test-encrypt-20151113.go

package main

import (
	"bytes"
	"encoding/hex"
	"errors"
	"fmt"
	"golang.org/x/crypto/openpgp"
	"io"
	"io/ioutil"
	"time"
)

func SymEncrypt(content, password []byte) ([]byte, error) {
	var byteWriter bytes.Buffer
	var err error
	var output io.WriteCloser
	var ret []byte
	var hints openpgp.FileHints
	hints.IsBinary = true
	hints.ModTime = time.Now()
	output, err = openpgp.SymmetricallyEncrypt(&byteWriter, password, &hints, nil)
	if err != nil {
		return nil, err
	}
	output.Write(content)
	output.Close()
	ret = byteWriter.Bytes()

	return ret, nil
}

func SymDecrypt(content, password []byte) ([]byte, error) {
	var err error
	var byteReader io.Reader
	var messageDetails *openpgp.MessageDetails
	var ret []byte
	byteReader = bytes.NewReader(content)
	fmt.Printf("openpgp.ReadMessage BEGIN\n")
	messageDetails, err = openpgp.ReadMessage(byteReader, nil,
		func(keys []openpgp.Key, symmetric bool) ([]byte, error) {
			return password, nil
		}, nil)
	fmt.Printf("openpgp.ReadMessage END\n")
	if err != nil {
		return nil, err
	}

	if !messageDetails.IsEncrypted {
		return nil, errors.New("PGP content was not encrypted")
	}
	ret, err = ioutil.ReadAll(messageDetails.UnverifiedBody)

	return ret, err
}

func main() {
	content := []byte("foo bar")
	password := []byte("0123456789abcdefgh")
	var encrypted []byte
	var decrypted []byte
	var err error
	fmt.Printf("Encrypting %s/%s\n", string(content), string(password))
	encrypted, err = SymEncrypt(content, password)
	if err == nil {
		// at this stage, we have some encrypted content

		fmt.Printf("encrypted content=\"%s\" encrypted=\"%s\"\n",
			string(content),
			hex.EncodeToString(encrypted))

		// 1st test, check encrypt/decrypt work in nominal case
		fmt.Printf("good pw BEGIN\n")
		decrypted, err =
			SymDecrypt(encrypted, password)
		fmt.Printf("bad pw BEGIN\n")
		if err == nil {
			fmt.Printf("decrypted encrypted=\"%s\" decrypted=\"%s\"\n",
				hex.EncodeToString(encrypted),
				string(decrypted))
			if string(content) != string(decrypted) {
				fmt.Errorf("Content and decrypted differ\n")
			}
		} else {
			fmt.Errorf("%s\n", err)
		}

		// 2nd test, check encrypt/decrypt work as expected
		// when password is wrong, that is, decrypt ends with
		// an error, and does not decrypt the content
		fmt.Printf("bad pw BEGIN\n")
		decrypted, err =SymDecrypt(encrypted,[]byte("this is a wrong password\n"))
		fmt.Printf("bad pw END\n")
		if err != nil {
			fmt.Printf("OK, decrypt is impossible with a bad password\n")
		} else {
			fmt.Errorf("decrypt is possible with a bad password, this *should* be impossible\n")
		}
	} else {
		fmt.Errorf("%s\n", err)
	}

}