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PR: 1794

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Submitted by: Peter Sylvester <peter.sylvester@edelweb.fr>
Reviewed by: steve

Remove unnecessary code for srp and to add some comments to
s_client.

- the callback to provide a user during client connect is
no longer necessary since rfc 5054 a connection attempt
with an srp cipher and no user is terminated when the
cipher is acceptable

- comments to indicate in s_client the (non-)usefulness of
th primalaty tests for non known group parameters.
This commit is contained in:
Dr. Stephen Henson
2011-12-14 22:17:06 +00:00
parent 1bfdb34f70
commit f2fc30751e
6 changed files with 28 additions and 60 deletions
Download Patch File Download Diff File Expand all files Collapse all files

35
apps/s_client.c
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@@ -403,18 +403,18 @@ typedef struct srp_arg_st
#define SRP_NUMBER_ITERATIONS_FOR_PRIME 64
static int SRP_Verify_N_and_g(const BIGNUM *N, const BIGNUM *g)
static int srp_Verify_N_and_g(const BIGNUM *N, const BIGNUM *g)
{
BN_CTX *bn_ctx = BN_CTX_new();
BIGNUM *p = BN_new();
BIGNUM *r = BN_new();
int ret =
g != NULL && N != NULL && bn_ctx != NULL && BN_is_odd(N) &&
BN_is_prime_ex(N,SRP_NUMBER_ITERATIONS_FOR_PRIME,bn_ctx,NULL) &&
BN_is_prime_ex(N, SRP_NUMBER_ITERATIONS_FOR_PRIME, bn_ctx, NULL) &&
p != NULL && BN_rshift1(p, N) &&
/* p = (N-1)/2 */
BN_is_prime_ex(p,SRP_NUMBER_ITERATIONS_FOR_PRIME,bn_ctx,NULL) &&
BN_is_prime_ex(p, SRP_NUMBER_ITERATIONS_FOR_PRIME, bn_ctx, NULL) &&
r != NULL &&
/* verify g^((N-1)/2) == -1 (mod N) */
@@ -431,6 +431,21 @@ static int SRP_Verify_N_and_g(const BIGNUM *N, const BIGNUM *g)
return ret;
}
/* This callback is used here for two purposes:
- extended debugging
- making some primality tests for unknown groups
The callback is only called for a non default group.
An application does not need the call back at all if
only the stanard groups are used. In real life situations,
client and server already share well known groups,
thus there is no need to verify them.
Furthermore, in case that a server actually proposes a group that
is not one of those defined in RFC 5054, it is more appropriate
to add the group to a static list and then compare since
primality tests are rather cpu consuming.
*/
static int MS_CALLBACK ssl_srp_verify_param_cb(SSL *s, void *arg)
{
SRP_ARG *srp_arg = (SRP_ARG *)arg;
@@ -453,11 +468,11 @@ static int MS_CALLBACK ssl_srp_verify_param_cb(SSL *s, void *arg)
if (srp_arg->debug)
BIO_printf(bio_err, "SRP param N and g are not known params, going to check deeper.\n");
/* The srp_moregroups must be used with caution, testing primes costs time.
/* The srp_moregroups is a real debugging feature.
Implementors should rather add the value to the known ones.
The minimal size has already been tested.
*/
if (BN_num_bits(g) <= BN_BITS && SRP_Verify_N_and_g(N,g))
if (BN_num_bits(g) <= BN_BITS && srp_Verify_N_and_g(N,g))
return 1;
}
BIO_printf(bio_err, "SRP param N and g rejected.\n");
@@ -486,12 +501,6 @@ static char * MS_CALLBACK ssl_give_srp_client_pwd_cb(SSL *s, void *arg)
return pass;
}
static char * MS_CALLBACK missing_srp_username_callback(SSL *s, void *arg)
{
SRP_ARG *srp_arg = (SRP_ARG *)arg;
return BUF_strdup(srp_arg->srplogin);
}
#endif
char *srtp_profiles = NULL;
@@ -1182,9 +1191,7 @@ bad:
#ifndef OPENSSL_NO_SRP
if (srp_arg.srplogin)
{
if (srp_lateuser)
SSL_CTX_set_srp_missing_srp_username_callback(ctx,missing_srp_username_callback);
else if (!SSL_CTX_set_srp_username(ctx, srp_arg.srplogin))
if (!srp_lateuser && !SSL_CTX_set_srp_username(ctx, srp_arg.srplogin))
{
BIO_printf(bio_err,"Unable to set SRP username\n");
goto end;