/*
 * Copyright (C) 2003-2006 Benny Prijono <benny@prijono.org>
 * Copyright (C) 2012      C Elston, Katalix Systems Ltd <celston@katalix.com>
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 *
 *  2012-08-21 - C Elston - Split md5_hmac function to allow incremental usage.
 *
 */


#include "config.h"

#include <string.h>

#include "pint.h"
#include "md5.h"
/*
 * 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.
 */

#if WORDS_BIGENDIAN == 1
#define HIGHFIRST 1
#endif

#ifndef HIGHFIRST
#define byteReverse(buf, len)    /* Nothing */
#else
/*
 * Note: this code is harmless on little-endian machines.
 */
static void byteReverse(guint32 *buf, unsigned int longs)
{
    guint32 t;
    do {
        t = pletoh32(buf);
        *buf = t;
        buf++;
    } while (--longs);
}
#endif

static void MD5Transform(guint32 buf[4], guint32 const in[16]);


/*
 * Start MD5 accumulation.  Set bit count to 0 and buffer to mysterious
 * initialization constants.
 */
void md5_init(md5_state_t *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( md5_state_t *ctx, const guint8 *buf, size_t len)
{
    guint32 t;

    /* Update bitcount */

    t = ctx->bits[0];
    if ((ctx->bits[0] = t + ((guint32) len << 3)) < t)
        ctx->bits[1]++;         /* Carry from low to high */
    ctx->bits[1] += (guint32) len >> 29;

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

    /* Handle any leading odd-sized chunks */

    if (t) {
        guint8 *p = (guint8 *) ctx->in + t;

        t = 64 - t;
        if (len < t) {
            memcpy(p, buf, len);
            return;
        }
        memcpy(p, buf, t);
        byteReverse(ctx->in, 16);
        MD5Transform(ctx->buf, ctx->in);
        buf += t;
        len -= t;
    }
    /* Process data in 64-byte chunks */

    while (len >= 64) {
        memcpy(ctx->in, buf, 64);
        byteReverse(ctx->in, 16);
        MD5Transform(ctx->buf, 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(md5_state_t *ctx, guint8 digest[16])
{
    guint count;
    guint8 *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 = (guint8 *) 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);
        byteReverse(ctx->in, 16);
        MD5Transform(ctx->buf, 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);
    }
    byteReverse(ctx->in, 14);

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

    MD5Transform(ctx->buf, ctx->in);
    byteReverse(ctx->buf, 4);
    memcpy(digest, ctx->buf, 16);
    memset(ctx, 0, sizeof(md5_state_t));    /* 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 MD5Transform(guint32 buf[4], guint32 const in[16])
{
    register guint32 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;
}

/* from RFC 2104 HMAC  Appendix -- Sample Code */

void md5_hmac_init(md5_hmac_state_t *hctx, const guint8* key, size_t key_len)
{
    guint8 k_ipad[65];    /* inner padding - * key XORd with ipad */
    guint8 tk[16];
    int i;

    /* if key is longer than 64 bytes reset it to key=MD5(key) */
    if (key_len > 64) {
        md5_state_t tctx;

        md5_init(&tctx);
        md5_append(&tctx, key, key_len);
        md5_finish(&tctx, tk);

        key = tk;
        key_len = 16;
    }

    /*
     * the HMAC_MD5 transform looks like:
     *
     * MD5(K XOR opad, MD5(K XOR ipad, text))
     *
     * where K is an n byte key
     * ipad is the byte 0x36 repeated 64 times
     * opad is the byte 0x5c repeated 64 times
     * and text is the data being protected
     */

    /* start out by storing key in pads */
    memset(k_ipad, 0, sizeof(k_ipad));
    memset(hctx->k_opad, 0, sizeof(hctx->k_opad));
    memcpy(k_ipad, key, key_len);
    memcpy(hctx->k_opad, key, key_len);

    /* XOR key with ipad and opad values */
    for (i=0; i<64; i++) {
        k_ipad[i] ^= 0x36;
        hctx->k_opad[i] ^= 0x5c;
    }

    /*
     * perform inner MD5
     */
    md5_init(&hctx->ctx);                   /* init context for 1st  pass */
    md5_append(&hctx->ctx, k_ipad, 64);     /* start with inner pad */
}

void md5_hmac_append(md5_hmac_state_t *hctx, const guint8* text, size_t text_len)
{
    md5_append(&hctx->ctx, text, text_len);
}

void md5_hmac_finish(md5_hmac_state_t *hctx, guint8 digest[16])
{
    md5_state_t context;

    md5_finish(&hctx->ctx, digest);          /* finish up 1st pass */

    /*
     * perform outer MD5
     */
    md5_init(&context);                     /* init context for 2nd pass */
    md5_append(&context, hctx->k_opad, 64); /* start with outer pad */
    md5_append(&context, digest, 16);       /* then results of 1st hash */
    md5_finish(&context, digest);           /* finish up 2nd pass */
}

void md5_hmac(const guint8* text, size_t text_len, const guint8* key, size_t key_len, guint8 digest[16])
{
    md5_hmac_state_t hctx;

    md5_hmac_init(&hctx, key, key_len);
    md5_hmac_append(&hctx, text, text_len);
    md5_hmac_finish(&hctx, digest);
}

/*
 * Editor modelines  -  http://www.wireshark.org/tools/modelines.html
 *
 * Local variables:
 * c-basic-offset: 4
 * tab-width: 8
 * indent-tabs-mode: nil
 * End:
 *
 * vi: set shiftwidth=4 tabstop=8 expandtab:
 * :indentSize=4:tabSize=8:noTabs=true:
 */