keygen.java

final KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA");
kpg.initialize(new RSAKeyGenParameterSpec(2048, RSAKeyGenParameterSpec.F4));
Log.i("hamatz", "generating RSA key pair...");
final long start = SystemClock.uptimeMillis();
final KeyPair kp = kpg.generateKeyPair();
final long end = SystemClock.uptimeMillis();
Log.i("hamatz", "done: " + (end-start) + "ms.");
final RSAPrivateKey privkey = (RSAPrivateKey) kp.getPrivate();
final RSAPublicKey pubkey = (RSAPublicKey) kp.getPublic();

final byte[] encodedPrivkey = privkey.getEncoded();
final byte[] encodedPubkey = pubkey.getEncoded();