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// Copyright 2024 OpenPubkey
//
// 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.
//
// SPDX-License-Identifier: Apache-2.0
package oidc
import (
"fmt"
)
type Jws struct {
Payload string `json:"payload"` // Base64 encoded
Signatures []Signature `json:"signatures"` // Base64 encoded
}
type SigOptStruct struct {
PublicHeader map[string]any
}
type SigOpts func(a *SigOptStruct)
// WithPublicHeader species that a public header be included in the
// signature. Public headers aren't Base64 encoded because they aren't signed.
// Example use: WithPublicHeader(map[string]any{"key1": "abc", "key2": "def"})
func WithPublicHeader(publicHeader map[string]any) SigOpts {
return func(o *SigOptStruct) {
o.PublicHeader = publicHeader
}
}
func (j *Jws) AddSignature(token []byte, opts ...SigOpts) error {
sigOpts := &SigOptStruct{}
for _, applyOpt := range opts {
applyOpt(sigOpts)
}
protected, payload, signature, err := SplitCompact(token)
if err != nil {
return err
}
if j.Payload != string(payload) {
return fmt.Errorf("payload in compact token does not match existing payload in jws, expected=(%s), got=(%s)",
string(j.Payload),
string(payload))
}
sig := Signature{
Protected: string(protected),
Public: sigOpts.PublicHeader,
Signature: string(signature),
}
if j.Signatures == nil {
j.Signatures = []Signature{}
}
j.Signatures = append(j.Signatures, sig)
return nil
}
func (j *Jws) GetToken(i int) ([]byte, error) {
if i < len(j.Signatures) && i >= 0 {
return []byte(j.Signatures[i].Protected + "." + j.Payload + "." + j.Signatures[i].Signature), nil
} else {
return nil, fmt.Errorf("no signature at index i (%d), len(signatures) (%d)", i, len(j.Signatures))
}
}
func (j *Jws) GetTokenByTyp(typ string) ([]byte, error) {
matchingTokens := []Signature{}
for _, v := range j.Signatures {
if typFound, err := v.GetTyp(); err != nil {
return nil, err
} else {
// Both the JWS standard and the OIDC standard states that typ is case sensitive
// so we treat it as case sensitive as well
//
// "The typ (type) header parameter is used to declare the type of the
// signed content. The typ value is case sensitive."
// https://openid.net/specs/draft-jones-json-web-signature-04.html#ReservedHeaderParameterName
//
// "The "typ" (type) Header Parameter is used by JWS applications to
// declare the media type [IANA.MediaTypes] of this complete JWS.
// [..] Per RFC 2045 [RFC2045], all media type values, subtype values, and
// parameter names are case insensitive. However, parameter values are case
// sensitive unless otherwise specified for the specific parameter."
// https://datatracker.ietf.org/doc/html/rfc7515#section-4.1.9
if typFound == typ {
matchingTokens = append(matchingTokens, v)
}
}
}
if len(matchingTokens) > 1 {
// Currently we only have one token per token typ. We can change this later
// for COS tokens. This check prevents hidden tokens, where one token of
// the same typ hides another token of the same typ.
return nil, fmt.Errorf("more than one token found, all current token typs are unique")
} else if len(matchingTokens) == 0 {
// if typ not found return nil
return nil, nil
} else {
return []byte(matchingTokens[0].Protected + "." + j.Payload + "." + matchingTokens[0].Signature), nil
}
}
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