2 * Copyright 2010-2020 The OpenSSL Project Authors. All Rights Reserved.
4 * Licensed under the Apache License 2.0 (the "License"). You may not use
5 * this file except in compliance with the License. You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
11 * CMAC low level APIs are deprecated for public use, but still ok for internal
14 #include "internal/deprecated.h"
19 #include "internal/cryptlib.h"
20 #include <openssl/cmac.h>
21 #include <openssl/err.h>
24 /* Cipher context to use */
27 unsigned char k1[EVP_MAX_BLOCK_LENGTH];
28 unsigned char k2[EVP_MAX_BLOCK_LENGTH];
30 unsigned char tbl[EVP_MAX_BLOCK_LENGTH];
31 /* Last (possibly partial) block */
32 unsigned char last_block[EVP_MAX_BLOCK_LENGTH];
33 /* Number of bytes in last block: -1 means context not initialised */
37 /* Make temporary keys K1 and K2 */
39 static void make_kn(unsigned char *k1, const unsigned char *l, int bl)
42 unsigned char c = l[0], carry = c >> 7, cnext;
44 /* Shift block to left, including carry */
45 for (i = 0; i < bl - 1; i++, c = cnext)
46 k1[i] = (c << 1) | ((cnext = l[i + 1]) >> 7);
48 /* If MSB set fixup with R */
49 k1[i] = (c << 1) ^ ((0 - carry) & (bl == 16 ? 0x87 : 0x1b));
52 CMAC_CTX *CMAC_CTX_new(void)
56 if ((ctx = OPENSSL_malloc(sizeof(*ctx))) == NULL) {
57 CRYPTOerr(CRYPTO_F_CMAC_CTX_NEW, ERR_R_MALLOC_FAILURE);
60 ctx->cctx = EVP_CIPHER_CTX_new();
61 if (ctx->cctx == NULL) {
65 ctx->nlast_block = -1;
69 void CMAC_CTX_cleanup(CMAC_CTX *ctx)
71 EVP_CIPHER_CTX_reset(ctx->cctx);
72 OPENSSL_cleanse(ctx->tbl, EVP_MAX_BLOCK_LENGTH);
73 OPENSSL_cleanse(ctx->k1, EVP_MAX_BLOCK_LENGTH);
74 OPENSSL_cleanse(ctx->k2, EVP_MAX_BLOCK_LENGTH);
75 OPENSSL_cleanse(ctx->last_block, EVP_MAX_BLOCK_LENGTH);
76 ctx->nlast_block = -1;
79 EVP_CIPHER_CTX *CMAC_CTX_get0_cipher_ctx(CMAC_CTX *ctx)
84 void CMAC_CTX_free(CMAC_CTX *ctx)
88 CMAC_CTX_cleanup(ctx);
89 EVP_CIPHER_CTX_free(ctx->cctx);
93 int CMAC_CTX_copy(CMAC_CTX *out, const CMAC_CTX *in)
97 if (in->nlast_block == -1)
99 if ((bl = EVP_CIPHER_CTX_block_size(in->cctx)) < 0)
101 if (!EVP_CIPHER_CTX_copy(out->cctx, in->cctx))
103 memcpy(out->k1, in->k1, bl);
104 memcpy(out->k2, in->k2, bl);
105 memcpy(out->tbl, in->tbl, bl);
106 memcpy(out->last_block, in->last_block, bl);
107 out->nlast_block = in->nlast_block;
111 int CMAC_Init(CMAC_CTX *ctx, const void *key, size_t keylen,
112 const EVP_CIPHER *cipher, ENGINE *impl)
114 static const unsigned char zero_iv[EVP_MAX_BLOCK_LENGTH] = { 0 };
116 /* All zeros means restart */
117 if (!key && !cipher && !impl && keylen == 0) {
118 /* Not initialised */
119 if (ctx->nlast_block == -1)
121 if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, zero_iv))
123 memset(ctx->tbl, 0, EVP_CIPHER_CTX_block_size(ctx->cctx));
124 ctx->nlast_block = 0;
127 /* Initialise context */
128 if (cipher != NULL) {
129 /* Ensure we can't use this ctx until we also have a key */
130 ctx->nlast_block = -1;
131 if (!EVP_EncryptInit_ex(ctx->cctx, cipher, impl, NULL, NULL))
134 /* Non-NULL key means initialisation complete */
138 /* If anything fails then ensure we can't use this ctx */
139 ctx->nlast_block = -1;
140 if (!EVP_CIPHER_CTX_cipher(ctx->cctx))
142 if (!EVP_CIPHER_CTX_set_key_length(ctx->cctx, keylen))
144 if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, key, zero_iv))
146 if ((bl = EVP_CIPHER_CTX_block_size(ctx->cctx)) < 0)
148 if (EVP_Cipher(ctx->cctx, ctx->tbl, zero_iv, bl) <= 0)
150 make_kn(ctx->k1, ctx->tbl, bl);
151 make_kn(ctx->k2, ctx->k1, bl);
152 OPENSSL_cleanse(ctx->tbl, bl);
153 /* Reset context again ready for first data block */
154 if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, zero_iv))
156 /* Zero tbl so resume works */
157 memset(ctx->tbl, 0, bl);
158 ctx->nlast_block = 0;
163 int CMAC_Update(CMAC_CTX *ctx, const void *in, size_t dlen)
165 const unsigned char *data = in;
168 if (ctx->nlast_block == -1)
172 if ((bl = EVP_CIPHER_CTX_block_size(ctx->cctx)) < 0)
174 /* Copy into partial block if we need to */
175 if (ctx->nlast_block > 0) {
178 nleft = bl - ctx->nlast_block;
181 memcpy(ctx->last_block + ctx->nlast_block, data, nleft);
183 ctx->nlast_block += nleft;
184 /* If no more to process return */
188 /* Else not final block so encrypt it */
189 if (EVP_Cipher(ctx->cctx, ctx->tbl, ctx->last_block, bl) <= 0)
192 /* Encrypt all but one of the complete blocks left */
193 while (dlen > (size_t)bl) {
194 if (EVP_Cipher(ctx->cctx, ctx->tbl, data, bl) <= 0)
199 /* Copy any data left to last block buffer */
200 memcpy(ctx->last_block, data, dlen);
201 ctx->nlast_block = dlen;
206 int CMAC_Final(CMAC_CTX *ctx, unsigned char *out, size_t *poutlen)
210 if (ctx->nlast_block == -1)
212 if ((bl = EVP_CIPHER_CTX_block_size(ctx->cctx)) < 0)
215 *poutlen = (size_t)bl;
218 lb = ctx->nlast_block;
219 /* Is last block complete? */
221 for (i = 0; i < bl; i++)
222 out[i] = ctx->last_block[i] ^ ctx->k1[i];
224 ctx->last_block[lb] = 0x80;
226 memset(ctx->last_block + lb + 1, 0, bl - lb - 1);
227 for (i = 0; i < bl; i++)
228 out[i] = ctx->last_block[i] ^ ctx->k2[i];
230 if (!EVP_Cipher(ctx->cctx, out, out, bl)) {
231 OPENSSL_cleanse(out, bl);
237 int CMAC_resume(CMAC_CTX *ctx)
239 if (ctx->nlast_block == -1)
242 * The buffer "tbl" contains the last fully encrypted block which is the
243 * last IV (or all zeroes if no last encrypted block). The last block has
244 * not been modified since CMAC_final(). So reinitialising using the last
245 * decrypted block will allow CMAC to continue after calling
248 return EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, ctx->tbl);