1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis 2 * 3 * LibTomCrypt is a library that provides various cryptographic 4 * algorithms in a highly modular and flexible manner. 5 * 6 * The library is free for all purposes without any express 7 * guarantee it works. 8 * 9 * Tom St Denis, tomstdenis (at) gmail.com, http://libtomcrypt.com 10 */ 11 #include "tomcrypt.h" 12 13 /** 14 @file katja_encrypt_key.c 15 Katja PKCS-style OAEP encryption, Tom St Denis 16 */ 17 18 #ifdef MKAT 19 20 /** 21 (PKCS #1 v2.0) OAEP pad then encrypt 22 @param in The plaintext 23 @param inlen The length of the plaintext (octets) 24 @param out [out] The ciphertext 25 @param outlen [in/out] The max size and resulting size of the ciphertext 26 @param lparam The system "lparam" for the encryption 27 @param lparamlen The length of lparam (octets) 28 @param prng An active PRNG 29 @param prng_idx The index of the desired prng 30 @param hash_idx The index of the desired hash 31 @param key The Katja key to encrypt to 32 @return CRYPT_OK if successful 33 */ 34 int katja_encrypt_key(const unsigned char *in, unsigned long inlen, 35 unsigned char *out, unsigned long *outlen, 36 const unsigned char *lparam, unsigned long lparamlen, 37 prng_state *prng, int prng_idx, int hash_idx, katja_key *key) 38 { 39 unsigned long modulus_bitlen, modulus_bytelen, x; 40 int err; 41 42 LTC_ARGCHK(in != NULL); 43 LTC_ARGCHK(out != NULL); 44 LTC_ARGCHK(outlen != NULL); 45 LTC_ARGCHK(key != NULL); 46 47 /* valid prng and hash ? */ 48 if ((err = prng_is_valid(prng_idx)) != CRYPT_OK) { 49 return err; 50 } 51 if ((err = hash_is_valid(hash_idx)) != CRYPT_OK) { 52 return err; 53 } 54 55 /* get modulus len in bits */ 56 modulus_bitlen = mp_count_bits((key->N)); 57 58 /* payload is upto pq, so we know q is 1/3rd the size of N and therefore pq is 2/3th the size */ 59 modulus_bitlen = ((modulus_bitlen << 1) / 3); 60 61 /* round down to next byte */ 62 modulus_bitlen -= (modulus_bitlen & 7) + 8; 63 64 /* outlen must be at least the size of the modulus */ 65 modulus_bytelen = mp_unsigned_bin_size((key->N)); 66 if (modulus_bytelen > *outlen) { 67 *outlen = modulus_bytelen; 68 return CRYPT_BUFFER_OVERFLOW; 69 } 70 71 /* OAEP pad the key */ 72 x = *outlen; 73 if ((err = pkcs_1_oaep_encode(in, inlen, lparam, 74 lparamlen, modulus_bitlen, prng, prng_idx, hash_idx, 75 out, &x)) != CRYPT_OK) { 76 return err; 77 } 78 79 /* Katja exptmod the OAEP pad */ 80 return katja_exptmod(out, x, out, outlen, PK_PUBLIC, key); 81 } 82 83 #endif /* MRSA */ 84 85 /* $Source: /cvs/libtom/libtomcrypt/src/pk/katja/katja_encrypt_key.c,v $ */ 86 /* $Revision: 1.5 $ */ 87 /* $Date: 2006/06/16 21:53:41 $ */ 88
