Mercurial > dropbear
view libtomcrypt/src/pk/dsa/dsa_shared_secret.c @ 463:33d5e9fb0f78 agent-client
propagate from branch 'au.asn.ucc.matt.dropbear' (head fb7080ca6e254faaf7cfaee93b0ab6ab6de4ed59)
to branch 'au.asn.ucc.matt.dropbear.cli-agent' (head 78d02301ae8310efa2639f15da0ea62dea110e4b)
author | Matt Johnston <matt@ucc.asn.au> |
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date | Thu, 29 Nov 2007 11:38:06 +0000 |
parents | 0cbe8f6dbf9e |
children | f849a5ca2efc |
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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, [email protected], http://libtomcrypt.com */ #include "tomcrypt.h" /** @file dsa_shared_secret.c DSA Crypto, Tom St Denis */ #ifdef MDSA /** Create a DSA shared secret between two keys @param private_key The private DSA key (the exponent) @param base The base of the exponentiation (allows this to be used for both encrypt and decrypt) @param public_key The public key @param out [out] Destination of the shared secret @param outlen [in/out] The max size and resulting size of the shared secret @return CRYPT_OK if successful */ int dsa_shared_secret(void *private_key, void *base, dsa_key *public_key, unsigned char *out, unsigned long *outlen) { unsigned long x; void *res; int err; LTC_ARGCHK(private_key != NULL); LTC_ARGCHK(public_key != NULL); LTC_ARGCHK(out != NULL); LTC_ARGCHK(outlen != NULL); /* make new point */ if ((err = mp_init(&res)) != CRYPT_OK) { return err; } if ((err = mp_exptmod(base, private_key, public_key->p, res)) != CRYPT_OK) { mp_clear(res); return err; } x = (unsigned long)mp_unsigned_bin_size(res); if (*outlen < x) { *outlen = x; err = CRYPT_BUFFER_OVERFLOW; goto done; } zeromem(out, x); if ((err = mp_to_unsigned_bin(res, out + (x - mp_unsigned_bin_size(res)))) != CRYPT_OK) { goto done; } err = CRYPT_OK; *outlen = x; done: mp_clear(res); return err; } #endif /* $Source: /cvs/libtom/libtomcrypt/src/pk/dsa/dsa_shared_secret.c,v $ */ /* $Revision: 1.7 $ */ /* $Date: 2006/12/04 03:18:43 $ */