// Construct takes the node and creates a new Key. The node must be
// a KeyInfo node
func Construct(n types.Node) (Key, error) {
ne, ok := n.(types.Element)
if !ok || ne.LocalName() != "KeyInfo" {
return nil, errors.New("invalid node (expected KeyInfo)")
}
kv, err := ne.FirstChild()
if err != nil {
return nil, err
}
kve, ok := kv.(types.Element)
if !ok || kve.LocalName() != "KeyValue" {
return nil, errors.New("invalid node (expected KeyValue)")
}
kn, err := kv.FirstChild()
if err != nil {
return nil, err
}
kne, ok := kn.(types.Element)
if !ok {
return nil, errors.New("invalid node (expected element node)")
}
switch kne.LocalName() {
case "RSAKeyValue":
pubkey := &rsa.PublicKey{}
children, err := kne.ChildNodes()
if err != nil {
return nil, err
}
for _, x := range children {
n, ok := x.(types.Element)
if !ok {
return nil, errors.New("invalid under RSAKeyValue")
}
switch n.LocalName() {
case "Modulus":
v, err := base64.StdEncoding.DecodeString(n.TextContent())
if err != nil {
return nil, err
}
pubkey.N = (&big.Int{}).SetBytes(v)
case "Exponent":
v, err := base64.StdEncoding.DecodeString(n.TextContent())
if err != nil {
return nil, err
}
if len(v) < 64 {
b := make([]byte, 64)
copy(b[64-len(v):], v)
v = b
}
pubkey.E = int(binary.BigEndian.Uint64(v))
}
}
return NewRSA(pubkey), nil
case "DSAKeyValue":
pubkey := &dsa.PublicKey{}
children, err := kne.ChildNodes()
if err != nil {
return nil, err
}
for _, x := range children {
n, ok := x.(types.Element)
if !ok {
return nil, errors.New("invalid under DSAKeyValue")
}
switch n.LocalName() {
case "P":
v, err := base64.StdEncoding.DecodeString(n.TextContent())
if err != nil {
return nil, err
}
pubkey.P = (&big.Int{}).SetBytes(v)
case "Q":
v, err := base64.StdEncoding.DecodeString(n.TextContent())
if err != nil {
return nil, err
}
pubkey.Q = (&big.Int{}).SetBytes(v)
case "G":
v, err := base64.StdEncoding.DecodeString(n.TextContent())
if err != nil {
return nil, err
}
pubkey.G = (&big.Int{}).SetBytes(v)
case "Y":
v, err := base64.StdEncoding.DecodeString(n.TextContent())
if err != nil {
return nil, err
}
pubkey.Y = (&big.Int{}).SetBytes(v)
}
}
return NewDSA(pubkey), nil
default:
return nil, errors.New("invalid node expected: DSAKeyValue or RSAKeyValue")
}
}
