Java RSA Encrypt

Question

I have used RSA Assymetric Key Encryption Algorithm in C# program (I have mentioned below) and I have to encrypt data through a java program. I want my java program to generate same encrypted key as like result of C# program.

Public Key:

<RSAKeyValue>
<Modulus>zgfXY1oUe4nyndX4qtobP1BMxtJ1/rfKU5csdAcWrSVu6ZaEAX3rL3cWnaSLzX4E1BNjSP9pjge6TH7UoaWqOQ==</Modulus>
<Exponent>AQAB</Exponent>
</RSAKeyValue>

C# Encryption Programme:

RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();

 rsa.FromXmlString(PublicKey); // read public key XML defined above

byte[] buffer = rsa.Encrypt(Encoding.UTF8.GetBytes(strToEncrypt), false);

string encryptedStr = HttpUtility.UrlEncode(buffer);// byteConverterGetString;

Java Encryption Programme:

byte[] modulusBytes = Base64.decode("zgfXY1oUe4nyndX4qtobP1BMxtJ1/rfKU5csdAcWrSVu6ZaEAX3rL3cWnaSLzX4E1BNjSP9pjge6TH7UoaWqOQ==");
byte[] exponentBytes = Base64.decode("AQAB");

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

RSAPublicKeySpec rsaPubKey = new RSAPublicKeySpec(modulus, exponent);

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

PublicKey pubKey = fact.generatePublic(rsaPubKey);

Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");

cipher.init(Cipher.ENCRYPT_MODE, pubKey);

byte[] plainBytes = new String("Admin123").getBytes("UTF-8");

byte[] cipherData = cipher.doFinal( plainBytes );

String encryptedString = Base64.encodeBytes(cipherData);

System.out.println(URLEncoder.encode(encryptedString));

I tried above java program but it gives me result like:

o%2Bgw7%2BXhYxA9ltDV5zERsF4DyXgMTc%2Fgx82wRtT1xfR3suY0XBJLadp7bXjmSX7CplDVdoQyH05Jpqgkd%2B1G4A%3D%3D

and C# program generates like

%23E%03%c2%10)%40E%bf%7b%f9%11%87c0%12q%b9w%ba%2c%98%b4%b1%96%bc%ee%c5_%c9t%1e'%e71%85%b68t%00%3a%b7%d9%fb%a1%18%ba%10%b4%c3c%e1'*%3b%f6D%e2%cc6%82%80%f2%a6

so can anyone help me to correct my java program.. thanks

Answer 1

It seems to me that you're URL encoding two different things:

• In Java you're encoding a Base64 encoded string, whereas
• In C# you're doing it on a byte array

The result of these two different approaches will not be the same. Perhaps you should encode new String( cipherData ) in the Java part - or just compare the two byte[] arrays before encoding?

Cheers,

Answer 2

You are URLencoding diferent objects, just try this code:

byte[] modulusBytes = Base64.decode("zgfXY1oUe4nyndX4qtobP1BMxtJ1/rfKU5csdAcWrSVu6ZaEAX3rL3cWnaSLzX4E1BNjSP9pjge6TH7UoaWqOQ==");
byte[] exponentBytes = Base64.decode("AQAB");

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

RSAPublicKeySpec rsaPubKey = new RSAPublicKeySpec(modulus, exponent);

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

PublicKey pubKey = fact.generatePublic(rsaPubKey);

Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");

cipher.init(Cipher.ENCRYPT_MODE, pubKey);

byte[] plainBytes = new String("Admin123").getBytes("UTF-8");

byte[] cipherData = cipher.doFinal( plainBytes );

String string = new String(cipherData);

System.out.println(URLEncoder.encode(string,"UTF-8"));