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jws.go
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jws.go
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/*-
* 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 (
"errors"
"fmt"
"strings"
"gopkg.in/square/go-jose.v1/json"
)
// rawJsonWebSignature represents a raw JWS JSON object. Used for parsing/serializing.
type rawJsonWebSignature struct {
Payload *byteBuffer `json:"payload,omitempty"`
Signatures []rawSignatureInfo `json:"signatures,omitempty"`
Protected *byteBuffer `json:"protected,omitempty"`
Header *rawHeader `json:"header,omitempty"`
Signature *byteBuffer `json:"signature,omitempty"`
}
// rawSignatureInfo represents a single JWS signature over the JWS payload and protected header.
type rawSignatureInfo struct {
Protected *byteBuffer `json:"protected,omitempty"`
Header *rawHeader `json:"header,omitempty"`
Signature *byteBuffer `json:"signature,omitempty"`
}
// JsonWebSignature represents a signed JWS object after parsing.
type JsonWebSignature struct {
payload []byte
// Signatures attached to this object (may be more than one for multi-sig).
// Be careful about accessing these directly, prefer to use Verify() or
// VerifyMulti() to ensure that the data you're getting is verified.
Signatures []Signature
}
// Signature represents a single signature over the JWS payload and protected header.
type Signature struct {
// Header fields, such as the signature algorithm
Header JoseHeader
// The actual signature value
Signature []byte
protected *rawHeader
header *rawHeader
original *rawSignatureInfo
}
// ParseSigned parses a signed message in compact or full serialization format.
func ParseSigned(input string) (*JsonWebSignature, error) {
input = stripWhitespace(input)
if strings.HasPrefix(input, "{") {
return parseSignedFull(input)
}
return parseSignedCompact(input)
}
// Get a header value
func (sig Signature) mergedHeaders() rawHeader {
out := rawHeader{}
out.merge(sig.protected)
out.merge(sig.header)
return out
}
// Compute data to be signed
func (obj JsonWebSignature) computeAuthData(signature *Signature) []byte {
var serializedProtected string
if signature.original != nil && signature.original.Protected != nil {
serializedProtected = signature.original.Protected.base64()
} else if signature.protected != nil {
serializedProtected = base64URLEncode(mustSerializeJSON(signature.protected))
} else {
serializedProtected = ""
}
return []byte(fmt.Sprintf("%s.%s",
serializedProtected,
base64URLEncode(obj.payload)))
}
// parseSignedFull parses a message in full format.
func parseSignedFull(input string) (*JsonWebSignature, error) {
var parsed rawJsonWebSignature
err := json.Unmarshal([]byte(input), &parsed)
if err != nil {
return nil, err
}
return parsed.sanitized()
}
// sanitized produces a cleaned-up JWS object from the raw JSON.
func (parsed *rawJsonWebSignature) sanitized() (*JsonWebSignature, error) {
if parsed.Payload == nil {
return nil, fmt.Errorf("square/go-jose: missing payload in JWS message")
}
obj := &JsonWebSignature{
payload: parsed.Payload.bytes(),
Signatures: make([]Signature, len(parsed.Signatures)),
}
if len(parsed.Signatures) == 0 {
// No signatures array, must be flattened serialization
signature := Signature{}
if parsed.Protected != nil && len(parsed.Protected.bytes()) > 0 {
signature.protected = &rawHeader{}
err := json.Unmarshal(parsed.Protected.bytes(), signature.protected)
if err != nil {
return nil, err
}
}
// Check that there is not a nonce in the unprotected header
if parsed.Header != nil && parsed.Header.Nonce != "" {
return nil, ErrUnprotectedNonce
}
signature.header = parsed.Header
signature.Signature = parsed.Signature.bytes()
// Make a fake "original" rawSignatureInfo to store the unprocessed
// Protected header. This is necessary because the Protected header can
// contain arbitrary fields not registered as part of the spec. See
// https://tools.ietf.org/html/draft-ietf-jose-json-web-signature-41#section-4
// If we unmarshal Protected into a rawHeader with its explicit list of fields,
// we cannot marshal losslessly. So we have to keep around the original bytes.
// This is used in computeAuthData, which will first attempt to use
// the original bytes of a protected header, and fall back on marshaling the
// header struct only if those bytes are not available.
signature.original = &rawSignatureInfo{
Protected: parsed.Protected,
Header: parsed.Header,
Signature: parsed.Signature,
}
signature.Header = signature.mergedHeaders().sanitized()
// As per RFC 7515 Section 4.1.3, only public keys are allowed to be embedded.
jwk := signature.Header.JsonWebKey
if jwk != nil && (!jwk.Valid() || !jwk.IsPublic()) {
return nil, errors.New("square/go-jose: invalid embedded jwk, must be public key")
}
obj.Signatures = append(obj.Signatures, signature)
}
for i, sig := range parsed.Signatures {
if sig.Protected != nil && len(sig.Protected.bytes()) > 0 {
obj.Signatures[i].protected = &rawHeader{}
err := json.Unmarshal(sig.Protected.bytes(), obj.Signatures[i].protected)
if err != nil {
return nil, err
}
}
// Check that there is not a nonce in the unprotected header
if sig.Header != nil && sig.Header.Nonce != "" {
return nil, ErrUnprotectedNonce
}
obj.Signatures[i].Header = obj.Signatures[i].mergedHeaders().sanitized()
obj.Signatures[i].Signature = sig.Signature.bytes()
// As per RFC 7515 Section 4.1.3, only public keys are allowed to be embedded.
jwk := obj.Signatures[i].Header.JsonWebKey
if jwk != nil && (!jwk.Valid() || !jwk.IsPublic()) {
return nil, errors.New("square/go-jose: invalid embedded jwk, must be public key")
}
// Copy value of sig
original := sig
obj.Signatures[i].header = sig.Header
obj.Signatures[i].original = &original
}
return obj, nil
}
// parseSignedCompact parses a message in compact format.
func parseSignedCompact(input string) (*JsonWebSignature, error) {
parts := strings.Split(input, ".")
if len(parts) != 3 {
return nil, fmt.Errorf("square/go-jose: compact JWS format must have three parts")
}
rawProtected, err := base64URLDecode(parts[0])
if err != nil {
return nil, err
}
payload, err := base64URLDecode(parts[1])
if err != nil {
return nil, err
}
signature, err := base64URLDecode(parts[2])
if err != nil {
return nil, err
}
raw := &rawJsonWebSignature{
Payload: newBuffer(payload),
Protected: newBuffer(rawProtected),
Signature: newBuffer(signature),
}
return raw.sanitized()
}
// CompactSerialize serializes an object using the compact serialization format.
func (obj JsonWebSignature) CompactSerialize() (string, error) {
if len(obj.Signatures) != 1 || obj.Signatures[0].header != nil || obj.Signatures[0].protected == nil {
return "", ErrNotSupported
}
serializedProtected := mustSerializeJSON(obj.Signatures[0].protected)
return fmt.Sprintf(
"%s.%s.%s",
base64URLEncode(serializedProtected),
base64URLEncode(obj.payload),
base64URLEncode(obj.Signatures[0].Signature)), nil
}
// FullSerialize serializes an object using the full JSON serialization format.
func (obj JsonWebSignature) FullSerialize() string {
raw := rawJsonWebSignature{
Payload: newBuffer(obj.payload),
}
if len(obj.Signatures) == 1 {
if obj.Signatures[0].protected != nil {
serializedProtected := mustSerializeJSON(obj.Signatures[0].protected)
raw.Protected = newBuffer(serializedProtected)
}
raw.Header = obj.Signatures[0].header
raw.Signature = newBuffer(obj.Signatures[0].Signature)
} else {
raw.Signatures = make([]rawSignatureInfo, len(obj.Signatures))
for i, signature := range obj.Signatures {
raw.Signatures[i] = rawSignatureInfo{
Header: signature.header,
Signature: newBuffer(signature.Signature),
}
if signature.protected != nil {
raw.Signatures[i].Protected = newBuffer(mustSerializeJSON(signature.protected))
}
}
}
return string(mustSerializeJSON(raw))
}