Android™

Add a Detached Signature (Header Placement Control)

Demonstrates the Chilkat Mime.AddDetachedSignature2 method, which creates the same multipart/signed structure as AddDetachedSignature, with a second argument controlling whether the existing message header fields are transferred to the new outer entity.

Note: The file paths are relative to the application's current working directory. Absolute paths may also be used. Supply the paths appropriate to your own environment.

Background: Signing wraps the content in a new outer multipart/signed, which raises the question of where the message-level headers (Subject, From, To) should live. This variant lets you choose: transfer them up to the outer entity so the signed message looks like a normal email, or leave them on the inner part. Transferring is typical for email; the finer control matters when the signed entity is embedded in a larger structure.

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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;

    CkMime mime = new CkMime();
    success = mime.SetBodyFromPlainText("This message will be signed.");
    if (success == false) {
        Log.i(TAG, mime.lastErrorText());
        return;
        }

    //  Load the signing certificate (which must have access to its private key) from a PFX file.
    //  The PFX password should come from a secure source rather than being hard-coded.
    String pfxPassword = "myPfxPassword";
    CkCert cert = new CkCert();
    success = cert.LoadPfxFile("qa_data/signer.pfx",pfxPassword);
    if (success == false) {
        Log.i(TAG, cert.lastErrorText());
        return;
        }

    //  AddDetachedSignature2 is the same as AddDetachedSignature, but the 2nd argument controls whether
    //  the existing message header fields are transferred to the new outer multipart/signed entity.
    boolean transferHeaderFields = true;
    success = mime.AddDetachedSignature2(cert,transferHeaderFields);
    if (success == false) {
        Log.i(TAG, mime.lastErrorText());
        return;
        }

    success = mime.SaveMime("qa_output/signed.eml");
    if (success == false) {
        Log.i(TAG, mime.lastErrorText());
        return;
        }

    Log.i(TAG, "Detached signature added (headers transferred).");

  }

  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."
  }
}