dex/vendor/gopkg.in/square/go-jose.v2/signing.go

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2016-07-26 01:30:28 +05:30
/*-
* Copyright 2014 Square Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package jose
import (
"crypto/ecdsa"
"crypto/rsa"
"encoding/base64"
"fmt"
)
// NonceSource represents a source of random nonces to go into JWS objects
type NonceSource interface {
Nonce() (string, error)
}
// Signer represents a signer which takes a payload and produces a signed JWS object.
type Signer interface {
Sign(payload []byte) (*JSONWebSignature, error)
}
// SigningKey represents an algorithm/key used to sign a message.
type SigningKey struct {
Algorithm SignatureAlgorithm
Key interface{}
}
// SignerOptions represents options that can be set when creating signers.
type SignerOptions struct {
NonceSource NonceSource
EmbedJWK bool
}
type payloadSigner interface {
signPayload(payload []byte, alg SignatureAlgorithm) (Signature, error)
}
type payloadVerifier interface {
verifyPayload(payload []byte, signature []byte, alg SignatureAlgorithm) error
}
type genericSigner struct {
recipients []recipientSigInfo
nonceSource NonceSource
embedJWK bool
}
type recipientSigInfo struct {
sigAlg SignatureAlgorithm
publicKey *JSONWebKey
signer payloadSigner
}
// NewSigner creates an appropriate signer based on the key type
func NewSigner(sig SigningKey, opts *SignerOptions) (Signer, error) {
return NewMultiSigner([]SigningKey{sig}, opts)
}
// NewMultiSigner creates a signer for multiple recipients
func NewMultiSigner(sigs []SigningKey, opts *SignerOptions) (Signer, error) {
signer := &genericSigner{recipients: []recipientSigInfo{}}
if opts != nil {
signer.nonceSource = opts.NonceSource
signer.embedJWK = opts.EmbedJWK
}
for _, sig := range sigs {
err := signer.addRecipient(sig.Algorithm, sig.Key)
if err != nil {
return nil, err
}
}
return signer, nil
}
// newVerifier creates a verifier based on the key type
func newVerifier(verificationKey interface{}) (payloadVerifier, error) {
switch verificationKey := verificationKey.(type) {
case *rsa.PublicKey:
return &rsaEncrypterVerifier{
publicKey: verificationKey,
}, nil
case *ecdsa.PublicKey:
return &ecEncrypterVerifier{
publicKey: verificationKey,
}, nil
case []byte:
return &symmetricMac{
key: verificationKey,
}, nil
case *JSONWebKey:
return newVerifier(verificationKey.Key)
default:
return nil, ErrUnsupportedKeyType
}
}
func (ctx *genericSigner) addRecipient(alg SignatureAlgorithm, signingKey interface{}) error {
recipient, err := makeJWSRecipient(alg, signingKey)
if err != nil {
return err
}
ctx.recipients = append(ctx.recipients, recipient)
return nil
}
func makeJWSRecipient(alg SignatureAlgorithm, signingKey interface{}) (recipientSigInfo, error) {
switch signingKey := signingKey.(type) {
case *rsa.PrivateKey:
return newRSASigner(alg, signingKey)
case *ecdsa.PrivateKey:
return newECDSASigner(alg, signingKey)
case []byte:
return newSymmetricSigner(alg, signingKey)
case *JSONWebKey:
recipient, err := makeJWSRecipient(alg, signingKey.Key)
if err != nil {
return recipientSigInfo{}, err
}
recipient.publicKey.KeyID = signingKey.KeyID
return recipient, nil
default:
return recipientSigInfo{}, ErrUnsupportedKeyType
}
}
func (ctx *genericSigner) Sign(payload []byte) (*JSONWebSignature, error) {
obj := &JSONWebSignature{}
obj.payload = payload
obj.Signatures = make([]Signature, len(ctx.recipients))
for i, recipient := range ctx.recipients {
protected := &rawHeader{
Alg: string(recipient.sigAlg),
}
if recipient.publicKey != nil {
if ctx.embedJWK {
protected.Jwk = recipient.publicKey
}
protected.Kid = recipient.publicKey.KeyID
}
if ctx.nonceSource != nil {
nonce, err := ctx.nonceSource.Nonce()
if err != nil {
return nil, fmt.Errorf("square/go-jose: Error generating nonce: %v", err)
}
protected.Nonce = nonce
}
serializedProtected := mustSerializeJSON(protected)
input := []byte(fmt.Sprintf("%s.%s",
base64.RawURLEncoding.EncodeToString(serializedProtected),
base64.RawURLEncoding.EncodeToString(payload)))
signatureInfo, err := recipient.signer.signPayload(input, recipient.sigAlg)
if err != nil {
return nil, err
}
signatureInfo.protected = protected
obj.Signatures[i] = signatureInfo
}
return obj, nil
}
// Verify validates the signature on the object and returns the payload.
func (obj JSONWebSignature) Verify(verificationKey interface{}) ([]byte, error) {
verifier, err := newVerifier(verificationKey)
if err != nil {
return nil, err
}
for _, signature := range obj.Signatures {
headers := signature.mergedHeaders()
if len(headers.Crit) > 0 {
// Unsupported crit header
continue
}
input := obj.computeAuthData(&signature)
alg := SignatureAlgorithm(headers.Alg)
err := verifier.verifyPayload(input, signature.Signature, alg)
if err == nil {
return obj.payload, nil
}
}
return nil, ErrCryptoFailure
}