2 * Copyright 2010-2023 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>
23 #define LOCAL_BUF_SIZE 2048
25 /* Cipher context to use */
28 unsigned char k1[EVP_MAX_BLOCK_LENGTH];
29 unsigned char k2[EVP_MAX_BLOCK_LENGTH];
31 unsigned char tbl[EVP_MAX_BLOCK_LENGTH];
32 /* Last (possibly partial) block */
33 unsigned char last_block[EVP_MAX_BLOCK_LENGTH];
34 /* Number of bytes in last block: -1 means context not initialised */
38 /* Make temporary keys K1 and K2 */
40 static void make_kn(unsigned char *k1, const unsigned char *l, int bl)
43 unsigned char c = l[0], carry = c >> 7, cnext;
45 /* Shift block to left, including carry */
46 for (i = 0; i < bl - 1; i++, c = cnext)
47 k1[i] = (c << 1) | ((cnext = l[i + 1]) >> 7);
49 /* If MSB set fixup with R */
50 k1[i] = (c << 1) ^ ((0 - carry) & (bl == 16 ? 0x87 : 0x1b));
53 CMAC_CTX *CMAC_CTX_new(void)
57 if ((ctx = OPENSSL_malloc(sizeof(*ctx))) == NULL)
59 ctx->cctx = EVP_CIPHER_CTX_new();
60 if (ctx->cctx == NULL) {
64 ctx->nlast_block = -1;
68 void CMAC_CTX_cleanup(CMAC_CTX *ctx)
70 EVP_CIPHER_CTX_reset(ctx->cctx);
71 OPENSSL_cleanse(ctx->tbl, EVP_MAX_BLOCK_LENGTH);
72 OPENSSL_cleanse(ctx->k1, EVP_MAX_BLOCK_LENGTH);
73 OPENSSL_cleanse(ctx->k2, EVP_MAX_BLOCK_LENGTH);
74 OPENSSL_cleanse(ctx->last_block, EVP_MAX_BLOCK_LENGTH);
75 ctx->nlast_block = -1;
78 EVP_CIPHER_CTX *CMAC_CTX_get0_cipher_ctx(CMAC_CTX *ctx)
83 void CMAC_CTX_free(CMAC_CTX *ctx)
87 CMAC_CTX_cleanup(ctx);
88 EVP_CIPHER_CTX_free(ctx->cctx);
92 int CMAC_CTX_copy(CMAC_CTX *out, const CMAC_CTX *in)
96 if (in->nlast_block == -1)
98 if ((bl = EVP_CIPHER_CTX_get_block_size(in->cctx)) == 0)
100 if (!EVP_CIPHER_CTX_copy(out->cctx, in->cctx))
102 memcpy(out->k1, in->k1, bl);
103 memcpy(out->k2, in->k2, bl);
104 memcpy(out->tbl, in->tbl, bl);
105 memcpy(out->last_block, in->last_block, bl);
106 out->nlast_block = in->nlast_block;
110 int CMAC_Init(CMAC_CTX *ctx, const void *key, size_t keylen,
111 const EVP_CIPHER *cipher, ENGINE *impl)
113 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 block_len = EVP_CIPHER_CTX_get_block_size(ctx->cctx);
126 memset(ctx->tbl, 0, block_len);
127 ctx->nlast_block = 0;
130 /* Initialise context */
131 if (cipher != NULL) {
132 /* Ensure we can't use this ctx until we also have a key */
133 ctx->nlast_block = -1;
134 if (!EVP_EncryptInit_ex(ctx->cctx, cipher, impl, NULL, NULL))
137 /* Non-NULL key means initialisation complete */
141 /* If anything fails then ensure we can't use this ctx */
142 ctx->nlast_block = -1;
143 if (EVP_CIPHER_CTX_get0_cipher(ctx->cctx) == NULL)
145 if (EVP_CIPHER_CTX_set_key_length(ctx->cctx, keylen) <= 0)
147 if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, key, zero_iv))
149 if ((bl = EVP_CIPHER_CTX_get_block_size(ctx->cctx)) < 0)
151 if (EVP_Cipher(ctx->cctx, ctx->tbl, zero_iv, bl) <= 0)
153 make_kn(ctx->k1, ctx->tbl, bl);
154 make_kn(ctx->k2, ctx->k1, bl);
155 OPENSSL_cleanse(ctx->tbl, bl);
156 /* Reset context again ready for first data block */
157 if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, zero_iv))
159 /* Zero tbl so resume works */
160 memset(ctx->tbl, 0, bl);
161 ctx->nlast_block = 0;
166 int CMAC_Update(CMAC_CTX *ctx, const void *in, size_t dlen)
168 const unsigned char *data = in;
170 size_t max_burst_blocks, cipher_blocks;
171 unsigned char buf[LOCAL_BUF_SIZE];
173 if (ctx->nlast_block == -1)
177 if ((bl = EVP_CIPHER_CTX_get_block_size(ctx->cctx)) == 0)
179 /* Copy into partial block if we need to */
180 if (ctx->nlast_block > 0) {
183 nleft = bl - ctx->nlast_block;
186 memcpy(ctx->last_block + ctx->nlast_block, data, nleft);
188 ctx->nlast_block += nleft;
189 /* If no more to process return */
193 /* Else not final block so encrypt it */
194 if (EVP_Cipher(ctx->cctx, ctx->tbl, ctx->last_block, bl) <= 0)
197 /* Encrypt all but one of the complete blocks left */
199 max_burst_blocks = LOCAL_BUF_SIZE / bl;
200 cipher_blocks = (dlen - 1) / bl;
201 if (max_burst_blocks == 0) {
203 * When block length is greater than local buffer size,
204 * use ctx->tbl as cipher output.
206 while (dlen > (size_t)bl) {
207 if (EVP_Cipher(ctx->cctx, ctx->tbl, data, bl) <= 0)
213 while (cipher_blocks > max_burst_blocks) {
214 if (EVP_Cipher(ctx->cctx, buf, data, max_burst_blocks * bl) <= 0)
216 dlen -= max_burst_blocks * bl;
217 data += max_burst_blocks * bl;
218 cipher_blocks -= max_burst_blocks;
220 if (cipher_blocks > 0) {
221 if (EVP_Cipher(ctx->cctx, buf, data, cipher_blocks * bl) <= 0)
223 dlen -= cipher_blocks * bl;
224 data += cipher_blocks * bl;
225 memcpy(ctx->tbl, &buf[(cipher_blocks - 1) * bl], bl);
228 /* Copy any data left to last block buffer */
229 memcpy(ctx->last_block, data, dlen);
230 ctx->nlast_block = dlen;
235 int CMAC_Final(CMAC_CTX *ctx, unsigned char *out, size_t *poutlen)
239 if (ctx->nlast_block == -1)
241 if ((bl = EVP_CIPHER_CTX_get_block_size(ctx->cctx)) == 0)
244 *poutlen = (size_t)bl;
247 lb = ctx->nlast_block;
248 /* Is last block complete? */
250 for (i = 0; i < bl; i++)
251 out[i] = ctx->last_block[i] ^ ctx->k1[i];
253 ctx->last_block[lb] = 0x80;
255 memset(ctx->last_block + lb + 1, 0, bl - lb - 1);
256 for (i = 0; i < bl; i++)
257 out[i] = ctx->last_block[i] ^ ctx->k2[i];
259 if (EVP_Cipher(ctx->cctx, out, out, bl) <= 0) {
260 OPENSSL_cleanse(out, bl);
266 int CMAC_resume(CMAC_CTX *ctx)
268 if (ctx->nlast_block == -1)
271 * The buffer "tbl" contains the last fully encrypted block which is the
272 * last IV (or all zeroes if no last encrypted block). The last block has
273 * not been modified since CMAC_final(). So reinitialising using the last
274 * decrypted block will allow CMAC to continue after calling
277 return EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, ctx->tbl);