Decrypt pgp file using bouncycastle api

What is the error/exception thrown  when you try to decrypt?

>>but when my client encrypts the file on his side I am not able to decrypt it using bouncycastle API

You are, i assume, attempting to decrypt it using his *public* key are you? That's what you must do

The error is throwing by my null check when I am checking if the key is null
throw new IllegalArgumentException("secret key for message not found.");

CEHJ, I am trying to decrypt the file by my secret key that I used to generate the public key for my client. Are you saying I should use public key to decrypt the file as well?

You decrypt messages *he* sends using *his* public key. He encrypts his own messages using his private key

CEHJ, no the message is being encrypted using public key that I sent to them. And I am able to decrypt the message on command prompt using GnuPG. I checked the path to the secret key and the file I am trying to decrypt all looks good just can't find the key to decrypt encrypted file using my implementation of bouncy castle api

Sorry alexk23, what i just said was wrong.

He encrypts messages he sends to you using *your* public key. Is that what's happening?

Yes. let me know if you would like to see the encrypted file.

Thaks CEHJ, let me look at it and will let you know!

The example does almost the same thing in comparing the keys, but the problem is that when I compare the public vs. private keys I am getting following results:

Data was encrypted using public key:  -4270675083819455261
Data was encrypted using public key:  5471684833902076854

Got secret key: -7878772790183064541 mask=true SigningKey = true
Got secret key: 5471684833902076854 mask=false SigningKey= false

But it still puzzles me how I was able to decrypt same file in command prompt I got couple messages but was able to decrypt it.

gpg: Signature made 04/21/09 03:41:20  using DSA key ID 2BD4FDE5
gpg: Can't check signature: public key not found
gpg: WARNING: message was not integrity protected

I figured it out the problem was with the message was encrypted and signed so I had to check the message signature first. Although example wasnt clear and had some issues but gave me an idea, thanks CEHJ

import org.bouncycastle.openpgp.*;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
 
 
import java.io.*;
import java.util.Iterator;
 
 
import java.security.NoSuchProviderException;
import java.security.Security;
 
 
 
public class PGPSecurityService {
 
 
    public static  void main(String[] args){
        try{
            Security.addProvider(new BouncyCastleProvider());
 
            /**
             * decrypt file
             **/
            // my private key
            InputStream privKey = new BufferedInputStream (new FileInputStream("C:\\apps\\private\\secring.gpg"));
            // file to decrypt
            InputStream file = new BufferedInputStream (new FileInputStream("C:\\apps\\encrypted.pgp"));
 
            decryptFile(file, privKey,"mykey".toCharArray());
        } catch (Exception ex){
            ex.printStackTrace();
        }
    }
 
    private static PGPPrivateKey findSecretKey(PGPSecretKeyRingCollection  pgpSec, long keyID, char[] pass)
        throws PGPException, NoSuchProviderException{
        PGPSecretKey pgpSecKey = pgpSec.getSecretKey(keyID);
        if (pgpSecKey == null){
            return null;
        } else {
            return pgpSecKey.extractPrivateKey(pass, "BC");
        }
    }
 
    private static PGPPublicKey readPublicKeyFromCol(InputStream in)throws Exception {
        PGPPublicKeyRing pkRing = null;
        PGPPublicKeyRingCollection pkCol = new PGPPublicKeyRingCollection(PGPUtil.getDecoderStream(in));
        //System.out.println("key ring size=" + pkCol.size());
        Iterator it = pkCol.getKeyRings();
        while (it.hasNext()) {
            pkRing = (PGPPublicKeyRing) it.next();
            Iterator pkIt = pkRing.getPublicKeys();
            while (pkIt.hasNext()) {
                PGPPublicKey key = (PGPPublicKey) pkIt.next();
                //System.out.println("Encryption key = " + key.isEncryptionKey() + ", Master key = " +key.isMasterKey());
                if (key.isMasterKey())
                    return key;
            }
        }
        return null;
    }
 
    private static void decryptFile( InputStream in, InputStream keyIn, char[] passwd)throws Exception{
        in = PGPUtil.getDecoderStream(in);
        try{
            PGPObjectFactory pgpF = new PGPObjectFactory(in);
            Object o = pgpF.nextObject();
            PGPEncryptedDataList enc = o instanceof PGPEncryptedDataList?(PGPEncryptedDataList)o : (PGPEncryptedDataList)pgpF.nextObject();
 
 
 
            //
            // the first object might be a PGP marker packet.
            //
            /*
            if (o instanceof PGPEncryptedDataList){
                enc = (PGPEncryptedDataList)o;
            }  else {
                enc = (PGPEncryptedDataList)pgpF.nextObject();
            }
            */
            //
            // find the secret key
            //
            Iterator it = enc.getEncryptedDataObjects();
            PGPPrivateKey sKey = null;
            PGPPublicKeyEncryptedData pbe = null;
            PGPSecretKeyRingCollection  pgpSec = new PGPSecretKeyRingCollection(PGPUtil.getDecoderStream(keyIn));
 
            while (sKey == null && it.hasNext()){
                pbe = (PGPPublicKeyEncryptedData)it.next();
                sKey = findSecretKey(pgpSec, pbe.getKeyID(), passwd);
            }
            if (sKey == null){
                throw new IllegalArgumentException("secret key for message not found.");
            }
 
            InputStream clear = pbe.getDataStream(sKey, "BC");
            PGPObjectFactory plainFact = new PGPObjectFactory(clear);
            Object message = plainFact.nextObject();
            if (message instanceof PGPCompressedData){
                PGPCompressedData   cData = (PGPCompressedData)message;
                PGPObjectFactory  pgpFact = new PGPObjectFactory(cData.getDataStream());
                message = pgpFact.nextObject();
                if (message instanceof PGPLiteralData){
                    PGPLiteralData      ld = (PGPLiteralData)message;
                    FileOutputStream    fOut = new FileOutputStream("C:\\apps\\private\\outputsigned.txt");
                    InputStream    unc = ld.getInputStream();
                    int    ch;
                    while ((ch = unc.read()) >= 0){
                        fOut.write(ch);
                    }
                }else if (message instanceof PGPOnePassSignatureList) {
 
                    PGPOnePassSignatureList p1 = (PGPOnePassSignatureList) message;
                    InputStream pubKey = new BufferedInputStream (new FileInputStream("C:\\apps\\private\\pubring.gpg"));
                    PGPPublicKey key =readPublicKeyFromCol(pubKey);
                    if(key!=null){
                        PGPOnePassSignature ops = p1.get(0);
                        System.out.println("ops.getKeyID()="+ops.getKeyID());
                        ops.initVerify(key, "BC");
                        // file output dirctory
                        FileOutputStream out = new FileOutputStream("C:\\apps\\private\\outputsigned.txt");
                        PGPLiteralData  p2 = (PGPLiteralData) pgpFact.nextObject();
                        int ch;
                        InputStream  dIn = p2.getInputStream();
                        while ((ch = dIn.read()) >= 0) {
                            ops.update((byte)ch);
                            out.write(ch);
                        }
                        out.close();
                    } else {
                        throw new PGPException ("unable to find public key for signed file");
                    }
                } else {
                    throw new PGPException("message is not a simple encrypted file - type unknown.");
                }
 
                if (pbe.isIntegrityProtected()){
                    if (!pbe.verify()){
                        System.err.println("message failed integrity check");
                    } else{
                        System.err.println("message integrity check passed");
                    }
                } else {
                    System.err.println("no message integrity check");
                }
            } else {
                System.out.println("unable to verify message");
            }
        }catch (PGPException e){
            System.err.println(e);
            if (e.getUnderlyingException() != null){
                e.getUnderlyingException().printStackTrace();
            }
        }
    }
 
 
}

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Although example wasnt clear and had some issues but gave me an idea, thanks CEHJ

Good :-)