HashUtil.cpp

#include "HashUtil.h"

unsigned char HashUtil::m_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
};

/** 
 * MD5 initialization. Begins an MD5 operation, writing a new context.
 */
void HashUtil::MD5Init(MD5_CTX *context){
  context->count[0] = context->count[1] = 0;
  // Load magic initialization constants.
  context->state[0] = 0x67452301;
  context->state[1] = 0xefcdab89;
  context->state[2] = 0x98badcfe;
  context->state[3] = 0x10325476;
}

/**
 * MD5 block update operation. Continues an MD5 message-digest
 * operation, processing another message block, and updating the
 * context.
 */
void HashUtil::MD5Update(MD5_CTX *context, unsigned char *input, unsigned int inputLen){
    unsigned int i, index, partLen;

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

    /* Update number of bits */
    if((context->count[0] += ((unsigned int)inputLen << 3)) < ((unsigned int)inputLen << 3)){
        context->count[1]++;
    }
  
    context->count[1] += ((unsigned int)inputLen >> 29);

    partLen = 64 - index;

    // Transform as many times as possible.
    if(inputLen >= partLen){
        MD5_memcpy((unsigned char*)&context->buffer[index], (unsigned char*)input, partLen);
        MD5Transform (context->state, context->buffer);

        for(i = partLen; i + 63 < inputLen; i += 64){
            MD5Transform (context->state, &input[i]);
        }
    
        index = 0;
    
    } else {
        i = 0;
    }

    // Buffer remaining input
    MD5_memcpy((unsigned char*)&context->buffer[index], (unsigned char*)&input[i], inputLen-i);
}

/**
 * MD5 finalization. Ends an MD5 message-digest operation, writing the the message digest and zeroizing the context.
 */
void HashUtil::MD5Final( std::array<unsigned char, 16> & digest, MD5_CTX *context){
    std::array<unsigned char, 8> bits;
    unsigned int index, padLen;

    // Save number of bits
    MD5_Encode<8>(bits, context->count);


    // Pad out to 56 mod 64.
    index = (unsigned int)((context->count[0] >> 3) & 0x3f);
    padLen = (index < 56) ? (56 - index) : (120 - index);
    MD5Update (context, m_PADDING, padLen);

    // Append length (before padding)
    MD5Update (context, bits.data( ), 8);
      
    // Store state in digest
    MD5_Encode<16>(digest, context->state);

    // Zeroize sensitive information.
    MD5_memset ((unsigned char*)context, 0, sizeof (*context));
}

/**
 * MD5 basic transformation. Transforms state based on block.
 */
void HashUtil::MD5Transform(unsigned int state[4], unsigned char block[64]){
    unsigned int a = state[0], b = state[1], c = state[2], d = state[3], x[16];

    MD5_Decode(x, block, 64);

    /* 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.
    MD5_memset ((unsigned char*)x, 0, sizeof (x));
}

/**
 * Decodes input (unsigned char) into output (unsigned int). Assumes len is a multiple of 4.
 */
void HashUtil::MD5_Decode(unsigned int *output, unsigned char *input, unsigned int len){
    for(unsigned int i = 0, j = 0; j < len; i++, j += 4){
        output[i] = ((unsigned int)input[j]) | (((unsigned int)input[j+1]) << 8) | (((unsigned int)input[j+2]) << 16) | (((unsigned int)input[j+3]) << 24);
    }
}

/**
 * Note: Replace "for loop" with standard memcpy if possible.
 */
void HashUtil::MD5_memcpy(unsigned char* output, unsigned char* input, unsigned int len){
    for(unsigned int i = 0; i < len; i++){
        output[i] = input[i];
    }
}

/**
 * Note: Replace "for loop" with standard memset if possible.
 */
void HashUtil::MD5_memset(unsigned char* output, int value, unsigned int len){
    for(unsigned int i = 0; i < len; i++){
        ((char *)output)[i] = (char)value;
    }
}


void HashUtil::getMD5Sum(unsigned char* pData, int size, std::array<unsigned char, 16> & Digest ){
    MD5_CTX context;
    
    MD5Init(&context);
    MD5Update(&context, pData, size);
    MD5Final(Digest, &context);

    return;
}