Show how to create a BCRSAPrivateCrtKey instance by Java Reflect API

RSATest.java

import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.math.BigInteger;

import org.bouncycastle.crypto.DataLengthException;
import org.bouncycastle.crypto.params.RSAPrivateCrtKeyParameters;
import org.bouncycastle.jcajce.provider.asymmetric.rsa.BCRSAPrivateCrtKey;

public class RSATest {

	public static void main(String[] args) throws Throwable {
		Constructor<BCRSAPrivateCrtKey> c0 = BCRSAPrivateCrtKey.class
				.getDeclaredConstructor(new Class[] { RSAPrivateCrtKeyParameters.class });
		c0.setAccessible(true);

		// BigInteger modulus =
		// BigInteger publicExponent,
		// BigInteger privateExponent,
		// BigInteger p,
		// BigInteger q,
		// BigInteger dP,
		// BigInteger dQ,
		// BigInteger qInv)

		BigInteger modulus = getBI(
				"848ea1162713230552139bf37b18152fdbd03703103516510269bde5f80e742d0b2796721eda900bcc6dc6b6ad89a206a6bb2be1ed551d3263b802106ffec89f08be8f0d4fdaee19329950bd3d62b60c02151a9d650c7c296075938aa569de88cb8988bd2553dd2e9bb629df6294cbeef8ed1fbdd2c8f3ce9104a8e775eafafd");
		BigInteger publicExponent = getBI("10001");
		BigInteger privateExponent = getBI(
				"32ca4fb0a44231ddfd07e46e5390f3b545bd2f06ee73d8dc2b5786da91c440016e4fb9d67a39f68d7ec3e52ae3ad63b6b6b5eae7833f6493851fe1329926ff895a61ca2d58c9bc94a78dd51af452cfaa7a50f6b884bd2939c5ef36712c2afd29e66581bd5ecd82a498b49d4bd1a42f0714148acfd9d95a34a02ea76b453ebfc5");
		BigInteger p = getBI(
				"c932a60cf84dba933f475a347e308beb80b7c21ca9f223db461897b54c860c054543b1d6d19c0b2a2abcc39536daa5b218a89e4ec034b0bcad0caef965f9780b");
		BigInteger q = getBI(
				"a8a9b95c255cae46291f7e0b759a40bf0364dbde0745633198cc6889324fb8531a9f590c05892cc7ad5864e37d7553fd35756bc9547c6d17c23b3ec69778d617");

		BigInteger dP = getBI(
				"63d53cedbc9b9d138957975beaad9e100a3ba416e300e267e05d3d91d959be47333a46d92802fccb3c8f93a0cbaa2c83b5969d8ec7f29d2bd1d634504e183e47");
		BigInteger dQ = getBI(
				"45e32e1f748bd6dad3a76cff2a97e444420fc4db577ff4fe54263f1aba72361a996975e87952c1ef6b70b93d5a7b077660746b595d5cc1879ac019df085cd5b9");
		BigInteger qInv = getBI(
				"10d6b2b9e740e1b4cb1783b19290d8b65918537f4e78a40f53d37fb37171be2806584d5d1ed28e1f5f8945d93a128e8877367d74f577ca1c1145d4a70e4b19d9");

		RSAPrivateCrtKeyParameters param = new RSAPrivateCrtKeyParameters(modulus, publicExponent, privateExponent, p,
				q, dP, dQ, qInv);
		BCRSAPrivateCrtKey privateKey = c0.newInstance(new Object[] { param });

		// setPrivateFieldValue(privateKey, "modulus", modulus);
		// setPrivateFieldValue(privateKey, "publicExponent", publicExponent);
		// setPrivateFieldValue(privateKey, "privateExponent", privateExponent);
		// setPrivateFieldValue(privateKey, "primeP", p);
		// setPrivateFieldValue(privateKey, "primeQ", q);
		// setPrivateFieldValue(privateKey, "primeExponentP", dP);
		// setPrivateFieldValue(privateKey, "primeExponentQ", dQ);
		// setPrivateFieldValue(privateKey, "crtCoefficient", qInv);

		int blockSize = getInputBlockSize(modulus, false);

		byte[] in = { -122, 110, 46, -120, 104, 0, -47, -82, 114, -72, -50, 11, -17, -82, 90, 83, -84, 64, -70, -102,
				-8, -87, -107, 53, 58, -110, -38, 45, -114, -2, 1, -58, -41, 69, 49, 79, 115, 15, 34, -86, -26, 106, 86,
				74, -22, -82, 70, -54, -72, -87, 96, 8, -24, -34, -18, 10, -45, 72, 95, 83, -108, -72, 122, 109, 91,
				-51, -70, 34, -33, 64, -22, 98, -110, -72, 113, -20, 3, -115, -56, 61, -44, -62, 95, -61, -81, 120, 72,
				73, -112, 63, -112, -108, -16, 79, -5, -71, -92, -41, 29, -85, 92, -125, 23, 71, 46, 112, -95, 14, -109,
				-94, 81, 56, -118, 19, -65, -80, -121, -17, 121, 2, -24, 107, -34, 115, 26, -92, 7, -14 };

		convertInput(in, 0, 128, modulus, false);
		String data = "866e2e886800d1ae72b8ce0befae5a53ac40ba9af8a995353a92da2d8efe01c6d745314f730f22aae66a564aeaae46cab8a96008e8deee0ad3485f5394b87a6d5bcdba22df40ea6292b871ec038dc83dd4c25fc3af784849903f9094f04ffbb9a4d71dab5c8317472e70a10e93a251388a13bfb087ef7902e86bde731aa407f2";

		String password = RSAUtils.decryptByPrivateKey(data, privateKey);

		System.out.println(password);
	}

	public static int getInputBlockSize(BigInteger modulus, boolean forEncryption) {
		int bitSize = modulus.bitLength();

		if (forEncryption) {
			return (bitSize + 7) / 8 - 1;
		} else {
			return (bitSize + 7) / 8;
		}
	}

	public static BigInteger convertInput(byte[] in, int inOff, int inLen, BigInteger modulus, boolean forEncryption) {
		if (inLen > (getInputBlockSize(modulus, forEncryption) + 1)) {
			throw new DataLengthException("input too large for RSA cipher.");
		} else if (inLen == (getInputBlockSize(modulus, forEncryption) + 1) && !forEncryption) {
			throw new DataLengthException("input too large for RSA cipher.");
		}

		byte[] block;

		if (inOff != 0 || inLen != in.length) {
			block = new byte[inLen];

			System.arraycopy(in, inOff, block, 0, inLen);
		} else {
			block = in;
		}

		BigInteger res = new BigInteger(1, block);
		if (res.compareTo(modulus) >= 0) {
			throw new DataLengthException("input too large for RSA cipher.");
		}

		return res;
	}

	private static BigInteger getBI(String value) {
		return new BigInteger(value, 16);
	}

	private static void setPrivateFieldValue(Object obj, String fieldName, Object value)
			throws NoSuchFieldException, IllegalAccessException {
		Field field = BCRSAPrivateCrtKey.class.getDeclaredField(fieldName);
		field.setAccessible(true);
		field.set(obj, value);
		field.setAccessible(false);
	}

}