diff options
author | Brad Fitzpatrick <bradfitz@golang.org> | 2016-04-05 20:40:40 +0000 |
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committer | Brad Fitzpatrick <bradfitz@golang.org> | 2016-04-05 21:03:20 +0000 |
commit | d7c699d9935ce2f99419faf81909b36409171705 (patch) | |
tree | 6517ad09be7e1bedf1d465b3880cf4e5cc51afe8 /src/crypto/ecdsa/ecdsa.go | |
parent | 7e0d66020c49ef56158346ce18dc3f538393829e (diff) | |
download | go-d7c699d9935ce2f99419faf81909b36409171705.tar.gz go-d7c699d9935ce2f99419faf81909b36409171705.zip |
crypto/rsa, crypto/ecdsa: fail earlier on zero parameters
Change-Id: Ia6ed49d5ef3a256a55e6d4eaa1b4d9f0fc447013
Reviewed-on: https://go-review.googlesource.com/21560
Reviewed-by: Robert Griesemer <gri@golang.org>
Diffstat (limited to 'src/crypto/ecdsa/ecdsa.go')
-rw-r--r-- | src/crypto/ecdsa/ecdsa.go | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/src/crypto/ecdsa/ecdsa.go b/src/crypto/ecdsa/ecdsa.go index 42ec92b6f9..e63bd8669e 100644 --- a/src/crypto/ecdsa/ecdsa.go +++ b/src/crypto/ecdsa/ecdsa.go @@ -23,6 +23,7 @@ import ( "crypto/elliptic" "crypto/sha512" "encoding/asn1" + "errors" "io" "math/big" ) @@ -140,6 +141,8 @@ func fermatInverse(k, N *big.Int) *big.Int { return new(big.Int).Exp(k, nMinus2, N) } +var errZeroParam = errors.New("zero parameter") + // Sign signs an arbitrary length hash (which should be the result of hashing a // larger message) using the private key, priv. It returns the signature as a // pair of integers. The security of the private key depends on the entropy of @@ -180,7 +183,9 @@ func Sign(rand io.Reader, priv *PrivateKey, hash []byte) (r, s *big.Int, err err // See [NSA] 3.4.1 c := priv.PublicKey.Curve N := c.Params().N - + if N.Sign() == 0 { + return nil, nil, errZeroParam + } var k, kInv *big.Int for { for { @@ -193,7 +198,7 @@ func Sign(rand io.Reader, priv *PrivateKey, hash []byte) (r, s *big.Int, err err if in, ok := priv.Curve.(invertible); ok { kInv = in.Inverse(k) } else { - kInv = fermatInverse(k, N) + kInv = fermatInverse(k, N) // N != 0 } r, _ = priv.Curve.ScalarBaseMult(k.Bytes()) @@ -207,7 +212,7 @@ func Sign(rand io.Reader, priv *PrivateKey, hash []byte) (r, s *big.Int, err err s = new(big.Int).Mul(priv.D, r) s.Add(s, e) s.Mul(s, kInv) - s.Mod(s, N) + s.Mod(s, N) // N != 0 if s.Sign() != 0 { break } |