(Android™) Duplicate openssl dgst -sha256 -sign private.pem -out sha256.sig in.dat

Demonstrates how to duplicate this OpenSSL command:

openssl dgst -sha256 -sign private.pem -out sha256.sig in.dat

1. Creates a SHA256 digest of the contents of the input file
2. Signs the SHA256 digest using the private key.

Chilkat Android™ Downloads Android™ Java Libraries Android C/C++ Libraries

// 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);

    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    CkPrivateKey pkey = new CkPrivateKey();

    // Load the private key from an PEM file:
    boolean success = pkey.LoadPemFile("private.pem");
    if (success != true) {
        Log.i(TAG, pkey.lastErrorText());
        return;
        }

    CkRsa rsa = new CkRsa();

    // Import the private key into the RSA component:
    success = rsa.ImportPrivateKeyObj(pkey);
    if (success != true) {
        Log.i(TAG, rsa.lastErrorText());
        return;
        }

    // OpenSSL uses big-endian.
    rsa.put_LittleEndian(false);

    // Load the file to be signed.
    CkBinData bdFileData = new CkBinData();
    success = bdFileData.LoadFile("in.dat");

    CkBinData bdSig = new CkBinData();
    success = rsa.SignBd(bdFileData,"sha256",bdSig);
    if (success != true) {
        Log.i(TAG, rsa.lastErrorText());
        return;
        }

    // Save the binary signature to a file.
    success = bdSig.WriteFile("signature.sig");
    if (success != true) {
        Log.i(TAG, "Failed to write signature.sig.");
        return;
        }

    Log.i(TAG, "Success.");

  }

  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."
  }
}