(Android™) Duplicate openssl dgst -sha256 -verify pubKey.pem -signature signature.sig in.dat

Demonstrates how to duplicate this OpenSSL command:

openssl dgst -sha256 -verify pubKey.pem -signature signature.sig in.dat

1. Creates a SHA256 digest of the contents of the input file.
2. Verifies the SHA256 digest using the public 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.

    CkPublicKey pubKey = new CkPublicKey();

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

    // Load the data of the original file that was signed.
    CkBinData bdFileData = new CkBinData();
    success = bdFileData.LoadFile("in.dat");

    // Load the signature.
    CkBinData bdSig = new CkBinData();
    success = bdSig.LoadFile("signature.sig");

    CkRsa rsa = new CkRsa();

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

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

    success = rsa.VerifyBd(bdFileData,"sha256",bdSig);
    if (success != true) {
        Log.i(TAG, rsa.lastErrorText());
        Log.i(TAG, "The signature was invalid.");
        return;
        }

    Log.i(TAG, "The signature was verified.");

  }

  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."
  }
}