hmac_md5函数

void
hmac_md5(
     unsigned char*  text,                /* pointer to data stream */
     int             text_len,            /* length of data stream */
     unsigned char*  key,                 /* pointer to authentication key */
     int             key_len,             /* length of authentication key */
     unsigned char*  digest               /* caller digest to be filled in */
     )


{
        MD5_CTX context;
        unsigned char k_ipad[65];    /* inner padding -
                                      * key XORd with ipad
                                      */
        unsigned char k_opad[65];    /* outer padding -
                                      * key XORd with opad
                                      */
        unsigned char tk[16];
        int i;
        /* if key is longer than 64 bytes reset it to key=MD5(key) */
        if (key_len > 64) {

                MD5_CTX      tctx;

                MD5Init(&tctx);
                MD5Update(&tctx, key, key_len);
                MD5Final(tk, &tctx);

                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( k_opad, 0, sizeof(k_opad));
        memcpy( k_ipad, key, key_len);
        memcpy( k_opad, key, key_len);

        /* XOR key with ipad and opad values */
        for (i=0; i<64; i++) {
                k_ipad[i] ^= 0x36;
                k_opad[i] ^= 0x5c;
        }
        /*
         * perform inner MD5
         */
        MD5Init(&context);                   /* init context for 1st
                                              * pass */
        MD5Update(&context, k_ipad, 64);      /* start with inner pad */
        MD5Update(&context, text, text_len); /* then text of datagram */
        MD5Final(digest, &context);          /* finish up 1st pass */
        /*
         * perform outer MD5
         */
        MD5Init(&context);                   /* init context for 2nd
                                              * pass */
        MD5Update(&context, k_opad, 64);     /* start with outer pad */
        MD5Update(&context, digest, 16);     /* then results of 1st
                                              * hash */
        MD5Final(digest, &context);          /* finish up 2nd pass */
}

/*
 * md5.h        Structures and prototypes for md5.
 *
 * Version:     $Id: md5.h,v 1.2 2007/06/21 18:07:24 cparker Exp $
 * License:    BSD, but largely derived from a public domain source.
 *
 */

#ifndef _RCRAD_MD5_H
#define _RCRAD_MD5_H

//#include "config.h"

#ifdef HAVE_NETTLE

#include <nettle/md5-compat.h>

#else

#ifdef HAVE_INTTYPES_H
#include <inttypes.h>
#endif

#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif

#ifdef HAVE_STDINT_H
#include <stdint.h>
#endif

#include <string.h>
/*
 *  FreeRADIUS Client defines to ensure globally unique MD5 function names,
 *  so that we don‘t pick up vendor-specific broken MD5 libraries.
 */
#define MD5_CTX        librad_MD5_CTX
#define MD5Init        librad_MD5Init
#define MD5Update    librad_MD5Update
#define MD5Final    librad_MD5Final
#define MD5Transform    librad_MD5Transform

/*  The below was retrieved from
 *  http://www.openbsd.org/cgi-bin/cvsweb/~checkout~/src/sys/crypto/md5.h?rev=1.1
 *  With the following changes: uint64_t => unsigned int[2]
 *  Commented out #include <sys/cdefs.h>
 *  Commented out the __BEGIN and __END _DECLS, and the __attributes.
 */

/*
 * 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.
 */

#define    MD5_BLOCK_LENGTH        64
#define    MD5_DIGEST_LENGTH        16

typedef struct MD5Context {
    unsigned int state[4];            /* state */
    unsigned int count[2];            /* number of bits, mod 2^64 */
    unsigned char buffer[MD5_BLOCK_LENGTH];    /* input buffer */
} MD5_CTX;

/* include <sys/cdefs.h> */

/* __BEGIN_DECLS */
void     MD5Init(MD5_CTX *);
void     MD5Update(MD5_CTX *, unsigned char const *, size_t)
/*        __attribute__((__bounded__(__string__,2,3)))*/;
void     MD5Final(unsigned char [MD5_DIGEST_LENGTH], MD5_CTX *)
/*        __attribute__((__bounded__(__minbytes__,1,MD5_DIGEST_LENGTH)))*/;
void     MD5Transform(unsigned int [4], unsigned char const [MD5_BLOCK_LENGTH])
/*        __attribute__((__bounded__(__minbytes__,1,4)))*/
/*        __attribute__((__bounded__(__minbytes__,2,MD5_BLOCK_LENGTH)))*/;
/* __END_DECLS */

#endif /* HAVE_NETTLE */

#endif /* _RCRAD_MD5_H */

#include "md5.h"

/*    The below was retrieved from
 *    http://www.openbsd.org/cgi-bin/cvsweb/~checkout~/src/sys/crypto/md5.c?rev=1.1
 *    with the following changes:
 *    #includes commented out.
 *    Support context->count as unsigned int[2] instead of uint64_t
 *    u_int* to uint*
 */

/*
 * 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/param.h>*/
/*#include <sys/systm.h>*/
/*#include <crypto/md5.h>*/

#define PUT_64BIT_LE(cp, value) do {                \
    (cp)[7] = (value)[1] >> 24;                        (cp)[6] = (value)[1] >> 16;                        (cp)[5] = (value)[1] >> 8;                        (cp)[4] = (value)[1];                            (cp)[3] = (value)[0] >> 24;                        (cp)[2] = (value)[0] >> 16;                        (cp)[1] = (value)[0] >> 8;                        (cp)[0] = (value)[0]; } while (0)

#define PUT_32BIT_LE(cp, value) do {                    \
    (cp)[3] = (value) >> 24;                        (cp)[2] = (value) >> 16;                        (cp)[1] = (value) >> 8;                            (cp)[0] = (value); } while (0)

static unsigned char PADDING[MD5_BLOCK_LENGTH] = {
    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
};

/*
 * Start MD5 accumulation.  Set bit count to 0 and buffer to mysterious
 * initialization constants.
 */
void
MD5Init(MD5_CTX *ctx)
{
    ctx->count[0] = 0;
    ctx->count[1] = 0;
    ctx->state[0] = 0x67452301;
    ctx->state[1] = 0xefcdab89;
    ctx->state[2] = 0x98badcfe;
    ctx->state[3] = 0x10325476;
}

/*
 * Update context to reflect the concatenation of another buffer full
 * of bytes.
 */
void
MD5Update(MD5_CTX *ctx, unsigned char const *input, size_t len)
{
    size_t have, need;

    /* Check how many bytes we already have and how many more we need. */
    have = (size_t)((ctx->count[0] >> 3) & (MD5_BLOCK_LENGTH - 1));
    need = MD5_BLOCK_LENGTH - have;

    /* Update bitcount */
/*    ctx->count += (uint64_t)len << 3;*/
    if ((ctx->count[0] += ((unsigned int)len << 3)) < (unsigned int)len) {
    /* Overflowed ctx->count[0] */
        ctx->count[1]++;
    }
    ctx->count[1] += ((unsigned int)len >> 29);



    if (len >= need) {
        if (have != 0) {
            memcpy(ctx->buffer + have, input, need);
            MD5Transform(ctx->state, ctx->buffer);
            input += need;
            len -= need;
            have = 0;
        }

        /* Process data in MD5_BLOCK_LENGTH-byte chunks. */
        while (len >= MD5_BLOCK_LENGTH) {
            MD5Transform(ctx->state, input);
            input += MD5_BLOCK_LENGTH;
            len -= MD5_BLOCK_LENGTH;
        }
    }

    /* Handle any remaining bytes of data. */
    if (len != 0)
        memcpy(ctx->buffer + have, input, len);
}

/*
 * Final wrapup - pad to 64-byte boundary with the bit pattern
 * 1 0* (64-bit count of bits processed, MSB-first)
 */
void
MD5Final(unsigned char digest[MD5_DIGEST_LENGTH], MD5_CTX *ctx)
{
    unsigned char count[8];
    size_t padlen;
    int i;

    /* Convert count to 8 bytes in little endian order. */
    PUT_64BIT_LE(count, ctx->count);

    /* Pad out to 56 mod 64. */
    padlen = MD5_BLOCK_LENGTH -
        ((ctx->count[0] >> 3) & (MD5_BLOCK_LENGTH - 1));
    if (padlen < 1 + 8)
        padlen += MD5_BLOCK_LENGTH;
    MD5Update(ctx, PADDING, padlen - 8);        /* padlen - 8 <= 64 */
    MD5Update(ctx, count, 8);

    if (digest != NULL) {
        for (i = 0; i < 4; i++)
            PUT_32BIT_LE(digest + i * 4, ctx->state[i]);
    }
    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.
 */
void
MD5Transform(unsigned int state[4], unsigned char const block[MD5_BLOCK_LENGTH])
{
    unsigned int a, b, c, d, in[MD5_BLOCK_LENGTH / 4];

    for (a = 0; a < MD5_BLOCK_LENGTH / 4; a++) {
        in[a] = (unsigned int)(
            (unsigned int)(block[a * 4 + 0]) |
            (unsigned int)(block[a * 4 + 1]) <<  8 |
            (unsigned int)(block[a * 4 + 2]) << 16 |
            (unsigned int)(block[a * 4 + 3]) << 24);
    }

    a = state[0];
    b = state[1];
    c = state[2];
    d = state[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);

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