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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 providers
import (
"context"
"crypto"
"crypto/rsa"
"encoding/json"
"fmt"
"github.com/lestrrat-go/jwx/v2/jwk"
"github.com/lestrrat-go/jwx/v2/jws"
"github.com/openpubkey/openpubkey/gq"
"github.com/openpubkey/openpubkey/util"
)
func CreateGQToken(ctx context.Context, idToken []byte, op OpenIdProvider) ([]byte, error) {
return createGQTokenAllParams(ctx, idToken, op, "", false)
}
func CreateGQBoundToken(ctx context.Context, idToken []byte, op OpenIdProvider, cicHash string) ([]byte, error) {
return createGQTokenAllParams(ctx, idToken, op, cicHash, true)
}
func createGQTokenAllParams(ctx context.Context, idToken []byte, op OpenIdProvider, cicHash string, gqCommitment bool) ([]byte, error) {
if cicHash != "" && !gqCommitment {
// If gqCommitment is false, we will ignore the cicHash. This is a
// misconfiguration, and we should fail because the caller is likely
// expecting the cicHash to be included in the token.
return nil, fmt.Errorf("misconfiguration, cicHash is set but gqCommitment is false, set gqCommitment to true to include cicHash in the gq signature")
}
headersB64, _, _, err := jws.SplitCompact(idToken)
if err != nil {
return nil, fmt.Errorf("error splitting compact ID Token: %w", err)
}
// TODO: We should create a util function for extracting headers from tokens
headersJson, err := util.Base64DecodeForJWT(headersB64)
if err != nil {
return nil, fmt.Errorf("error base64 decoding ID Token headers: %w", err)
}
headers := jws.NewHeaders()
err = json.Unmarshal(headersJson, &headers)
if err != nil {
return nil, fmt.Errorf("error unmarshalling ID Token headers: %w", err)
}
if headers.Algorithm() != "RS256" {
return nil, fmt.Errorf("gq signatures require ID Token have signed with an RSA key, ID Token alg was (%s)", headers.Algorithm())
}
opKey, err := op.PublicKeyByToken(ctx, idToken)
if err != nil {
return nil, err
}
if opKey.Alg != "RS256" {
return nil, fmt.Errorf("gq signatures require original provider to have signed with an RSA key, jWK.alg was (%s)", opKey.Alg)
}
rsaKey, ok := opKey.PublicKey.(*rsa.PublicKey)
if !ok {
return nil, fmt.Errorf("gq signatures require original provider to have signed with an RSA key")
}
jktB64, err := createJkt(rsaKey)
if err != nil {
return nil, err
}
if cicHash == "" {
return gq.GQ256SignJWT(rsaKey, idToken, gq.WithExtraClaim("jkt", jktB64))
} else {
return gq.GQ256SignJWT(rsaKey, idToken, gq.WithExtraClaim("jkt", jktB64), gq.WithExtraClaim("cic", cicHash))
}
}
func createJkt(publicKey crypto.PublicKey) (string, error) {
jwkKey, err := jwk.PublicKeyOf(publicKey)
if err != nil {
return "", err
}
thumbprint, err := jwkKey.Thumbprint(crypto.SHA256)
if err != nil {
return "", err
}
return string(util.Base64EncodeForJWT(thumbprint)), nil
}
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