diff --git a/crypto/crypto.go b/crypto/crypto.go
index aa4fa45a2c..0371073270 100644
--- a/crypto/crypto.go
+++ b/crypto/crypto.go
@@ -199,23 +199,32 @@ func SigToPub(hash, sig []byte) (*ecdsa.PublicKey, error) {
 }
 
 // Sign calculates an ECDSA signature.
-// Note: the signature is not Ethereum compliant. The yellow paper dictates
-// Ethereum singature to have a V value with and offset of 27 v in [27,28].
+// This function is susceptible to choosen plaintext attacks that can leak
+// information about the private key that is used for signing. Callers must
+// be aware that the given hash cannot be choosen by an adversery. Common
+// solution is to hash any input before calculating the signature.
+//
+// Note: the calculated signature is not Ethereum compliant. The yellow paper
+// dictates Ethereum singature to have a V value with and offset of 27 v in [27,28].
 // Use SignEthereum to get an Ethereum compliant signature.
-func Sign(hash []byte, prv *ecdsa.PrivateKey) (sig []byte, err error) {
-	if len(hash) != 32 {
-		return nil, fmt.Errorf("hash is required to be exactly 32 bytes (%d)", len(hash))
+func Sign(data []byte, prv *ecdsa.PrivateKey) (sig []byte, err error) {
+	if len(data) != 32 {
+		return nil, fmt.Errorf("hash is required to be exactly 32 bytes (%d)", len(data))
 	}
 
 	seckey := common.LeftPadBytes(prv.D.Bytes(), prv.Params().BitSize/8)
 	defer zeroBytes(seckey)
-	sig, err = secp256k1.Sign(hash, seckey)
+	sig, err = secp256k1.Sign(data, seckey)
 	return
 }
 
 // SignEthereum calculates an Ethereum ECDSA signature.
-func SignEthereum(hash []byte, prv *ecdsa.PrivateKey) ([]byte, error) {
-	sig, err := Sign(hash, prv)
+// This function is susceptible to choosen plaintext attacks that can leak
+// information about the private key that is used for signing. Callers must
+// be aware that the given hash cannot be choosen by an adversery. Common
+// solution is to hash any input before calculating the signature.
+func SignEthereum(data []byte, prv *ecdsa.PrivateKey) ([]byte, error) {
+	sig, err := Sign(data, prv)
 	if err != nil {
 		return nil, err
 	}