From 2cfbb875208f4acecfb0b72de5aebe37e8d03a35 Mon Sep 17 00:00:00 2001

From: Robert Griesemer <[email protected]>

Date: Tue, 5 Apr 2016 09:44:00 -0700

Subject: [PATCH 74/79] crypto/dsa: eliminate invalid PublicKey early

For PublicKey.P == 0, Verify will fail. Don't even try.

Change-Id: I1009f2b3dead8d0041626c946633acb10086d8c8

Reviewed-on: https://go-review.googlesource.com/21533

Reviewed-by: Brad Fitzpatrick <[email protected]>

Run-TryBot: Brad Fitzpatrick <[email protected]>

TryBot-Result: Gobot Gobot <[email protected]>

Reviewed-on: https://go-review.googlesource.com/21637

---

 src/crypto/dsa/dsa.go | 4 ++++

 1 file changed, 4 insertions(+)

diff --git a/src/crypto/dsa/dsa.go b/src/crypto/dsa/dsa.go

index b7565a6..0ecb24a 100644

--- a/src/crypto/dsa/dsa.go

+++ b/src/crypto/dsa/dsa.go

@@ -249,6 +249,10 @@ func Sign(rand io.Reader, priv *PrivateKey, hash []byte) (r, s *big.Int, err err

 func Verify(pub *PublicKey, hash []byte, r, s *big.Int) bool {

 	// FIPS 186-3, section 4.7

+	if pub.P.Sign() == 0 {

+		return false

+	}

+

 	if r.Sign() < 1 || r.Cmp(pub.Q) >= 0 {

 		return false

 	}

-- 

2.7.4