/** Set IV + counter data (with RFC7905-magic) to the ChaCha20Poly1305 state and reset the context @param st The ChaCha20Poly1305 state @param iv The IV data to add @param ivlen The length of the IV (must be 12 or 8) @param sequence_number 64bit sequence number which is incorporated into IV as described in RFC7905 @return CRYPT_OK on success */ int chacha20poly1305_setiv_rfc7905(chacha20poly1305_state *st, const unsigned char *iv, unsigned long ivlen, ulong64 sequence_number) { int i; unsigned char combined_iv[12] = { 0 }; LTC_ARGCHK(st != NULL); LTC_ARGCHK(iv != NULL); LTC_ARGCHK(ivlen == 12); STORE64L(sequence_number, combined_iv + 4); for (i = 0; i < 12; i++) combined_iv[i] = iv[i] ^ combined_iv[i]; return chacha20poly1305_setiv(st, combined_iv, 12); }
/** Process an entire GCM packet in one call. @param key The secret key @param keylen The length of the secret key @param iv The initialization vector @param ivlen The length of the initialization vector @param aad The additional authentication data (header) @param aadlen The length of the aad @param in The plaintext @param inlen The length of the plaintext (ciphertext length is the same) @param out The ciphertext @param tag [out] The MAC tag @param taglen [in/out] The MAC tag length @param direction Encrypt or Decrypt mode (CHCHA20POLY1305_ENCRYPT or CHCHA20POLY1305_DECRYPT) @return CRYPT_OK on success */ int chacha20poly1305_memory(const unsigned char *key, unsigned long keylen, const unsigned char *iv, unsigned long ivlen, const unsigned char *aad, unsigned long aadlen, const unsigned char *in, unsigned long inlen, unsigned char *out, unsigned char *tag, unsigned long *taglen, int direction) { chacha20poly1305_state st; int err; LTC_ARGCHK(key != NULL); LTC_ARGCHK(iv != NULL); LTC_ARGCHK(in != NULL); LTC_ARGCHK(out != NULL); LTC_ARGCHK(tag != NULL); if ((err = chacha20poly1305_init(&st, key, keylen)) != CRYPT_OK) { goto LBL_ERR; } if ((err = chacha20poly1305_setiv(&st, iv, ivlen)) != CRYPT_OK) { goto LBL_ERR; } if (aad && aadlen > 0) { if ((err = chacha20poly1305_add_aad(&st, aad, aadlen)) != CRYPT_OK) { goto LBL_ERR; } } if (direction == CHCHA20POLY1305_ENCRYPT) { if ((err = chacha20poly1305_encrypt(&st, in, inlen, out)) != CRYPT_OK) { goto LBL_ERR; } } else if (direction == CHCHA20POLY1305_DECRYPT) { if ((err = chacha20poly1305_decrypt(&st, in, inlen, out)) != CRYPT_OK) { goto LBL_ERR; } } else { err = CRYPT_INVALID_ARG; goto LBL_ERR; } err = chacha20poly1305_done(&st, tag, taglen); LBL_ERR: #ifdef LTC_CLEAN_STACK zeromem(&st, sizeof(chacha20poly1305_state)); #endif return err; }