88 lines
2.4 KiB
C
88 lines
2.4 KiB
C
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/* LibTomCrypt, modular cryptographic library -- Tom St Denis
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*
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* LibTomCrypt is a library that provides various cryptographic
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* algorithms in a highly modular and flexible manner.
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*
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* The library is free for all purposes without any express
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* guarantee it works.
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*
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* Tom St Denis, tomstdenis@gmail.com, http://libtom.org
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*/
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#include "../../headers/tomcrypt.h"
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/**
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@file rsa_verify_simple.c
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Created by Ladislav Zezula (zezula@volny.cz) as modification
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for Blizzard strong signature verification
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*/
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#ifdef LTC_MRSA
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/**
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Simple RSA decryption
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@param sig The signature data
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@param siglen The length of the signature data (octets)
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@param hash The hash of the message that was signed
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@param hashlen The length of the hash of the message that was signed (octets)
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@param stat [out] The result of the signature comparison, 1==valid, 0==invalid
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@param key The public RSA key corresponding
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@return Error code
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*/
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int rsa_verify_simple(const unsigned char *sig, unsigned long siglen,
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const unsigned char *hash, unsigned long hashlen,
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int *stat,
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rsa_key *key)
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{
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unsigned long modulus_bitlen, modulus_bytelen, x;
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unsigned char *tmpbuf;
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int err;
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LTC_ARGCHK(sig != NULL);
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LTC_ARGCHK(hash != NULL);
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LTC_ARGCHK(stat != NULL);
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LTC_ARGCHK(key != NULL);
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/* default to invalid */
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*stat = 0;
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/* get modulus len in bits */
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modulus_bitlen = mp_count_bits( (key->N));
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/* outlen must be at least the size of the modulus */
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modulus_bytelen = mp_unsigned_bin_size( (key->N));
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if (modulus_bytelen != siglen) {
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return CRYPT_INVALID_PACKET;
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}
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/* allocate temp buffer for decoded sig */
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tmpbuf = XMALLOC(siglen);
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if (tmpbuf == NULL) {
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return CRYPT_MEM;
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}
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/* RSA decode it */
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x = siglen;
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if ((err = ltc_mp.rsa_me(sig, siglen, tmpbuf, &x, PK_PUBLIC, key)) != CRYPT_OK) {
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XFREE(tmpbuf);
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return err;
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}
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/* make sure the output is the right size */
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if (x != siglen) {
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XFREE(tmpbuf);
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return CRYPT_INVALID_PACKET;
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}
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/* compare the decrypted signature with the given hash */
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if(x == hashlen && XMEMCMP(tmpbuf, hash, hashlen) == 0)
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*stat = 1;
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#ifdef LTC_CLEAN_STACK
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zeromem(tmpbuf, siglen);
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#endif
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XFREE(tmpbuf);
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return CRYPT_OK;
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}
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#endif /* LTC_MRSA */
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