457 lines
11 KiB
Go
457 lines
11 KiB
Go
/*-
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* Copyright 2014 Square Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package jose
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import (
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"crypto"
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"crypto/ecdsa"
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"crypto/elliptic"
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"crypto/rsa"
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"crypto/x509"
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"encoding/base64"
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"errors"
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"fmt"
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"math/big"
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"reflect"
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"strings"
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"gopkg.in/square/go-jose.v1/json"
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)
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// rawJsonWebKey represents a public or private key in JWK format, used for parsing/serializing.
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type rawJsonWebKey struct {
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Use string `json:"use,omitempty"`
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Kty string `json:"kty,omitempty"`
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Kid string `json:"kid,omitempty"`
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Crv string `json:"crv,omitempty"`
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Alg string `json:"alg,omitempty"`
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K *byteBuffer `json:"k,omitempty"`
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X *byteBuffer `json:"x,omitempty"`
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Y *byteBuffer `json:"y,omitempty"`
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N *byteBuffer `json:"n,omitempty"`
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E *byteBuffer `json:"e,omitempty"`
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// -- Following fields are only used for private keys --
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// RSA uses D, P and Q, while ECDSA uses only D. Fields Dp, Dq, and Qi are
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// completely optional. Therefore for RSA/ECDSA, D != nil is a contract that
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// we have a private key whereas D == nil means we have only a public key.
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D *byteBuffer `json:"d,omitempty"`
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P *byteBuffer `json:"p,omitempty"`
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Q *byteBuffer `json:"q,omitempty"`
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Dp *byteBuffer `json:"dp,omitempty"`
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Dq *byteBuffer `json:"dq,omitempty"`
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Qi *byteBuffer `json:"qi,omitempty"`
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// Certificates
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X5c []string `json:"x5c,omitempty"`
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}
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// JsonWebKey represents a public or private key in JWK format.
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type JsonWebKey struct {
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Key interface{}
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Certificates []*x509.Certificate
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KeyID string
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Algorithm string
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Use string
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}
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// MarshalJSON serializes the given key to its JSON representation.
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func (k JsonWebKey) MarshalJSON() ([]byte, error) {
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var raw *rawJsonWebKey
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var err error
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switch key := k.Key.(type) {
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case *ecdsa.PublicKey:
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raw, err = fromEcPublicKey(key)
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case *rsa.PublicKey:
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raw = fromRsaPublicKey(key)
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case *ecdsa.PrivateKey:
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raw, err = fromEcPrivateKey(key)
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case *rsa.PrivateKey:
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raw, err = fromRsaPrivateKey(key)
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case []byte:
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raw, err = fromSymmetricKey(key)
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default:
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return nil, fmt.Errorf("square/go-jose: unknown key type '%s'", reflect.TypeOf(key))
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}
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if err != nil {
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return nil, err
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}
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raw.Kid = k.KeyID
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raw.Alg = k.Algorithm
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raw.Use = k.Use
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for _, cert := range k.Certificates {
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raw.X5c = append(raw.X5c, base64.StdEncoding.EncodeToString(cert.Raw))
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}
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return json.Marshal(raw)
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}
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// UnmarshalJSON reads a key from its JSON representation.
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func (k *JsonWebKey) UnmarshalJSON(data []byte) (err error) {
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var raw rawJsonWebKey
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err = json.Unmarshal(data, &raw)
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if err != nil {
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return err
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}
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var key interface{}
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switch raw.Kty {
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case "EC":
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if raw.D != nil {
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key, err = raw.ecPrivateKey()
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} else {
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key, err = raw.ecPublicKey()
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}
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case "RSA":
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if raw.D != nil {
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key, err = raw.rsaPrivateKey()
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} else {
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key, err = raw.rsaPublicKey()
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}
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case "oct":
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key, err = raw.symmetricKey()
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default:
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err = fmt.Errorf("square/go-jose: unknown json web key type '%s'", raw.Kty)
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}
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if err == nil {
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*k = JsonWebKey{Key: key, KeyID: raw.Kid, Algorithm: raw.Alg, Use: raw.Use}
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}
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k.Certificates = make([]*x509.Certificate, len(raw.X5c))
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for i, cert := range raw.X5c {
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raw, err := base64.StdEncoding.DecodeString(cert)
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if err != nil {
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return err
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}
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k.Certificates[i], err = x509.ParseCertificate(raw)
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if err != nil {
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return err
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}
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}
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return
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}
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// JsonWebKeySet represents a JWK Set object.
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type JsonWebKeySet struct {
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Keys []JsonWebKey `json:"keys"`
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}
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// Key convenience method returns keys by key ID. Specification states
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// that a JWK Set "SHOULD" use distinct key IDs, but allows for some
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// cases where they are not distinct. Hence method returns a slice
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// of JsonWebKeys.
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func (s *JsonWebKeySet) Key(kid string) []JsonWebKey {
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var keys []JsonWebKey
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for _, key := range s.Keys {
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if key.KeyID == kid {
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keys = append(keys, key)
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}
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}
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return keys
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}
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const rsaThumbprintTemplate = `{"e":"%s","kty":"RSA","n":"%s"}`
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const ecThumbprintTemplate = `{"crv":"%s","kty":"EC","x":"%s","y":"%s"}`
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func ecThumbprintInput(curve elliptic.Curve, x, y *big.Int) (string, error) {
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coordLength := curveSize(curve)
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crv, err := curveName(curve)
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if err != nil {
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return "", err
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}
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return fmt.Sprintf(ecThumbprintTemplate, crv,
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newFixedSizeBuffer(x.Bytes(), coordLength).base64(),
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newFixedSizeBuffer(y.Bytes(), coordLength).base64()), nil
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}
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func rsaThumbprintInput(n *big.Int, e int) (string, error) {
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return fmt.Sprintf(rsaThumbprintTemplate,
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newBufferFromInt(uint64(e)).base64(),
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newBuffer(n.Bytes()).base64()), nil
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}
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// Thumbprint computes the JWK Thumbprint of a key using the
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// indicated hash algorithm.
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func (k *JsonWebKey) Thumbprint(hash crypto.Hash) ([]byte, error) {
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var input string
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var err error
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switch key := k.Key.(type) {
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case *ecdsa.PublicKey:
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input, err = ecThumbprintInput(key.Curve, key.X, key.Y)
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case *ecdsa.PrivateKey:
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input, err = ecThumbprintInput(key.Curve, key.X, key.Y)
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case *rsa.PublicKey:
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input, err = rsaThumbprintInput(key.N, key.E)
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case *rsa.PrivateKey:
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input, err = rsaThumbprintInput(key.N, key.E)
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default:
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return nil, fmt.Errorf("square/go-jose: unknown key type '%s'", reflect.TypeOf(key))
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}
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if err != nil {
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return nil, err
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}
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h := hash.New()
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h.Write([]byte(input))
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return h.Sum(nil), nil
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}
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// IsPublic returns true if the JWK represents a public key (not symmetric, not private).
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func (k *JsonWebKey) IsPublic() bool {
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switch k.Key.(type) {
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case *ecdsa.PublicKey, *rsa.PublicKey:
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return true
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default:
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return false
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}
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}
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// Valid checks that the key contains the expected parameters.
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func (k *JsonWebKey) Valid() bool {
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if k.Key == nil {
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return false
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}
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switch key := k.Key.(type) {
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case *ecdsa.PublicKey:
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if key.Curve == nil || key.X == nil || key.Y == nil {
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return false
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}
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case *ecdsa.PrivateKey:
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if key.Curve == nil || key.X == nil || key.Y == nil || key.D == nil {
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return false
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}
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case *rsa.PublicKey:
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if key.N == nil || key.E == 0 {
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return false
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}
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case *rsa.PrivateKey:
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if key.N == nil || key.E == 0 || key.D == nil || len(key.Primes) < 2 {
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return false
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}
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default:
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return false
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}
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return true
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}
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func (key rawJsonWebKey) rsaPublicKey() (*rsa.PublicKey, error) {
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if key.N == nil || key.E == nil {
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return nil, fmt.Errorf("square/go-jose: invalid RSA key, missing n/e values")
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}
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return &rsa.PublicKey{
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N: key.N.bigInt(),
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E: key.E.toInt(),
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}, nil
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}
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func fromRsaPublicKey(pub *rsa.PublicKey) *rawJsonWebKey {
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return &rawJsonWebKey{
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Kty: "RSA",
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N: newBuffer(pub.N.Bytes()),
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E: newBufferFromInt(uint64(pub.E)),
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}
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}
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func (key rawJsonWebKey) ecPublicKey() (*ecdsa.PublicKey, error) {
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var curve elliptic.Curve
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switch key.Crv {
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case "P-256":
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curve = elliptic.P256()
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case "P-384":
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curve = elliptic.P384()
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case "P-521":
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curve = elliptic.P521()
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default:
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return nil, fmt.Errorf("square/go-jose: unsupported elliptic curve '%s'", key.Crv)
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}
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if key.X == nil || key.Y == nil {
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return nil, errors.New("square/go-jose: invalid EC key, missing x/y values")
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}
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x := key.X.bigInt()
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y := key.Y.bigInt()
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if !curve.IsOnCurve(x, y) {
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return nil, errors.New("square/go-jose: invalid EC key, X/Y are not on declared curve")
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}
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return &ecdsa.PublicKey{
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Curve: curve,
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X: x,
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Y: y,
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}, nil
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}
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func fromEcPublicKey(pub *ecdsa.PublicKey) (*rawJsonWebKey, error) {
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if pub == nil || pub.X == nil || pub.Y == nil {
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return nil, fmt.Errorf("square/go-jose: invalid EC key (nil, or X/Y missing)")
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}
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name, err := curveName(pub.Curve)
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if err != nil {
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return nil, err
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}
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size := curveSize(pub.Curve)
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xBytes := pub.X.Bytes()
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yBytes := pub.Y.Bytes()
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if len(xBytes) > size || len(yBytes) > size {
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return nil, fmt.Errorf("square/go-jose: invalid EC key (X/Y too large)")
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}
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key := &rawJsonWebKey{
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Kty: "EC",
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Crv: name,
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X: newFixedSizeBuffer(xBytes, size),
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Y: newFixedSizeBuffer(yBytes, size),
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}
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return key, nil
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}
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func (key rawJsonWebKey) rsaPrivateKey() (*rsa.PrivateKey, error) {
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var missing []string
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switch {
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case key.N == nil:
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missing = append(missing, "N")
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case key.E == nil:
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missing = append(missing, "E")
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case key.D == nil:
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missing = append(missing, "D")
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case key.P == nil:
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missing = append(missing, "P")
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case key.Q == nil:
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missing = append(missing, "Q")
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}
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if len(missing) > 0 {
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return nil, fmt.Errorf("square/go-jose: invalid RSA private key, missing %s value(s)", strings.Join(missing, ", "))
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}
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rv := &rsa.PrivateKey{
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PublicKey: rsa.PublicKey{
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N: key.N.bigInt(),
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E: key.E.toInt(),
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},
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D: key.D.bigInt(),
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Primes: []*big.Int{
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key.P.bigInt(),
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key.Q.bigInt(),
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},
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}
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if key.Dp != nil {
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rv.Precomputed.Dp = key.Dp.bigInt()
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}
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if key.Dq != nil {
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rv.Precomputed.Dq = key.Dq.bigInt()
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}
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if key.Qi != nil {
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rv.Precomputed.Qinv = key.Qi.bigInt()
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}
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err := rv.Validate()
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return rv, err
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}
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func fromRsaPrivateKey(rsa *rsa.PrivateKey) (*rawJsonWebKey, error) {
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if len(rsa.Primes) != 2 {
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return nil, ErrUnsupportedKeyType
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}
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raw := fromRsaPublicKey(&rsa.PublicKey)
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raw.D = newBuffer(rsa.D.Bytes())
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raw.P = newBuffer(rsa.Primes[0].Bytes())
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raw.Q = newBuffer(rsa.Primes[1].Bytes())
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return raw, nil
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}
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func (key rawJsonWebKey) ecPrivateKey() (*ecdsa.PrivateKey, error) {
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var curve elliptic.Curve
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switch key.Crv {
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case "P-256":
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curve = elliptic.P256()
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case "P-384":
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curve = elliptic.P384()
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case "P-521":
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curve = elliptic.P521()
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default:
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return nil, fmt.Errorf("square/go-jose: unsupported elliptic curve '%s'", key.Crv)
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}
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if key.X == nil || key.Y == nil || key.D == nil {
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return nil, fmt.Errorf("square/go-jose: invalid EC private key, missing x/y/d values")
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}
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x := key.X.bigInt()
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y := key.Y.bigInt()
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if !curve.IsOnCurve(x, y) {
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return nil, errors.New("square/go-jose: invalid EC key, X/Y are not on declared curve")
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}
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return &ecdsa.PrivateKey{
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PublicKey: ecdsa.PublicKey{
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Curve: curve,
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X: x,
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Y: y,
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},
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D: key.D.bigInt(),
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}, nil
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}
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func fromEcPrivateKey(ec *ecdsa.PrivateKey) (*rawJsonWebKey, error) {
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raw, err := fromEcPublicKey(&ec.PublicKey)
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if err != nil {
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return nil, err
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}
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if ec.D == nil {
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return nil, fmt.Errorf("square/go-jose: invalid EC private key")
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}
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raw.D = newBuffer(ec.D.Bytes())
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return raw, nil
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}
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func fromSymmetricKey(key []byte) (*rawJsonWebKey, error) {
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return &rawJsonWebKey{
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Kty: "oct",
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K: newBuffer(key),
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}, nil
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}
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func (key rawJsonWebKey) symmetricKey() ([]byte, error) {
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if key.K == nil {
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return nil, fmt.Errorf("square/go-jose: invalid OCT (symmetric) key, missing k value")
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}
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return key.K.bytes(), nil
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}
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