keyctl/pgp

A "helper" package for use with the golang.org/x/crypto/openpgp package which can transparently cache private key passphrases using the linux kernel's secure keyring system. Such cached passphrases can automatically expire after a configurable duration.

Usage

To use, simply import the parent pkg keyctl, open the user session keyring, embed it in a static pgp.PassphraseKeyring struct and call ReadMessage on this struct instead of using goglang.org/x/crypto/openpgp.ReadMessage. To customize the passphrase prompt, either assign your own pgp.Prompter compatible interface to PassphraseKeyring or pass in an openpgp.PromptFunction in the ReadMessage() method call.

For convenience, an openpgp.PromptFunction compatible func named PassphrasePrompt is exposed in the package.

Example

package main

import (
  "io"
  "log"
  "golang.org/x/crypto/openpgp"
  "github.com/cobraqxx/keyctl"
  "github.com/cobraqxx/keyctl/pgp"
)

func decryptReader(r io.Reader, pgpKeyring openpgp.KeyRing) {
  kr, err := keyctl.UserSessionKeyring()
  if err != nil {
    log.Fatal(err)
  }
  
  pkr := pgp.PassphraseKeyring{Keyring:kr}
  // Discard passphrases after 10 minutes
  pkr.SetDefaultTimeout(600)

  msgDetails, err := pkr.ReadMessage(r, pgpKeyring, pgp.PassphrasePrompt, nil)
  if err != nil {
    log.Fatal(err)
  }
  log.Printf("%#v\n", msgDetails)
}