1 /* crypto/cmac/cmac.c */
3 * Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
6 /* ====================================================================
7 * Copyright (c) 2010 The OpenSSL Project. All rights reserved.
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
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
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/)"
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.
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.
35 * 6. Redistributions of any form whatsoever must retain the following
37 * "This product includes software developed by the OpenSSL Project
38 * for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
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
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50 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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52 * ====================================================================
59 #include <openssl/cmac.h>
62 /* Cipher context to use */
65 unsigned char k1[EVP_MAX_BLOCK_LENGTH];
66 unsigned char k2[EVP_MAX_BLOCK_LENGTH];
68 unsigned char tbl[EVP_MAX_BLOCK_LENGTH];
69 /* Last (possibly partial) block */
70 unsigned char last_block[EVP_MAX_BLOCK_LENGTH];
71 /* Number of bytes in last block: -1 means context not initialised */
75 /* Make temporary keys K1 and K2 */
77 static void make_kn(unsigned char *k1, const unsigned char *l, int bl)
80 unsigned char c = l[0], carry = c >> 7, cnext;
82 /* Shift block to left, including carry */
83 for (i = 0; i < bl - 1; i++, c = cnext)
84 k1[i] = (c << 1) | ((cnext = l[i + 1]) >> 7);
86 /* If MSB set fixup with R */
87 k1[i] = (c << 1) ^ ((0 - carry) & (bl == 16 ? 0x87 : 0x1b));
90 CMAC_CTX *CMAC_CTX_new(void)
93 ctx = OPENSSL_malloc(sizeof(CMAC_CTX));
96 EVP_CIPHER_CTX_init(&ctx->cctx);
97 ctx->nlast_block = -1;
101 void CMAC_CTX_cleanup(CMAC_CTX *ctx)
103 EVP_CIPHER_CTX_cleanup(&ctx->cctx);
104 OPENSSL_cleanse(ctx->tbl, EVP_MAX_BLOCK_LENGTH);
105 OPENSSL_cleanse(ctx->k1, EVP_MAX_BLOCK_LENGTH);
106 OPENSSL_cleanse(ctx->k2, EVP_MAX_BLOCK_LENGTH);
107 OPENSSL_cleanse(ctx->last_block, EVP_MAX_BLOCK_LENGTH);
108 ctx->nlast_block = -1;
111 EVP_CIPHER_CTX *CMAC_CTX_get0_cipher_ctx(CMAC_CTX *ctx)
116 void CMAC_CTX_free(CMAC_CTX *ctx)
120 CMAC_CTX_cleanup(ctx);
124 int CMAC_CTX_copy(CMAC_CTX *out, const CMAC_CTX *in)
127 if (in->nlast_block == -1)
129 if (!EVP_CIPHER_CTX_copy(&out->cctx, &in->cctx))
131 bl = M_EVP_CIPHER_CTX_block_size(&in->cctx);
132 memcpy(out->k1, in->k1, bl);
133 memcpy(out->k2, in->k2, bl);
134 memcpy(out->tbl, in->tbl, bl);
135 memcpy(out->last_block, in->last_block, bl);
136 out->nlast_block = in->nlast_block;
140 int CMAC_Init(CMAC_CTX *ctx, const void *key, size_t keylen,
141 const EVP_CIPHER *cipher, ENGINE *impl)
143 static const unsigned char zero_iv[EVP_MAX_BLOCK_LENGTH] = { 0 };
144 /* All zeros means restart */
145 if (!key && !cipher && !impl && keylen == 0) {
146 /* Not initialised */
147 if (ctx->nlast_block == -1)
149 if (!M_EVP_EncryptInit_ex(&ctx->cctx, NULL, NULL, NULL, zero_iv))
151 memset(ctx->tbl, 0, M_EVP_CIPHER_CTX_block_size(&ctx->cctx));
152 ctx->nlast_block = 0;
155 /* Initialiase context */
156 if (cipher && !M_EVP_EncryptInit_ex(&ctx->cctx, cipher, impl, NULL, NULL))
158 /* Non-NULL key means initialisation complete */
161 if (!M_EVP_CIPHER_CTX_cipher(&ctx->cctx))
163 if (!EVP_CIPHER_CTX_set_key_length(&ctx->cctx, keylen))
165 if (!M_EVP_EncryptInit_ex(&ctx->cctx, NULL, NULL, key, zero_iv))
167 bl = M_EVP_CIPHER_CTX_block_size(&ctx->cctx);
168 if (!EVP_Cipher(&ctx->cctx, ctx->tbl, zero_iv, bl))
170 make_kn(ctx->k1, ctx->tbl, bl);
171 make_kn(ctx->k2, ctx->k1, bl);
172 OPENSSL_cleanse(ctx->tbl, bl);
173 /* Reset context again ready for first data block */
174 if (!M_EVP_EncryptInit_ex(&ctx->cctx, NULL, NULL, NULL, zero_iv))
176 /* Zero tbl so resume works */
177 memset(ctx->tbl, 0, bl);
178 ctx->nlast_block = 0;
183 int CMAC_Update(CMAC_CTX *ctx, const void *in, size_t dlen)
185 const unsigned char *data = in;
187 if (ctx->nlast_block == -1)
191 bl = M_EVP_CIPHER_CTX_block_size(&ctx->cctx);
192 /* Copy into partial block if we need to */
193 if (ctx->nlast_block > 0) {
195 nleft = bl - ctx->nlast_block;
198 memcpy(ctx->last_block + ctx->nlast_block, data, nleft);
200 ctx->nlast_block += nleft;
201 /* If no more to process return */
205 /* Else not final block so encrypt it */
206 if (!EVP_Cipher(&ctx->cctx, ctx->tbl, ctx->last_block, bl))
209 /* Encrypt all but one of the complete blocks left */
211 if (!EVP_Cipher(&ctx->cctx, ctx->tbl, data, bl))
216 /* Copy any data left to last block buffer */
217 memcpy(ctx->last_block, data, dlen);
218 ctx->nlast_block = dlen;
223 int CMAC_Final(CMAC_CTX *ctx, unsigned char *out, size_t *poutlen)
226 if (ctx->nlast_block == -1)
228 bl = M_EVP_CIPHER_CTX_block_size(&ctx->cctx);
229 *poutlen = (size_t)bl;
232 lb = ctx->nlast_block;
233 /* Is last block complete? */
235 for (i = 0; i < bl; i++)
236 out[i] = ctx->last_block[i] ^ ctx->k1[i];
238 ctx->last_block[lb] = 0x80;
240 memset(ctx->last_block + lb + 1, 0, bl - lb - 1);
241 for (i = 0; i < bl; i++)
242 out[i] = ctx->last_block[i] ^ ctx->k2[i];
244 if (!EVP_Cipher(&ctx->cctx, out, out, bl)) {
245 OPENSSL_cleanse(out, bl);
251 int CMAC_resume(CMAC_CTX *ctx)
253 if (ctx->nlast_block == -1)
256 * The buffer "tbl" containes the last fully encrypted block which is the
257 * last IV (or all zeroes if no last encrypted block). The last block has
258 * not been modified since CMAC_final(). So reinitliasing using the last
259 * decrypted block will allow CMAC to continue after calling
262 return M_EVP_EncryptInit_ex(&ctx->cctx, NULL, NULL, NULL, ctx->tbl);