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    if (!ctx)
130        return;
131    CMAC_CTX_cleanup(ctx);
132    OPENSSL_free(ctx);
133}
134
135int CMAC_CTX_copy(CMAC_CTX *out, const CMAC_CTX *in)
136{
137    int bl;
138    if (in->nlast_block == -1)
139        return 0;
140    if (!EVP_CIPHER_CTX_copy(&out->cctx, &in->cctx))
141        return 0;
142    bl = EVP_CIPHER_CTX_block_size(&in->cctx);
143    memcpy(out->k1, in->k1, bl);
144    memcpy(out->k2, in->k2, bl);
145    memcpy(out->tbl, in->tbl, bl);
146    memcpy(out->last_block, in->last_block, bl);
147    out->nlast_block = in->nlast_block;
148    return 1;
149}
150
151int CMAC_Init(CMAC_CTX *ctx, const void *key, size_t keylen,
152              const EVP_CIPHER *cipher, ENGINE *impl)
153{
154    static unsigned char zero_iv[EVP_MAX_BLOCK_LENGTH];
155#ifdef OPENSSL_FIPS
156    if (FIPS_mode()) {
157        /* If we have an ENGINE need to allow non FIPS */
158        if ((impl || ctx->cctx.engine)
159            && !(ctx->cctx.flags & EVP_CIPH_FLAG_NON_FIPS_ALLOW)) {
160            EVPerr(EVP_F_CMAC_INIT, EVP_R_DISABLED_FOR_FIPS);
161            return 0;
162        }
163
164        /* Switch to FIPS cipher implementation if possible */
165        if (cipher != NULL) {
166            const EVP_CIPHER *fcipher;
167            fcipher = FIPS_get_cipherbynid(EVP_CIPHER_nid(cipher));
168            if (fcipher != NULL)
169                cipher = fcipher;
170        }
171        /*
172         * Other algorithm blocking will be done in FIPS_cmac_init, via
173         * FIPS_cipherinit().
174         */
175        if (!impl && !ctx->cctx.engine)
176            return FIPS_cmac_init(ctx, key, keylen, cipher, NULL);
177    }
178#endif
179    /* All zeros means restart */
180    if (!key && !cipher && !impl && keylen == 0) {
181        /* Not initialised */
182        if (ctx->nlast_block == -1)
183            return 0;
184        if (!EVP_EncryptInit_ex(&ctx->cctx, NULL, NULL, NULL, zero_iv))
185            return 0;
186        memset(ctx->tbl, 0, EVP_CIPHER_CTX_block_size(&ctx->cctx));
187        ctx->nlast_block = 0;
188        return 1;
189    }
190    /* Initialiase context */
191    if (cipher && !EVP_EncryptInit_ex(&ctx->cctx, cipher, impl, NULL, NULL))
192        return 0;
193    /* Non-NULL key means initialisation complete */
194    if (key) {
195        int bl;
196        if (!EVP_CIPHER_CTX_cipher(&ctx->cctx))
197            return 0;
198        if (!EVP_CIPHER_CTX_set_key_length(&ctx->cctx, keylen))
199            return 0;
200        if (!EVP_EncryptInit_ex(&ctx->cctx, NULL, NULL, key, zero_iv))
201            return 0;
202        bl = EVP_CIPHER_CTX_block_size(&ctx->cctx);
203        if (!EVP_Cipher(&ctx->cctx, ctx->tbl, zero_iv, bl))
204            return 0;
205        make_kn(ctx->k1, ctx->tbl, bl);
206        make_kn(ctx->k2, ctx->k1, bl);
207        OPENSSL_cleanse(ctx->tbl, bl);
208        /* Reset context again ready for first data block */
209        if (!EVP_EncryptInit_ex(&ctx->cctx, NULL, NULL, NULL, zero_iv))
210            return 0;
211        /* Zero tbl so resume works */
212        memset(ctx->tbl, 0, bl);
213        ctx->nlast_block = 0;
214    }
215    return 1;
216}
217
218int CMAC_Update(CMAC_CTX *ctx, const void *in, size_t dlen)
219{
220    const unsigned char *data = in;
221    size_t bl;
222#ifdef OPENSSL_FIPS
223    if (FIPS_mode() && !ctx->cctx.engine)
224        return FIPS_cmac_update(ctx, in, dlen);
225#endif
226    if (ctx->nlast_block == -1)
227        return 0;
228    if (dlen == 0)
229        return 1;
230    bl = EVP_CIPHER_CTX_block_size(&ctx->cctx);
231    /* Copy into partial block if we need to */
232    if (ctx->nlast_block > 0) {
233        size_t nleft;
234        nleft = bl - ctx->nlast_block;
235        if (dlen < nleft)
236            nleft = dlen;
237        memcpy(ctx->last_block + ctx->nlast_block, data, nleft);
238        dlen -= nleft;
239        ctx->nlast_block += nleft;
240        /* If no more to process return */
241        if (dlen == 0)
242            return 1;
243        data += nleft;
244        /* Else not final block so encrypt it */
245        if (!EVP_Cipher(&ctx->cctx, ctx->tbl, ctx->last_block, bl))
246            return 0;
247    }
248    /* Encrypt all but one of the complete blocks left */
249    while (dlen > bl) {
250        if (!EVP_Cipher(&ctx->cctx, ctx->tbl, data, bl))
251            return 0;
252        dlen -= bl;
253        data += bl;
254    }
255    /* Copy any data left to last block buffer */
256    memcpy(ctx->last_block, data, dlen);
257    ctx->nlast_block = dlen;
258    return 1;
259
260}
261
262int CMAC_Final(CMAC_CTX *ctx, unsigned char *out, size_t *poutlen)
263{
264    int i, bl, lb;
265#ifdef OPENSSL_FIPS
266    if (FIPS_mode() && !ctx->cctx.engine)
267        return FIPS_cmac_final(ctx, out, poutlen);
268#endif
269    if (ctx->nlast_block == -1)
270        return 0;
271    bl = EVP_CIPHER_CTX_block_size(&ctx->cctx);
272    *poutlen = (size_t)bl;
273    if (!out)
274        return 1;
275    lb = ctx->nlast_block;
276    /* Is last block complete? */
277    if (lb == bl) {
278        for (i = 0; i < bl; i++)
279            out[i] = ctx->last_block[i] ^ ctx->k1[i];
280    } else {
281        ctx->last_block[lb] = 0x80;
282        if (bl - lb > 1)
283            memset(ctx->last_block + lb + 1, 0, bl - lb - 1);
284        for (i = 0; i < bl; i++)
285            out[i] = ctx->last_block[i] ^ ctx->k2[i];
286    }
287    if (!EVP_Cipher(&ctx->cctx, out, out, bl)) {
288        OPENSSL_cleanse(out, bl);
289        return 0;
290    }
291    return 1;
292}
293
294int CMAC_resume(CMAC_CTX *ctx)
295{
296    if (ctx->nlast_block == -1)
297        return 0;
298    /*
299     * The buffer "tbl" containes the last fully encrypted block which is the
300     * last IV (or all zeroes if no last encrypted block). The last block has
301     * not been modified since CMAC_final(). So reinitliasing using the last
302     * decrypted block will allow CMAC to continue after calling
303     * CMAC_Final().
304     */
305    return EVP_EncryptInit_ex(&ctx->cctx, NULL, NULL, NULL, ctx->tbl);
306}
307