source: lib/md5.c @ 3e1ef92c

/*
 * MD5 hashing code copied from Lepton's crack <http://usuarios.lycos.es/reinob/>
 *
 * Adapted to be API-compatible with the previous (GPL-incompatible) code.
 */

/*
 * This code implements the MD5 message-digest algorithm.
 * The algorithm is due to Ron Rivest.  This code was
 * written by Colin Plumb in 1993, no copyright is claimed.
 * This code is in the public domain; do with it what you wish.
 *
 * Equivalent code is available from RSA Data Security, Inc.
 * This code has been tested against that, and is equivalent,
 * except that you don't need to include two pages of legalese
 * with every copy.
 *
 * To compute the message digest of a chunk of bytes, declare an
 * MD5Context structure, pass it to MD5Init, call MD5Update as
 * needed on buffers full of bytes, and then call MD5Final, which
 * will fill a supplied 16-byte array with the digest.
 */

#include <sys/types.h>
#include <string.h>             /* for memcpy() */
#include "md5.h"

static void md5_transform(uint32_t buf[4], uint32_t const in[16]);

/*
 * Wrapper function for all-in-one MD5
 *
 * Bernardo Reino, aka Lepton.
 * 20021120
 */

/* Turns out MD5 was designed for little-endian machines. If we're running
   on a big-endian machines, we have to swap some bytes. Since detecting
   endianness at compile time reliably seems pretty hard, let's do it at
   run-time. It's not like we're going to checksum megabytes of data... */
static uint32_t cvt32(uint32_t val)
{
        static int little_endian = -1;
        
        if (little_endian == -1)
        {
                little_endian = 1;
                little_endian = *((char*) &little_endian);
        }
        
        if (little_endian)
                return val;
        else
                return (val >> 24) |
                       ((val >> 8) & 0xff00) |
                       ((val << 8) & 0xff0000) |
                       (val << 24);
}

void md5_init(struct MD5Context *ctx)
{
        ctx->buf[0] = 0x67452301;
        ctx->buf[1] = 0xefcdab89;
        ctx->buf[2] = 0x98badcfe;
        ctx->buf[3] = 0x10325476;

        ctx->bits[0] = 0;
        ctx->bits[1] = 0;
}

/*
 * Update context to reflect the concatenation of another buffer full
 * of bytes.
 */
void md5_append(struct MD5Context *ctx, const md5_byte_t *buf,
                unsigned int len)
{
        uint32_t t;

        /* Update bitcount */

        t = ctx->bits[0];
        if ((ctx->bits[0] = t + ((uint32_t) len << 3)) < t)
                ctx->bits[1]++; /* Carry from low to high */
        ctx->bits[1] += len >> 29;

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

        /* Handle any leading odd-sized chunks */

        if (t) {
                unsigned char *p = (unsigned char *) ctx->in + t;

                t = 64 - t;
                if (len < t) {
                        memcpy(p, buf, len);
                        return;
                }
                memcpy(p, buf, t);
                md5_transform(ctx->buf, (uint32_t *) ctx->in);
                buf += t;
                len -= t;
        }
        /* Process data in 64-byte chunks */

        while (len >= 64) {
                memcpy(ctx->in, buf, 64);
                md5_transform(ctx->buf, (uint32_t *) ctx->in);
                buf += 64;
                len -= 64;
        }

        /* Handle any remaining bytes of data. */

        memcpy(ctx->in, buf, len);
}

/*
 * Final wrapup - pad to 64-byte boundary with the bit pattern 
 * 1 0* (64-bit count of bits processed, MSB-first)
 */
void md5_finish(struct MD5Context *ctx, md5_byte_t digest[16])
{
        unsigned count;
        unsigned char *p;

        /* Compute number of bytes mod 64 */
        count = (ctx->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 = ctx->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);
                md5_transform(ctx->buf, (uint32_t *) ctx->in);

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

        /* Append length in bits and transform */
        ((uint32_t *) ctx->in)[14] = cvt32(ctx->bits[0]);
        ((uint32_t *) ctx->in)[15] = cvt32(ctx->bits[1]);

        md5_transform(ctx->buf, (uint32_t *) ctx->in);
        ctx->buf[0] = cvt32(ctx->buf[0]);
        ctx->buf[1] = cvt32(ctx->buf[1]);
        ctx->buf[2] = cvt32(ctx->buf[2]);
        ctx->buf[3] = cvt32(ctx->buf[3]);
        memcpy(digest, ctx->buf, 16);
        memset(ctx, 0, sizeof(ctx));    /* In case it's sensitive */
}

/* 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))

/* This is the central step in the MD5 algorithm. */
#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.
 */
static void md5_transform(uint32_t buf[4], uint32_t const in[16])
{
        register uint32_t a, b, c, d;

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

        MD5STEP(F1, a, b, c, d, cvt32(in[0]) + 0xd76aa478, 7);
        MD5STEP(F1, d, a, b, c, cvt32(in[1]) + 0xe8c7b756, 12);
        MD5STEP(F1, c, d, a, b, cvt32(in[2]) + 0x242070db, 17);
        MD5STEP(F1, b, c, d, a, cvt32(in[3]) + 0xc1bdceee, 22);
        MD5STEP(F1, a, b, c, d, cvt32(in[4]) + 0xf57c0faf, 7);
        MD5STEP(F1, d, a, b, c, cvt32(in[5]) + 0x4787c62a, 12);
        MD5STEP(F1, c, d, a, b, cvt32(in[6]) + 0xa8304613, 17);
        MD5STEP(F1, b, c, d, a, cvt32(in[7]) + 0xfd469501, 22);
        MD5STEP(F1, a, b, c, d, cvt32(in[8]) + 0x698098d8, 7);
        MD5STEP(F1, d, a, b, c, cvt32(in[9]) + 0x8b44f7af, 12);
        MD5STEP(F1, c, d, a, b, cvt32(in[10]) + 0xffff5bb1, 17);
        MD5STEP(F1, b, c, d, a, cvt32(in[11]) + 0x895cd7be, 22);
        MD5STEP(F1, a, b, c, d, cvt32(in[12]) + 0x6b901122, 7);
        MD5STEP(F1, d, a, b, c, cvt32(in[13]) + 0xfd987193, 12);
        MD5STEP(F1, c, d, a, b, cvt32(in[14]) + 0xa679438e, 17);
        MD5STEP(F1, b, c, d, a, cvt32(in[15]) + 0x49b40821, 22);

        MD5STEP(F2, a, b, c, d, cvt32(in[1]) + 0xf61e2562, 5);
        MD5STEP(F2, d, a, b, c, cvt32(in[6]) + 0xc040b340, 9);
        MD5STEP(F2, c, d, a, b, cvt32(in[11]) + 0x265e5a51, 14);
        MD5STEP(F2, b, c, d, a, cvt32(in[0]) + 0xe9b6c7aa, 20);
        MD5STEP(F2, a, b, c, d, cvt32(in[5]) + 0xd62f105d, 5);
        MD5STEP(F2, d, a, b, c, cvt32(in[10]) + 0x02441453, 9);
        MD5STEP(F2, c, d, a, b, cvt32(in[15]) + 0xd8a1e681, 14);
        MD5STEP(F2, b, c, d, a, cvt32(in[4]) + 0xe7d3fbc8, 20);
        MD5STEP(F2, a, b, c, d, cvt32(in[9]) + 0x21e1cde6, 5);
        MD5STEP(F2, d, a, b, c, cvt32(in[14]) + 0xc33707d6, 9);
        MD5STEP(F2, c, d, a, b, cvt32(in[3]) + 0xf4d50d87, 14);
        MD5STEP(F2, b, c, d, a, cvt32(in[8]) + 0x455a14ed, 20);
        MD5STEP(F2, a, b, c, d, cvt32(in[13]) + 0xa9e3e905, 5);
        MD5STEP(F2, d, a, b, c, cvt32(in[2]) + 0xfcefa3f8, 9);
        MD5STEP(F2, c, d, a, b, cvt32(in[7]) + 0x676f02d9, 14);
        MD5STEP(F2, b, c, d, a, cvt32(in[12]) + 0x8d2a4c8a, 20);

        MD5STEP(F3, a, b, c, d, cvt32(in[5]) + 0xfffa3942, 4);
        MD5STEP(F3, d, a, b, c, cvt32(in[8]) + 0x8771f681, 11);
        MD5STEP(F3, c, d, a, b, cvt32(in[11]) + 0x6d9d6122, 16);
        MD5STEP(F3, b, c, d, a, cvt32(in[14]) + 0xfde5380c, 23);
        MD5STEP(F3, a, b, c, d, cvt32(in[1]) + 0xa4beea44, 4);
        MD5STEP(F3, d, a, b, c, cvt32(in[4]) + 0x4bdecfa9, 11);
        MD5STEP(F3, c, d, a, b, cvt32(in[7]) + 0xf6bb4b60, 16);
        MD5STEP(F3, b, c, d, a, cvt32(in[10]) + 0xbebfbc70, 23);
        MD5STEP(F3, a, b, c, d, cvt32(in[13]) + 0x289b7ec6, 4);
        MD5STEP(F3, d, a, b, c, cvt32(in[0]) + 0xeaa127fa, 11);
        MD5STEP(F3, c, d, a, b, cvt32(in[3]) + 0xd4ef3085, 16);
        MD5STEP(F3, b, c, d, a, cvt32(in[6]) + 0x04881d05, 23);
        MD5STEP(F3, a, b, c, d, cvt32(in[9]) + 0xd9d4d039, 4);
        MD5STEP(F3, d, a, b, c, cvt32(in[12]) + 0xe6db99e5, 11);
        MD5STEP(F3, c, d, a, b, cvt32(in[15]) + 0x1fa27cf8, 16);
        MD5STEP(F3, b, c, d, a, cvt32(in[2]) + 0xc4ac5665, 23);

        MD5STEP(F4, a, b, c, d, cvt32(in[0]) + 0xf4292244, 6);
        MD5STEP(F4, d, a, b, c, cvt32(in[7]) + 0x432aff97, 10);
        MD5STEP(F4, c, d, a, b, cvt32(in[14]) + 0xab9423a7, 15);
        MD5STEP(F4, b, c, d, a, cvt32(in[5]) + 0xfc93a039, 21);
        MD5STEP(F4, a, b, c, d, cvt32(in[12]) + 0x655b59c3, 6);
        MD5STEP(F4, d, a, b, c, cvt32(in[3]) + 0x8f0ccc92, 10);
        MD5STEP(F4, c, d, a, b, cvt32(in[10]) + 0xffeff47d, 15);
        MD5STEP(F4, b, c, d, a, cvt32(in[1]) + 0x85845dd1, 21);
        MD5STEP(F4, a, b, c, d, cvt32(in[8]) + 0x6fa87e4f, 6);
        MD5STEP(F4, d, a, b, c, cvt32(in[15]) + 0xfe2ce6e0, 10);
        MD5STEP(F4, c, d, a, b, cvt32(in[6]) + 0xa3014314, 15);
        MD5STEP(F4, b, c, d, a, cvt32(in[13]) + 0x4e0811a1, 21);
        MD5STEP(F4, a, b, c, d, cvt32(in[4]) + 0xf7537e82, 6);
        MD5STEP(F4, d, a, b, c, cvt32(in[11]) + 0xbd3af235, 10);
        MD5STEP(F4, c, d, a, b, cvt32(in[2]) + 0x2ad7d2bb, 15);
        MD5STEP(F4, b, c, d, a, cvt32(in[9]) + 0xeb86d391, 21);

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