KeyPairGenerator generatorRSA = KeyPairGenerator.getInstance("RSA");
generatorRSA.initialize(2048, new SecureRandom());
KeyPair keyRSA = generatorRSA.generateKeyPair();
 
DataInputStream pInRSA = new DataInputStream(new FileInputStream(inFile));
DataOutputStream eOutRSA = new DataOutputStream(new FileOutputStream("RSACipherText.txt"));
encoderRSA = Cipher.getInstance("RSA/ECB/NoPadding");
encoderRSA.init(Cipher.ENCRYPT_MODE, keyRSA.getPublic());
blockSize = (2048 / 8) - 11;
 
while (pInRSA.available() > 0) {
	buffer = new byte[Math.min(blockSize, pInRSA.available())];
	for (int i = 0; i < buffer.length; i++) {
		buffer[i] = pInRSA.readByte();
	}
	encodedMsg = encoderRSA.doFinal(buffer);
	eOutRSA.write(encodedMsg, 0, encodedMsg.length);
}
pInRSA.close();
eOutRSA.close();
 
DataInputStream eInRSA = new DataInputStream(new FileInputStream("RSACipherText.txt"));
DataOutputStream pOutRSA = new DataOutputStream(new FileOutputStream("RSAPlainText.txt"));
decoderRSA = Cipher.getInstance("RSA/ECB/NoPadding");
decoderRSA.init(Cipher.DECRYPT_MODE, keyRSA.getPrivate());
blockSize = encodedMsg.length;
buffer = new byte[blockSize];
 
while (eInRSA.available() > 0) {
	for (int i = 0; i < blockSize; i++) {
		buffer[i] = eInRSA.readByte();
	}
	decodedMsg = decoderRSA.doFinal(buffer);
	pOutRSA.write(decodedMsg, 0, decodedMsg.length);
}
eInRSA.close();
pOutRSA.close();