mirror of
https://github.com/edgelesssys/constellation.git
synced 2024-09-19 15:56:03 +00:00
95 lines
2.5 KiB
Go
95 lines
2.5 KiB
Go
/*
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Copyright (c) Edgeless Systems GmbH
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SPDX-License-Identifier: AGPL-3.0-only
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*/
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package sigstore
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import (
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"bytes"
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"crypto"
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"crypto/ecdsa"
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"crypto/ed25519"
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"crypto/rsa"
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"crypto/x509"
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"encoding/base64"
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"encoding/pem"
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"errors"
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"fmt"
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"github.com/secure-systems-lab/go-securesystemslib/encrypted"
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"github.com/sigstore/sigstore/pkg/signature"
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)
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const (
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cosignPrivateKeyPemType = "ENCRYPTED COSIGN PRIVATE KEY"
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sigstorePrivateKeyPemType = "ENCRYPTED SIGSTORE PRIVATE KEY"
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)
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// Signer is used to sign the version file. Used for unit testing.
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type Signer interface {
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Sign(content []byte) (res []byte, err error)
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}
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// NewSigner returns a new Signer.
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func NewSigner(cosignPwd, privKey []byte) Signer {
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return signer{cosignPwd: cosignPwd, privKey: privKey}
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}
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type signer struct {
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cosignPwd []byte // used to decrypt the cosign private key
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privKey []byte // used to sign
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}
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func (s signer) Sign(content []byte) (signature []byte, err error) {
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signature, err = SignContent(s.cosignPwd, s.privKey, content)
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if err != nil {
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return signature, fmt.Errorf("sign version file: %w", err)
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}
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return
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}
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// SignContent signs the content with the cosign encrypted private key and corresponding cosign password.
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func SignContent(password, encryptedPrivateKey, content []byte) ([]byte, error) {
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sv, err := loadPrivateKey(encryptedPrivateKey, password)
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if err != nil {
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return nil, fmt.Errorf("loading private key: %w", err)
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}
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sig, err := sv.SignMessage(bytes.NewReader(content))
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if err != nil {
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return nil, fmt.Errorf("signing message: %w", err)
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}
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return []byte(base64.StdEncoding.EncodeToString(sig)), nil
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}
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func loadPrivateKey(key []byte, pass []byte) (signature.SignerVerifier, error) {
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// Decrypt first
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p, _ := pem.Decode(key)
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if p == nil {
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return nil, errors.New("invalid pem block")
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}
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if p.Type != cosignPrivateKeyPemType && p.Type != sigstorePrivateKeyPemType {
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return nil, fmt.Errorf("unsupported pem type: %s", p.Type)
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}
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x509Encoded, err := encrypted.Decrypt(p.Bytes, pass)
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if err != nil {
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return nil, fmt.Errorf("decrypt: %w", err)
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}
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pk, err := x509.ParsePKCS8PrivateKey(x509Encoded)
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if err != nil {
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return nil, fmt.Errorf("parsing private key: %w", err)
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}
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switch pk := pk.(type) {
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case *rsa.PrivateKey:
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return signature.LoadRSAPKCS1v15SignerVerifier(pk, crypto.SHA256)
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case *ecdsa.PrivateKey:
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return signature.LoadECDSASignerVerifier(pk, crypto.SHA256)
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case ed25519.PrivateKey:
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return signature.LoadED25519SignerVerifier(pk)
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default:
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return nil, errors.New("unsupported key type")
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}
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}
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