Command line to convert a private OpenPGP key in its representation in armor.

openpgp_armored.go

package main

import (
	"flag"
	"fmt"
	"io"
	"log"
	"os"

	"golang.org/x/crypto/openpgp"
	"golang.org/x/crypto/openpgp/armor"
)

func openPGPArmored(filename string) error {
	if filename == "" {
		return io.EOF
	}
	f, err := os.Open(filename)
	if err != nil {
		return err
	}
	defer func() { _ = f.Close() }()

	w, err := armor.Encode(os.Stdout, openpgp.PrivateKeyType, nil)
	if err != nil {
		return fmt.Errorf("openpgp: begin armor: %s", err)
	}
	defer func() { _ = w.Close() }()

	b, err := io.ReadAll(f)
	if err != nil {
		return fmt.Errorf("openpgp: key file: %s", err)
	}
	_, err = w.Write(b)
	if err != nil {
		return fmt.Errorf("openpgp: writing key: %s", err)
	}
	return nil
}

func main() {
	flag.Parse()

	err := openPGPArmored(flag.Arg(0))
	if err != nil {
		log.Fatalln(err.Error())
	}
	os.Exit(0)
}