Mercurial > dropbear
comparison libtomcrypt/src/pk/dsa/dsa_shared_secret.c @ 478:d4f32c3443ac dbclient-netcat-alike
propagate from branch 'au.asn.ucc.matt.dropbear' (head f21045c791002d81fc6b8dde6537ea481e513eb2)
to branch 'au.asn.ucc.matt.dropbear.dbclient-netcat-alike' (head d1f69334581dc4c35f9ca16aa5355074c9dd315d)
| author | Matt Johnston <matt@ucc.asn.au> |
|---|---|
| date | Sun, 14 Sep 2008 06:47:51 +0000 |
| parents | 0cbe8f6dbf9e |
| children | f849a5ca2efc |
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| 296:6b41e2cbf071 | 478:d4f32c3443ac |
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| 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, [email protected], http://libtomcrypt.com | |
| 10 */ | |
| 11 #include "tomcrypt.h" | |
| 12 | |
| 13 /** | |
| 14 @file dsa_shared_secret.c | |
| 15 DSA Crypto, Tom St Denis | |
| 16 */ | |
| 17 | |
| 18 #ifdef MDSA | |
| 19 | |
| 20 /** | |
| 21 Create a DSA shared secret between two keys | |
| 22 @param private_key The private DSA key (the exponent) | |
| 23 @param base The base of the exponentiation (allows this to be used for both encrypt and decrypt) | |
| 24 @param public_key The public key | |
| 25 @param out [out] Destination of the shared secret | |
| 26 @param outlen [in/out] The max size and resulting size of the shared secret | |
| 27 @return CRYPT_OK if successful | |
| 28 */ | |
| 29 int dsa_shared_secret(void *private_key, void *base, | |
| 30 dsa_key *public_key, | |
| 31 unsigned char *out, unsigned long *outlen) | |
| 32 { | |
| 33 unsigned long x; | |
| 34 void *res; | |
| 35 int err; | |
| 36 | |
| 37 LTC_ARGCHK(private_key != NULL); | |
| 38 LTC_ARGCHK(public_key != NULL); | |
| 39 LTC_ARGCHK(out != NULL); | |
| 40 LTC_ARGCHK(outlen != NULL); | |
| 41 | |
| 42 /* make new point */ | |
| 43 if ((err = mp_init(&res)) != CRYPT_OK) { | |
| 44 return err; | |
| 45 } | |
| 46 | |
| 47 if ((err = mp_exptmod(base, private_key, public_key->p, res)) != CRYPT_OK) { | |
| 48 mp_clear(res); | |
| 49 return err; | |
| 50 } | |
| 51 | |
| 52 x = (unsigned long)mp_unsigned_bin_size(res); | |
| 53 if (*outlen < x) { | |
| 54 *outlen = x; | |
| 55 err = CRYPT_BUFFER_OVERFLOW; | |
| 56 goto done; | |
| 57 } | |
| 58 zeromem(out, x); | |
| 59 if ((err = mp_to_unsigned_bin(res, out + (x - mp_unsigned_bin_size(res)))) != CRYPT_OK) { goto done; } | |
| 60 | |
| 61 err = CRYPT_OK; | |
| 62 *outlen = x; | |
| 63 done: | |
| 64 mp_clear(res); | |
| 65 return err; | |
| 66 } | |
| 67 | |
| 68 #endif | |
| 69 /* $Source: /cvs/libtom/libtomcrypt/src/pk/dsa/dsa_shared_secret.c,v $ */ | |
| 70 /* $Revision: 1.7 $ */ | |
| 71 /* $Date: 2006/12/04 03:18:43 $ */ | |
| 72 |