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package sigstore
import (
"crypto"
"crypto/ecdsa"
"crypto/ed25519"
"crypto/rsa"
"crypto/x509"
"encoding/pem"
"errors"
"fmt"
"github.com/secure-systems-lab/go-securesystemslib/encrypted"
"github.com/sigstore/sigstore/pkg/cryptoutils"
"github.com/sigstore/sigstore/pkg/signature"
)
// The following code was copied from github.com/sigstore.
// FIXME: Eliminate that duplication.
// Copyright 2021 The Sigstore Authors.
// 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.
const (
// from sigstore/cosign/pkg/cosign.CosignPrivateKeyPemType.
cosignPrivateKeyPemType = "ENCRYPTED COSIGN PRIVATE KEY"
// from sigstore/cosign/pkg/cosign.SigstorePrivateKeyPemType.
sigstorePrivateKeyPemType = "ENCRYPTED SIGSTORE PRIVATE KEY"
)
// from sigstore/cosign/pkg/cosign.loadPrivateKey
// FIXME: Do we need all of these key formats?
func loadPrivateKey(key []byte, pass []byte) (signature.SignerVerifier, error) {
// Decrypt first
p, _ := pem.Decode(key)
if p == nil {
return nil, errors.New("invalid pem block")
}
if p.Type != sigstorePrivateKeyPemType && p.Type != cosignPrivateKeyPemType {
return nil, fmt.Errorf("unsupported pem type: %s", p.Type)
}
x509Encoded, err := encrypted.Decrypt(p.Bytes, pass)
if err != nil {
return nil, fmt.Errorf("decrypt: %w", err)
}
pk, err := x509.ParsePKCS8PrivateKey(x509Encoded)
if err != nil {
return nil, fmt.Errorf("parsing private key: %w", err)
}
switch pk := pk.(type) {
case *rsa.PrivateKey:
return signature.LoadRSAPKCS1v15SignerVerifier(pk, crypto.SHA256)
case *ecdsa.PrivateKey:
return signature.LoadECDSASignerVerifier(pk, crypto.SHA256)
case ed25519.PrivateKey:
return signature.LoadED25519SignerVerifier(pk)
default:
return nil, errors.New("unsupported key type")
}
}
// simplified from sigstore/cosign/pkg/cosign.marshalKeyPair
// loadPrivateKey always requires a encryption, so this always requires a passphrase.
func marshalKeyPair(privateKey crypto.PrivateKey, publicKey crypto.PublicKey, password []byte) (_privateKey []byte, _publicKey []byte, err error) {
x509Encoded, err := x509.MarshalPKCS8PrivateKey(privateKey)
if err != nil {
return nil, nil, fmt.Errorf("x509 encoding private key: %w", err)
}
encBytes, err := encrypted.Encrypt(x509Encoded, password)
if err != nil {
return nil, nil, err
}
// store in PEM format
privBytes := pem.EncodeToMemory(&pem.Block{
Bytes: encBytes,
// Use the older “COSIGN” type name; as of 2023-03-30 cosign’s main branch generates “SIGSTORE” types,
// but a version of cosign that can accept them has not yet been released.
Type: cosignPrivateKeyPemType,
})
// Now do the public key
pubBytes, err := cryptoutils.MarshalPublicKeyToPEM(publicKey)
if err != nil {
return nil, nil, err
}
return privBytes, pubBytes, nil
}
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