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      1 /*	$NetBSD: hmac.c,v 1.5 2017/10/05 09:59:04 roy Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2016 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Christos Zoulas.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 #include <sys/cdefs.h>
     32 __RCSID("$NetBSD: hmac.c,v 1.5 2017/10/05 09:59:04 roy Exp $");
     33 
     34 #include <string.h>
     35 #include <stdlib.h>
     36 
     37 #include <md2.h>
     38 #include <md4.h>
     39 #include <md5.h>
     40 #include <rmd160.h>
     41 #include <sha1.h>
     42 #include <sha2.h>
     43 
     44 #define HMAC_SIZE	128
     45 #define HMAC_IPAD	0x36
     46 #define HMAC_OPAD	0x5C
     47 
     48 static const struct hmac {
     49 	const char *name;
     50 	size_t ctxsize;
     51 	size_t digsize;
     52 	size_t blocksize;
     53 	void (*init)(void *);
     54 	void (*update)(void *, const uint8_t *, unsigned int);
     55 	void (*final)(uint8_t *, void *);
     56 } hmacs[] = {
     57 	{
     58 		"md2", sizeof(MD2_CTX), MD2_DIGEST_LENGTH, MD2_BLOCK_LENGTH,
     59 		(void *)MD2Init, (void *)MD2Update, (void *)MD2Final,
     60 	},
     61 	{
     62 		"md4", sizeof(MD4_CTX), MD4_DIGEST_LENGTH, MD4_BLOCK_LENGTH,
     63 		(void *)MD4Init, (void *)MD4Update, (void *)MD4Final,
     64 	},
     65 	{
     66 		"md5", sizeof(MD5_CTX), MD5_DIGEST_LENGTH, MD5_BLOCK_LENGTH,
     67 		(void *)MD5Init, (void *)MD5Update, (void *)MD5Final,
     68 	},
     69 	{
     70 		"rmd160", sizeof(RMD160_CTX), RMD160_DIGEST_LENGTH,
     71 		RMD160_BLOCK_LENGTH,
     72 		(void *)RMD160Init, (void *)RMD160Update, (void *)RMD160Final,
     73 	},
     74 	{
     75 		"sha1", sizeof(SHA1_CTX), SHA1_DIGEST_LENGTH, SHA1_BLOCK_LENGTH,
     76 		(void *)SHA1Init, (void *)SHA1Update, (void *)SHA1Final,
     77 	},
     78 	{
     79 		"sha224", sizeof(SHA224_CTX), SHA224_DIGEST_LENGTH,
     80 		SHA224_BLOCK_LENGTH,
     81 		(void *)SHA224_Init, (void *)SHA224_Update,
     82 		(void *)SHA224_Final,
     83 	},
     84 	{
     85 		"sha256", sizeof(SHA256_CTX), SHA256_DIGEST_LENGTH,
     86 		SHA256_BLOCK_LENGTH,
     87 		(void *)SHA256_Init, (void *)SHA256_Update,
     88 		(void *)SHA256_Final,
     89 	},
     90 	{
     91 		"sha384", sizeof(SHA384_CTX), SHA384_DIGEST_LENGTH,
     92 		SHA384_BLOCK_LENGTH,
     93 		(void *)SHA384_Init, (void *)SHA384_Update,
     94 		(void *)SHA384_Final,
     95 	},
     96 	{
     97 		"sha512", sizeof(SHA512_CTX), SHA512_DIGEST_LENGTH,
     98 		SHA512_BLOCK_LENGTH,
     99 		(void *)SHA512_Init, (void *)SHA512_Update,
    100 		(void *)SHA512_Final,
    101 	},
    102 };
    103 
    104 static const struct hmac *
    105 hmac_find(const char *name)
    106 {
    107 	for (size_t i = 0; i < __arraycount(hmacs); i++) {
    108 		if (strcmp(hmacs[i].name, name) != 0)
    109 			continue;
    110 		return &hmacs[i];
    111 	}
    112 	return NULL;
    113 }
    114 
    115 ssize_t
    116 hmac(const char *name,
    117     const void *key, size_t klen,
    118     const void *text, size_t tlen,
    119     void *digest, size_t dlen)
    120 {
    121 	uint8_t ipad[HMAC_SIZE], opad[HMAC_SIZE], d[HMAC_SIZE];
    122 	const uint8_t *k = key;
    123 	const struct hmac *h;
    124 	uint64_t c[32];
    125 	void *p;
    126 
    127 	if ((h = hmac_find(name)) == NULL)
    128 		return -1;
    129 
    130 
    131 	if (klen > h->blocksize) {
    132 		(*h->init)(c);
    133 		(*h->update)(c, k, (unsigned int)klen);
    134 		(*h->final)(d, c);
    135 		k = (void *)d;
    136 		klen = h->digsize;
    137 	}
    138 
    139 	/* Form input and output pads for the digests */
    140 	for (size_t i = 0; i < sizeof(ipad); i++) {
    141 		ipad[i] = (i < klen ? k[i] : 0) ^ HMAC_IPAD;
    142 		opad[i] = (i < klen ? k[i] : 0) ^ HMAC_OPAD;
    143 	}
    144 
    145 	p = dlen >= h->digsize ? digest : d;
    146 	if (p != digest) {
    147 		memcpy(p, digest, dlen);
    148 		memset((char *)p + dlen, 0, h->digsize - dlen);
    149 	}
    150 	(*h->init)(c);
    151 	(*h->update)(c, ipad, (unsigned int)h->blocksize);
    152 	(*h->update)(c, text, (unsigned int)tlen);
    153 	(*h->final)(p, c);
    154 
    155 	(*h->init)(c);
    156 	(*h->update)(c, opad, (unsigned int)h->blocksize);
    157 	(*h->update)(c, digest, (unsigned int)h->digsize);
    158 	(*h->final)(p, c);
    159 
    160 	if (p != digest)
    161 		memcpy(digest, p, dlen);
    162 
    163 	return (ssize_t)h->digsize;
    164 }
    165