Question
I have created a small program to generate a DSA / El Gamal PGP Key Ring using Bouncy Castle 1.47 API. The key generation goes real well without an error. I export the private and public key to a file using armored output and when I try to import the generated private key with GPG (KGpg to be exact) I get the following error:
https://stackoverflow.com/questions/13733260
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Russian[GNUPG:] NODATA 1
[GNUPG:] IMPORT_OK 17 1277C25B455C71D91EE42C8FF9A6087305C00DA6
[GNUPG:] IMPORTED F9A6087305C00DA6 test@gmail.com
[GNUPG:] IMPORT_OK 1 1277C25B455C71D91EE42C8FF9A6087305C00DA6
[GNUPG:] IMPORT_RES 1 0 1 0 0 0 0 0 0 1 1 0 0 0
After I click OK it tells me that only 1 key has been processed. It looks like it only took the DSA key because in the screen it shows up as 1024/0.
** EDIT ** I just tried openning the keys in PGP 10.1.0 on Windows and it also gives me an error "The key ring contains a bad (corrupted) PGP packet."
The code I am using is shown below, the first is the Utility class, the second is the program that invokes it to create the Key.
package george.crypto.pgp;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.Security;
import java.util.Date;
import org.bouncycastle.bcpg.ArmoredOutputStream;
import org.bouncycastle.bcpg.HashAlgorithmTags;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.jce.spec.ElGamalParameterSpec;
import org.bouncycastle.openpgp.PGPEncryptedData;
import org.bouncycastle.openpgp.PGPKeyPair;
import org.bouncycastle.openpgp.PGPKeyRingGenerator;
import org.bouncycastle.openpgp.PGPPublicKey;
import org.bouncycastle.openpgp.PGPPublicKeyRing;
import org.bouncycastle.openpgp.PGPSecretKeyRing;
import org.bouncycastle.openpgp.PGPSignature;
import org.bouncycastle.openpgp.operator.PGPDigestCalculator;
import org.bouncycastle.openpgp.operator.jcajce.JcaPGPContentSignerBuilder;
import org.bouncycastle.openpgp.operator.jcajce.JcaPGPDigestCalculatorProviderBuilder;
import org.bouncycastle.openpgp.operator.jcajce.JcePBESecretKeyEncryptorBuilder;
public final class PGPTools {
static {
Security.addProvider(new BouncyCastleProvider());
}
private PGPTools() {
}
public static final void exportSecretKey(PGPKeyRingGenerator pgpKeyRingGen, File keyFile, boolean asciiArmor) throws IOException {
PGPSecretKeyRing pgpSecKeyRing = pgpKeyRingGen.generateSecretKeyRing();
if(asciiArmor) {
pgpSecKeyRing.encode(new ArmoredOutputStream(new FileOutputStream(keyFile)));
}
else {
pgpSecKeyRing.encode(new FileOutputStream(keyFile));
}
}
public static final void exportPublicKey(PGPKeyRingGenerator pgpKeyRingGen, File keyFile, boolean asciiArmor) throws IOException {
PGPPublicKeyRing pgpPubKeyRing = pgpKeyRingGen.generatePublicKeyRing();
if(asciiArmor) {
pgpPubKeyRing.encode(new ArmoredOutputStream(new FileOutputStream(keyFile)));
}
else {
pgpPubKeyRing.encode(new FileOutputStream(keyFile));
}
}
/**
*
* @param dsaKeyPair - the generated DSA key pair
* @param elGamalKeyPair - the generated El Gamal key pair
* @param identity - the given identity of the key pair ring
* @param passphrase - the secret pass phrase to protect the key pair
* @return a PGP Key Ring Generate with the El Gamal key pair added as sub key
* @throws Exception
*/
@SuppressWarnings("deprecation")
public static final PGPKeyRingGenerator createPGPKeyRingGenerator(KeyPair dsaKeyPair, KeyPair elGamalKeyPair, String identity, char[] passphrase) throws Exception
{
PGPKeyPair dsaPgpKeyPair = new PGPKeyPair(PGPPublicKey.DSA, dsaKeyPair, new Date());
PGPKeyPair elGamalPgpKeyPair = new PGPKeyPair(PGPPublicKey.ELGAMAL_ENCRYPT, elGamalKeyPair, new Date());
PGPDigestCalculator sha1Calc = new JcaPGPDigestCalculatorProviderBuilder().build().get(HashAlgorithmTags.SHA1);
PGPKeyRingGenerator keyRingGen = new PGPKeyRingGenerator(PGPSignature.POSITIVE_CERTIFICATION, dsaPgpKeyPair, identity, sha1Calc, null, null, new JcaPGPContentSignerBuilder(dsaPgpKeyPair.getPublicKey().getAlgorithm(), HashAlgorithmTags.SHA1), new JcePBESecretKeyEncryptorBuilder(PGPEncryptedData.AES_256, sha1Calc).setProvider("BC").build(passphrase));
keyRingGen.addSubKey(elGamalPgpKeyPair);
return keyRingGen;
}
/**
*
* @param keySize 512 - 1024 (multiple of 64)
* @return the DSA generated key pair
* @throws NoSuchProviderException
* @throws NoSuchAlgorithmException
*/
public static final KeyPair generateDsaKeyPair(int keySize) throws NoSuchAlgorithmException, NoSuchProviderException
{
KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("DSA", "BC");
keyPairGenerator.initialize(keySize);
KeyPair keyPair = keyPairGenerator.generateKeyPair();
return keyPair;
}
/**
*
* @param keySize - 1024, 2048, 4096
* @return the El Gamal generated key pair
* @throws Exception
*/
public static final KeyPair generateElGamalKeyPair(int keySize) throws Exception
{
KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("ELGAMAL", "BC");
keyPairGenerator.initialize(keySize);
KeyPair keyPair = keyPairGenerator.generateKeyPair();
return keyPair;
}
/**
*
* @param paramSpecs - the pre-defined parameter specs
* @return the El Gamal generated key pair
* @throws Exception
*/
public static final KeyPair generateElGamalKeyPair(ElGamalParameterSpec paramSpecs) throws Exception
{
KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("ELGAMAL", "BC");
keyPairGenerator.initialize(paramSpecs);
KeyPair keyPair = keyPairGenerator.generateKeyPair();
return keyPair;
}
}
package george.crypto.pgp;
import java.io.File;
import java.math.BigInteger;
import java.security.KeyPair;
import org.bouncycastle.jce.spec.ElGamalParameterSpec;
import org.bouncycastle.openpgp.PGPKeyRingGenerator;
public class PGPCryptoBC {
public PGPCryptoBC() {
try {
String keysDir = System.getProperty("user.dir")+File.separator+"src/george/crypto/pgp/keys";
//Generating a safe prime is a very long process so it's better to use
//a pre-generated safe prime, I took this from http://www.cryptopp.com/fom-serve/cache/71.html
BigInteger primeModulous = new BigInteger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
BigInteger baseGenerator = new BigInteger("2", 16);
ElGamalParameterSpec paramSpecs = new ElGamalParameterSpec(primeModulous, baseGenerator);
KeyPair dsaKeyPair = PGPTools.generateDsaKeyPair(1024);
KeyPair elGamalKeyPair = PGPTools.generateElGamalKeyPair(paramSpecs);
PGPKeyRingGenerator pgpKeyRingGen = PGPTools.createPGPKeyRingGenerator(dsaKeyPair, elGamalKeyPair, "test@gmail.com", "TestPass12345!".toCharArray());
PGPTools.exportSecretKey(pgpKeyRingGen, new File(keysDir+File.separator+"secret.asc"), true);
PGPTools.exportPublicKey(pgpKeyRingGen, new File(keysDir+File.separator+"public.asc"), true);
}
catch(Exception ex) {
ex.printStackTrace();
}
}
public static void main(String ... args) {
new PGPCryptoBC();
}
}
The generated output are 2 files "secret.asc" and "public.asc" If I try to import "secret.asc" in GPG I get errors and El Gamal sub key does not get imported.
Does anyone know what could be wrong with this?
Solution
I managed to solve my own problem. I needed to explicitly close the output streams at the end. Not doing so will cause corrupted data.
And secondly as a extra bonus, if I use the Safe Prime (prime modulus) listed in the rfc3526 it allows me to generate El Gamal Keys of varying bit size lengths.
