MD5Hash.cpp

Go to the documentation of this file.

#include <string.h>
#include "MD5Hash.h"

void byteReverse(unsigned char *buffer, unsigned longs)
{
    __int32 t;
    do 
    {
        t = (__int32) ((unsigned) buffer[3] << 8 | buffer[2]) << 16 | 
                ((unsigned) buffer[1] << 8 | buffer[0]);
        *(__int32 *) buffer = t;
        buffer += 4;
    }
    while (--longs);
}

/*
 * Start MD5 accumulation.  Set bit count to 0 and buffer to mysterious
 * initialization constants.
 */

MD5Hash::MD5Hash()
{
    Init();
}

MD5Hash::~MD5Hash()
{
}

void MD5Hash::Init()
{
    m_Buffer[0] = 0x67452301;
    m_Buffer[1] = 0xefcdab89;
    m_Buffer[2] = 0x98badcfe;
    m_Buffer[3] = 0x10325476;

    m_Bits[0] = 0;
    m_Bits[1] = 0;
}

/*
 * Update context to reflect the concatenation of another buffer full
 * of bytes.
 */

void MD5Hash::Update(unsigned char const *buffer, unsigned length)
{
    unsigned __int32 t;

    /* Update bitcount */

    t = m_Bits[0];
    if ((m_Bits[0] = t + ((unsigned __int32) length << 3)) < t)
        m_Bits[1]++;            // Carry from low to high
    m_Bits[1] += length >> 29;

    t = (t >> 3) & 0x3f;        // Bytes already in shsInfo->data

    // Handle any leading odd-sized chunks
    if (t) 
    {
        unsigned char *p = (unsigned char *) m_In + t;

        t = 64 - t;
        if (length < t)
        {
            memcpy(p, buffer, length);
            return;
        }

        memcpy(p, buffer, t);
        byteReverse(m_In, 16);
        Transform(m_Buffer, (unsigned __int32*) m_In);
        buffer += t;
        length -= t;
    }
    /* Process data in 64-byte chunks */

    while (length >= 64) {
    memcpy(m_In, buffer, 64);
    byteReverse(m_In, 16);
    Transform(m_Buffer, (unsigned __int32*) m_In);
    buffer += 64;
    length -= 64;
    }

    /* Handle any remaining bytes of data. */

    memcpy(m_In, buffer, length);
}


/*
 * Final wrapup - pad to 64-byte boundary with the bit pattern 
 * 1 0* (64-bit count of bits processed, MSB-first)
 */

void MD5Hash::Final(unsigned char Digest[MD5_HASHBYTES])
{
    unsigned count;
    unsigned char *p;

    /* Compute number of bytes mod 64 */
    count = (m_Bits[0] >> 3) & 0x3F;

    /* Set the first char of padding to 0x80.  This is safe since there is
       always at least one byte free */
    p = m_In + count;
    *p++ = 0x80;

    /* Bytes of padding needed to make 64 bytes */
    count = 64 - 1 - count;

    /* Pad out to 56 mod 64 */
    if (count < 8) 
    {
        /* Two lots of padding:  Pad the first block to 64 bytes */
        memset(p, 0, count);
        byteReverse(m_In, 16);
        Transform(m_Buffer, (unsigned __int32*) m_In);

        /* Now fill the next block with 56 bytes */
        memset(m_In, 0, 56);
    } 
    else
    {
        /* Pad block to 56 bytes */
        memset(p, 0, count - 8);
    }

    byteReverse(m_In, 14);

    /* Append length in bits and transform */
    ((unsigned __int32*) m_In)[14] = m_Bits[0];
    ((unsigned __int32*) m_In)[15] = m_Bits[1];

    Transform(m_Buffer, (unsigned __int32*) m_In);
    byteReverse((unsigned char *) m_Buffer, 4);
    memcpy(Digest, m_Buffer, 16);

    m_Buffer[0] = m_Buffer[1] = m_Buffer[2] = m_Buffer[3] = 0;
    m_Bits[0] = m_Bits[1] = 0;
    memset(m_In, 0, 64);
}

/* The four core functions - F1 is optimized somewhat */

/* #define F1(x, y, z) (x & y | ~x & z) */
#define F1(x, y, z) (z ^ (x & (y ^ z)))

#define F2(x, y, z) F1(z, x, y)

#define F3(x, y, z) (x ^ y ^ z)

#define F4(x, y, z) (y ^ (x | ~z))

#define MD5STEP(f, w, x, y, z, data, s) \
    ( w += f(x, y, z) + data,  w = w<<s | w>>(32-s),  w += x )

/*
 * The core of the MD5 algorithm, this alters an existing MD5 hash to
 * reflect the addition of 16 longwords of new data.  MD5Update blocks
 * the data and converts bytes into longwords for this routine.
 */

void MD5Hash::Transform(unsigned __int32 buf[4], unsigned __int32 const in[16])
{
    register unsigned __int32 a, b, c, d;

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

    MD5STEP(F1, a, b, c, d, in[0] + 0xd76aa478, 7);
    MD5STEP(F1, d, a, b, c, in[1] + 0xe8c7b756, 12);
    MD5STEP(F1, c, d, a, b, in[2] + 0x242070db, 17);
    MD5STEP(F1, b, c, d, a, in[3] + 0xc1bdceee, 22);
    MD5STEP(F1, a, b, c, d, in[4] + 0xf57c0faf, 7);
    MD5STEP(F1, d, a, b, c, in[5] + 0x4787c62a, 12);
    MD5STEP(F1, c, d, a, b, in[6] + 0xa8304613, 17);
    MD5STEP(F1, b, c, d, a, in[7] + 0xfd469501, 22);
    MD5STEP(F1, a, b, c, d, in[8] + 0x698098d8, 7);
    MD5STEP(F1, d, a, b, c, in[9] + 0x8b44f7af, 12);
    MD5STEP(F1, c, d, a, b, in[10] + 0xffff5bb1, 17);
    MD5STEP(F1, b, c, d, a, in[11] + 0x895cd7be, 22);
    MD5STEP(F1, a, b, c, d, in[12] + 0x6b901122, 7);
    MD5STEP(F1, d, a, b, c, in[13] + 0xfd987193, 12);
    MD5STEP(F1, c, d, a, b, in[14] + 0xa679438e, 17);
    MD5STEP(F1, b, c, d, a, in[15] + 0x49b40821, 22);

    MD5STEP(F2, a, b, c, d, in[1] + 0xf61e2562, 5);
    MD5STEP(F2, d, a, b, c, in[6] + 0xc040b340, 9);
    MD5STEP(F2, c, d, a, b, in[11] + 0x265e5a51, 14);
    MD5STEP(F2, b, c, d, a, in[0] + 0xe9b6c7aa, 20);
    MD5STEP(F2, a, b, c, d, in[5] + 0xd62f105d, 5);
    MD5STEP(F2, d, a, b, c, in[10] + 0x02441453, 9);
    MD5STEP(F2, c, d, a, b, in[15] + 0xd8a1e681, 14);
    MD5STEP(F2, b, c, d, a, in[4] + 0xe7d3fbc8, 20);
    MD5STEP(F2, a, b, c, d, in[9] + 0x21e1cde6, 5);
    MD5STEP(F2, d, a, b, c, in[14] + 0xc33707d6, 9);
    MD5STEP(F2, c, d, a, b, in[3] + 0xf4d50d87, 14);
    MD5STEP(F2, b, c, d, a, in[8] + 0x455a14ed, 20);
    MD5STEP(F2, a, b, c, d, in[13] + 0xa9e3e905, 5);
    MD5STEP(F2, d, a, b, c, in[2] + 0xfcefa3f8, 9);
    MD5STEP(F2, c, d, a, b, in[7] + 0x676f02d9, 14);
    MD5STEP(F2, b, c, d, a, in[12] + 0x8d2a4c8a, 20);

    MD5STEP(F3, a, b, c, d, in[5] + 0xfffa3942, 4);
    MD5STEP(F3, d, a, b, c, in[8] + 0x8771f681, 11);
    MD5STEP(F3, c, d, a, b, in[11] + 0x6d9d6122, 16);
    MD5STEP(F3, b, c, d, a, in[14] + 0xfde5380c, 23);
    MD5STEP(F3, a, b, c, d, in[1] + 0xa4beea44, 4);
    MD5STEP(F3, d, a, b, c, in[4] + 0x4bdecfa9, 11);
    MD5STEP(F3, c, d, a, b, in[7] + 0xf6bb4b60, 16);
    MD5STEP(F3, b, c, d, a, in[10] + 0xbebfbc70, 23);
    MD5STEP(F3, a, b, c, d, in[13] + 0x289b7ec6, 4);
    MD5STEP(F3, d, a, b, c, in[0] + 0xeaa127fa, 11);
    MD5STEP(F3, c, d, a, b, in[3] + 0xd4ef3085, 16);
    MD5STEP(F3, b, c, d, a, in[6] + 0x04881d05, 23);
    MD5STEP(F3, a, b, c, d, in[9] + 0xd9d4d039, 4);
    MD5STEP(F3, d, a, b, c, in[12] + 0xe6db99e5, 11);
    MD5STEP(F3, c, d, a, b, in[15] + 0x1fa27cf8, 16);
    MD5STEP(F3, b, c, d, a, in[2] + 0xc4ac5665, 23);

    MD5STEP(F4, a, b, c, d, in[0] + 0xf4292244, 6);
    MD5STEP(F4, d, a, b, c, in[7] + 0x432aff97, 10);
    MD5STEP(F4, c, d, a, b, in[14] + 0xab9423a7, 15);
    MD5STEP(F4, b, c, d, a, in[5] + 0xfc93a039, 21);
    MD5STEP(F4, a, b, c, d, in[12] + 0x655b59c3, 6);
    MD5STEP(F4, d, a, b, c, in[3] + 0x8f0ccc92, 10);
    MD5STEP(F4, c, d, a, b, in[10] + 0xffeff47d, 15);
    MD5STEP(F4, b, c, d, a, in[1] + 0x85845dd1, 21);
    MD5STEP(F4, a, b, c, d, in[8] + 0x6fa87e4f, 6);
    MD5STEP(F4, d, a, b, c, in[15] + 0xfe2ce6e0, 10);
    MD5STEP(F4, c, d, a, b, in[6] + 0xa3014314, 15);
    MD5STEP(F4, b, c, d, a, in[13] + 0x4e0811a1, 21);
    MD5STEP(F4, a, b, c, d, in[4] + 0xf7537e82, 6);
    MD5STEP(F4, d, a, b, c, in[11] + 0xbd3af235, 10);
    MD5STEP(F4, c, d, a, b, in[2] + 0x2ad7d2bb, 15);
    MD5STEP(F4, b, c, d, a, in[9] + 0xeb86d391, 21);

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

---