Using RSA private-public key with c# app for decyption(server) and java app for encryption(client)

Using RSACryptoServiceProvider (c#) we created public and private key pair. Public key is then used by Java client to encrypt data and corresponding private key is used by c# server to decrypt data encrypted by java client

Java client encryting message with public key as following xml

<rsakeyvalue><modulus>z3iQSLN4e7LEZDkb6QSvHXXmQuMRPOYpP6R18WflUGMUk38xGEwd6ieO5DqpqdLnQ+GafFuKOnnPv9wXSuGX0xb9mTgaKQJX0LJSFKHc8G7A511UYn2wuOBDnRSOB09GcPa4T/CYjdP1MRxMecwL2eZ7BJWHU94TtBxfe0soQf0=</modulus><exponent>AQAB</exponent>


public class RSATest {



public static void Encrypt() throws Exception {

Cipher rsa = Cipher.getInstance("RSA");

KeyFactory keyFactory = KeyFactory.getInstance("RSA");

byte[] modulusBytes = new BASE64Decoder().decodeBuffer("z3iQSLN4e7LEZDkb6QSvHXXmQuMRPOYpP6R18WflUGMUk38xGEwd6ieO5DqpqdLnQ+GafFuKOnnPv9wXSuGX0xb9mTgaKQJX0LJSFKHc8G7A511UYn2wuOBDnRSOB09GcPa4T/CYjdP1MRxMecwL2eZ7BJWHU94TtBxfe0soQf0=");
byte[] exponentBytes = new BASE64Decoder().decodeBuffer("AQAB");

BigInteger modulus = new BigInteger(1, modulusBytes);
BigInteger exponent = new BigInteger(1, exponentBytes);

RSAPublicKeySpec keySpec = new RSAPublicKeySpec(modulus, exponent);
PublicKey publicKey = keyFactory.generatePublic(keySpec);

rsa.init(Cipher.ENCRYPT_MODE, publicKey);

byte[] encryptedData = rsa.doFinal("password would workahdsasdfiosfadioasdio".getBytes(new US_ASCII()));

String encryptedString = HexConversions.bytesToHex(encryptedData);
System.out.println(encryptedString);
System.out.println(encryptedString.length());

}

public static void main(String []arg) throws Exception {
Encrypt();
}
}

C# Code to decrypt what was encrypted by java client

using System;
using System.Globalization;
using System.IO;
using System.Security.Cryptography;
using System.Text;

namespace ConsoleApplication1
{
internal class Program
{
private static RSACryptoServiceProvider rsa;
private static string publicKey;
private static string privateKey;

private static void Main(string[] args)
{
GenerateKeys();
string encryptedPassword = EncryptData();

string decryptedPassword =

DecryptData("57851E00296519064288CF5B014FE478B703D046648D8F3DEFE715C424670E63F6EFBDC2D7964E17C7C7618EF206F46871536184663725F2EB16FBE9E76872D1

2977F50EE2BDC2C6289A4FBC3C4DA48ED85F12734F97170BA1670BAF610FBA5DB407B18A98CECAA9EFEC4D48C5FA13B4AB771029239B501BB5CCC6235E4041F6");

Console.WriteLine(decryptedPassword);
Console.ReadKey();
}


private static string DecryptData(string encryptedPassword)
{
RSACryptoServiceProvider clientRSAProvider = new RSACryptoServiceProvider();
clientRSAProvider.FromXmlString(File.ReadAllText("D:\\wsgCertificates\\privateKey.txt"));
byte[] bytes = new byte[encryptedPassword.Length/2];
for (int i = 0; i < encryptedPassword.Length; i += 2)
{
bytes[i/2] = byte.Parse(encryptedPassword.Substring(i, 2), NumberStyles.HexNumber);
}

byte[] decrypt = clientRSAProvider.Decrypt(bytes, false);
return Encoding.ASCII.GetString(decrypt);
}

public static string EncryptData()
{
RSACryptoServiceProvider clientRSAProvider = new RSACryptoServiceProvider();
clientRSAProvider.FromXmlString(publicKey);

byte[] encrypt = clientRSAProvider.Encrypt(Encoding.ASCII.GetBytes("hi tesint aaaaaaaaassword"), false);
StringBuilder stringBuilder = new StringBuilder();
foreach (var byteValue in encrypt)
{
stringBuilder.Append(byteValue.ToString("X2"));
}
return stringBuilder.ToString();
}

public static string EncryptDataDSA()
{
DSACryptoServiceProvider clientRSAProvider = new DSACryptoServiceProvider();
clientRSAProvider.FromXmlString(publicKey);

byte[] encrypt = clientRSAProvider.SignData(Encoding.ASCII.GetBytes("hi tesint aaaaaaaaassword"));
StringBuilder stringBuilder = new StringBuilder();
foreach (var byteValue in encrypt)
{
stringBuilder.Append(byteValue.ToString("X2"));
}
return stringBuilder.ToString();
}

public static void GenerateKeys()
{
RSACryptoServiceProvider rsaCryptoServiceProvider = new RSACryptoServiceProvider();
publicKey = rsaCryptoServiceProvider.ToXmlString(false);
privateKey = rsaCryptoServiceProvider.ToXmlString(true);
WriteKey(publicKey, "D:\\wsgCertificates\\publicKey.txt");
WriteKey(privateKey, "D:\\wsgCertificates\\privateKey.txt");
}



private static void WriteKey(string key, string keyFileName)
{
StreamWriter writer = new StreamWriter(keyFileName);
writer.WriteLine(key);
writer.Close();
}
}
}