lh | 9ed821d | 2023-04-07 01:36:19 -0700 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 2010-2020 The OpenSSL Project Authors. All Rights Reserved. |
| 3 | * |
| 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 |
| 8 | */ |
| 9 | |
| 10 | #include <stdio.h> |
| 11 | #include <stdlib.h> |
| 12 | #include <string.h> |
| 13 | #include "internal/cryptlib.h" |
| 14 | #include <openssl/cmac.h> |
| 15 | #include <openssl/err.h> |
| 16 | |
| 17 | struct CMAC_CTX_st { |
| 18 | /* Cipher context to use */ |
| 19 | EVP_CIPHER_CTX *cctx; |
| 20 | /* Keys k1 and k2 */ |
| 21 | unsigned char k1[EVP_MAX_BLOCK_LENGTH]; |
| 22 | unsigned char k2[EVP_MAX_BLOCK_LENGTH]; |
| 23 | /* Temporary block */ |
| 24 | unsigned char tbl[EVP_MAX_BLOCK_LENGTH]; |
| 25 | /* Last (possibly partial) block */ |
| 26 | unsigned char last_block[EVP_MAX_BLOCK_LENGTH]; |
| 27 | /* Number of bytes in last block: -1 means context not initialised */ |
| 28 | int nlast_block; |
| 29 | }; |
| 30 | |
| 31 | /* Make temporary keys K1 and K2 */ |
| 32 | |
| 33 | static void make_kn(unsigned char *k1, const unsigned char *l, int bl) |
| 34 | { |
| 35 | int i; |
| 36 | unsigned char c = l[0], carry = c >> 7, cnext; |
| 37 | |
| 38 | /* Shift block to left, including carry */ |
| 39 | for (i = 0; i < bl - 1; i++, c = cnext) |
| 40 | k1[i] = (c << 1) | ((cnext = l[i + 1]) >> 7); |
| 41 | |
| 42 | /* If MSB set fixup with R */ |
| 43 | k1[i] = (c << 1) ^ ((0 - carry) & (bl == 16 ? 0x87 : 0x1b)); |
| 44 | } |
| 45 | |
| 46 | CMAC_CTX *CMAC_CTX_new(void) |
| 47 | { |
| 48 | CMAC_CTX *ctx; |
| 49 | |
| 50 | if ((ctx = OPENSSL_malloc(sizeof(*ctx))) == NULL) { |
| 51 | CRYPTOerr(CRYPTO_F_CMAC_CTX_NEW, ERR_R_MALLOC_FAILURE); |
| 52 | return NULL; |
| 53 | } |
| 54 | ctx->cctx = EVP_CIPHER_CTX_new(); |
| 55 | if (ctx->cctx == NULL) { |
| 56 | OPENSSL_free(ctx); |
| 57 | return NULL; |
| 58 | } |
| 59 | ctx->nlast_block = -1; |
| 60 | return ctx; |
| 61 | } |
| 62 | |
| 63 | void CMAC_CTX_cleanup(CMAC_CTX *ctx) |
| 64 | { |
| 65 | EVP_CIPHER_CTX_reset(ctx->cctx); |
| 66 | OPENSSL_cleanse(ctx->tbl, EVP_MAX_BLOCK_LENGTH); |
| 67 | OPENSSL_cleanse(ctx->k1, EVP_MAX_BLOCK_LENGTH); |
| 68 | OPENSSL_cleanse(ctx->k2, EVP_MAX_BLOCK_LENGTH); |
| 69 | OPENSSL_cleanse(ctx->last_block, EVP_MAX_BLOCK_LENGTH); |
| 70 | ctx->nlast_block = -1; |
| 71 | } |
| 72 | |
| 73 | EVP_CIPHER_CTX *CMAC_CTX_get0_cipher_ctx(CMAC_CTX *ctx) |
| 74 | { |
| 75 | return ctx->cctx; |
| 76 | } |
| 77 | |
| 78 | void CMAC_CTX_free(CMAC_CTX *ctx) |
| 79 | { |
| 80 | if (!ctx) |
| 81 | return; |
| 82 | CMAC_CTX_cleanup(ctx); |
| 83 | EVP_CIPHER_CTX_free(ctx->cctx); |
| 84 | OPENSSL_free(ctx); |
| 85 | } |
| 86 | |
| 87 | int CMAC_CTX_copy(CMAC_CTX *out, const CMAC_CTX *in) |
| 88 | { |
| 89 | int bl; |
| 90 | if (in->nlast_block == -1) |
| 91 | return 0; |
| 92 | if (!EVP_CIPHER_CTX_copy(out->cctx, in->cctx)) |
| 93 | return 0; |
| 94 | bl = EVP_CIPHER_CTX_block_size(in->cctx); |
| 95 | memcpy(out->k1, in->k1, bl); |
| 96 | memcpy(out->k2, in->k2, bl); |
| 97 | memcpy(out->tbl, in->tbl, bl); |
| 98 | memcpy(out->last_block, in->last_block, bl); |
| 99 | out->nlast_block = in->nlast_block; |
| 100 | return 1; |
| 101 | } |
| 102 | |
| 103 | int CMAC_Init(CMAC_CTX *ctx, const void *key, size_t keylen, |
| 104 | const EVP_CIPHER *cipher, ENGINE *impl) |
| 105 | { |
| 106 | static const unsigned char zero_iv[EVP_MAX_BLOCK_LENGTH] = { 0 }; |
| 107 | /* All zeros means restart */ |
| 108 | if (!key && !cipher && !impl && keylen == 0) { |
| 109 | /* Not initialised */ |
| 110 | if (ctx->nlast_block == -1) |
| 111 | return 0; |
| 112 | if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, zero_iv)) |
| 113 | return 0; |
| 114 | memset(ctx->tbl, 0, EVP_CIPHER_CTX_block_size(ctx->cctx)); |
| 115 | ctx->nlast_block = 0; |
| 116 | return 1; |
| 117 | } |
| 118 | /* Initialise context */ |
| 119 | if (cipher != NULL) { |
| 120 | /* Ensure we can't use this ctx until we also have a key */ |
| 121 | ctx->nlast_block = -1; |
| 122 | if (!EVP_EncryptInit_ex(ctx->cctx, cipher, impl, NULL, NULL)) |
| 123 | return 0; |
| 124 | } |
| 125 | /* Non-NULL key means initialisation complete */ |
| 126 | if (key != NULL) { |
| 127 | int bl; |
| 128 | |
| 129 | /* If anything fails then ensure we can't use this ctx */ |
| 130 | ctx->nlast_block = -1; |
| 131 | if (!EVP_CIPHER_CTX_cipher(ctx->cctx)) |
| 132 | return 0; |
| 133 | if (!EVP_CIPHER_CTX_set_key_length(ctx->cctx, keylen)) |
| 134 | return 0; |
| 135 | if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, key, zero_iv)) |
| 136 | return 0; |
| 137 | bl = EVP_CIPHER_CTX_block_size(ctx->cctx); |
| 138 | if (EVP_Cipher(ctx->cctx, ctx->tbl, zero_iv, bl) <= 0) |
| 139 | return 0; |
| 140 | make_kn(ctx->k1, ctx->tbl, bl); |
| 141 | make_kn(ctx->k2, ctx->k1, bl); |
| 142 | OPENSSL_cleanse(ctx->tbl, bl); |
| 143 | /* Reset context again ready for first data block */ |
| 144 | if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, zero_iv)) |
| 145 | return 0; |
| 146 | /* Zero tbl so resume works */ |
| 147 | memset(ctx->tbl, 0, bl); |
| 148 | ctx->nlast_block = 0; |
| 149 | } |
| 150 | return 1; |
| 151 | } |
| 152 | |
| 153 | int CMAC_Update(CMAC_CTX *ctx, const void *in, size_t dlen) |
| 154 | { |
| 155 | const unsigned char *data = in; |
| 156 | size_t bl; |
| 157 | if (ctx->nlast_block == -1) |
| 158 | return 0; |
| 159 | if (dlen == 0) |
| 160 | return 1; |
| 161 | bl = EVP_CIPHER_CTX_block_size(ctx->cctx); |
| 162 | /* Copy into partial block if we need to */ |
| 163 | if (ctx->nlast_block > 0) { |
| 164 | size_t nleft; |
| 165 | nleft = bl - ctx->nlast_block; |
| 166 | if (dlen < nleft) |
| 167 | nleft = dlen; |
| 168 | memcpy(ctx->last_block + ctx->nlast_block, data, nleft); |
| 169 | dlen -= nleft; |
| 170 | ctx->nlast_block += nleft; |
| 171 | /* If no more to process return */ |
| 172 | if (dlen == 0) |
| 173 | return 1; |
| 174 | data += nleft; |
| 175 | /* Else not final block so encrypt it */ |
| 176 | if (EVP_Cipher(ctx->cctx, ctx->tbl, ctx->last_block, bl) <= 0) |
| 177 | return 0; |
| 178 | } |
| 179 | /* Encrypt all but one of the complete blocks left */ |
| 180 | while (dlen > bl) { |
| 181 | if (EVP_Cipher(ctx->cctx, ctx->tbl, data, bl) <= 0) |
| 182 | return 0; |
| 183 | dlen -= bl; |
| 184 | data += bl; |
| 185 | } |
| 186 | /* Copy any data left to last block buffer */ |
| 187 | memcpy(ctx->last_block, data, dlen); |
| 188 | ctx->nlast_block = dlen; |
| 189 | return 1; |
| 190 | |
| 191 | } |
| 192 | |
| 193 | int CMAC_Final(CMAC_CTX *ctx, unsigned char *out, size_t *poutlen) |
| 194 | { |
| 195 | int i, bl, lb; |
| 196 | if (ctx->nlast_block == -1) |
| 197 | return 0; |
| 198 | bl = EVP_CIPHER_CTX_block_size(ctx->cctx); |
| 199 | *poutlen = (size_t)bl; |
| 200 | if (!out) |
| 201 | return 1; |
| 202 | lb = ctx->nlast_block; |
| 203 | /* Is last block complete? */ |
| 204 | if (lb == bl) { |
| 205 | for (i = 0; i < bl; i++) |
| 206 | out[i] = ctx->last_block[i] ^ ctx->k1[i]; |
| 207 | } else { |
| 208 | ctx->last_block[lb] = 0x80; |
| 209 | if (bl - lb > 1) |
| 210 | memset(ctx->last_block + lb + 1, 0, bl - lb - 1); |
| 211 | for (i = 0; i < bl; i++) |
| 212 | out[i] = ctx->last_block[i] ^ ctx->k2[i]; |
| 213 | } |
| 214 | if (!EVP_Cipher(ctx->cctx, out, out, bl)) { |
| 215 | OPENSSL_cleanse(out, bl); |
| 216 | return 0; |
| 217 | } |
| 218 | return 1; |
| 219 | } |
| 220 | |
| 221 | int CMAC_resume(CMAC_CTX *ctx) |
| 222 | { |
| 223 | if (ctx->nlast_block == -1) |
| 224 | return 0; |
| 225 | /* |
| 226 | * The buffer "tbl" contains the last fully encrypted block which is the |
| 227 | * last IV (or all zeroes if no last encrypted block). The last block has |
| 228 | * not been modified since CMAC_final(). So reinitialising using the last |
| 229 | * decrypted block will allow CMAC to continue after calling |
| 230 | * CMAC_Final(). |
| 231 | */ |
| 232 | return EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, ctx->tbl); |
| 233 | } |