md5.cpp

// SPDX-FileCopyrightText: 2023 Open Salamander Authors
// SPDX-License-Identifier: GPL-2.0-or-later

#include "precomp.h" // include slouzi pouze k prelozitelnosti v Salamanderu

//#include <assert.h>
//#include <string.h>
//#include <iostream.h>

#include "md5.h"

// MD5 simple initialization method

MD5::MD5()
{
    init();
}

// MD5 block update operation. Continues an MD5 message-digest
// operation, processing another message block, and updating the
// context.

void MD5::update(uint1* input, uint4 input_length)
{

    uint4 input_index, buffer_index;
    uint4 buffer_space; // how much space is left in buffer

    if (finalized)
    { // so we can't update!
        TRACE_E("MD5::update:  Can't update a finalized digest!");
        return;
    }

    // Compute number of bytes mod 64
    buffer_index = (unsigned int)((count[0] >> 3) & 0x3F);

    // Update number of bits
    if ((count[0] += ((uint4)input_length << 3)) < ((uint4)input_length << 3))
        count[1]++;

    count[1] += ((uint4)input_length >> 29);

    buffer_space = 64 - buffer_index; // how much space is left in buffer

    // Transform as many times as possible.
    if (input_length >= buffer_space)
    { // ie. we have enough to fill the buffer
        // fill the rest of the buffer and transform
        memcpy(buffer + buffer_index, input, buffer_space);
        transform(buffer);

        // now, transform each 64-byte piece of the input, bypassing the buffer
        for (input_index = buffer_space; input_index + 63 < input_length;
             input_index += 64)
            transform(input + input_index);

        buffer_index = 0; // so we can buffer remaining
    }
    else
        input_index = 0; // so we can buffer the whole input

    // and here we do the buffering:
    memcpy(buffer + buffer_index, input + input_index, input_length - input_index);
}

// MD5 finalization. Ends an MD5 message-digest operation, writing the
// the message digest and zeroizing the context.

void MD5::finalize()
{

    unsigned char bits[8];
    unsigned int index, padLen;
    static uint1 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};

    if (finalized)
    {
        TRACE_E("MD5::finalize:  Already finalized this digest!");
        return;
    }

    // Save number of bits
    encode(bits, count, 8);

    // Pad out to 56 mod 64.
    index = (uint4)((count[0] >> 3) & 0x3f);
    padLen = (index < 56) ? (56 - index) : (120 - index);
    update(PADDING, padLen);

    // Append length (before padding)
    update(bits, 8);

    // Store state in digest
    encode(digest, state, 16);

    // Zeroize sensitive information
    memset(buffer, 0, sizeof(*buffer));

    finalized = 1;
}

void MD5::init()
{
    finalized = 0; // we just started!

    // Nothing counted, so count=0
    count[0] = 0;
    count[1] = 0;

    // Load magic initialization constants.
    state[0] = 0x67452301;
    state[1] = 0xefcdab89;
    state[2] = 0x98badcfe;
    state[3] = 0x10325476;
}

// Constants for MD5Transform routine.
// Although we could use C++ style constants, defines are actually better,
// since they let us easily evade scope clashes.

#define S11 7
#define S12 12
#define S13 17
#define S14 22
#define S21 5
#define S22 9
#define S23 14
#define S24 20
#define S31 4
#define S32 11
#define S33 16
#define S34 23
#define S41 6
#define S42 10
#define S43 15
#define S44 21

// MD5 basic transformation. Transforms state based on block.
void MD5::transform(uint1 block[64])
{

    uint4 a = state[0], b = state[1], c = state[2], d = state[3], x[16];

    decode(x, block, 64);

    //  assert(!finalized);  // not just a user error, since the method is private

    /* Round 1 */
    FF(a, b, c, d, x[0], S11, 0xd76aa478);  /* 1 */
    FF(d, a, b, c, x[1], S12, 0xe8c7b756);  /* 2 */
    FF(c, d, a, b, x[2], S13, 0x242070db);  /* 3 */
    FF(b, c, d, a, x[3], S14, 0xc1bdceee);  /* 4 */
    FF(a, b, c, d, x[4], S11, 0xf57c0faf);  /* 5 */
    FF(d, a, b, c, x[5], S12, 0x4787c62a);  /* 6 */
    FF(c, d, a, b, x[6], S13, 0xa8304613);  /* 7 */
    FF(b, c, d, a, x[7], S14, 0xfd469501);  /* 8 */
    FF(a, b, c, d, x[8], S11, 0x698098d8);  /* 9 */
    FF(d, a, b, c, x[9], S12, 0x8b44f7af);  /* 10 */
    FF(c, d, a, b, x[10], S13, 0xffff5bb1); /* 11 */
    FF(b, c, d, a, x[11], S14, 0x895cd7be); /* 12 */
    FF(a, b, c, d, x[12], S11, 0x6b901122); /* 13 */
    FF(d, a, b, c, x[13], S12, 0xfd987193); /* 14 */
    FF(c, d, a, b, x[14], S13, 0xa679438e); /* 15 */
    FF(b, c, d, a, x[15], S14, 0x49b40821); /* 16 */

    /* Round 2 */
    GG(a, b, c, d, x[1], S21, 0xf61e2562);  /* 17 */
    GG(d, a, b, c, x[6], S22, 0xc040b340);  /* 18 */
    GG(c, d, a, b, x[11], S23, 0x265e5a51); /* 19 */
    GG(b, c, d, a, x[0], S24, 0xe9b6c7aa);  /* 20 */
    GG(a, b, c, d, x[5], S21, 0xd62f105d);  /* 21 */
    GG(d, a, b, c, x[10], S22, 0x2441453);  /* 22 */
    GG(c, d, a, b, x[15], S23, 0xd8a1e681); /* 23 */
    GG(b, c, d, a, x[4], S24, 0xe7d3fbc8);  /* 24 */
    GG(a, b, c, d, x[9], S21, 0x21e1cde6);  /* 25 */
    GG(d, a, b, c, x[14], S22, 0xc33707d6); /* 26 */
    GG(c, d, a, b, x[3], S23, 0xf4d50d87);  /* 27 */
    GG(b, c, d, a, x[8], S24, 0x455a14ed);  /* 28 */
    GG(a, b, c, d, x[13], S21, 0xa9e3e905); /* 29 */
    GG(d, a, b, c, x[2], S22, 0xfcefa3f8);  /* 30 */
    GG(c, d, a, b, x[7], S23, 0x676f02d9);  /* 31 */
    GG(b, c, d, a, x[12], S24, 0x8d2a4c8a); /* 32 */

    /* Round 3 */
    HH(a, b, c, d, x[5], S31, 0xfffa3942);  /* 33 */
    HH(d, a, b, c, x[8], S32, 0x8771f681);  /* 34 */
    HH(c, d, a, b, x[11], S33, 0x6d9d6122); /* 35 */
    HH(b, c, d, a, x[14], S34, 0xfde5380c); /* 36 */
    HH(a, b, c, d, x[1], S31, 0xa4beea44);  /* 37 */
    HH(d, a, b, c, x[4], S32, 0x4bdecfa9);  /* 38 */
    HH(c, d, a, b, x[7], S33, 0xf6bb4b60);  /* 39 */
    HH(b, c, d, a, x[10], S34, 0xbebfbc70); /* 40 */
    HH(a, b, c, d, x[13], S31, 0x289b7ec6); /* 41 */
    HH(d, a, b, c, x[0], S32, 0xeaa127fa);  /* 42 */
    HH(c, d, a, b, x[3], S33, 0xd4ef3085);  /* 43 */
    HH(b, c, d, a, x[6], S34, 0x4881d05);   /* 44 */
    HH(a, b, c, d, x[9], S31, 0xd9d4d039);  /* 45 */
    HH(d, a, b, c, x[12], S32, 0xe6db99e5); /* 46 */
    HH(c, d, a, b, x[15], S33, 0x1fa27cf8); /* 47 */
    HH(b, c, d, a, x[2], S34, 0xc4ac5665);  /* 48 */

    /* Round 4 */
    II(a, b, c, d, x[0], S41, 0xf4292244);  /* 49 */
    II(d, a, b, c, x[7], S42, 0x432aff97);  /* 50 */
    II(c, d, a, b, x[14], S43, 0xab9423a7); /* 51 */
    II(b, c, d, a, x[5], S44, 0xfc93a039);  /* 52 */
    II(a, b, c, d, x[12], S41, 0x655b59c3); /* 53 */
    II(d, a, b, c, x[3], S42, 0x8f0ccc92);  /* 54 */
    II(c, d, a, b, x[10], S43, 0xffeff47d); /* 55 */
    II(b, c, d, a, x[1], S44, 0x85845dd1);  /* 56 */
    II(a, b, c, d, x[8], S41, 0x6fa87e4f);  /* 57 */
    II(d, a, b, c, x[15], S42, 0xfe2ce6e0); /* 58 */
    II(c, d, a, b, x[6], S43, 0xa3014314);  /* 59 */
    II(b, c, d, a, x[13], S44, 0x4e0811a1); /* 60 */
    II(a, b, c, d, x[4], S41, 0xf7537e82);  /* 61 */
    II(d, a, b, c, x[11], S42, 0xbd3af235); /* 62 */
    II(c, d, a, b, x[2], S43, 0x2ad7d2bb);  /* 63 */
    II(b, c, d, a, x[9], S44, 0xeb86d391);  /* 64 */

    state[0] += a;
    state[1] += b;
    state[2] += c;
    state[3] += d;

    // Zeroize sensitive information.
    memset((uint1*)x, 0, sizeof(x));
}

// Encodes input (UINT4) into output (unsigned char). Assumes len is
// a multiple of 4.
void MD5::encode(uint1* output, uint4* input, uint4 len)
{

    unsigned int i, j;

    for (i = 0, j = 0; j < len; i++, j += 4)
    {
        output[j] = (uint1)(input[i] & 0xff);
        output[j + 1] = (uint1)((input[i] >> 8) & 0xff);
        output[j + 2] = (uint1)((input[i] >> 16) & 0xff);
        output[j + 3] = (uint1)((input[i] >> 24) & 0xff);
    }
}

// Decodes input (unsigned char) into output (UINT4). Assumes len is
// a multiple of 4.
void MD5::decode(uint4* output, uint1* input, uint4 len)
{

    unsigned int i, j;

    for (i = 0, j = 0; j < len; i++, j += 4)
        output[i] = ((uint4)input[j]) | (((uint4)input[j + 1]) << 8) |
                    (((uint4)input[j + 2]) << 16) | (((uint4)input[j + 3]) << 24);
}

// Note: Replace "for loop" with standard memcpy if possible.
void MD5::memcpy(uint1* output, uint1* input, uint4 len)
{

    unsigned int i;

    for (i = 0; i < len; i++)
        output[i] = input[i];
}

// Note: Replace "for loop" with standard memset if possible.
void MD5::memset(uint1* output, uint1 value, uint4 len)
{

    unsigned int i;

    for (i = 0; i < len; i++)
        output[i] = value;
}

// ROTATE_LEFT rotates x left n bits.

inline unsigned int MD5::rotate_left(uint4 x, uint4 n)
{
    return (x << n) | (x >> (32 - n));
}

// F, G, H and I are basic MD5 functions.

inline unsigned int MD5::F(uint4 x, uint4 y, uint4 z)
{
    return (x & y) | (~x & z);
}

inline unsigned int MD5::G(uint4 x, uint4 y, uint4 z)
{
    return (x & z) | (y & ~z);
}

inline unsigned int MD5::H(uint4 x, uint4 y, uint4 z)
{
    return x ^ y ^ z;
}

inline unsigned int MD5::I(uint4 x, uint4 y, uint4 z)
{
    return y ^ (x | ~z);
}

// FF, GG, HH, and II transformations for rounds 1, 2, 3, and 4.
// Rotation is separate from addition to prevent recomputation.

inline void MD5::FF(uint4& a, uint4 b, uint4 c, uint4 d, uint4 x,
                    uint4 s, uint4 ac)
{
    a += F(b, c, d) + x + ac;
    a = rotate_left(a, s) + b;
}

inline void MD5::GG(uint4& a, uint4 b, uint4 c, uint4 d, uint4 x,
                    uint4 s, uint4 ac)
{
    a += G(b, c, d) + x + ac;
    a = rotate_left(a, s) + b;
}

inline void MD5::HH(uint4& a, uint4 b, uint4 c, uint4 d, uint4 x,
                    uint4 s, uint4 ac)
{
    a += H(b, c, d) + x + ac;
    a = rotate_left(a, s) + b;
}

inline void MD5::II(uint4& a, uint4 b, uint4 c, uint4 d, uint4 x,
                    uint4 s, uint4 ac)
{
    a += I(b, c, d) + x + ac;
    a = rotate_left(a, s) + b;
}