go: x/crypto/openpgp: cannot encrypt a message to key id 83378a94fa6c4994 because it has no encryption keys

What version of Go are you using (go version)?

go version go1.10.2 linux/amd64

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

GOARCH=“amd64” GOBIN=“” GOCACHE=“/home/rbt/.cache/go-build” GOEXE=“” GOHOSTARCH=“amd64” GOHOSTOS=“linux” GOOS=“linux” GOPATH=“/home/rbt/go” GORACE=“” GOROOT=“/home/rbt/go1.10” GOTMPDIR=“” GOTOOLDIR=“/home/rbt/go1.10/pkg/tool/linux_amd64” GCCGO=“gccgo” CC=“gcc” CXX=“g++” CGO_ENABLED=“1” CGO_CFLAGS=“-g -O2” CGO_CPPFLAGS=“” CGO_CXXFLAGS=“-g -O2” CGO_FFLAGS=“-g -O2” CGO_LDFLAGS=“-g -O2” PKG_CONFIG=“pkg-config” GOGCCFLAGS=“-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build778390304=/tmp/go-build -gno-record-gcc-switches”

What did you do?

I ran this program that I wrote. It encrypts a file to PGP keys, but some keys fail with the error below even though they are valid and have encryption sub-keys.

If possible, provide a recipe for reproducing the error.

import (
	"io"
	"io/ioutil"
	"log"
	"os"
	"os/user"
	"path/filepath"

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

func main() {
	filePath := os.Args[1]

	usr, err := user.Current()
	if err != nil {
		log.Fatal(err)
	}

	// Read Public Key files from /home/user/keys
	// These keys **are not** ascii armored
	// gpg --export 83378a94fa6c4994 > /home/rbt/keys/phil.pub.key
	keyFiles, err := ioutil.ReadDir(usr.HomeDir + "/keys/")
	if err != nil {
		log.Fatal(err)
	}

	entities := []*openpgp.Entity{}

	for _, keyFile := range keyFiles {
		log.Print("Using key file: " + usr.HomeDir + "/keys/" + keyFile.Name())
		kf, err := os.Open(usr.HomeDir + "/keys/" + keyFile.Name())
		if err != nil {
			log.Fatalf("Open pub.key %s\n", err)
		}
		defer kf.Close()

		keyReader := packet.NewReader(kf)
		theEntity, err := openpgp.ReadEntity(keyReader)
		if err != nil {
			log.Fatalf("ReadEntity %s\n", err)
		}

		entities = append(entities, theEntity)
	}

	hints := &openpgp.FileHints{
		IsBinary: true,
	}

	for _, entity := range entities {
		log.Printf("Encrypting to Key FP: %X", entity.PrimaryKey.Fingerprint)
	}

	efilePath := "/tmp/" + filepath.Base(filePath) + ".gpg"
	out, err := os.Create(efilePath)
	if err != nil {
		log.Fatal(err)
	}
	defer out.Close()

	packetConfig := &packet.Config{
		DefaultCipher: packet.CipherAES256,
	}

	wc, err := openpgp.Encrypt(out, entities, nil, hints, packetConfig)
	if err != nil {
		log.Fatal(err)
	}
	defer wc.Close()

	plainTextFile, err := os.Open(filePath)
	if err != nil {
		log.Fatal(err)
	}
	defer plainTextFile.Close()

	buf := make([]byte, 64*1024)
	n, err := io.CopyBuffer(wc, plainTextFile, buf)
	if err != nil {
		log.Fatal(err)
	}
	log.Printf("%d bytes read into wc.\n", n)

	plainTextFile.Close()
	wc.Close()
	out.Close()
}

What did you expect to see?

I expected the file to be encrypted. The key is valid and has an encryption sub-key. And, many other keys work just fine, but several do not.

2018/07/19 09:45:19 Using key file: /home/rbt/keys/brad.pub.key 2018/07/19 09:45:19 Using key file: /home/rbt/keys/itso.pub.key 2018/07/19 09:45:19 Using key file: /home/rbt/keys/jeff.pub.key 2018/07/19 09:45:19 Using key file: /home/rbt/keys/phil.pub.key 2018/07/19 09:45:19 Using key file: /home/rbt/keys/tester.pub.key 2018/07/19 09:45:19 Encrypting to Key FP: 83CBAF6B683329125FE436CCE915EE8B2FE6EC56 2018/07/19 09:45:19 Encrypting to Key FP: F3D2F6714EF6B251BDFF18947279C76A0FAC6413 2018/07/19 09:45:19 Encrypting to Key FP: 4952772637B2B44012070E47B87FE76E05BAA569 2018/07/19 09:45:19 Encrypting to Key FP: 5CD5EFA3E1C520B1B0EDE38C83378A94FA6C4994 2018/07/19 09:45:19 Encrypting to Key FP: E2958B99360A0F93AD440FD01E7854496A3E0199 2018/07/19 09:45:19 openpgp: invalid argument: cannot encrypt a message to key id 83378a94fa6c4994 because it has no encryption keys

What did you see instead?

openpgp: invalid argument: cannot encrypt a message to key id 83378a94fa6c4994 because it has no encryption keys

Get the key that causes the error

This is a public key on public key servers. You can download it and re-create the issue.

gpg --recv-key 83378a94fa6c4994
gpg: key 83378A94FA6C4994: 171 signatures not checked due to missing keys
gpg: key 83378A94FA6C4994: 1 bad signature
gpg: key 83378A94FA6C4994: "Phillip E Benchoff <benchoff@n3pb.org>" not changed
gpg: Total number processed: 1
gpg:              unchanged: 1