diff options
author | Filippo Valsorda <filippo@golang.org> | 2023-05-05 13:22:02 +0200 |
---|---|---|
committer | Gopher Robot <gobot@golang.org> | 2023-05-17 14:48:13 +0000 |
commit | bf8571c5d6ce823e3ad7491429cf26d3a74461aa (patch) | |
tree | c0b98d0f7949106a338e13db420450368f43982f | |
parent | b7e767b022f96687ecbde61ee7efd61a711f798b (diff) | |
download | go-git-bf8571c5d6ce823e3ad7491429cf26d3a74461aa.tar.gz |
crypto/ed25519,crypto/rsa: make Equal methods constant time
Fixes #53849
Updates #57752
Change-Id: I055564f31a47c79565b82bf9844fcf626989b295
Reviewed-on: https://go-review.googlesource.com/c/go/+/492955
Auto-Submit: Russ Cox <rsc@golang.org>
Reviewed-by: Heschi Kreinick <heschi@google.com>
Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
-rw-r--r-- | src/crypto/ed25519/ed25519.go | 5 | ||||
-rw-r--r-- | src/crypto/rsa/rsa.go | 12 |
2 files changed, 12 insertions, 5 deletions
diff --git a/src/crypto/ed25519/ed25519.go b/src/crypto/ed25519/ed25519.go index a043eaf807..32a8d9e86c 100644 --- a/src/crypto/ed25519/ed25519.go +++ b/src/crypto/ed25519/ed25519.go @@ -18,6 +18,7 @@ import ( "crypto/internal/edwards25519" cryptorand "crypto/rand" "crypto/sha512" + "crypto/subtle" "errors" "io" "strconv" @@ -46,7 +47,7 @@ func (pub PublicKey) Equal(x crypto.PublicKey) bool { if !ok { return false } - return bytes.Equal(pub, xx) + return subtle.ConstantTimeCompare(pub, xx) == 1 } // PrivateKey is the type of Ed25519 private keys. It implements [crypto.Signer]. @@ -65,7 +66,7 @@ func (priv PrivateKey) Equal(x crypto.PrivateKey) bool { if !ok { return false } - return bytes.Equal(priv, xx) + return subtle.ConstantTimeCompare(priv, xx) == 1 } // Seed returns the private key seed corresponding to priv. It is provided for diff --git a/src/crypto/rsa/rsa.go b/src/crypto/rsa/rsa.go index 64a27660dc..6f0221d74b 100644 --- a/src/crypto/rsa/rsa.go +++ b/src/crypto/rsa/rsa.go @@ -64,7 +64,7 @@ func (pub *PublicKey) Equal(x crypto.PublicKey) bool { if !ok { return false } - return pub.N.Cmp(xx.N) == 0 && pub.E == xx.E + return bigIntEqual(pub.N, xx.N) && pub.E == xx.E } // OAEPOptions is an interface for passing options to OAEP decryption using the @@ -130,20 +130,26 @@ func (priv *PrivateKey) Equal(x crypto.PrivateKey) bool { if !ok { return false } - if !priv.PublicKey.Equal(&xx.PublicKey) || priv.D.Cmp(xx.D) != 0 { + if !priv.PublicKey.Equal(&xx.PublicKey) || !bigIntEqual(priv.D, xx.D) { return false } if len(priv.Primes) != len(xx.Primes) { return false } for i := range priv.Primes { - if priv.Primes[i].Cmp(xx.Primes[i]) != 0 { + if !bigIntEqual(priv.Primes[i], xx.Primes[i]) { return false } } return true } +// bigIntEqual reports whether a and b are equal leaking only their bit length +// through timing side-channels. +func bigIntEqual(a, b *big.Int) bool { + return subtle.ConstantTimeCompare(a.Bytes(), b.Bytes()) == 1 +} + // Sign signs digest with priv, reading randomness from rand. If opts is a // *PSSOptions then the PSS algorithm will be used, otherwise PKCS #1 v1.5 will // be used. digest must be the result of hashing the input message using |