Speed up DH with small generator.

1 files changed, 14 insertions, 7 deletions

diff --git a/crypto/dh/dh_key.c b/crypto/dh/dh_key.c
index 0c7eeaf260..6f9426dd6f 100644
--- a/crypto/dh/dh_key.c
+++ b/crypto/dh/dh_key.c
@@ -193,19 +193,26 @@ err:
 static int dh_bn_mod_exp(DH *dh, BIGNUM *r, BIGNUM *a, const BIGNUM *p,
 			const BIGNUM *m, BN_CTX *ctx,
 			BN_MONT_CTX *m_ctx)
-{
-	return BN_mod_exp_mont(r, a, p, m, ctx, m_ctx);
-}
+	{
+	if (a->top == 1)
+		{
+		BN_ULONG A = a->d[0];
+		return BN_mod_exp_mont_word(r,A,p,m,ctx,m_ctx);
+		}
+	else
+		return BN_mod_exp_mont(r,a,p,m,ctx,m_ctx);
+	}
+
 
 static int dh_init(DH *dh)
-{
+	{
 	dh->flags |= DH_FLAG_CACHE_MONT_P;
 	return(1);
-}
+	}
 
 static int dh_finish(DH *dh)
-{
+	{
 	if(dh->method_mont_p)
 		BN_MONT_CTX_free((BN_MONT_CTX *)dh->method_mont_p);
 	return(1);
-}
+	}