helper.go

// Copyright © 2017 Aeneas Rekkas <aeneas+oss@aeneas.io>
//
// 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 jwk

import (
	"crypto/ecdsa"
	"crypto/rsa"
	"crypto/x509"
	"encoding/pem"

	"github.com/pkg/errors"
	"github.com/square/go-jose"
)

func First(keys []jose.JSONWebKey) *jose.JSONWebKey {
	if len(keys) == 0 {
		return nil
	}
	return &keys[0]
}

func PEMBlockForKey(key interface{}) (*pem.Block, error) {
	switch k := key.(type) {
	case *rsa.PrivateKey:
		return &pem.Block{Type: "RSA PRIVATE KEY", Bytes: x509.MarshalPKCS1PrivateKey(k)}, nil
	case *ecdsa.PrivateKey:
		b, err := x509.MarshalECPrivateKey(k)
		if err != nil {
			return nil, errors.WithStack(err)
		}
		return &pem.Block{Type: "EC PRIVATE KEY", Bytes: b}, nil
	default:
		return nil, errors.New("Invalid key type")
	}
}