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/* $OpenBSD: hmac.c,v 1.14 2020/02/26 13:40:09 jsg Exp $ */
/*
* Copyright (c) 2014 Markus Friedl. All rights reserved.
*
* 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 THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR 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 THIS SOFTWARE.
*/
#include <sys/types.h>
#include <string.h>
#include <stdlib.h>
#include "sshbuf.h"
#include "digest.h"
#include "hmac.h"
struct ssh_hmac_ctx {
int alg;
struct ssh_digest_ctx *ictx;
struct ssh_digest_ctx *octx;
struct ssh_digest_ctx *digest;
u_char *buf;
size_t buf_len;
};
size_t
ssh_hmac_bytes(int alg)
{
return ssh_digest_bytes(alg);
}
struct ssh_hmac_ctx *
ssh_hmac_start(int alg)
{
struct ssh_hmac_ctx *ret;
if ((ret = calloc(1, sizeof(*ret))) == NULL)
return NULL;
ret->alg = alg;
if ((ret->ictx = ssh_digest_start(alg)) == NULL ||
(ret->octx = ssh_digest_start(alg)) == NULL ||
(ret->digest = ssh_digest_start(alg)) == NULL)
goto fail;
ret->buf_len = ssh_digest_blocksize(ret->ictx);
if ((ret->buf = calloc(1, ret->buf_len)) == NULL)
goto fail;
return ret;
fail:
ssh_hmac_free(ret);
return NULL;
}
int
ssh_hmac_init(struct ssh_hmac_ctx *ctx, const void *key, size_t klen)
{
size_t i;
/* reset ictx and octx if no is key given */
if (key != NULL) {
/* truncate long keys */
if (klen <= ctx->buf_len)
memcpy(ctx->buf, key, klen);
else if (ssh_digest_memory(ctx->alg, key, klen, ctx->buf,
ctx->buf_len) < 0)
return -1;
for (i = 0; i < ctx->buf_len; i++)
ctx->buf[i] ^= 0x36;
if (ssh_digest_update(ctx->ictx, ctx->buf, ctx->buf_len) < 0)
return -1;
for (i = 0; i < ctx->buf_len; i++)
ctx->buf[i] ^= 0x36 ^ 0x5c;
if (ssh_digest_update(ctx->octx, ctx->buf, ctx->buf_len) < 0)
return -1;
explicit_bzero(ctx->buf, ctx->buf_len);
}
/* start with ictx */
if (ssh_digest_copy_state(ctx->ictx, ctx->digest) < 0)
return -1;
return 0;
}
int
ssh_hmac_update(struct ssh_hmac_ctx *ctx, const void *m, size_t mlen)
{
return ssh_digest_update(ctx->digest, m, mlen);
}
int
ssh_hmac_update_buffer(struct ssh_hmac_ctx *ctx, const struct sshbuf *b)
{
return ssh_digest_update_buffer(ctx->digest, b);
}
int
ssh_hmac_final(struct ssh_hmac_ctx *ctx, u_char *d, size_t dlen)
{
size_t len;
len = ssh_digest_bytes(ctx->alg);
if (dlen < len ||
ssh_digest_final(ctx->digest, ctx->buf, len))
return -1;
/* switch to octx */
if (ssh_digest_copy_state(ctx->octx, ctx->digest) < 0 ||
ssh_digest_update(ctx->digest, ctx->buf, len) < 0 ||
ssh_digest_final(ctx->digest, d, dlen) < 0)
return -1;
return 0;
}
void
ssh_hmac_free(struct ssh_hmac_ctx *ctx)
{
if (ctx != NULL) {
ssh_digest_free(ctx->ictx);
ssh_digest_free(ctx->octx);
ssh_digest_free(ctx->digest);
if (ctx->buf) {
explicit_bzero(ctx->buf, ctx->buf_len);
free(ctx->buf);
}
freezero(ctx, sizeof(*ctx));
}
}
#ifdef TEST
/* cc -DTEST hmac.c digest.c buffer.c cleanup.c fatal.c log.c xmalloc.c -lcrypto */
static void
hmac_test(void *key, size_t klen, void *m, size_t mlen, u_char *e, size_t elen)
{
struct ssh_hmac_ctx *ctx;
size_t i;
u_char digest[16];
if ((ctx = ssh_hmac_start(SSH_DIGEST_MD5)) == NULL)
printf("ssh_hmac_start failed");
if (ssh_hmac_init(ctx, key, klen) < 0 ||
ssh_hmac_update(ctx, m, mlen) < 0 ||
ssh_hmac_final(ctx, digest, sizeof(digest)) < 0)
printf("ssh_hmac_xxx failed");
ssh_hmac_free(ctx);
if (memcmp(e, digest, elen)) {
for (i = 0; i < elen; i++)
printf("[%zu] %2.2x %2.2x\n", i, e[i], digest[i]);
printf("mismatch\n");
} else
printf("ok\n");
}
int
main(int argc, char **argv)
{
/* try test vectors from RFC 2104 */
u_char key1[16] = {
0xb, 0xb, 0xb, 0xb, 0xb, 0xb, 0xb, 0xb,
0xb, 0xb, 0xb, 0xb, 0xb, 0xb, 0xb, 0xb };
u_char *data1 = "Hi There";
u_char dig1[16] = {
0x92, 0x94, 0x72, 0x7a, 0x36, 0x38, 0xbb, 0x1c,
0x13, 0xf4, 0x8e, 0xf8, 0x15, 0x8b, 0xfc, 0x9d };
u_char *key2 = "Jefe";
u_char *data2 = "what do ya want for nothing?";
u_char dig2[16] = {
0x75, 0x0c, 0x78, 0x3e, 0x6a, 0xb0, 0xb5, 0x03,
0xea, 0xa8, 0x6e, 0x31, 0x0a, 0x5d, 0xb7, 0x38 };
u_char key3[16];
u_char data3[50];
u_char dig3[16] = {
0x56, 0xbe, 0x34, 0x52, 0x1d, 0x14, 0x4c, 0x88,
0xdb, 0xb8, 0xc7, 0x33, 0xf0, 0xe8, 0xb3, 0xf6 };
memset(key3, 0xaa, sizeof(key3));
memset(data3, 0xdd, sizeof(data3));
hmac_test(key1, sizeof(key1), data1, strlen(data1), dig1, sizeof(dig1));
hmac_test(key2, strlen(key2), data2, strlen(data2), dig2, sizeof(dig2));
hmac_test(key3, sizeof(key3), data3, sizeof(data3), dig3, sizeof(dig3));
return 0;
}
#endif
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