(Android™) Create PKCS7 Attached/Opaque Signature (S/MIME)

Create an S/MIME message with a PKCS7 attached/opaque signature.

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.

    CkMime mime = new CkMime();

    // Load a certificate w/ private key for signing.
    // There are many ways of getting a certificate object:
    // from a pfx file, from .cer and private-key files, from the
    // Windows registry-based certificate stores, etc.
    // Load a PFX file into a certificate object.
    CkCert cert = new CkCert();
    String pfxFilepath = "pfxFiles/something.pfx";
    String pfxPassword = "secret";
    boolean success = cert.LoadPfxFile(pfxFilepath,pfxPassword);
    if (success == false) {
        Log.i(TAG, cert.lastErrorText());
        return;
        }

    // Create a very simple MIME message to be signed:
    success = mime.AddHeaderField("Subject","This is a test");
    success = mime.AddHeaderField("MyCustomHeader","abc123");
    mime.put_ContentType("text/plain");
    mime.SetBody("This is a plain-text body.");

    // Examine the MIME prior to signing:
    Log.i(TAG, "--- MIME prior to signing ---");
    Log.i(TAG, mime.getMime());

    // The MIME prior to signing looks like this:
    // -------------------------------------------------------------------------------

    // Subject: This is a test
    // MyCustomHeader: abc123
    // Content-Type: text/plain
    // 
    // This is a plain-text body.

    // -------------------------------------------------------------------------------

    // The default hash algorithm used in the signing process is "SHA1".
    // To change it, set the SigningHashAlg property:
    mime.put_SigningHashAlg("SHA256");

    // Convert the MIME to PKCS7 signed-data.
    success = mime.ConvertToSigned(cert);
    if (success == false) {
        Log.i(TAG, mime.lastErrorText());
        return;
        }

    // Examine the signed MIME
    Log.i(TAG, "--- MIME converted to PKCS7 signed-data ---");
    Log.i(TAG, mime.getMime());

    // The MIME after signing looks like this:
    // -------------------------------------------------------------------------------

    // Subject: This is a test
    // MyCustomHeader: abc123
    // Content-Disposition: attachment; filename="smime.p7m"
    // Content-Transfer-Encoding: base64
    // Content-Type: application/x-pkcs7-mime;
    //  name="smime.p7m"; smime-type="signed-data"
    // 
    // MIIObAYJKoZIhvcNAQcCoIIOXTCCDlkCAQExDzANBglghkgBZQMEAgEFADB2BgkqhkiG9w0BBwGg
    // aQRnU3ViamVjdDogVGhpcyBpcyBhIHRlc3QNCk15Q3VzdG9tSGVhZGVyOiBhYmMxMjMNCkNvbnRl
    // bnQtVHlwZTogdGV4dC9wbGFpbg0KDQpUaGlzIGlzIGEgcGxhaW4tdGV4dCBib2R5LqCCCaAwggRm
    // MIIDTqADAgECAhBEvgyLUAAktBHTNi3gs18bMA0GCSqGSIb3DQEBBQUAMIGVMQswCQYDVQQGEwJV
    // UzELMAkGA1UECBMCVVQxFzAVBgNVBAcTDlNhbHQgTGFrZSBDaXR5MR4wHAYDVQQKExVUaGUgVVNF
    // UlRSVVNUIE5ldHdvcmsxITAfBgNVBAsTGGh0dHA6Ly93d3cudXNlcnRydXN0LmNvbTEdMBsGA1UE
    // AxMUVVROLVVTRVJGaXJzdC1PYmplY3QwHhcNOTkwNzA5MTgzMTIwWhcNMTkwNzA5MTg0MDM2WjCB
    // lTELMAkGA1UEBhMCVVMxCzAJBgNVBAgTAlVUMRcwFQYDVQQHEw5TYWx0IExha2UgQ2l0eTEeMBwG
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    // AQ8AMIIBCgKCAQEAzqqBP6OjYXiqMQBVlRGeJw8fHN86m4JoMMBKYR3xLw76vnn3pSPvVVGWhM3b
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    // BgNVHR8EOzA5MDegNaAzhjFodHRwOi8vY3JsLnVzZXJ0cnVzdC5jb20vVVROLVVTRVJGaXJzdC1P
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    // d/gz241M8KBT8yvqTAjv6NJz9tHNUqhYO5mTT65nsIwKQ5/T8L+hsOHi4VM2QdVW6ZD9jrfPIfES
    // yOyfXCx2l9oEHfB3gwgdYQ4Mq9hRG77mIc9H+pw1V0yMmQmEVs0LP6hvAgMBAAGjggFuMIIBajAf
    // BgNVHSMEGDAWgBTa7WR0FJwUPKvdmam9WyhNizzJ2DAdBgNVHQ4EFgQUBMe/RfjpWAOjAMHml1qw
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    // 

    // ------------------------------------------------------------------------------

  }

  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."
  }
}