path: root/rpmio/md5.c

/** \ingroup signature
 * \file rpmio/md5.c
 *
 * 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 "system.h"

#include "rpmio_internal.h"

typedef unsigned int uint32;
typedef unsigned char byte;

/**
 * The MD5 block size and message digest sizes, in bytes.
 */
#define MD5_DATASIZE    64
#define MD5_DATALEN     16
#define MD5_DIGESTSIZE  16
#define MD5_DIGESTLEN    4

/**
 * MD5 private data.
 */
typedef struct MD5Context_s {
    uint32 digest[MD5_DIGESTLEN];	/*!< Message digest. */
    uint32 bits[2];
    byte in[MD5_DATASIZE];	/*!< Data buffer. */
    int doByteReverse;
} * MD5Context;

static int _ie = 0x44332211;
static union _mendian { int i; char b[4]; } *_endian = (union _mendian *)&_ie;
#define	IS_BIG_ENDIAN()		(_endian->b[0] == '\x44')
#define	IS_LITTLE_ENDIAN()	(_endian->b[0] == '\x11')

/* 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.
 * @param private	MD5 private data
 */
static void
MD5Transform(void * private)
{
    MD5Context ctx = (MD5Context) private;
    register uint32 * in = (uint32 *)ctx->in;
    register uint32 a = ctx->digest[0];
    register uint32 b = ctx->digest[1];
    register uint32 c = ctx->digest[2];
    register uint32 d = ctx->digest[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);

    ctx->digest[0] += a;
    ctx->digest[1] += b;
    ctx->digest[2] += c;
    ctx->digest[3] += d;
}

/*
 * Note: this code is harmless on little-endian machines.
 */
static void
byteReverse(byte *buf, unsigned longs)
{
    uint32 t;
    do {
	t = (uint32) ((unsigned) buf[3] << 8 | buf[2]) << 16 |
	    ((unsigned) buf[1] << 8 | buf[0]);
	*(uint32 *) buf = t;
	buf += 4;
    } while (--longs);
}

/**
 * Initialize MD5 hash.
 * Set bit count to 0 and buffer to mysterious initialization constants.
 * @param brokenEndian	calculate broken MD5 sum?
 * @return		MD5 private data
 */
static void *
MD5Init(int brokenEndian)
{
    MD5Context ctx = xcalloc(1, sizeof(*ctx));

    ctx->digest[0] = 0x67452301;
    ctx->digest[1] = 0xefcdab89;
    ctx->digest[2] = 0x98badcfe;
    ctx->digest[3] = 0x10325476;

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

    if (IS_BIG_ENDIAN())
	ctx->doByteReverse = (brokenEndian ? 0 : 1);
    else
	ctx->doByteReverse = 0;
    return ctx;
}

/**
 * Update context to reflect the concatenation of another buffer full
 * of bytes.
 * @param private	private data
 * @param data		next data buffer
 * @param len		no. bytes of data
 */
static void
MD5Update(void * private, const void * data, size_t len)
{
    MD5Context ctx = (MD5Context) private;
    const byte * buf = data;
    uint32 t;

    /* Update bitcount */

    t = ctx->bits[0];
    if ((ctx->bits[0] = t + ((uint32) len << 3)) < t)
	ctx->bits[1]++;		/* Carry from low to high */
    ctx->bits[1] += len >> 29;

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

    /* Handle any leading odd-sized chunks */

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

	t = MD5_DATASIZE - t;	/* Bytes left in ctx->in */
	if (len < t) {
	    memcpy(p, buf, len);
	    return;
	}
	memcpy(p, buf, t);
	if (ctx->doByteReverse)
	    byteReverse(ctx->in, 16);
	MD5Transform(ctx);
	buf += t;
	len -= t;
    }

    /* Process data in MD5_DATASIZE chunks */

    for (; len >= MD5_DATASIZE; buf += MD5_DATASIZE, len -= MD5_DATASIZE) {
	memcpy(ctx->in, buf, MD5_DATASIZE);
	if (ctx->doByteReverse)
	    byteReverse(ctx->in, 16);
	MD5Transform(ctx);
    }

    /* Handle any remaining bytes of data. */
    memcpy(ctx->in, buf, len);
}

/**
 * Return MD5 sum and destroy context.
 * Final wrapup - pad to 64-byte boundary with the bit pattern 
 * 1 0* (64-bit count of bits processed, MSB-first)
 *
 * @param private	private data
 * @retval datap	address of returned digest
 * @retval lenp		address of digest length
 * @param asAscii	return digest as ascii string?
 */
static void
MD5Final(/*@only@*/ void * private, /*@out@*/ void ** datap,
	/*@out@*/ size_t *lenp, int asAscii)
{
    MD5Context ctx = (MD5Context) private;
    unsigned count;
    byte *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 = MD5_DATASIZE - 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);
	if (ctx->doByteReverse)
	    byteReverse(ctx->in, 16);
	MD5Transform(ctx);

	/* Now fill the next block with 56 bytes */
	memset(ctx->in, 0, 56);
    } else {
	/* Pad block to 56 bytes */
	memset(p, 0, count - 8);
    }
    if (ctx->doByteReverse)
	byteReverse(ctx->in, 14);

    /* Append length in bits and transform */
    ((uint32 *) ctx->in)[14] = ctx->bits[0];
    ((uint32 *) ctx->in)[15] = ctx->bits[1];

    MD5Transform(ctx);

    if (ctx->doByteReverse)
	byteReverse((byte *) ctx->digest, MD5_DIGESTLEN);

    if (!asAscii) {
	if (lenp) *lenp = MD5_DIGESTSIZE;
	if (datap) {
	    *datap = xmalloc(MD5_DIGESTSIZE);
	    memcpy(*datap, ctx->digest, MD5_DIGESTSIZE);
	}
    } else {
	if (lenp) *lenp = (2*MD5_DIGESTSIZE) + 1;
	if (datap) {
	    const byte * s = (const byte *) ctx->digest;
	    static const char hex[] = "0123456789abcdef";
	    char * t;
	    int i;

	    *datap = t = xmalloc((2*MD5_DIGESTSIZE) + 1);

	    for (i = 0 ; i < MD5_DIGESTSIZE; i++) {
		*t++ = hex[ (unsigned)((*s >> 4) & 0x0f) ];
		*t++ = hex[ (unsigned)((*s++   ) & 0x0f) ];
	    }
	    *t = '\0';
	}
    }
    memset(ctx, 0, sizeof(*ctx));	/* In case it's sensitive */
    free(ctx);
}

/**
 * MD5 transform vectors.
 */
FDHASH_t rpmio_md5hash = {
    NULL, MD5Init, MD5Update, MD5Final, MD5Transform
};