brainGpg.groovy

// Similar in spirit to https://github.com/arttukasvio/deterministic
// It's a really bad idea to use this unless you absolutely know what
// you are doing.

@Grab(group='org.bouncycastle', module='bcpg-jdk15on', version='1.51')

import java.security.*;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.bcpg.ArmoredOutputStream;
import org.bouncycastle.bcpg.HashAlgorithmTags;
import org.bouncycastle.openpgp.*;
import org.bouncycastle.openpgp.operator.jcajce.*;

def size = 4096;
def identity = args[0];
def passPhrase = args[1];
def seed = passPhrase.getBytes("UTF-8");

def outputArmored(obj) {
    def armoredOut = new ArmoredOutputStream(System.out);
    obj.encode(armoredOut);
    armoredOut.close();
}

Security.addProvider(new BouncyCastleProvider());
prng = SecureRandom.getInstance("SHA1PRNG");
prng.setSeed(seed)
kpg = KeyPairGenerator.getInstance("RSA", "BC");
kpg.initialize(size, prng);
keyPair = new JcaPGPKeyPair(PGPPublicKey.RSA_GENERAL, kpg.generateKeyPair(), new Date(0));
sha1Calc = new JcaPGPDigestCalculatorProviderBuilder().build().get(HashAlgorithmTags.SHA1);
secretKey = new PGPSecretKey(PGPSignature.DEFAULT_CERTIFICATION, keyPair, identity, sha1Calc, null, null, 
    new JcaPGPContentSignerBuilder(keyPair.getPublicKey().getAlgorithm(), HashAlgorithmTags.SHA1), 
    new JcePBESecretKeyEncryptorBuilder(PGPEncryptedData.CAST5, sha1Calc).setProvider("BC").build(passPhrase.toCharArray()));
outputArmored(secretKey);
outputArmored(secretKey.getPublicKey());
println("KEYID: " + Long.toHexString(keyPair.getKeyID()).toUpperCase());