JavaScript RSA with C# encrypting in Unity

Unity Engine
1

The server uses JSEncript to create private and public keys. The public key is then send to the webclient to provide a safe Login. Now I need to encript the user data
{"u":"username","p":"password"} with a given public key. for example:

MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAwzWTnw4NNz4349i5O9Mv
zfXIoDDlyrSYP/kTj3BbKy1j4CD27tWfHXKomeWKNgLAOZZg9DlHNn7O2ji7lpLg
GTCL/7sU82si9tnbYy8waOqq1uIgzd1SjCN0ZpvWbopZeEpK2w2Ua3R/TgG7wSXf
2uzOoRcThobYporK5g97My50dZrKCSKzAOqRxGOa3YkVRYJ1cVhn5db9CKg2UtR0
plvxAHvIBQWzdmv20mjyekfRwl/CzVKf1b5VLqCznHbz7JPZMnHkqdVv1TKMlBMV
Or7lf3MgzhsMmhUFghIx/kznUCQL9SrTkCTkeNiUfsfmzuWSTf7fsxREczxmFlIb
FQIDAQAB
-----END PUBLIC KEY-----```
Has anyone got an idea how to do that? I don't understand RSACryptoServiceProvider. It seems to me that it always needs to use it's own private key. Please help.
2

RSACryptoServiceProvider Класс (System.Security.Cryptography) | Microsoft Learn there’s an example code

3

That does not work for me since the keys are not generated on my local machine.
I only take a public key in base64 and have to encrpit login data with that.

4

I just found a solution:

  1. implement BouncyCastle.dll found here: http://www.bouncycastle.org/csharp/

using Org.BouncyCastle.Asn1;
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Security;

private string EncryptWithBC(string pkey, string stringToEncrypt)
    {
        Asn1Object obj = Asn1Object.FromByteArray(Convert.FromBase64String(pkey));

        DerSequence publicKeySequence = (DerSequence)obj;
        DerBitString encodedPublicKey = (DerBitString)publicKeySequence[1];
        DerSequence publicKey = (DerSequence)Asn1Object.FromByteArray(encodedPublicKey.GetBytes());

        DerInteger modulus = (DerInteger)publicKey[0];
        DerInteger exponent = (DerInteger)publicKey[1];

        RsaKeyParameters keyParameters = new RsaKeyParameters(false, modulus.PositiveValue, exponent.PositiveValue);

        RSAParameters parameters = DotNetUtilities.ToRSAParameters(keyParameters);
        RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
        rsa.ImportParameters(parameters);

        byte[] dataToEncrypt = Encoding.UTF8.GetBytes(stringToEncrypt);
        byte[] encryptedData = rsa.Encrypt(dataToEncrypt, false);
        return Convert.ToBase64String(encryptedData);
    }
1 Like
5

This seems very useful. How do I go about installing the dll?

6

Oh, ok. I figured it out. It was super easy. Just drag the DLL into unity.