add URI attribute to <Reference>

signature.go

@@ -10,6 +10,18 @@ import (
 type Method struct {
 	Algorithm string `xml:",attr"`
 }
+type Reference struct {
+	URI                 string   `xml:"URI,attr"`
+	ReferenceTransforms []Method `xml:"Transforms>Transform"`
+	DigestMethod        Method   `xml:"DigestMethod"`
+	DigestValue         string   `xml:"DigestValue"`
+}
+
+type SignedInfo struct {
+	CanonicalizationMethod Method    `xml:"CanonicalizationMethod"`
+	SignatureMethod        Method    `xml:"SignatureMethod"`
+	Reference              Reference `xml:"Reference"`
+}
 
 // Signature is a model for the Signature object specified by XMLDSIG. This is
 // convenience object when constructing XML that you'd like to sign. For example:
@@ -25,16 +37,11 @@ type Method struct {
 //    buf, _ = Sign(key, buf)
 //
 type Signature struct {
-	XMLName xml.Name `xml:"http://www.w3.org/2000/09/xmldsig# Signature"`
-
-	CanonicalizationMethod Method             `xml:"SignedInfo>CanonicalizationMethod"`
-	SignatureMethod        Method             `xml:"SignedInfo>SignatureMethod"`
-	ReferenceTransforms    []Method           `xml:"SignedInfo>Reference>Transforms>Transform"`
-	DigestMethod           Method             `xml:"SignedInfo>Reference>DigestMethod"`
-	DigestValue            string             `xml:"SignedInfo>Reference>DigestValue"`
-	SignatureValue         string             `xml:"SignatureValue"`
-	KeyName                string             `xml:"KeyInfo>KeyName,omitempty"`
-	X509Certificate        *SignatureX509Data `xml:"KeyInfo>X509Data,omitempty"`
+	XMLName         xml.Name `xml:"http://www.w3.org/2000/09/xmldsig# Signature"`
+	SignedInfo      SignedInfo
+	SignatureValue  string             `xml:"SignatureValue"`
+	KeyName         string             `xml:"KeyInfo>KeyName,omitempty"`
+	X509Certificate *SignatureX509Data `xml:"KeyInfo>X509Data,omitempty"`
 }
 
 // SignatureX509Data represents the <X509Data> element of <Signature>
@@ -50,17 +57,21 @@ func DefaultSignature(pemEncodedPublicKey []byte) Signature {
 	certStr := base64.StdEncoding.EncodeToString(pemBlock.Bytes)
 
 	return Signature{
-		CanonicalizationMethod: Method{
-			Algorithm: "http://www.w3.org/TR/2001/REC-xml-c14n-20010315",
-		},
-		SignatureMethod: Method{
-			Algorithm: "http://www.w3.org/2000/09/xmldsig#rsa-sha1",
-		},
-		ReferenceTransforms: []Method{
-			Method{Algorithm: "http://www.w3.org/2000/09/xmldsig#enveloped-signature"},
-		},
-		DigestMethod: Method{
-			Algorithm: "http://www.w3.org/2000/09/xmldsig#sha1",
+		SignedInfo: SignedInfo{
+			CanonicalizationMethod: Method{
+				Algorithm: "http://www.w3.org/TR/2001/REC-xml-c14n-20010315",
+			},
+			SignatureMethod: Method{
+				Algorithm: "http://www.w3.org/2000/09/xmldsig#rsa-sha1",
+			},
+			Reference: Reference{
+				ReferenceTransforms: []Method{
+					Method{Algorithm: "http://www.w3.org/2000/09/xmldsig#enveloped-signature"},
+				},
+				DigestMethod: Method{
+					Algorithm: "http://www.w3.org/2000/09/xmldsig#sha1",
+				},
+			},
 		},
 		X509Certificate: &SignatureX509Data{
 			X509Certificate: certStr,