// 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") } }