2 * Copyright 2010-2021 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)
58 ctx->cctx = EVP_CIPHER_CTX_new();
59 if (ctx->cctx == NULL) {
63 ctx->nlast_block = -1;
67 void CMAC_CTX_cleanup(CMAC_CTX *ctx)
69 EVP_CIPHER_CTX_reset(ctx->cctx);
70 OPENSSL_cleanse(ctx->tbl, EVP_MAX_BLOCK_LENGTH);
71 OPENSSL_cleanse(ctx->k1, EVP_MAX_BLOCK_LENGTH);
72 OPENSSL_cleanse(ctx->k2, EVP_MAX_BLOCK_LENGTH);
73 OPENSSL_cleanse(ctx->last_block, EVP_MAX_BLOCK_LENGTH);
74 ctx->nlast_block = -1;
77 EVP_CIPHER_CTX *CMAC_CTX_get0_cipher_ctx(CMAC_CTX *ctx)
82 void CMAC_CTX_free(CMAC_CTX *ctx)
86 CMAC_CTX_cleanup(ctx);
87 EVP_CIPHER_CTX_free(ctx->cctx);
91 int CMAC_CTX_copy(CMAC_CTX *out, const CMAC_CTX *in)
95 if (in->nlast_block == -1)
97 if ((bl = EVP_CIPHER_CTX_get_block_size(in->cctx)) < 0)
99 if (!EVP_CIPHER_CTX_copy(out->cctx, in->cctx))
101 memcpy(out->k1, in->k1, bl);
102 memcpy(out->k2, in->k2, bl);
103 memcpy(out->tbl, in->tbl, bl);
104 memcpy(out->last_block, in->last_block, bl);
105 out->nlast_block = in->nlast_block;
109 int CMAC_Init(CMAC_CTX *ctx, const void *key, size_t keylen,
110 const EVP_CIPHER *cipher, ENGINE *impl)
112 static const unsigned char zero_iv[EVP_MAX_BLOCK_LENGTH] = { 0 };
114 /* All zeros means restart */
115 if (!key && !cipher && !impl && keylen == 0) {
116 /* Not initialised */
117 if (ctx->nlast_block == -1)
119 if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, zero_iv))
121 memset(ctx->tbl, 0, EVP_CIPHER_CTX_get_block_size(ctx->cctx));
122 ctx->nlast_block = 0;
125 /* Initialise context */
126 if (cipher != NULL) {
127 /* Ensure we can't use this ctx until we also have a key */
128 ctx->nlast_block = -1;
129 if (!EVP_EncryptInit_ex(ctx->cctx, cipher, impl, NULL, NULL))
132 /* Non-NULL key means initialisation complete */
136 /* If anything fails then ensure we can't use this ctx */
137 ctx->nlast_block = -1;
138 if (EVP_CIPHER_CTX_get0_cipher(ctx->cctx) == NULL)
140 if (EVP_CIPHER_CTX_set_key_length(ctx->cctx, keylen) <= 0)
142 if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, key, zero_iv))
144 if ((bl = EVP_CIPHER_CTX_get_block_size(ctx->cctx)) < 0)
146 if (EVP_Cipher(ctx->cctx, ctx->tbl, zero_iv, bl) <= 0)
148 make_kn(ctx->k1, ctx->tbl, bl);
149 make_kn(ctx->k2, ctx->k1, bl);
150 OPENSSL_cleanse(ctx->tbl, bl);
151 /* Reset context again ready for first data block */
152 if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, zero_iv))
154 /* Zero tbl so resume works */
155 memset(ctx->tbl, 0, bl);
156 ctx->nlast_block = 0;
161 int CMAC_Update(CMAC_CTX *ctx, const void *in, size_t dlen)
163 const unsigned char *data = in;
166 if (ctx->nlast_block == -1)
170 if ((bl = EVP_CIPHER_CTX_get_block_size(ctx->cctx)) < 0)
172 /* Copy into partial block if we need to */
173 if (ctx->nlast_block > 0) {
176 nleft = bl - ctx->nlast_block;
179 memcpy(ctx->last_block + ctx->nlast_block, data, nleft);
181 ctx->nlast_block += nleft;
182 /* If no more to process return */
186 /* Else not final block so encrypt it */
187 if (EVP_Cipher(ctx->cctx, ctx->tbl, ctx->last_block, bl) <= 0)
190 /* Encrypt all but one of the complete blocks left */
191 while (dlen > (size_t)bl) {
192 if (EVP_Cipher(ctx->cctx, ctx->tbl, data, bl) <= 0)
197 /* Copy any data left to last block buffer */
198 memcpy(ctx->last_block, data, dlen);
199 ctx->nlast_block = dlen;
204 int CMAC_Final(CMAC_CTX *ctx, unsigned char *out, size_t *poutlen)
208 if (ctx->nlast_block == -1)
210 if ((bl = EVP_CIPHER_CTX_get_block_size(ctx->cctx)) < 0)
213 *poutlen = (size_t)bl;
216 lb = ctx->nlast_block;
217 /* Is last block complete? */
219 for (i = 0; i < bl; i++)
220 out[i] = ctx->last_block[i] ^ ctx->k1[i];
222 ctx->last_block[lb] = 0x80;
224 memset(ctx->last_block + lb + 1, 0, bl - lb - 1);
225 for (i = 0; i < bl; i++)
226 out[i] = ctx->last_block[i] ^ ctx->k2[i];
228 if (EVP_Cipher(ctx->cctx, out, out, bl) <= 0) {
229 OPENSSL_cleanse(out, bl);
235 int CMAC_resume(CMAC_CTX *ctx)
237 if (ctx->nlast_block == -1)
240 * The buffer "tbl" contains the last fully encrypted block which is the
241 * last IV (or all zeroes if no last encrypted block). The last block has
242 * not been modified since CMAC_final(). So reinitialising using the last
243 * decrypted block will allow CMAC to continue after calling
246 return EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, ctx->tbl);