| // SPDX-License-Identifier: BSD-2-Clause |
| /* LibTomCrypt, modular cryptographic library -- Tom St Denis |
| * |
| * LibTomCrypt is a library that provides various cryptographic |
| * algorithms in a highly modular and flexible manner. |
| * |
| * The library is free for all purposes without any express |
| * guarantee it works. |
| */ |
| #include "tomcrypt_private.h" |
| |
| #ifdef LTC_CCM_MODE |
| |
| /** |
| Initialize a CCM state |
| @param ccm The CCM state to initialize |
| @param cipher The index of the cipher to use |
| @param key The secret key |
| @param keylen The length of the secret key |
| @param ptlen The length of the plain/cipher text that will be processed |
| @param taglen The max length of the MAC tag |
| @param aadlen The length of the AAD |
| |
| @return CRYPT_OK on success |
| */ |
| int ccm_init(ccm_state *ccm, int cipher, |
| const unsigned char *key, int keylen, int ptlen, int taglen, int aadlen) |
| { |
| int err; |
| |
| LTC_ARGCHK(ccm != NULL); |
| LTC_ARGCHK(key != NULL); |
| |
| XMEMSET(ccm, 0, sizeof(ccm_state)); |
| |
| /* check cipher input */ |
| if ((err = cipher_is_valid(cipher)) != CRYPT_OK) { |
| return err; |
| } |
| if (cipher_descriptor[cipher]->block_length != 16) { |
| return CRYPT_INVALID_CIPHER; |
| } |
| |
| /* make sure the taglen is valid */ |
| if (taglen < 4 || taglen > 16 || (taglen % 2) == 1) { |
| return CRYPT_INVALID_ARG; |
| } |
| ccm->taglen = taglen; |
| |
| /* schedule key */ |
| if ((err = cipher_descriptor[cipher]->setup(key, keylen, 0, &ccm->K)) != CRYPT_OK) { |
| return err; |
| } |
| ccm->cipher = cipher; |
| |
| /* let's get the L value */ |
| ccm->ptlen = ptlen; |
| ccm->L = 0; |
| while (ptlen) { |
| ++ccm->L; |
| ptlen >>= 8; |
| } |
| if (ccm->L <= 1) { |
| ccm->L = 2; |
| } |
| |
| ccm->aadlen = aadlen; |
| return CRYPT_OK; |
| } |
| |
| #endif |
| |
| /* ref: $Format:%D$ */ |
| /* git commit: $Format:%H$ */ |
| /* commit time: $Format:%ai$ */ |