < len; i += 64 ) + md5_process_block( buffer + i ); + index = 0; + } + else i = 0; + + std::memcpy( ibuf + index, buffer + i, len - i ); // save remaining input + } + + +// finish computation and return the digest +void MD5SUM::md5_finish( uint8_t digest[16] ) + { + uint8_t padding[64] = { + 0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 + }; + uint8_t bits[8]; + uint64_t c = count << 3; // save data length in bits + for( int i = 0; i <= 7; ++i ) { bits[i] = (uint8_t)c; c >>= 8; } + + const unsigned index = count & 0x3F; // data length in bytes mod 64 + const unsigned len = (index < 56) ? (56 - index) : (120 - index); + md5_update( padding, len ); // pad to 56 mod 64 + md5_update( bits, 8 ); // append data length in bits + + for( int i = 0, j = 0; i < 4; i++, j += 4 ) // store state in digest + { + digest[j ] = (uint8_t)state[i]; + digest[j+1] = (uint8_t)(state[i] >> 8); + digest[j+2] = (uint8_t)(state[i] >> 16); + digest[j+3] = (uint8_t)(state[i] >> 24); + } + } + + +void compute_md5( const uint8_t * const buffer, const unsigned long len, + uint8_t digest[16] ) + { + MD5SUM md5sum; + if( len > 0 ) md5sum.md5_update( buffer, len ); + md5sum.md5_finish( digest ); + } + + +bool check_md5( const uint8_t * const buffer, const unsigned long len, + const uint8_t digest[16] ) + { + uint8_t new_digest[16]; + compute_md5( buffer, len, new_digest ); + return ( std::memcmp( digest, new_digest, 16 ) == 0 ); + } |