//go:build pkcs11

// Copyright 2017 Google LLC. All Rights Reserved.
//
// 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 pkcs11 provides access to private keys using a PKCS#11 interface.
package pkcs11

import (
	"crypto"
	"crypto/x509"
	"encoding/pem"
	"errors"
	"fmt"

	"github.com/google/trillian/crypto/keyspb"

	pkcs11key "github.com/letsencrypt/pkcs11key/v4"
)

// FromConfig returns a crypto.Signer that uses a PKCS#11 interface.
func FromConfig(modulePath string, config *keyspb.PKCS11Config) (crypto.Signer, error) {
	if modulePath == "" {
		return nil, errors.New("pkcs11: No module path")
	}

	pubKeyPEM := config.GetPublicKey()
	block, rest := pem.Decode([]byte(pubKeyPEM))
	if len(rest) > 0 {
		return nil, fmt.Errorf("pkcs11: extra data found after first PEM block from %q", pubKeyPEM)
	}

	pubKey, err := x509.ParsePKIXPublicKey(block.Bytes)
	if err != nil {
		return nil, fmt.Errorf("pkcs11: error loading public key from %q: %v", pubKeyPEM, err)
	}

	return pkcs11key.New(modulePath, config.GetTokenLabel(), config.GetPin(), pubKey)
}