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

1.16.5

Does this issue reproduce with the latest release?

Not sure

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

GO111MODULE="on"
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/mustafa/.cache/go-build"
GOENV="/home/mustafa/.config/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/mustafa/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/mustafa/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="go1.16.5"
GCCGO="gccgo"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD=""
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-build3209265659=/tmp/go-build -gno-record-gcc-switches"

What did you do?

I want to encrypt and sign messages using Encrypt method with compression enabled

encryptedTextBuffer := new(bytes.Buffer)
encryptor, err := openpgp.Encrypt(encryptedTextBuffer, publicKeyRing, privateKeyRing[0], nil, &packet.Config{
	DefaultCipher:          packet.CipherAES256,
	DefaultHash:            crypto.SHA256,
	DefaultCompressionAlgo: packet.CompressionZIP,
	CompressionConfig:      &packet.CompressionConfig{Level: 9},
})
if err != nil {
        return "", err
}

But the PGP message is not compressed, I found that Encrypt method don't have compression in place

func Encrypt(ciphertext io.Writer, to []*Entity, signed *Entity, hints *FileHints, config *packet.Config) (plaintext io.WriteCloser, err error) {
	...

	payload, err := packet.SerializeSymmetricallyEncrypted(ciphertext, cipher, symKey, config)
	if err != nil {
		return
	}

	literaldata := payload
	if algo := config.Compression(); algo != packet.CompressionNone {
		var compConfig *packet.CompressionConfig
		if config != nil {
			compConfig = config.CompressionConfig
		}
		literaldata, err = packet.SerializeCompressed(payload, algo, compConfig)
		if err != nil {
			return
		}
	}

	return writeAndSign(literaldata, candidateHashes, signed, hints, config)
}

I think need to add compression before calling writeAndSign method, can I make a pull request to fix this problem?

What did you expect to see?

Compressed encrypted and signed PGP message

What did you see instead?

Encrypted and signed but not compressed PGP message