diff options
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 0731f2b670..e54488c9cf 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 } |