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Implement Diffie-Hellman computations in crypto backends. (#149)

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Not all backends feature the low level API needed to compute a Diffie-Hellman
secret, but some of them directly implement Diffie-Hellman support with opaque
private data. The later approach is now generalized and backends are
responsible for all Diffie Hellman computations.
As a side effect, procedures/macros _libssh2_bn_rand and _libssh2_bn_mod_exp
are no longer needed outside the backends.
This commit is contained in:
monnerat
2016-11-27 19:39:00 +01:00
committed by Alexander Lamaison
parent 5abceec571
commit f7daf3185a
10 changed files with 215 additions and 96 deletions
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34
src/openssl.c
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@@ -1189,4 +1189,38 @@ _libssh2_pub_priv_keyfilememory(LIBSSH2_SESSION *session,
return st;
}
void
_libssh2_dh_init(_libssh2_dh_ctx *dhctx)
{
*dhctx = BN_new(); /* Random from client */
}
int
_libssh2_dh_key_pair(_libssh2_dh_ctx *dhctx, _libssh2_bn *public,
_libssh2_bn *g, _libssh2_bn *p, int group_order,
_libssh2_bn_ctx *bnctx)
{
/* Generate x and e */
BN_rand(*dhctx, group_order * 8 - 1, 0, -1);
BN_mod_exp(public, g, *dhctx, p, bnctx);
return 0;
}
int
_libssh2_dh_secret(_libssh2_dh_ctx *dhctx, _libssh2_bn *secret,
_libssh2_bn *f, _libssh2_bn *p,
_libssh2_bn_ctx *bnctx)
{
/* Compute the shared secret */
BN_mod_exp(secret, f, *dhctx, p, bnctx);
return 0;
}
void
_libssh2_dh_dtor(_libssh2_dh_ctx *dhctx)
{
BN_clear_free(*dhctx);
*dhctx = NULL;
}
#endif /* LIBSSH2_OPENSSL */