Android™

RSA Signature using Private Key from .snk File

See more RSA Examples

A .snk file (Strong Name Key file) is a file format used in the .NET ecosystem to store an RSA public/private key pair. This key pair is typically used for strong-naming assemblies, which is a process of signing .NET assemblies to ensure their integrity and to uniquely identify them.

This example loads a private key from a .snk file and creates an RSA signature.

Android™

// Important: Don't forget to include the call to System.loadLibrary
// as shown at the bottom of this code sample.
package com.test;

import android.app.Activity;
import com.chilkatsoft.*;

import android.widget.TextView;
import android.os.Bundle;

public class SimpleActivity extends Activity {

  private static final String TAG = "Chilkat";

  // Called when the activity is first created.
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    boolean success = false;

    CkRsa rsa = new CkRsa();

    //  Load the .snk and return the private key as XML.
    String xmlStr = rsa.snkToXml("./test.snk");
    if (rsa.get_LastMethodSuccess() == false) {
        Log.i(TAG, rsa.lastErrorText());
        return;
        }

    CkPrivateKey privKey = new CkPrivateKey();
    success = privKey.LoadXml(xmlStr);
    if (success == false) {
        Log.i(TAG, privKey.lastErrorText());
        return;
        }

    success = rsa.UsePrivateKey(privKey);
    if (success == false) {
        Log.i(TAG, rsa.lastErrorText());
        return;
        }

    //  Sign the SHA-256 hash of the utf-8 byte representation of the contents of sb
    //  Return the signature in base64 format.
    rsa.put_EncodingMode("base64");
    rsa.put_Charset("utf-8");
    String sigBase64 = rsa.signStringENC("This is the text to be hashed and signed.","sha256");
    if (rsa.get_LastMethodSuccess() == false) {
        Log.i(TAG, rsa.lastErrorText());
        return;
        }

    Log.i(TAG, "RSA signature as base64: " + sigBase64);

  }

  static {
      System.loadLibrary("chilkat");

      // Note: If the incorrect library name is passed to System.loadLibrary,
      // then you will see the following error message at application startup:
      //"The application <your-application-name> has stopped unexpectedly. Please try again."
  }
}