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x/crypto/openpgp: Support non detached sign #20545

tsl0922 opened this issue Jun 1, 2017 · 1 comment

x/crypto/openpgp: Support non detached sign #20545

tsl0922 opened this issue Jun 1, 2017 · 1 comment


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@tsl0922 tsl0922 commented Jun 1, 2017

Hi, I'm looking for an alternative to gpg -s, but it seems no api can be used directly.

I've implemented a Sign function for this, but it requires some private structures from the openpgp package which I don't want to copy outside. It would be nice if this can be provided by the library.

// Sign acts like gpg -s: it makes a signature with the private key (which must
// already have been decrypted) from signer and writes the signature with the
// original data to w.
// The resulting WriteCloser must be closed after the contents of the file have
// been written.
// If config is nil, sensible defaults will be used.
func Sign(w io.Writer, signer *openpgp.Entity, hints *openpgp.FileHints, config *packet.Config) (plaintext io.WriteCloser, err error) {
	if signer.PrivateKey == nil {
		return nil, errors.InvalidArgumentError("signing key doesn't have a private key")
	if signer.PrivateKey.Encrypted {
		return nil, errors.InvalidArgumentError("signing key is encrypted")

	hashType := config.Hash()
	ops := &packet.OnePassSignature{
		SigType:    packet.SigTypeBinary,
		Hash:       hashType,
		PubKeyAlgo: signer.PrivateKey.PubKeyAlgo,
		KeyId:      signer.PrivateKey.KeyId,
		IsLast:     true,
	if err := ops.Serialize(w); err != nil {
		return nil, err

	if hints == nil {
		hints = &openpgp.FileHints{}

	var epochSeconds uint32
	if !hints.ModTime.IsZero() {
		epochSeconds = uint32(hints.ModTime.Unix())

	encryptedData := noOpCloser{w: w}
	literalData, err := packet.SerializeLiteral(encryptedData, hints.IsBinary, hints.FileName, epochSeconds)
	if err != nil {
		return nil, err

	return signatureWriter{encryptedData, literalData, hashType, hashType.New(), signer.PrivateKey, config}, nil

The signatureWriter and noOpCloser is private in the openpgp package.

@gopherbot gopherbot added this to the Unreleased milestone Jun 1, 2017
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@FiloSottile FiloSottile commented Mar 29, 2021

Per the accepted #44226 proposal and due to lack of maintenance, the package is now frozen and deprecated. No new changes will be accepted except for security fixes. The package will not be removed.

If this is a security issue, please email and we will assess it and provide a fix.

If you're looking for alternatives, consider the crypto/ed25519 package for simple signatures, for inline signatures, or for encryption. You can read a summary of OpenPGP issues and alternatives here.

If you are required to interoperate with OpenPGP systems and need a maintained package, we suggest considering one of multiple community forks of We don't endorse any specific one.

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