Java 字符串的 PGP 加密

Question

I have a requirement to encrypt a java string (which is part of a JSON file) using PGP encryption. I tried out quite a lot of examples which I could mine out from Google searches. All of these examples were making use of bouncycastle openpgp methods, which are deprecated. Below is the code I used:

import java.io.BufferedReader;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.security.NoSuchProviderException;
import java.security.SecureRandom;
import java.security.Security;
import org.bouncycastle.bcpg.ArmoredOutputStream;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.openpgp.PGPCompressedDataGenerator;
import org.bouncycastle.openpgp.PGPEncryptedDataGenerator;
import org.bouncycastle.openpgp.PGPException;
import org.bouncycastle.openpgp.PGPLiteralData;
import org.bouncycastle.openpgp.PGPPublicKey;
import org.bouncycastle.openpgp.PGPPublicKeyRing;
import org.bouncycastle.openpgp.PGPUtil;


public class BouncyCastlePGPTest {

    public static void main(String[] args) {

        // the keyring that holds the public key we're encrypting with
        String publicKeyFilePath = "C:\\pgp6.5.8\\pubring.pkr";

        // init the security provider
        Security.addProvider(new BouncyCastleProvider());

        try {

            System.out.println("Creating a temp file...");

            // create a file and write the string to it
            File outputfile = File.createTempFile("pgp", null);
            FileWriter writer = new FileWriter(outputfile);
            writer.write("the message I want to encrypt".toCharArray());
            writer.close();

            System.out.println("Temp file created at ");
            System.out.println(outputfile.getAbsolutePath());
            System.out.println("Reading the temp file to make sure that the bits were written\n----------------------------");

            BufferedReader isr = new BufferedReader(new FileReader(outputfile));
            String line = "";
            while ((line = isr.readLine()) != null) {
                System.out.println(line + "\n");
            }

            // read the key 
            FileInputStream in = new FileInputStream(publicKeyFilePath);
            PGPPublicKey key = readPublicKey(in);

            // find out a little about the keys in the public key ring
            System.out.println("Key Strength = " + key.getBitStrength());
            System.out.println("Algorithm = " + key.getAlgorithm());

            int count = 0;
            for (java.util.Iterator iterator = key.getUserIDs(); iterator.hasNext();) {
                count++;
                System.out.println((String)iterator.next());    
            }
            System.out.println("Key Count = " + count);
            // create an armored ascii file
            FileOutputStream out = new FileOutputStream(outputfile.getAbsolutePath() + ".asc");

            // encrypt the file
            encryptFile(outputfile.getAbsolutePath(), out, key);

            System.out.println("Reading the encrypted file\n----------------------------");
            BufferedReader isr2 = new BufferedReader(new FileReader(new File(outputfile.getAbsolutePath() + ".asc")));
            String line2 = "";
            while ((line2 = isr2.readLine()) != null) {
                System.out.println(line2);
            }



        } catch (PGPException e) {
            System.out.println(e.toString());
            System.out.println(e.getUnderlyingException().toString());

        } catch (Exception e) {
            System.out.println(e.toString());
        }

    }

    private static PGPPublicKey readPublicKey(InputStream in) throws IOException {
        try {
            PGPPublicKeyRing pgpPub = new PGPPublicKeyRing(in);
            return pgpPub.getPublicKey();
        } catch (IOException io) {
            System.out.println("readPublicKey() threw an IOException");
            System.out.println(io.toString());
            throw io;
        }

    }

    private static void encryptFile(String fileName, OutputStream out, PGPPublicKey encKey)
    throws IOException, NoSuchProviderException, PGPException  
    {

        out = new ArmoredOutputStream(out);

        ByteArrayOutputStream bOut = new ByteArrayOutputStream();

        System.out.println("creating comData...");

        // get the data from the original file 
        PGPCompressedDataGenerator comData = new PGPCompressedDataGenerator(PGPCompressedDataGenerator.ZIP);
        PGPUtil.writeFileToLiteralData(comData.open(bOut), PGPLiteralData.BINARY, new File(fileName));
        comData.close();

        System.out.println("comData created...");

        System.out.println("using PGPEncryptedDataGenerator...");

        // object that encrypts the data
        PGPEncryptedDataGenerator cPk = new PGPEncryptedDataGenerator(PGPEncryptedDataGenerator.CAST5, new SecureRandom(), "BC");
        cPk.addMethod(encKey);

        System.out.println("used PGPEncryptedDataGenerator...");

        // take the outputstream of the original file and turn it into a byte array
        byte[] bytes = bOut.toByteArray();

        System.out.println("wrote bOut to byte array...");

        // write the plain text bytes to the armored outputstream
        OutputStream cOut = cPk.open(out, bytes.length);
        cOut.write(bytes);


        // cOut.close();
        cPk.close();
        out.close();


    }

}

Below is a snapshot of my error log:

BouncyCastlePGPTest.java:96: cannot find symbol                            
symbol  : constructor PGPPublicKeyRing(java.io.InputStream)                
location: class org.bouncycastle.openpgp.PGPPublicKeyRing                  
                        PGPPublicKeyRing pgpPub = new PGPPublicKeyRing(in);
BouncyCastlePGPTest.java:126: cannot find symbol                             
symbol  : constructor PGPEncryptedDataGenerator(int,java.security.SecureRandom,java.lang.String)                                                          
location: class org.bouncycastle.openpgp.PGPEncryptedDataGenerator           
                PGPEncryptedDataGenerator cPk = new PGPEncryptedDataGenerator(PGPEncryptedDataGenerator.CAST5, new SecureRandom(), "BC");                 
                                                ^                            
BouncyCastlePGPTest.java:127: addMethod(org.bouncycastle.openpgp.operator.PGP
KeyEncryptionMethodGenerator) in org.bouncycastle.openpgp.PGPEncryptedDataGen
erator cannot be applied to (org.bouncycastle.openpgp.PGPPublicKey)          
                cPk.addMethod(encKey);                                       
                   ^                    

Can someone point me out to a working sample code which I can use with the latest jars from https://www.bouncycastle.org/latest_releases.html ?

Apart from bouncycastle, are there other alternatives? I'm sure it's a very common use case people would come across. What is being used these days, if not bouncycastle openpgp?

Answer 1

Bouncy Castle is a Java lightweight crypto API and a Java security provider. It also provides separate libraries for specific functionality, mainly CMS (Cryptographic Message Syntax) and PGP (Pretty Good Privacy).

These libraries can be downloaded separately or within the complete crypto- distributions. They are named bcpkix-jdk15on-159.jar and bcpg-jdk15on-159.jar respectively (for version 1.59). You need to include those libraries in your classpath or your Maven setup to perform the compilation.

You can actually leave out the Bouncy Castle provider bcprov-... during compilation if your projects do not use the extended API but access everything through the standard Java API. However, you can only use the PGP functionality through the PGP API of Bouncy Castle itself, so that won't work for PGP.

Answer 2

I am using the Bouncy Castle list as follows:

I have the same exceptions with yours because of the api changing. So, here is complete your sample code.

private static PGPPublicKey readPublicKey(InputStream in) throws IOException {
    try {
        PGPPublicKeyRing pgpPub = new PGPPublicKeyRing(in, new JcaKeyFingerprintCalculator());
        //PGPPublicKeyRing pgpPub = new PGPPublicKeyRing(in);
        return pgpPub.getPublicKey();
    } catch (IOException io) {
        System.out.println("readPublicKey() threw an IOException");
        System.out.println(io.toString());
        throw io;
    }

}

private static void encryptFile(String fileName, OutputStream out, PGPPublicKey encKey)
throws IOException, NoSuchProviderException, PGPException  
{

    out = new ArmoredOutputStream(out);

    ByteArrayOutputStream bOut = new ByteArrayOutputStream();

    System.out.println("creating comData...");

    // get the data from the original file 
    PGPCompressedDataGenerator comData = new PGPCompressedDataGenerator(PGPCompressedDataGenerator.ZIP);
    PGPUtil.writeFileToLiteralData(comData.open(bOut), PGPLiteralData.BINARY, new File(fileName));
    comData.close();

    System.out.println("comData created...");

    System.out.println("using PGPEncryptedDataGenerator...");

    // object that encrypts the data
    //PGPEncryptedDataGenerator cPk = new PGPEncryptedDataGenerator(PGPEncryptedDataGenerator.CAST5, new SecureRandom(), "BC");
    //cPk.addMethod(encKey);
    // object that encrypts the data
    PGPEncryptedDataGenerator cPk = new PGPEncryptedDataGenerator(new JcePGPDataEncryptorBuilder(SymmetricKeyAlgorithmTags.CAST5)
            .setSecureRandom(new SecureRandom()).setProvider("BC"));
    cPk.addMethod(new JcePublicKeyKeyEncryptionMethodGenerator(encKey));

    System.out.println("used PGPEncryptedDataGenerator...");

    // take the outputstream of the original file and turn it into a byte array
    byte[] bytes = bOut.toByteArray();

    System.out.println("wrote bOut to byte array...");

    // write the plain text bytes to the armored outputstream
    OutputStream cOut = cPk.open(out, bytes.length);
    cOut.write(bytes);


    // cOut.close();
    cPk.close();
    out.close();


}

To say about encryption of strings, it depends on your requirement what to do with it. You know that even a base64 encoding might be one option..

You can google or search this site, plenty of them found.

Have a good coding