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Diffstat (limited to 'src/pk/katja/katja_encrypt_key.c')
| -rw-r--r-- | src/pk/katja/katja_encrypt_key.c | 87 |
1 files changed, 87 insertions, 0 deletions
diff --git a/src/pk/katja/katja_encrypt_key.c b/src/pk/katja/katja_encrypt_key.c new file mode 100644 index 0000000..ce93356 --- /dev/null +++ b/src/pk/katja/katja_encrypt_key.c @@ -0,0 +1,87 @@ +/* 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 katja_encrypt_key.c + Katja PKCS-style OAEP encryption, Tom St Denis +*/ + +#ifdef MKAT + +/** + (PKCS #1 v2.0) OAEP pad then encrypt + @param in The plaintext + @param inlen The length of the plaintext (octets) + @param out [out] The ciphertext + @param outlen [in/out] The max size and resulting size of the ciphertext + @param lparam The system "lparam" for the encryption + @param lparamlen The length of lparam (octets) + @param prng An active PRNG + @param prng_idx The index of the desired prng + @param hash_idx The index of the desired hash + @param key The Katja key to encrypt to + @return CRYPT_OK if successful +*/ +int katja_encrypt_key(const unsigned char *in, unsigned long inlen, + unsigned char *out, unsigned long *outlen, + const unsigned char *lparam, unsigned long lparamlen, + prng_state *prng, int prng_idx, int hash_idx, katja_key *key) +{ + unsigned long modulus_bitlen, modulus_bytelen, x; + int err; + + LTC_ARGCHK(in != NULL); + LTC_ARGCHK(out != NULL); + LTC_ARGCHK(outlen != NULL); + LTC_ARGCHK(key != NULL); + + /* valid prng and hash ? */ + if ((err = prng_is_valid(prng_idx)) != CRYPT_OK) { + return err; + } + if ((err = hash_is_valid(hash_idx)) != CRYPT_OK) { + return err; + } + + /* get modulus len in bits */ + modulus_bitlen = mp_count_bits((key->N)); + + /* payload is upto pq, so we know q is 1/3rd the size of N and therefore pq is 2/3th the size */ + modulus_bitlen = ((modulus_bitlen << 1) / 3); + + /* round down to next byte */ + modulus_bitlen -= (modulus_bitlen & 7) + 8; + + /* outlen must be at least the size of the modulus */ + modulus_bytelen = mp_unsigned_bin_size((key->N)); + if (modulus_bytelen > *outlen) { + *outlen = modulus_bytelen; + return CRYPT_BUFFER_OVERFLOW; + } + + /* OAEP pad the key */ + x = *outlen; + if ((err = pkcs_1_oaep_encode(in, inlen, lparam, + lparamlen, modulus_bitlen, prng, prng_idx, hash_idx, + out, &x)) != CRYPT_OK) { + return err; + } + + /* Katja exptmod the OAEP pad */ + return katja_exptmod(out, x, out, outlen, PK_PUBLIC, key); +} + +#endif /* MRSA */ + +/* $Source: /cvs/libtom/libtomcrypt/src/pk/katja/katja_encrypt_key.c,v $ */ +/* $Revision: 1.5 $ */ +/* $Date: 2006/06/16 21:53:41 $ */ |