CreateKeyPair.cs

private static void CreateKeyPair()
{
    ECKeyPairGenerator keyPairGenerator = (ECKeyPairGenerator)GeneratorUtilities.GetKeyPairGenerator("ECDH");
    keyPairGenerator.Init(new KeyGenerationParameters(new SecureRandom(), 521));
    
    AsymmetricCipherKeyPair keyPair = keyPairGenerator.GenerateKeyPair();
    ECPrivateKeyParameters clientPrivKey = (ECPrivateKeyParameters)keyPair.Private;
    ECPublicKeyParameters clientPubKey = (ECPublicKeyParameters)keyPair.Public;
    
    StringWriter sw1 = new StringWriter();
    PemWriter pemWriter1 = new PemWriter(sw1);
    pemWriter1.WriteObject(clientPubKey);
    pemWriter1.Writer.Flush();
    String clientPubKeyPem = sw1.ToString();
    PlayerPrefs.SetString("clientPublicKey", clientPubKeyPem);
    pemWriter1.Writer.Close();
    
    StringWriter sw2 = new StringWriter();
    PemWriter pemWriter2 = new PemWriter(sw2);
    pemWriter2.WriteObject(clientPrivKey);
    pemWriter2.Writer.Flush();
    String clientPrivKeyPem = sw2.ToString();
    PlayerPrefs.SetString("clientPrivateKey", clientPrivKeyPem);
    pemWriter2.Writer.Close();
}