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/* 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://libtom.org
*/
#include "tomcrypt.h"
/**
@file rsa_sign_hash.c
RSA LTC_PKCS #1 v1.5 and v2 PSS sign hash, Tom St Denis and Andreas Lange
*/
#ifdef LTC_MRSA
/**
LTC_PKCS #1 pad then sign
@param in The hash to sign
@param inlen The length of the hash to sign (octets)
@param out [out] The signature
@param outlen [in/out] The max size and resulting size of the signature
@param padding Type of padding (LTC_LTC_PKCS_1_PSS or LTC_LTC_PKCS_1_V1_5)
@param hash_idx The index of the hash desired
@param saltlen The length of the salt desired (octets)
@param key The private RSA key to use
@return CRYPT_OK if successful
*/
int rsa_sign_hash_ex(const unsigned char *in, unsigned long inlen,
unsigned char *out, unsigned long *outlen,
int padding,
int hash_idx, unsigned long saltlen,
rsa_key *key)
{
unsigned long modulus_bitlen, modulus_bytelen, x, y;
int err;
LTC_ARGCHK(in != NULL);
LTC_ARGCHK(out != NULL);
LTC_ARGCHK(outlen != NULL);
LTC_ARGCHK(key != NULL);
/* valid padding? */
if ((padding != LTC_LTC_PKCS_1_V1_5) && (padding != LTC_LTC_PKCS_1_PSS)) {
return CRYPT_PK_INVALID_PADDING;
}
if (padding == LTC_LTC_PKCS_1_PSS) {
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 > *outlen) {
*outlen = modulus_bytelen;
return CRYPT_BUFFER_OVERFLOW;
}
if (padding == LTC_LTC_PKCS_1_PSS) {
/* PSS pad the key */
x = *outlen;
if ((err = pkcs_1_pss_encode(in, inlen, saltlen,
hash_idx, modulus_bitlen, out, &x)) != CRYPT_OK) {
return err;
}
} else {
/* LTC_PKCS #1 v1.5 pad the hash */
unsigned char *tmpin;
ltc_asn1_list digestinfo[2], siginfo[2];
oid_st st;
/* not all hashes have OIDs... so sad */
if (hash_get_oid(hash_idx, &st) != CRYPT_OK) {
return CRYPT_INVALID_ARG;
}
/* construct the SEQUENCE
SEQUENCE {
SEQUENCE {hashoid OID
blah NULL
}
hash OCTET STRING
}
*/
LTC_SET_ASN1(digestinfo, 0, LTC_ASN1_OBJECT_IDENTIFIER, st.OID, st.OIDlen);
LTC_SET_ASN1(digestinfo, 1, LTC_ASN1_NULL, NULL, 0);
LTC_SET_ASN1(siginfo, 0, LTC_ASN1_SEQUENCE, digestinfo, 2);
LTC_SET_ASN1(siginfo, 1, LTC_ASN1_OCTET_STRING, in, inlen);
/* allocate memory for the encoding */
y = mp_unsigned_bin_size(&key->N);
tmpin = XMALLOC(y);
if (tmpin == NULL) {
return CRYPT_MEM;
}
if ((err = der_encode_sequence(siginfo, 2, tmpin, &y)) != CRYPT_OK) {
XFREE(tmpin);
return err;
}
x = *outlen;
if ((err = pkcs_1_v1_5_encode(tmpin, y, LTC_LTC_PKCS_1_EMSA,
modulus_bitlen,
out, &x)) != CRYPT_OK) {
XFREE(tmpin);
return err;
}
XFREE(tmpin);
}
/* RSA encode it */
return rsa_exptmod(out, x, out, outlen, PK_PRIVATE, key);
}
#endif /* LTC_MRSA */
/* $Source: /cvs/libtom/libtomcrypt/src/pk/rsa/rsa_sign_hash.c,v $ */
/* $Revision: 1.11 $ */
/* $Date: 2007/05/12 14:32:35 $ */
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