| /* 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. |
| * |
| * Tom St Denis, tomstdenis@iahu.ca, http://libtomcrypt.org |
| */ |
| |
| /* EAX Implementation by Tom St Denis */ |
| #include "mycrypt.h" |
| |
| #ifdef EAX_MODE |
| |
| int eax_decrypt_verify_memory(int cipher, |
| const unsigned char *key, unsigned long keylen, |
| const unsigned char *nonce, unsigned long noncelen, |
| const unsigned char *header, unsigned long headerlen, |
| const unsigned char *ct, unsigned long ctlen, |
| unsigned char *pt, |
| unsigned char *tag, unsigned long taglen, |
| int *res) |
| { |
| int err; |
| eax_state *eax; |
| unsigned char *buf; |
| unsigned long buflen; |
| |
| _ARGCHK(res != NULL); |
| |
| /* default to zero */ |
| *res = 0; |
| |
| /* allocate ram */ |
| buf = XMALLOC(taglen); |
| eax = XMALLOC(sizeof(eax_state)); |
| if (eax == NULL || buf == NULL) { |
| if (eax != NULL) { |
| XFREE(eax); |
| } |
| if (buf != NULL) { |
| XFREE(buf); |
| } |
| return CRYPT_MEM; |
| } |
| |
| if ((err = eax_init(eax, cipher, key, keylen, nonce, noncelen, header, headerlen)) != CRYPT_OK) { |
| goto __ERR; |
| } |
| |
| if ((err = eax_decrypt(eax, ct, pt, ctlen)) != CRYPT_OK) { |
| goto __ERR; |
| } |
| |
| buflen = taglen; |
| if ((err = eax_done(eax, buf, &buflen)) != CRYPT_OK) { |
| goto __ERR; |
| } |
| |
| /* compare tags */ |
| if (buflen >= taglen && memcmp(buf, tag, taglen) == 0) { |
| *res = 1; |
| } |
| |
| err = CRYPT_OK; |
| __ERR: |
| #ifdef CLEAN_STACK |
| zeromem(buf, taglen); |
| zeromem(eax, sizeof(eax_state)); |
| #endif |
| |
| XFREE(eax); |
| XFREE(buf); |
| |
| return err; |
| } |
| |
| #endif |