common/dst/hmac_link.c

/*
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */


#ifdef HMAC_MD5
#ifndef LINT
static const char rcsid[] = "$Header: /proj/cvs/prod/libbind/dst/hmac_link.c,v 1.8 2007/09/24 17:18:25 each Exp $";
#endif
/*
 * Portions Copyright (c) 1995-1998 by Trusted Information Systems, Inc.
 *
 * Permission to use, copy modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND TRUSTED INFORMATION SYSTEMS
 * DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL
 * TRUSTED INFORMATION SYSTEMS BE LIABLE FOR ANY SPECIAL, DIRECT,
 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
 * FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
 * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
 * WITH THE USE OR PERFORMANCE OF THE SOFTWARE.
 */

/*%
 * This file contains an implementation of the HMAC-MD5 algorithm.
 */
#include "port_before.h"

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <memory.h>
#include <sys/param.h>
#include <sys/time.h>
#include <netinet/in.h>
#include <arpa/nameser.h>
#include <resolv.h>

#include "dst_internal.h"

#ifdef USE_MD5
# ifndef HAVE_MD5
#  include "md5.h"
# else
#  ifdef SOLARIS2
#   include <sys/md5.h>
#  endif
# endif
# ifndef _MD5_H_
#  define _MD5_H_ 1 /*%< make sure we do not include rsaref md5.h file */
# endif
#endif

#include "port_after.h"


#define HMAC_LEN    64
#define HMAC_IPAD   0x36
#define HMAC_OPAD   0x5c
#define MD5_LEN     16


typedef struct hmackey {
    u_char hk_ipad[64], hk_opad[64];
} HMAC_Key;


/**************************************************************************
 * dst_hmac_md5_sign
 *     Call HMAC signing functions to sign a block of data.
 *     There are three steps to signing, INIT (initialize structures),
 *     UPDATE (hash (more) data), FINAL (generate a signature).  This
 *     routine performs one or more of these steps.
 * Parameters
 *     mode SIG_MODE_INIT, SIG_MODE_UPDATE and/or SIG_MODE_FINAL.
 *     priv_key    key to use for signing.
 *     context   the context to be used in this digest
 *     data data to be signed.
 *     len   length in bytes of data.
 *     signature   location to store signature.
 *     sig_len     size of the signature location
 * returns
 *  N  Success on SIG_MODE_FINAL = returns signature length in bytes
 *  0  Success on SIG_MODE_INIT  and UPDATE
 *   <0  Failure
 */

static int
dst_hmac_md5_sign(const int mode, DST_KEY *d_key, void **context,
          const u_char *data, const int len,
          u_char *signature, const int sig_len)
{
    HMAC_Key *key;
    int sign_len = 0;
    MD5_CTX *ctx = NULL;

    if (d_key == NULL || d_key->dk_KEY_struct == NULL)
        return (-1);

    if (mode & SIG_MODE_INIT)
        ctx = (MD5_CTX *) malloc(sizeof(*ctx));
    else if (context)
        ctx = (MD5_CTX *) *context;
    if (ctx == NULL)
        return (-1);

    key = (HMAC_Key *) d_key->dk_KEY_struct;

    if (mode & SIG_MODE_INIT) {
        MD5Init(ctx);
        MD5Update(ctx, key->hk_ipad, HMAC_LEN);
    }

    if ((mode & SIG_MODE_UPDATE) && (data && len > 0))
        MD5Update(ctx, data, len);

    if (mode & SIG_MODE_FINAL) {
        if (signature == NULL || sig_len < MD5_LEN)
            return (SIGN_FINAL_FAILURE);
        MD5Final(signature, ctx);

        /* perform outer MD5 */
        MD5Init(ctx);
        MD5Update(ctx, key->hk_opad, HMAC_LEN);
        MD5Update(ctx, signature, MD5_LEN);
        MD5Final(signature, ctx);
        sign_len = MD5_LEN;
        SAFE_FREE(ctx);
    }
    else {
        if (context == NULL)
            return (-1);
        *context = (void *) ctx;
    }
    return (sign_len);
}


/**************************************************************************
 * dst_hmac_md5_verify()
 *     Calls HMAC verification routines.  There are three steps to
 *     verification, INIT (initialize structures), UPDATE (hash (more) data),
 *     FINAL (generate a signature).  This routine performs one or more of
 *     these steps.
 * Parameters
 *     mode SIG_MODE_INIT, SIG_MODE_UPDATE and/or SIG_MODE_FINAL.
 *     dkey key to use for verify.
 *     data data signed.
 *     len   length in bytes of data.
 *     signature   signature.
 *     sig_len     length in bytes of signature.
 * returns
 *     0  Success
 *    <0  Failure
 */

static int
dst_hmac_md5_verify(const int mode, DST_KEY *d_key, void **context,
        const u_char *data, const int len,
        const u_char *signature, const int sig_len)
{
    HMAC_Key *key;
    MD5_CTX *ctx = NULL;

    if (d_key == NULL || d_key->dk_KEY_struct == NULL)
        return (-1);

    if (mode & SIG_MODE_INIT)
        ctx = (MD5_CTX *) malloc(sizeof(*ctx));
    else if (context)
        ctx = (MD5_CTX *) *context;
    if (ctx == NULL)
        return (-1);

    key = (HMAC_Key *) d_key->dk_KEY_struct;
    if (mode & SIG_MODE_INIT) {
        MD5Init(ctx);
        MD5Update(ctx, key->hk_ipad, HMAC_LEN);
    }
    if ((mode & SIG_MODE_UPDATE) && (data && len > 0))
        MD5Update(ctx, data, len);

    if (mode & SIG_MODE_FINAL) {
        u_char digest[MD5_LEN];
        if (signature == NULL || key == NULL || sig_len != MD5_LEN)
            return (VERIFY_FINAL_FAILURE);
        MD5Final(digest, ctx);

        /* perform outer MD5 */
        MD5Init(ctx);
        MD5Update(ctx, key->hk_opad, HMAC_LEN);
        MD5Update(ctx, digest, MD5_LEN);
        MD5Final(digest, ctx);

        SAFE_FREE(ctx);
        if (memcmp(digest, signature, MD5_LEN) != 0)
            return (VERIFY_FINAL_FAILURE);
    }
    else {
        if (context == NULL)
            return (-1);
        *context = (void *) ctx;
    }
    return (0);
}


/**************************************************************************
 * dst_buffer_to_hmac_md5
 *     Converts key from raw data to an HMAC Key
 *     This function gets in a pointer to the data
 * Parameters
 *     hkey the HMAC key to be filled in
 *     key  the key in raw format
 *     keylen   the length of the key
 * Return
 *  0   Success
 *  <0  Failure
 */
static int
dst_buffer_to_hmac_md5(DST_KEY *dkey, const u_char *key, const int keylen)
{
    int i;
    HMAC_Key *hkey = NULL;
    MD5_CTX ctx;
    int local_keylen = keylen;
    u_char tk[MD5_LEN];

    if (dkey == NULL || key == NULL || keylen < 0)
        return (-1);

    if ((hkey = (HMAC_Key *) malloc(sizeof(HMAC_Key))) == NULL)
          return (-2);

    memset(hkey->hk_ipad, 0, sizeof(hkey->hk_ipad));
    memset(hkey->hk_opad, 0, sizeof(hkey->hk_opad));

    /* if key is longer than HMAC_LEN bytes reset it to key=MD5(key) */
    if (keylen > HMAC_LEN) {
        MD5Init(&ctx);
        MD5Update(&ctx, key, keylen);
        MD5Final(tk, &ctx);
        memset((void *) &ctx, 0, sizeof(ctx));
        key = tk;
        local_keylen = MD5_LEN;
    }
    /* start out by storing key in pads */
    memcpy(hkey->hk_ipad, key, local_keylen);
    memcpy(hkey->hk_opad, key, local_keylen);

    /* XOR key with hk_ipad and opad values */
    for (i = 0; i < HMAC_LEN; i++) {
        hkey->hk_ipad[i] ^= HMAC_IPAD;
        hkey->hk_opad[i] ^= HMAC_OPAD;
    }
    dkey->dk_key_size = local_keylen;
    dkey->dk_KEY_struct = (void *) hkey;
    return (1);
}


/**************************************************************************
 *  dst_hmac_md5_key_to_file_format
 *  Encodes an HMAC Key into the portable file format.
 *  Parameters
 *  hkey      HMAC KEY structure
 *  buff      output buffer
 *  buff_len  size of output buffer
 *  Return
 *  0  Failure - null input hkey
 *     -1  Failure - not enough space in output area
 *  N  Success - Length of data returned in buff
 */

static int
dst_hmac_md5_key_to_file_format(const DST_KEY *dkey, char *buff,
                    const int buff_len)
{
    char *bp;
    int len, i, key_len;
    u_char key[HMAC_LEN];
    HMAC_Key *hkey;

    if (dkey == NULL || dkey->dk_KEY_struct == NULL)
        return (0);
    /*
     * Using snprintf() would be so much simpler here.
     */
    if (buff == NULL ||
        buff_len <= (int)(strlen(key_file_fmt_str) +
                  strlen(KEY_FILE_FORMAT) + 4))
        return (-1);    /*%< no OR not enough space in output area */
    hkey = (HMAC_Key *) dkey->dk_KEY_struct;
    memset(buff, 0, buff_len);  /*%< just in case */
    /* write file header */
    sprintf(buff, key_file_fmt_str, KEY_FILE_FORMAT, KEY_HMAC_MD5, "HMAC");

    bp = buff + strlen(buff);

    memset(key, 0, HMAC_LEN);
    for (i = 0; i < HMAC_LEN; i++)
        key[i] = hkey->hk_ipad[i] ^ HMAC_IPAD;
    for (i = HMAC_LEN - 1; i >= 0; i--)
        if (key[i] != 0)
            break;
    key_len = i + 1;

    if (buff_len - (bp - buff) < 6)
        return (-1);
    strcat(bp, "Key: ");
    bp += strlen("Key: ");

    len = b64_ntop(key, key_len, bp, buff_len - (bp - buff));
    if (len < 0)
        return (-1);
    bp += len;
    if (buff_len - (bp - buff) < 2)
        return (-1);
    *(bp++) = '\n';
    *bp = '\0';

    return (bp - buff);
}


/**************************************************************************
 * dst_hmac_md5_key_from_file_format
 *     Converts contents of a key file into an HMAC key.
 * Parameters
 *     hkey    structure to put key into
 *     buff       buffer containing the encoded key
 *     buff_len   the length of the buffer
 * Return
 *     n >= 0 Foot print of the key converted
 *     n <  0 Error in conversion
 */

static int
dst_hmac_md5_key_from_file_format(DST_KEY *dkey, const char *buff,
                  const int buff_len)
{
    const char *p = buff, *eol;
    u_char key[HMAC_LEN+1]; /* b64_pton needs more than 64 bytes do decode
                 * it should probably be fixed rather than doing
                 * this
                 */
    u_char *tmp;
    int key_len, len;

    if (dkey == NULL)
        return (-2);
    if (buff == NULL || buff_len < 0)
        return (-1);

    memset(key, 0, sizeof(key));

    if (!dst_s_verify_str(&p, "Key: "))
        return (-3);

    eol = strchr(p, '\n');
    if (eol == NULL)
        return (-4);
    len = eol - p;
    tmp = malloc(len + 2);
    if (tmp == NULL)
        return (-5);
    memcpy(tmp, p, len);
    *(tmp + len) = 0x0;
    key_len = b64_pton((char *)tmp, key, HMAC_LEN+1);   /*%< see above */
    SAFE_FREE2(tmp, len + 2);

    if (dst_buffer_to_hmac_md5(dkey, key, key_len) < 0) {
        return (-6);
    }
    return (0);
}

/*%
 * dst_hmac_md5_to_dns_key()
 *         function to extract hmac key from DST_KEY structure
 * intput:
 *      in_key:  HMAC-MD5 key
 * output:
 *  out_str: buffer to write ot
 *      out_len: size of output buffer
 * returns:
 *      number of bytes written to output buffer
 */
static int
dst_hmac_md5_to_dns_key(const DST_KEY *in_key, u_char *out_str,
            const int out_len)
{

    HMAC_Key *hkey;
    int i;

    if (in_key == NULL || in_key->dk_KEY_struct == NULL ||
        out_len <= in_key->dk_key_size || out_str == NULL)
        return (-1);

    hkey = (HMAC_Key *) in_key->dk_KEY_struct;
    for (i = 0; i < in_key->dk_key_size; i++)
        out_str[i] = hkey->hk_ipad[i] ^ HMAC_IPAD;
    return (i);
}

/**************************************************************************
 *  dst_hmac_md5_compare_keys
 *  Compare two keys for equality.
 *  Return
 *  0     The keys are equal
 *  NON-ZERO   The keys are not equal
 */

static int
dst_hmac_md5_compare_keys(const DST_KEY *key1, const DST_KEY *key2)
{
    HMAC_Key *hkey1 = (HMAC_Key *) key1->dk_KEY_struct;
    HMAC_Key *hkey2 = (HMAC_Key *) key2->dk_KEY_struct;
    return memcmp(hkey1->hk_ipad, hkey2->hk_ipad, HMAC_LEN);
}

/**************************************************************************
 * dst_hmac_md5_free_key_structure
 *     Frees all (none) dynamically allocated structures in hkey
 */

static void *
dst_hmac_md5_free_key_structure(void *key)
{
    HMAC_Key *hkey = key;
    SAFE_FREE(hkey);
    return (NULL);
}


/***************************************************************************
 * dst_hmac_md5_generate_key
 *     Creates a HMAC key of size size with a maximum size of 63 bytes
 *     generating a HMAC key larger than 63 bytes makes no sense as that key
 *     is digested before use.
 */

static int
dst_hmac_md5_generate_key(DST_KEY *key, const int nothing)
{
    (void)key;
    (void)nothing;
    return (-1);
}

/*%
 * dst_hmac_md5_init()  Function to answer set up function pointers for HMAC
 *     related functions
 */
int
dst_hmac_md5_init()
{
    if (dst_t_func[KEY_HMAC_MD5] != NULL)
        return (1);
    dst_t_func[KEY_HMAC_MD5] = malloc(sizeof(struct dst_func));
    if (dst_t_func[KEY_HMAC_MD5] == NULL)
        return (0);
    memset(dst_t_func[KEY_HMAC_MD5], 0, sizeof(struct dst_func));
    dst_t_func[KEY_HMAC_MD5]->sign = dst_hmac_md5_sign;
    dst_t_func[KEY_HMAC_MD5]->verify = dst_hmac_md5_verify;
    dst_t_func[KEY_HMAC_MD5]->compare = dst_hmac_md5_compare_keys;
    dst_t_func[KEY_HMAC_MD5]->generate = dst_hmac_md5_generate_key;
    dst_t_func[KEY_HMAC_MD5]->destroy = dst_hmac_md5_free_key_structure;
    dst_t_func[KEY_HMAC_MD5]->to_dns_key = dst_hmac_md5_to_dns_key;
    dst_t_func[KEY_HMAC_MD5]->from_dns_key = dst_buffer_to_hmac_md5;
    dst_t_func[KEY_HMAC_MD5]->to_file_fmt = dst_hmac_md5_key_to_file_format;
    dst_t_func[KEY_HMAC_MD5]->from_file_fmt = dst_hmac_md5_key_from_file_format;
    return (1);
}

#else
#define dst_hmac_md5_init   __dst_hmac_md5_init

int
dst_hmac_md5_init(){
    return (0);
}
#endif

/*! \file */