| /* 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@gmail.com, http://libtomcrypt.com |
| */ |
| #include "tomcrypt.h" |
| |
| /** |
| @file rsa_decrypt_key.c |
| RSA PKCS #1 Decryption, Tom St Denis and Andreas Lange |
| */ |
| |
| #ifdef MRSA |
| |
| /** |
| 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_PKCS_1_OAEP or 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_PKCS_1_V1_5) && |
| (padding != LTC_PKCS_1_OAEP)) { |
| return CRYPT_PK_INVALID_PADDING; |
| } |
| |
| if (padding == 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_PRIVATE, key)) != CRYPT_OK) { |
| XFREE(tmp); |
| return err; |
| } |
| |
| if (padding == 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 PKCS #1 v1.5 depad the packet */ |
| err = pkcs_1_v1_5_decode(tmp, x, LTC_PKCS_1_EME, modulus_bitlen, out, outlen, stat); |
| } |
| |
| XFREE(tmp); |
| return err; |
| } |
| |
| #endif /* MRSA */ |
| |
| /* $Source: /cvs/libtom/libtomcrypt/src/pk/rsa/rsa_decrypt_key.c,v $ */ |
| /* $Revision: 1.8 $ */ |
| /* $Date: 2006/11/01 09:18:22 $ */ |