61 lines
1.9 KiB
Diff
61 lines
1.9 KiB
Diff
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From ad33fdc8f4bce612842d922ca701c3062fe4d4c6 Mon Sep 17 00:00:00 2001
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From: Filippo Valsorda <filippo@golang.org>
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Date: Thu, 31 Mar 2022 12:31:58 -0400
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Subject: [Backport 1/2] [release-branch.go1.17] crypto/elliptic: tolerate
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zero-padded scalars in generic P-256
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Updates #52075
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Fixes #52076
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Fixes CVE-2022-28327
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Change-Id: I595a7514c9a0aa1b9c76aedfc2307e1124271f27
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Reviewed-on: https://go-review.googlesource.com/c/go/+/397136
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Trust: Filippo Valsorda <filippo@golang.org>
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Reviewed-by: Julie Qiu <julie@golang.org>
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Conflict:NA
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Reference:https://go-review.googlesource.com/c/go/+/399816,https://go-review.googlesource.com/c/go/+/397136
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---
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src/crypto/elliptic/p256.go | 2 +-
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src/crypto/elliptic/p256_test.go | 14 ++++++++++++++
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2 files changed, 15 insertions(+), 1 deletion(-)
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diff --git a/src/crypto/elliptic/p256.go b/src/crypto/elliptic/p256.go
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index b2b12c8f13..da5283735c 100644
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--- a/src/crypto/elliptic/p256.go
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+++ b/src/crypto/elliptic/p256.go
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@@ -52,7 +52,7 @@ func p256GetScalar(out *[32]byte, in []byte) {
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n := new(big.Int).SetBytes(in)
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var scalarBytes []byte
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- if n.Cmp(p256Params.N) >= 0 {
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+ if n.Cmp(p256Params.N) >= 0 || len(in) > len(out) {
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n.Mod(n, p256Params.N)
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scalarBytes = n.Bytes()
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} else {
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diff --git a/src/crypto/elliptic/p256_test.go b/src/crypto/elliptic/p256_test.go
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index 1435f5e1a5..694186df81 100644
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--- a/src/crypto/elliptic/p256_test.go
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+++ b/src/crypto/elliptic/p256_test.go
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@@ -153,3 +153,17 @@ func TestP256CombinedMult(t *testing.T) {
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t.Errorf("1×G + (-1)×G = (%d, %d), should be ∞", x, y)
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}
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}
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+
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+func TestIssue52075(t *testing.T) {
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+ Gx, Gy := P256().Params().Gx, P256().Params().Gy
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+ scalar := make([]byte, 33)
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+ scalar[32] = 1
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+ x, y := P256().ScalarBaseMult(scalar)
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+ if x.Cmp(Gx) != 0 || y.Cmp(Gy) != 0 {
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+ t.Errorf("unexpected output (%v,%v)", x, y)
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+ }
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+ x, y = P256().ScalarMult(Gx, Gy, scalar)
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+ if x.Cmp(Gx) != 0 || y.Cmp(Gy) != 0 {
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+ t.Errorf("unexpected output (%v,%v)", x, y)
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+ }
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+}
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--
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2.30.0
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