cmac.c revision 280304 
1/* crypto/cmac/cmac.c */
2/*
3 * Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
4 * project.
5 */
6/* ====================================================================
7 * Copyright (c) 2010 The OpenSSL Project.  All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 *
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 *
16 * 2. Redistributions in binary form must reproduce the above copyright
17 *    notice, this list of conditions and the following disclaimer in
18 *    the documentation and/or other materials provided with the
19 *    distribution.
20 *
21 * 3. All advertising materials mentioning features or use of this
22 *    software must display the following acknowledgment:
23 *    "This product includes software developed by the OpenSSL Project
24 *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
25 *
26 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
27 *    endorse or promote products derived from this software without
28 *    prior written permission. For written permission, please contact
29 *    licensing@OpenSSL.org.
30 *
31 * 5. Products derived from this software may not be called "OpenSSL"
32 *    nor may "OpenSSL" appear in their names without prior written
33 *    permission of the OpenSSL Project.
34 *
35 * 6. Redistributions of any form whatsoever must retain the following
36 *    acknowledgment:
37 *    "This product includes software developed by the OpenSSL Project
38 *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
39 *
40 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
41 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
42 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
43 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
44 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
45 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
46 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
47 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
48 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
49 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
50 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
51 * OF THE POSSIBILITY OF SUCH DAMAGE.
52 * ====================================================================
53 */
54
55#include <stdio.h>
56#include <stdlib.h>
57#include <string.h>
58#include "cryptlib.h"
59#include <openssl/cmac.h>
60
61#ifdef OPENSSL_FIPS
62# include <openssl/fips.h>
63#endif
64
65struct CMAC_CTX_st {
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/* Make temporary keys K1 and K2 */
80
81static void make_kn(unsigned char *k1, unsigned char *l, int bl)
82{
83    int i;
84    /* Shift block to left, including carry */
85    for (i = 0; i < bl; i++) {
86        k1[i] = l[i] << 1;
87        if (i < bl - 1 && l[i + 1] & 0x80)
88            k1[i] |= 1;
89    }
90    /* If MSB set fixup with R */
91    if (l[0] & 0x80)
92        k1[bl - 1] ^= bl == 16 ? 0x87 : 0x1b;
93}
94
95CMAC_CTX *CMAC_CTX_new(void)
96{
97    CMAC_CTX *ctx;
98    ctx = OPENSSL_malloc(sizeof(CMAC_CTX));
99    if (!ctx)
100        return NULL;
101    EVP_CIPHER_CTX_init(&ctx->cctx);
102    ctx->nlast_block = -1;
103    return ctx;
104}
105
106void CMAC_CTX_cleanup(CMAC_CTX *ctx)
107{
108#ifdef OPENSSL_FIPS
109    if (FIPS_mode() && !ctx->cctx.engine) {
110        FIPS_cmac_ctx_cleanup(ctx);
111        return;
112    }
113#endif
114    EVP_CIPHER_CTX_cleanup(&ctx->cctx);
115    OPENSSL_cleanse(ctx->tbl, EVP_MAX_BLOCK_LENGTH);
116    OPENSSL_cleanse(ctx->k1, EVP_MAX_BLOCK_LENGTH);
117    OPENSSL_cleanse(ctx->k2, EVP_MAX_BLOCK_LENGTH);
118    OPENSSL_cleanse(ctx->last_block, EVP_MAX_BLOCK_LENGTH);
119    ctx->nlast_block = -1;
120}
121
122EVP_CIPHER_CTX *CMAC_CTX_get0_cipher_ctx(CMAC_CTX *ctx)
123{
124    return &ctx->cctx;
125}
126
127void CMAC_CTX_free(CMAC_CTX *ctx)
128{
129    CMAC_CTX_cleanup(ctx);
130    OPENSSL_free(ctx);
131}
132
133int CMAC_CTX_copy(CMAC_CTX *out, const CMAC_CTX *in)
134{
135    int bl;
136    if (in->nlast_block == -1)
137        return 0;
138    if (!EVP_CIPHER_CTX_copy(&out->cctx, &in->cctx))
139        return 0;
140    bl = EVP_CIPHER_CTX_block_size(&in->cctx);
141    memcpy(out->k1, in->k1, bl);
142    memcpy(out->k2, in->k2, bl);
143    memcpy(out->tbl, in->tbl, bl);
144    memcpy(out->last_block, in->last_block, bl);
145    out->nlast_block = in->nlast_block;
146    return 1;
147}
148
149int CMAC_Init(CMAC_CTX *ctx, const void *key, size_t keylen,
150              const EVP_CIPHER *cipher, ENGINE *impl)
151{
152    static unsigned char zero_iv[EVP_MAX_BLOCK_LENGTH];
153#ifdef OPENSSL_FIPS
154    if (FIPS_mode()) {
155        /* If we have an ENGINE need to allow non FIPS */
156        if ((impl || ctx->cctx.engine)
157            && !(ctx->cctx.flags & EVP_CIPH_FLAG_NON_FIPS_ALLOW)) {
158            EVPerr(EVP_F_CMAC_INIT, EVP_R_DISABLED_FOR_FIPS);
159            return 0;
160        }
161        /*
162         * Other algorithm blocking will be done in FIPS_cmac_init, via
163         * FIPS_cipherinit().
164         */
165        if (!impl && !ctx->cctx.engine)
166            return FIPS_cmac_init(ctx, key, keylen, cipher, NULL);
167    }
168#endif
169    /* All zeros means restart */
170    if (!key && !cipher && !impl && keylen == 0) {
171        /* Not initialised */
172        if (ctx->nlast_block == -1)
173            return 0;
174        if (!EVP_EncryptInit_ex(&ctx->cctx, NULL, NULL, NULL, zero_iv))
175            return 0;
176        memset(ctx->tbl, 0, EVP_CIPHER_CTX_block_size(&ctx->cctx));
177        ctx->nlast_block = 0;
178        return 1;
179    }
180    /* Initialiase context */
181    if (cipher && !EVP_EncryptInit_ex(&ctx->cctx, cipher, impl, NULL, NULL))
182        return 0;
183    /* Non-NULL key means initialisation complete */
184    if (key) {
185        int bl;
186        if (!EVP_CIPHER_CTX_cipher(&ctx->cctx))
187            return 0;
188        if (!EVP_CIPHER_CTX_set_key_length(&ctx->cctx, keylen))
189            return 0;
190        if (!EVP_EncryptInit_ex(&ctx->cctx, NULL, NULL, key, zero_iv))
191            return 0;
192        bl = EVP_CIPHER_CTX_block_size(&ctx->cctx);
193        if (!EVP_Cipher(&ctx->cctx, ctx->tbl, zero_iv, bl))
194            return 0;
195        make_kn(ctx->k1, ctx->tbl, bl);
196        make_kn(ctx->k2, ctx->k1, bl);
197        OPENSSL_cleanse(ctx->tbl, bl);
198        /* Reset context again ready for first data block */
199        if (!EVP_EncryptInit_ex(&ctx->cctx, NULL, NULL, NULL, zero_iv))
200            return 0;
201        /* Zero tbl so resume works */
202        memset(ctx->tbl, 0, bl);
203        ctx->nlast_block = 0;
204    }
205    return 1;
206}
207
208int CMAC_Update(CMAC_CTX *ctx, const void *in, size_t dlen)
209{
210    const unsigned char *data = in;
211    size_t bl;
212#ifdef OPENSSL_FIPS
213    if (FIPS_mode() && !ctx->cctx.engine)
214        return FIPS_cmac_update(ctx, in, dlen);
215#endif
216    if (ctx->nlast_block == -1)
217        return 0;
218    if (dlen == 0)
219        return 1;
220    bl = EVP_CIPHER_CTX_block_size(&ctx->cctx);
221    /* Copy into partial block if we need to */
222    if (ctx->nlast_block > 0) {
223        size_t nleft;
224        nleft = bl - ctx->nlast_block;
225        if (dlen < nleft)
226            nleft = dlen;
227        memcpy(ctx->last_block + ctx->nlast_block, data, nleft);
228        dlen -= nleft;
229        ctx->nlast_block += nleft;
230        /* If no more to process return */
231        if (dlen == 0)
232            return 1;
233        data += nleft;
234        /* Else not final block so encrypt it */
235        if (!EVP_Cipher(&ctx->cctx, ctx->tbl, ctx->last_block, bl))
236            return 0;
237    }
238    /* Encrypt all but one of the complete blocks left */
239    while (dlen > bl) {
240        if (!EVP_Cipher(&ctx->cctx, ctx->tbl, data, bl))
241            return 0;
242        dlen -= bl;
243        data += bl;
244    }
245    /* Copy any data left to last block buffer */
246    memcpy(ctx->last_block, data, dlen);
247    ctx->nlast_block = dlen;
248    return 1;
249
250}
251
252int CMAC_Final(CMAC_CTX *ctx, unsigned char *out, size_t *poutlen)
253{
254    int i, bl, lb;
255#ifdef OPENSSL_FIPS
256    if (FIPS_mode() && !ctx->cctx.engine)
257        return FIPS_cmac_final(ctx, out, poutlen);
258#endif
259    if (ctx->nlast_block == -1)
260        return 0;
261    bl = EVP_CIPHER_CTX_block_size(&ctx->cctx);
262    *poutlen = (size_t)bl;
263    if (!out)
264        return 1;
265    lb = ctx->nlast_block;
266    /* Is last block complete? */
267    if (lb == bl) {
268        for (i = 0; i < bl; i++)
269            out[i] = ctx->last_block[i] ^ ctx->k1[i];
270    } else {
271        ctx->last_block[lb] = 0x80;
272        if (bl - lb > 1)
273            memset(ctx->last_block + lb + 1, 0, bl - lb - 1);
274        for (i = 0; i < bl; i++)
275            out[i] = ctx->last_block[i] ^ ctx->k2[i];
276    }
277    if (!EVP_Cipher(&ctx->cctx, out, out, bl)) {
278        OPENSSL_cleanse(out, bl);
279        return 0;
280    }
281    return 1;
282}
283
284int CMAC_resume(CMAC_CTX *ctx)
285{
286    if (ctx->nlast_block == -1)
287        return 0;
288    /*
289     * The buffer "tbl" containes the last fully encrypted block which is the
290     * last IV (or all zeroes if no last encrypted block). The last block has
291     * not been modified since CMAC_final(). So reinitliasing using the last
292     * decrypted block will allow CMAC to continue after calling
293     * CMAC_Final().
294     */
295    return EVP_EncryptInit_ex(&ctx->cctx, NULL, NULL, NULL, ctx->tbl);
296}
297