(Chilkat for Android™ API)
Sending S/MIME Encrypted Email

Sends an encrypted email using the recipient's digital certificate from a .cer file.

Download: Chilkat for Android™ Java 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 {
  // Called when the activity is first created.
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    TextView tv = new TextView(this);
    String outStr = "";

    //  The mailman object is used for sending and receiving email.
    CkMailMan mailman = new CkMailMan();

    //  Any string argument automatically begins the 30-day trial.
    boolean success;
    success = mailman.UnlockComponent("30-day trial");
    if (success != true) {
        outStr += mailman.lastErrorText() + "\n";
        tv.setText(outStr);
        setContentView(tv);
        return;
    }

    //  Set the SMTP server.
    mailman.put_SmtpHost("smtp.comcast.net");

    //  Load the .cer file into a certificate object.
    //  When sending S/MIME encrypted email, it is the recipient's
    //  certificate that is used for encryption.  Only the public key
    //  is needed to encrypt.  The recipient is the only
    //  one possessing the private key, and therefore is the only
    //  one able to decrypt.
    CkCert cert = new CkCert();
    success = cert.LoadFromFile("cknotes.cer");
    if (success != true) {
        outStr += cert.lastErrorText() + "\n";
        tv.setText(outStr);
        setContentView(tv);
        return;
    }

    //  Create a new email object
    CkEmail email = new CkEmail();

    email.put_Subject("This email is encrypted");
    email.put_Body("This is a digitally encrypted mail");
    email.put_From("Chilkat Support <support@chilkatsoft.com>");
    email.AddTo("Chilkat Blog","admin@cknotes.com");

    //  Indicate that the email is to be sent encrypted.
    email.put_SendEncrypted(true);

    //  Specify the certificate to be used for encryption.
    email.SetEncryptCert(cert);

    success = mailman.SendEmail(email);
    if (success != true) {
        outStr += mailman.lastErrorText() + "\n";
    }
    else {
        outStr += "Mail Sent!" + "\n";
    }

    tv.setText(outStr);
    setContentView(tv);
  }

  static {
      // Important: Make sure the name passed to loadLibrary matches the shared library
      // found in your project's libs/armeabi directory.
      //  for "libchilkat.so", pass "chilkat" to loadLibrary
      //  for "libchilkatemail.so", pass "chilkatemail" to loadLibrary
      //  etc.
      // 
      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."
  }
}