add the support for ecdsa in hash certificates

utils/hash.go

@@ -1,8 +1,10 @@
 package utils
 
 import (
+	"crypto/ecdsa"
 	"crypto/rsa"
 	"fmt"
+	"math/big"
 
 	"github.com/iden3/go-iden3-crypto/keccak256"
 	"github.com/rarimo/certificate-transparency-go/x509"
@@ -14,12 +16,19 @@ const ignoredKeyLength = 768
 
 var ErrUnsupportedPublicKey = errors.New("unsupported public key, supported formats: rsa, ecdsa")
 
-// HashCertificate hashes the RSA public key of the certificate
+// HashCertificate hashes the public key of the certificate
 func HashCertificate(certificate *x509.Certificate) ([]byte, error) {
-	rsaPK, ok := certificate.PublicKey.(*rsa.PublicKey)
-	if !ok {
+	var keyValue *big.Int
+
+	switch key := certificate.PublicKey.(type) {
+	case *rsa.PublicKey:
+		keyValue = key.N
+	case *ecdsa.PublicKey:
+		rawKeyBytes := append(key.X.Bytes(), key.Y.Bytes()...)
+		keyValue = new(big.Int).SetBytes(rawKeyBytes)
+	default:
 		return nil, fmt.Errorf("%T: %w", certificate.PublicKey, ErrUnsupportedPublicKey)
 	}
 
-	return keccak256.Hash(rsaPK.N.Bytes()), nil
+	return keccak256.Hash(keyValue.Bytes()), nil
 }