Remove flags for disabling constant-time operations.

This removes support for DSA_FLAG_NO_EXP_CONSTTIME, DH_FLAG_NO_EXP_CONSTTIME,
and RSA_FLAG_NO_CONSTTIME flags, making all of these operations unconditionally
constant-time.

Based on the original patch by César Pereid.  ok beck@

2 files changed, 5 insertions, 14 deletions

diff --git a/src/lib/libcrypto/dsa/dsa.h b/src/lib/libcrypto/dsa/dsa.h
index f7f81cfa94..b4d7c1ff0f 100644
--- a/src/lib/libcrypto/dsa/dsa.h
+++ b/src/lib/libcrypto/dsa/dsa.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: dsa.h,v 1.20 2016/06/21 04:16:53 bcook Exp $ */
+/* $OpenBSD: dsa.h,v 1.21 2016/06/30 02:02:06 bcook Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -89,9 +89,6 @@
 #endif
 
 #define DSA_FLAG_CACHE_MONT_P   0x01
-#define DSA_FLAG_NO_EXP_CONSTTIME       0x00 /* Does nothing. Previously this switched off 
-                                              * constant time behaviour.
-                                              */
 
 /* If this flag is set the DSA method is FIPS compliant and can be used
  * in FIPS mode. This is set in the validated module method. If an
diff --git a/src/lib/libcrypto/dsa/dsa_key.c b/src/lib/libcrypto/dsa/dsa_key.c
index 4732c471ed..fc4eb9c433 100644
--- a/src/lib/libcrypto/dsa/dsa_key.c
+++ b/src/lib/libcrypto/dsa/dsa_key.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: dsa_key.c,v 1.21 2016/06/21 04:16:53 bcook Exp $ */
+/* $OpenBSD: dsa_key.c,v 1.22 2016/06/30 02:02:06 bcook Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -104,18 +104,12 @@ dsa_builtin_keygen(DSA *dsa)
                 pub_key=dsa->pub_key;
         
         {
-                BIGNUM *prk = BN_new();
+                BIGNUM prk;
 
-                if (prk == NULL)
-                        goto err;
-
-                BN_with_flags(prk, priv_key, BN_FLG_CONSTTIME);
+                BN_with_flags(&prk, priv_key, BN_FLG_CONSTTIME);
 
-                if (!BN_mod_exp(pub_key, dsa->g, prk, dsa->p, ctx)) {
-                        BN_free(prk);
+                if (!BN_mod_exp(pub_key, dsa->g, &prk, dsa->p, ctx))
                         goto err;
-                }
-                BN_free(prk);
         }
 
         dsa->priv_key = priv_key;