cmac.c revision a1a5710c055e139ea00e785f9eb55b3af3e4dab1 
1/* crypto/cmac/cmac.c */
2/* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
3 * project.
4 */
5/* ====================================================================
6 * Copyright (c) 2010 The OpenSSL Project.  All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * 1. Redistributions of source code must retain the above copyright
13 *    notice, this list of conditions and the following disclaimer.
14 *
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in
17 *    the documentation and/or other materials provided with the
18 *    distribution.
19 *
20 * 3. All advertising materials mentioning features or use of this
21 *    software must display the following acknowledgment:
22 *    "This product includes software developed by the OpenSSL Project
23 *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
24 *
25 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
26 *    endorse or promote products derived from this software without
27 *    prior written permission. For written permission, please contact
28 *    licensing@OpenSSL.org.
29 *
30 * 5. Products derived from this software may not be called "OpenSSL"
31 *    nor may "OpenSSL" appear in their names without prior written
32 *    permission of the OpenSSL Project.
33 *
34 * 6. Redistributions of any form whatsoever must retain the following
35 *    acknowledgment:
36 *    "This product includes software developed by the OpenSSL Project
37 *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
38 *
39 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
40 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
41 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
42 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
43 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
44 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
45 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
46 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
47 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
48 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
49 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
50 * OF THE POSSIBILITY OF SUCH DAMAGE.
51 * ====================================================================
52 */
53
54#include <stdio.h>
55#include <stdlib.h>
56#include <string.h>
57#include "cryptlib.h"
58#include <openssl/cmac.h>
59
60#ifdef OPENSSL_FIPS
61#include <openssl/fips.h>
62#endif
63
64struct CMAC_CTX_st
65	{
66	/* Cipher context to use */
67	EVP_CIPHER_CTX cctx;
68	/* Keys k1 and k2 */
69	unsigned char k1[EVP_MAX_BLOCK_LENGTH];
70	unsigned char k2[EVP_MAX_BLOCK_LENGTH];
71	/* Temporary block */
72	unsigned char tbl[EVP_MAX_BLOCK_LENGTH];
73	/* Last (possibly partial) block */
74	unsigned char last_block[EVP_MAX_BLOCK_LENGTH];
75	/* Number of bytes in last block: -1 means context not initialised */
76	int nlast_block;
77	};
78
79
80/* Make temporary keys K1 and K2 */
81
82static void make_kn(unsigned char *k1, unsigned char *l, int bl)
83	{
84	int i;
85	/* Shift block to left, including carry */
86	for (i = 0; i < bl; i++)
87		{
88		k1[i] = l[i] << 1;
89		if (i < bl - 1 && l[i + 1] & 0x80)
90			k1[i] |= 1;
91		}
92	/* If MSB set fixup with R */
93	if (l[0] & 0x80)
94		k1[bl - 1] ^= bl == 16 ? 0x87 : 0x1b;
95	}
96
97CMAC_CTX *CMAC_CTX_new(void)
98	{
99	CMAC_CTX *ctx;
100	ctx = OPENSSL_malloc(sizeof(CMAC_CTX));
101	if (!ctx)
102		return NULL;
103	EVP_CIPHER_CTX_init(&ctx->cctx);
104	ctx->nlast_block = -1;
105	return ctx;
106	}
107
108void CMAC_CTX_cleanup(CMAC_CTX *ctx)
109	{
110#ifdef OPENSSL_FIPS
111	if (FIPS_mode() && !ctx->cctx.engine)
112		{
113		FIPS_cmac_ctx_cleanup(ctx);
114		return;
115		}
116#endif
117	EVP_CIPHER_CTX_cleanup(&ctx->cctx);
118	OPENSSL_cleanse(ctx->tbl, EVP_MAX_BLOCK_LENGTH);
119	OPENSSL_cleanse(ctx->k1, EVP_MAX_BLOCK_LENGTH);
120	OPENSSL_cleanse(ctx->k2, EVP_MAX_BLOCK_LENGTH);
121	OPENSSL_cleanse(ctx->last_block, EVP_MAX_BLOCK_LENGTH);
122	ctx->nlast_block = -1;
123	}
124
125EVP_CIPHER_CTX *CMAC_CTX_get0_cipher_ctx(CMAC_CTX *ctx)
126	{
127	return &ctx->cctx;
128	}
129
130void CMAC_CTX_free(CMAC_CTX *ctx)
131	{
132	CMAC_CTX_cleanup(ctx);
133	OPENSSL_free(ctx);
134	}
135
136int CMAC_CTX_copy(CMAC_CTX *out, const CMAC_CTX *in)
137	{
138	int bl;
139	if (in->nlast_block == -1)
140		return 0;
141	if (!EVP_CIPHER_CTX_copy(&out->cctx, &in->cctx))
142		return 0;
143	bl = EVP_CIPHER_CTX_block_size(&in->cctx);
144	memcpy(out->k1, in->k1, bl);
145	memcpy(out->k2, in->k2, bl);
146	memcpy(out->tbl, in->tbl, bl);
147	memcpy(out->last_block, in->last_block, bl);
148	out->nlast_block = in->nlast_block;
149	return 1;
150	}
151
152int CMAC_Init(CMAC_CTX *ctx, const void *key, size_t keylen,
153			const EVP_CIPHER *cipher, ENGINE *impl)
154	{
155	static unsigned char zero_iv[EVP_MAX_BLOCK_LENGTH];
156#ifdef OPENSSL_FIPS
157	if (FIPS_mode())
158		{
159		/* If we have an ENGINE need to allow non FIPS */
160		if ((impl || ctx->cctx.engine)
161			&& !(ctx->cctx.flags & EVP_CIPH_FLAG_NON_FIPS_ALLOW))
162
163			{
164			EVPerr(EVP_F_CMAC_INIT, EVP_R_DISABLED_FOR_FIPS);
165			return 0;
166			}
167		/* Other algorithm blocking will be done in FIPS_cmac_init,
168		 * via FIPS_cipherinit().
169		 */
170		if (!impl && !ctx->cctx.engine)
171			return FIPS_cmac_init(ctx, key, keylen, cipher, NULL);
172		}
173#endif
174	/* All zeros means restart */
175	if (!key && !cipher && !impl && keylen == 0)
176		{
177		/* Not initialised */
178		if (ctx->nlast_block == -1)
179			return 0;
180		if (!EVP_EncryptInit_ex(&ctx->cctx, NULL, NULL, NULL, zero_iv))
181			return 0;
182		memset(ctx->tbl, 0, EVP_CIPHER_CTX_block_size(&ctx->cctx));
183		ctx->nlast_block = 0;
184		return 1;
185		}
186	/* Initialiase context */
187	if (cipher && !EVP_EncryptInit_ex(&ctx->cctx, cipher, impl, NULL, NULL))
188		return 0;
189	/* Non-NULL key means initialisation complete */
190	if (key)
191		{
192		int bl;
193		if (!EVP_CIPHER_CTX_cipher(&ctx->cctx))
194			return 0;
195		if (!EVP_CIPHER_CTX_set_key_length(&ctx->cctx, keylen))
196			return 0;
197		if (!EVP_EncryptInit_ex(&ctx->cctx, NULL, NULL, key, zero_iv))
198			return 0;
199		bl = EVP_CIPHER_CTX_block_size(&ctx->cctx);
200		if (!EVP_Cipher(&ctx->cctx, ctx->tbl, zero_iv, bl))
201			return 0;
202		make_kn(ctx->k1, ctx->tbl, bl);
203		make_kn(ctx->k2, ctx->k1, bl);
204		OPENSSL_cleanse(ctx->tbl, bl);
205		/* Reset context again ready for first data block */
206		if (!EVP_EncryptInit_ex(&ctx->cctx, NULL, NULL, NULL, zero_iv))
207			return 0;
208		/* Zero tbl so resume works */
209		memset(ctx->tbl, 0, bl);
210		ctx->nlast_block = 0;
211		}
212	return 1;
213	}
214
215int CMAC_Update(CMAC_CTX *ctx, const void *in, size_t dlen)
216	{
217	const unsigned char *data = in;
218	size_t bl;
219#ifdef OPENSSL_FIPS
220	if (FIPS_mode() && !ctx->cctx.engine)
221		return FIPS_cmac_update(ctx, in, dlen);
222#endif
223	if (ctx->nlast_block == -1)
224		return 0;
225	if (dlen == 0)
226		return 1;
227	bl = EVP_CIPHER_CTX_block_size(&ctx->cctx);
228	/* Copy into partial block if we need to */
229	if (ctx->nlast_block > 0)
230		{
231		size_t nleft;
232		nleft = bl - ctx->nlast_block;
233		if (dlen < nleft)
234			nleft = dlen;
235		memcpy(ctx->last_block + ctx->nlast_block, data, nleft);
236		dlen -= nleft;
237		ctx->nlast_block += nleft;
238		/* If no more to process return */
239		if (dlen == 0)
240			return 1;
241		data += nleft;
242		/* Else not final block so encrypt it */
243		if (!EVP_Cipher(&ctx->cctx, ctx->tbl, ctx->last_block,bl))
244			return 0;
245		}
246	/* Encrypt all but one of the complete blocks left */
247	while(dlen > bl)
248		{
249		if (!EVP_Cipher(&ctx->cctx, ctx->tbl, data, bl))
250			return 0;
251		dlen -= bl;
252		data += bl;
253		}
254	/* Copy any data left to last block buffer */
255	memcpy(ctx->last_block, data, dlen);
256	ctx->nlast_block = dlen;
257	return 1;
258
259	}
260
261int CMAC_Final(CMAC_CTX *ctx, unsigned char *out, size_t *poutlen)
262	{
263	int i, bl, lb;
264#ifdef OPENSSL_FIPS
265	if (FIPS_mode() && !ctx->cctx.engine)
266		return FIPS_cmac_final(ctx, out, poutlen);
267#endif
268	if (ctx->nlast_block == -1)
269		return 0;
270	bl = EVP_CIPHER_CTX_block_size(&ctx->cctx);
271	*poutlen = (size_t)bl;
272	if (!out)
273		return 1;
274	lb = ctx->nlast_block;
275	/* Is last block complete? */
276	if (lb == bl)
277		{
278		for (i = 0; i < bl; i++)
279			out[i] = ctx->last_block[i] ^ ctx->k1[i];
280		}
281	else
282		{
283		ctx->last_block[lb] = 0x80;
284		if (bl - lb > 1)
285			memset(ctx->last_block + lb + 1, 0, bl - lb - 1);
286		for (i = 0; i < bl; i++)
287			out[i] = ctx->last_block[i] ^ ctx->k2[i];
288		}
289	if (!EVP_Cipher(&ctx->cctx, out, out, bl))
290		{
291		OPENSSL_cleanse(out, bl);
292		return 0;
293		}
294	return 1;
295	}
296
297int CMAC_resume(CMAC_CTX *ctx)
298	{
299	if (ctx->nlast_block == -1)
300		return 0;
301	/* The buffer "tbl" containes the last fully encrypted block
302	 * which is the last IV (or all zeroes if no last encrypted block).
303	 * The last block has not been modified since CMAC_final().
304	 * So reinitliasing using the last decrypted block will allow
305	 * CMAC to continue after calling CMAC_Final().
306	 */
307	return EVP_EncryptInit_ex(&ctx->cctx, NULL, NULL, NULL, ctx->tbl);
308	}
309