2 * Copyright 2010-2016 The OpenSSL Project Authors. All Rights Reserved.
4 * Licensed under the OpenSSL license (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
13 #include "internal/cryptlib.h"
14 #include <openssl/cmac.h>
17 /* Cipher context to use */
20 unsigned char k1[EVP_MAX_BLOCK_LENGTH];
21 unsigned char k2[EVP_MAX_BLOCK_LENGTH];
23 unsigned char tbl[EVP_MAX_BLOCK_LENGTH];
24 /* Last (possibly partial) block */
25 unsigned char last_block[EVP_MAX_BLOCK_LENGTH];
26 /* Number of bytes in last block: -1 means context not initialised */
30 /* Make temporary keys K1 and K2 */
32 static void make_kn(unsigned char *k1, const unsigned char *l, int bl)
35 unsigned char c = l[0], carry = c >> 7, cnext;
37 /* Shift block to left, including carry */
38 for (i = 0; i < bl - 1; i++, c = cnext)
39 k1[i] = (c << 1) | ((cnext = l[i + 1]) >> 7);
41 /* If MSB set fixup with R */
42 k1[i] = (c << 1) ^ ((0 - carry) & (bl == 16 ? 0x87 : 0x1b));
45 CMAC_CTX *CMAC_CTX_new(void)
49 ctx = OPENSSL_malloc(sizeof(*ctx));
52 ctx->cctx = EVP_CIPHER_CTX_new();
53 if (ctx->cctx == NULL) {
57 ctx->nlast_block = -1;
61 void CMAC_CTX_cleanup(CMAC_CTX *ctx)
63 EVP_CIPHER_CTX_free(ctx->cctx);
64 OPENSSL_cleanse(ctx->tbl, EVP_MAX_BLOCK_LENGTH);
65 OPENSSL_cleanse(ctx->k1, EVP_MAX_BLOCK_LENGTH);
66 OPENSSL_cleanse(ctx->k2, EVP_MAX_BLOCK_LENGTH);
67 OPENSSL_cleanse(ctx->last_block, EVP_MAX_BLOCK_LENGTH);
68 ctx->nlast_block = -1;
71 EVP_CIPHER_CTX *CMAC_CTX_get0_cipher_ctx(CMAC_CTX *ctx)
76 void CMAC_CTX_free(CMAC_CTX *ctx)
80 CMAC_CTX_cleanup(ctx);
84 int CMAC_CTX_copy(CMAC_CTX *out, const CMAC_CTX *in)
87 if (in->nlast_block == -1)
89 if (!EVP_CIPHER_CTX_copy(out->cctx, in->cctx))
91 bl = EVP_CIPHER_CTX_block_size(in->cctx);
92 memcpy(out->k1, in->k1, bl);
93 memcpy(out->k2, in->k2, bl);
94 memcpy(out->tbl, in->tbl, bl);
95 memcpy(out->last_block, in->last_block, bl);
96 out->nlast_block = in->nlast_block;
100 int CMAC_Init(CMAC_CTX *ctx, const void *key, size_t keylen,
101 const EVP_CIPHER *cipher, ENGINE *impl)
103 static const unsigned char zero_iv[EVP_MAX_BLOCK_LENGTH] = { 0 };
104 /* All zeros means restart */
105 if (!key && !cipher && !impl && keylen == 0) {
106 /* Not initialised */
107 if (ctx->nlast_block == -1)
109 if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, zero_iv))
111 memset(ctx->tbl, 0, EVP_CIPHER_CTX_block_size(ctx->cctx));
112 ctx->nlast_block = 0;
115 /* Initialise context */
116 if (cipher && !EVP_EncryptInit_ex(ctx->cctx, cipher, impl, NULL, NULL))
118 /* Non-NULL key means initialisation complete */
121 if (!EVP_CIPHER_CTX_cipher(ctx->cctx))
123 if (!EVP_CIPHER_CTX_set_key_length(ctx->cctx, keylen))
125 if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, key, zero_iv))
127 bl = EVP_CIPHER_CTX_block_size(ctx->cctx);
128 if (!EVP_Cipher(ctx->cctx, ctx->tbl, zero_iv, bl))
130 make_kn(ctx->k1, ctx->tbl, bl);
131 make_kn(ctx->k2, ctx->k1, bl);
132 OPENSSL_cleanse(ctx->tbl, bl);
133 /* Reset context again ready for first data block */
134 if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, zero_iv))
136 /* Zero tbl so resume works */
137 memset(ctx->tbl, 0, bl);
138 ctx->nlast_block = 0;
143 int CMAC_Update(CMAC_CTX *ctx, const void *in, size_t dlen)
145 const unsigned char *data = in;
147 if (ctx->nlast_block == -1)
151 bl = EVP_CIPHER_CTX_block_size(ctx->cctx);
152 /* Copy into partial block if we need to */
153 if (ctx->nlast_block > 0) {
155 nleft = bl - ctx->nlast_block;
158 memcpy(ctx->last_block + ctx->nlast_block, data, nleft);
160 ctx->nlast_block += nleft;
161 /* If no more to process return */
165 /* Else not final block so encrypt it */
166 if (!EVP_Cipher(ctx->cctx, ctx->tbl, ctx->last_block, bl))
169 /* Encrypt all but one of the complete blocks left */
171 if (!EVP_Cipher(ctx->cctx, ctx->tbl, data, bl))
176 /* Copy any data left to last block buffer */
177 memcpy(ctx->last_block, data, dlen);
178 ctx->nlast_block = dlen;
183 int CMAC_Final(CMAC_CTX *ctx, unsigned char *out, size_t *poutlen)
186 if (ctx->nlast_block == -1)
188 bl = EVP_CIPHER_CTX_block_size(ctx->cctx);
189 *poutlen = (size_t)bl;
192 lb = ctx->nlast_block;
193 /* Is last block complete? */
195 for (i = 0; i < bl; i++)
196 out[i] = ctx->last_block[i] ^ ctx->k1[i];
198 ctx->last_block[lb] = 0x80;
200 memset(ctx->last_block + lb + 1, 0, bl - lb - 1);
201 for (i = 0; i < bl; i++)
202 out[i] = ctx->last_block[i] ^ ctx->k2[i];
204 if (!EVP_Cipher(ctx->cctx, out, out, bl)) {
205 OPENSSL_cleanse(out, bl);
211 int CMAC_resume(CMAC_CTX *ctx)
213 if (ctx->nlast_block == -1)
216 * The buffer "tbl" contains the last fully encrypted block which is the
217 * last IV (or all zeroes if no last encrypted block). The last block has
218 * not been modified since CMAC_final(). So reinitialising using the last
219 * decrypted block will allow CMAC to continue after calling
222 return EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, ctx->tbl);