CCCryptorStatus CCRSACryptorDecodePayloadPKCS1( CCRSACryptorRef publicKey, const void *cipherText, size_t cipherTextLen, void *plainText, size_t *plainTextLen) { int tcReturn; int stat = 0; CCRSACryptor *publicCryptor = publicKey; uint8_t *message; unsigned long messageLen, modulusLen; CCCryptorStatus retval = kCCSuccess; modulusLen = CCRSAGetKeySize(publicKey); messageLen = modulusLen / 8; if((message = CC_XMALLOC(messageLen)) == NULL) return kCCMemoryFailure; tcReturn = rsa_exptmod(cipherText, cipherTextLen, message, messageLen, publicCryptor->keyType, &publicCryptor->key); if(tcReturn) { retval = kCCDecodeError; goto out; } tcReturn = pkcs_1_v1_5_decode(message, messageLen, LTC_PKCS_1_EME, modulusLen, plainText, plainTextLen, &stat); if(tcReturn) { retval = kCCDecodeError; goto out; } if(!stat) { retval = kCCDecodeError; goto out; } out: CC_XZEROMEM(message, messageLen); CC_XFREE(message, messageLen); return retval; }
/** LTC_PKCS #1 decrypt then v1.5 or OAEP depad @param in The ciphertext @param inlen The length of the ciphertext (octets) @param out [out] The plaintext @param outlen [in/out] The max size and resulting size of the plaintext (octets) @param lparam The system "lparam" value @param lparamlen The length of the lparam value (octets) @param hash_idx The index of the hash desired @param padding Type of padding (LTC_LTC_PKCS_1_OAEP or LTC_LTC_PKCS_1_V1_5) @param stat [out] Result of the decryption, 1==valid, 0==invalid @param key The corresponding private RSA key @return CRYPT_OK if succcessul (even if invalid) */ int rsa_decrypt_key_ex(const unsigned char *in, unsigned long inlen, unsigned char *out, unsigned long *outlen, const unsigned char *lparam, unsigned long lparamlen, int hash_idx, int padding, int *stat, rsa_key *key) { unsigned long modulus_bitlen, modulus_bytelen, x; int err; unsigned char *tmp; LTC_ARGCHK(out != NULL); LTC_ARGCHK(outlen != NULL); LTC_ARGCHK(key != NULL); LTC_ARGCHK(stat != NULL); /* default to invalid */ *stat = 0; /* valid padding? */ if ((padding != LTC_LTC_PKCS_1_V1_5) && (padding != LTC_LTC_PKCS_1_OAEP)) { return CRYPT_PK_INVALID_PADDING; } if (padding == LTC_LTC_PKCS_1_OAEP) { /* valid hash ? */ if ((err = hash_is_valid(hash_idx)) != CRYPT_OK) { return err; } } /* get modulus len in bits */ modulus_bitlen = mp_count_bits( (key->N)); /* outlen must be at least the size of the modulus */ modulus_bytelen = mp_unsigned_bin_size( (key->N)); if (modulus_bytelen != inlen) { return CRYPT_INVALID_PACKET; } /* allocate ram */ tmp = XMALLOC(inlen); if (tmp == NULL) { return CRYPT_MEM; } /* rsa decode the packet */ x = inlen; if ((err = ltc_mp.rsa_me(in, inlen, tmp, &x, PK_PUBLIC, key)) != CRYPT_OK) { XFREE(tmp); return err; } if (padding == LTC_LTC_PKCS_1_OAEP) { /* now OAEP decode the packet */ err = pkcs_1_oaep_decode(tmp, x, lparam, lparamlen, modulus_bitlen, hash_idx, out, outlen, stat); } else { /* now LTC_PKCS #1 v1.5 depad the packet */ err = pkcs_1_v1_5_decode(tmp, x, LTC_LTC_PKCS_1_EME, modulus_bitlen, out, outlen, stat); } XFREE(tmp); return err; }