x/crypto/openpgp: ReadMessage never returns an error if decryption failed

[xqianwang]

Please answer these questions before submitting your issue. Thanks!

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

1.10.2

Does this issue reproduce with the latest release?

I don't know

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

set GOARCH=amd64
set GOBIN=
set GOCACHE=C:\Users\xqian\AppData\Local\go-build
set GOEXE=.exe
set GOHOSTARCH=amd64
set GOHOSTOS=windows
set GOOS=windows
set GOPATH=******
set GORACE=
set GOROOT=C:\Go
set GOTMPDIR=
set GOTOOLDIR=C:\Go\pkg\tool\windows_amd64
set GCCGO=gccgo
set CC=gcc
set CXX=g++
set CGO_ENABLED=1
set CGO_CFLAGS=-g -O2
set CGO_CPPFLAGS=
set CGO_CXXFLAGS=-g -O2
set CGO_FFLAGS=-g -O2
set CGO_LDFLAGS=-g -O2
set PKG_CONFIG=pkg-config
set GOGCCFLAGS=-m64 -mthreads -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=C:\Users******\AppData\Local\Temp\go-build060555462=/tmp/go-build -gno-record-gcc-switches

What did you do?

func (o *OpenpgpEntity) decryptFile(file *BankFile, entityList openpgp.EntityList, passphrase []byte, testEnv bool) (bankFile *BankFile, err error) {
	zipFile := NewBankFile()
	zipFile.Path = file.DstPath
	zipFile.DstPath = file.DstPath
	fs := strings.Split(file.Filename, ".")
	zipFile.Filename = fs[0]
	nf := filepath.Join(zipFile.Path, zipFile.Filename)
	w, err := os.Create(nf)
	if err != nil {
		return nil, fmt.Errorf("Failed to create new file %s, Error: %s", nf, err)
	}

	fr, err := os.Open(filepath.Join(file.DstPath, file.Filename))
	if err != nil {
		return nil, err
	}
	defer func() {
		if err = fr.Close(); err != nil {
			log.Panicln(err)
		}
	}()

	block, err := armor.Decode(fr)
	if err != nil {
		return nil, fmt.Errorf("Failed to decode, error: %s", err)
	}
	if testEnv == true {
		if block.Type != "Message" {
			return nil, errors.New("Invalid message type")
		}
	} else {
		if block.Type != "PGP MESSAGE" {
			return nil, errors.New("Invalid message type")
		}
	}

	prompt := func(keys []openpgp.Key, symmetric bool) ([]byte, error) {
		if symmetric {
			return nil, errors.New("prompt: message was marked as symmetrically encrypted")
		}

		if len(keys) == 0 {
			return nil, errors.New("prompt: no keys requested")
		}

		err = keys[0].PrivateKey.Decrypt(passphrase)
		if err != nil {
			return nil, fmt.Errorf("prompt: error decrypting key, error: %s", err)
		}

		return nil, nil
	}

	md, err := openpgp.ReadMessage(block.Body, entityList, prompt, getConfig())
	if err != nil || md == nil {
		return nil, errors.New("Failed to read content")
	}
	n, err := io.Copy(w, md.UnverifiedBody)
	if err != nil || n == 0 {
		return nil, errors.New("Failed to write to zip file")
	}
	if err = w.Close(); err != nil {
		log.Panicln(err)
	}
	zipFile.Filesize = int64(n)
	return zipFile, nil
}

What did you expect to see?

returned file point should not be nil, if it is nil, there should be some error returned when doing decruption

What did you see instead?

returned file pointer is nil and there was no error before that