(Android™) CMS Sign Hash

Demonstrates how to use the SignHashENC method to sign a pre-computed hash. This method creates a CMS signature (PKCS7 detached signature).

This example requires Chilkat v9.5.0.90 or later.

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.

    CkCrypt2 crypt = new CkCrypt2();

    // Create the hash to be signed...
    crypt.put_HashAlgorithm("sha256");
    crypt.put_EncodingMode("base64");
    crypt.put_Charset("utf-8");
    // Create the SHA256 hash of a string using the utf-8 byte representation.
    // Return the hash as base64.
    String base64Hash = crypt.hashStringENC("This is the string to be hashed");

    // Load a certificate for signing.
    CkCert cert = new CkCert();
    boolean success = cert.LoadPfxFile("qa_data/pfx/cert_test123.pfx","test123");
    if (success == false) {
        Log.i(TAG, cert.lastErrorText());
        return;
        }

    crypt.SetSigningCert(cert);

    // Sign the hash to create a base64 CMS signature (which does not contain the original data).
    // We can get the signature in a single line of base64 by specifying "base64", or 
    // we can get multi-line base64 by specifying "base64_mime".
    crypt.put_EncodingMode("base64_mime");
    String base64CmsSig = crypt.signHashENC(base64Hash,"sha256","base64");
    if (crypt.get_LastMethodSuccess() == false) {
        Log.i(TAG, crypt.lastErrorText());
        return;
        }

    // Note: In the above call to SignHashENC, the encoding of the returned CMS signature is specified by the EncodingMode property.
    // However, the encoding of the passed-in hash is indicated by the 3rd argument.

    Log.i(TAG, "CMS Signature: " + base64CmsSig);

  }

  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."
  }
}