[331] | 1 | /*
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| 2 | * Copyright 2010-2016 The OpenSSL Project Authors. All Rights Reserved.
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| 3 | *
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| 4 | * Licensed under the OpenSSL license (the "License"). You may not use
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| 5 | * this file except in compliance with the License. You can obtain a copy
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| 6 | * in the file LICENSE in the source distribution or at
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| 7 | * https://www.openssl.org/source/license.html
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| 8 | */
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| 9 |
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| 10 | #include <stdio.h>
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| 11 | #include <stdlib.h>
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| 12 | #include <string.h>
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| 13 | #include "internal/cryptlib.h"
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| 14 | #include <openssl/cmac.h>
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| 15 |
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| 16 | struct CMAC_CTX_st {
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| 17 | /* Cipher context to use */
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| 18 | EVP_CIPHER_CTX *cctx;
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| 19 | /* Keys k1 and k2 */
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| 20 | unsigned char k1[EVP_MAX_BLOCK_LENGTH];
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| 21 | unsigned char k2[EVP_MAX_BLOCK_LENGTH];
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| 22 | /* Temporary block */
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| 23 | unsigned char tbl[EVP_MAX_BLOCK_LENGTH];
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| 24 | /* Last (possibly partial) block */
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| 25 | unsigned char last_block[EVP_MAX_BLOCK_LENGTH];
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| 26 | /* Number of bytes in last block: -1 means context not initialised */
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| 27 | int nlast_block;
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| 28 | };
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| 29 |
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| 30 | /* Make temporary keys K1 and K2 */
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| 31 |
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| 32 | static void make_kn(unsigned char *k1, const unsigned char *l, int bl)
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| 33 | {
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| 34 | int i;
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| 35 | unsigned char c = l[0], carry = c >> 7, cnext;
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| 36 |
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| 37 | /* Shift block to left, including carry */
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| 38 | for (i = 0; i < bl - 1; i++, c = cnext)
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| 39 | k1[i] = (c << 1) | ((cnext = l[i + 1]) >> 7);
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| 40 |
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| 41 | /* If MSB set fixup with R */
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| 42 | k1[i] = (c << 1) ^ ((0 - carry) & (bl == 16 ? 0x87 : 0x1b));
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| 43 | }
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| 44 |
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| 45 | CMAC_CTX *CMAC_CTX_new(void)
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| 46 | {
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| 47 | CMAC_CTX *ctx;
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| 48 |
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| 49 | ctx = OPENSSL_malloc(sizeof(*ctx));
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| 50 | if (ctx == NULL)
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| 51 | return NULL;
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| 52 | ctx->cctx = EVP_CIPHER_CTX_new();
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| 53 | if (ctx->cctx == NULL) {
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| 54 | OPENSSL_free(ctx);
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| 55 | return NULL;
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| 56 | }
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| 57 | ctx->nlast_block = -1;
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| 58 | return ctx;
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| 59 | }
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| 60 |
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| 61 | void CMAC_CTX_cleanup(CMAC_CTX *ctx)
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| 62 | {
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| 63 | EVP_CIPHER_CTX_free(ctx->cctx);
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| 64 | OPENSSL_cleanse(ctx->tbl, EVP_MAX_BLOCK_LENGTH);
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| 65 | OPENSSL_cleanse(ctx->k1, EVP_MAX_BLOCK_LENGTH);
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| 66 | OPENSSL_cleanse(ctx->k2, EVP_MAX_BLOCK_LENGTH);
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| 67 | OPENSSL_cleanse(ctx->last_block, EVP_MAX_BLOCK_LENGTH);
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| 68 | ctx->nlast_block = -1;
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| 69 | }
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| 70 |
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| 71 | EVP_CIPHER_CTX *CMAC_CTX_get0_cipher_ctx(CMAC_CTX *ctx)
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| 72 | {
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| 73 | return ctx->cctx;
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| 74 | }
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| 75 |
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| 76 | void CMAC_CTX_free(CMAC_CTX *ctx)
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| 77 | {
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| 78 | if (!ctx)
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| 79 | return;
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| 80 | CMAC_CTX_cleanup(ctx);
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| 81 | OPENSSL_free(ctx);
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| 82 | }
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| 83 |
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| 84 | int CMAC_CTX_copy(CMAC_CTX *out, const CMAC_CTX *in)
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| 85 | {
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| 86 | int bl;
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| 87 | if (in->nlast_block == -1)
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| 88 | return 0;
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| 89 | if (!EVP_CIPHER_CTX_copy(out->cctx, in->cctx))
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| 90 | return 0;
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| 91 | bl = EVP_CIPHER_CTX_block_size(in->cctx);
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| 92 | memcpy(out->k1, in->k1, bl);
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| 93 | memcpy(out->k2, in->k2, bl);
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| 94 | memcpy(out->tbl, in->tbl, bl);
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| 95 | memcpy(out->last_block, in->last_block, bl);
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| 96 | out->nlast_block = in->nlast_block;
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| 97 | return 1;
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| 98 | }
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| 99 |
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| 100 | int CMAC_Init(CMAC_CTX *ctx, const void *key, size_t keylen,
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| 101 | const EVP_CIPHER *cipher, ENGINE *impl)
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| 102 | {
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| 103 | static const unsigned char zero_iv[EVP_MAX_BLOCK_LENGTH] = { 0 };
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| 104 | /* All zeros means restart */
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| 105 | if (!key && !cipher && !impl && keylen == 0) {
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| 106 | /* Not initialised */
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| 107 | if (ctx->nlast_block == -1)
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| 108 | return 0;
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| 109 | if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, zero_iv))
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| 110 | return 0;
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| 111 | memset(ctx->tbl, 0, EVP_CIPHER_CTX_block_size(ctx->cctx));
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| 112 | ctx->nlast_block = 0;
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| 113 | return 1;
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| 114 | }
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| 115 | /* Initialise context */
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| 116 | if (cipher && !EVP_EncryptInit_ex(ctx->cctx, cipher, impl, NULL, NULL))
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| 117 | return 0;
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| 118 | /* Non-NULL key means initialisation complete */
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| 119 | if (key) {
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| 120 | int bl;
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| 121 | if (!EVP_CIPHER_CTX_cipher(ctx->cctx))
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| 122 | return 0;
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| 123 | if (!EVP_CIPHER_CTX_set_key_length(ctx->cctx, keylen))
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| 124 | return 0;
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| 125 | if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, key, zero_iv))
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| 126 | return 0;
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| 127 | bl = EVP_CIPHER_CTX_block_size(ctx->cctx);
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| 128 | if (!EVP_Cipher(ctx->cctx, ctx->tbl, zero_iv, bl))
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| 129 | return 0;
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| 130 | make_kn(ctx->k1, ctx->tbl, bl);
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| 131 | make_kn(ctx->k2, ctx->k1, bl);
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| 132 | OPENSSL_cleanse(ctx->tbl, bl);
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| 133 | /* Reset context again ready for first data block */
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| 134 | if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, zero_iv))
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| 135 | return 0;
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| 136 | /* Zero tbl so resume works */
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| 137 | memset(ctx->tbl, 0, bl);
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| 138 | ctx->nlast_block = 0;
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| 139 | }
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| 140 | return 1;
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| 141 | }
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| 142 |
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| 143 | int CMAC_Update(CMAC_CTX *ctx, const void *in, size_t dlen)
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| 144 | {
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| 145 | const unsigned char *data = in;
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| 146 | size_t bl;
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| 147 | if (ctx->nlast_block == -1)
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| 148 | return 0;
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| 149 | if (dlen == 0)
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| 150 | return 1;
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| 151 | bl = EVP_CIPHER_CTX_block_size(ctx->cctx);
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| 152 | /* Copy into partial block if we need to */
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| 153 | if (ctx->nlast_block > 0) {
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| 154 | size_t nleft;
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| 155 | nleft = bl - ctx->nlast_block;
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| 156 | if (dlen < nleft)
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| 157 | nleft = dlen;
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| 158 | memcpy(ctx->last_block + ctx->nlast_block, data, nleft);
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| 159 | dlen -= nleft;
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| 160 | ctx->nlast_block += nleft;
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| 161 | /* If no more to process return */
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| 162 | if (dlen == 0)
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| 163 | return 1;
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| 164 | data += nleft;
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| 165 | /* Else not final block so encrypt it */
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| 166 | if (!EVP_Cipher(ctx->cctx, ctx->tbl, ctx->last_block, bl))
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| 167 | return 0;
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| 168 | }
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| 169 | /* Encrypt all but one of the complete blocks left */
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| 170 | while (dlen > bl) {
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| 171 | if (!EVP_Cipher(ctx->cctx, ctx->tbl, data, bl))
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| 172 | return 0;
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| 173 | dlen -= bl;
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| 174 | data += bl;
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| 175 | }
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| 176 | /* Copy any data left to last block buffer */
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| 177 | memcpy(ctx->last_block, data, dlen);
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| 178 | ctx->nlast_block = dlen;
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| 179 | return 1;
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| 180 |
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| 181 | }
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| 182 |
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| 183 | int CMAC_Final(CMAC_CTX *ctx, unsigned char *out, size_t *poutlen)
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| 184 | {
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| 185 | int i, bl, lb;
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| 186 | if (ctx->nlast_block == -1)
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| 187 | return 0;
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| 188 | bl = EVP_CIPHER_CTX_block_size(ctx->cctx);
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| 189 | *poutlen = (size_t)bl;
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| 190 | if (!out)
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| 191 | return 1;
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| 192 | lb = ctx->nlast_block;
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| 193 | /* Is last block complete? */
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| 194 | if (lb == bl) {
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| 195 | for (i = 0; i < bl; i++)
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| 196 | out[i] = ctx->last_block[i] ^ ctx->k1[i];
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| 197 | } else {
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| 198 | ctx->last_block[lb] = 0x80;
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| 199 | if (bl - lb > 1)
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| 200 | memset(ctx->last_block + lb + 1, 0, bl - lb - 1);
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| 201 | for (i = 0; i < bl; i++)
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| 202 | out[i] = ctx->last_block[i] ^ ctx->k2[i];
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| 203 | }
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| 204 | if (!EVP_Cipher(ctx->cctx, out, out, bl)) {
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| 205 | OPENSSL_cleanse(out, bl);
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| 206 | return 0;
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| 207 | }
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| 208 | return 1;
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| 209 | }
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| 210 |
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| 211 | int CMAC_resume(CMAC_CTX *ctx)
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| 212 | {
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| 213 | if (ctx->nlast_block == -1)
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| 214 | return 0;
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| 215 | /*
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| 216 | * The buffer "tbl" contains the last fully encrypted block which is the
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| 217 | * last IV (or all zeroes if no last encrypted block). The last block has
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| 218 | * not been modified since CMAC_final(). So reinitialising using the last
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| 219 | * decrypted block will allow CMAC to continue after calling
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| 220 | * CMAC_Final().
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| 221 | */
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| 222 | return EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, ctx->tbl);
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| 223 | }
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