Verify an Argon2 Password with a Secret and Memory Guard

Demonstrates Crypt2.Argon2VerifyPassword when the hash was created with a secret (pepper) or ad, and the use of maxMemoryKb to guard against untrusted hash strings.

// 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);

    CkCrypt2 crypt = new CkCrypt2();

    //  The password should come from a secure source rather than being hard-coded.
    String password = "correct horse battery staple";

    String phcHash = "$argon2id$v=19$m=131072,t=4,p=2$c29tZXJhbmRvbXNhbHQ$3fJ7v1qKcVJ0lHqXjBQZ8mYm3sNTfSPRt0bqDl9kEyM";

    //  When the hash was created with a secret (pepper) or ad, the same values must be supplied to verify.
    //  Only the secret, ad, encoding, passwordCharset, and maxMemoryKb members of the options are used;
    //  everything else is ignored.
    CkJsonObject json = new CkJsonObject();
    json.UpdateString("secret","application-wide-pepper");
    json.UpdateString("secretEncoding","utf-8");

    //  maxMemoryKb guards against a hash from an untrusted source claiming an enormous memory cost.  The
    //  memory cost is taken from the hash string, so this limit is checked before any memory is allocated.
    //  It defaults to 2 GB.
    json.UpdateInt("maxMemoryKb",262144);

    //  Argon2VerifyPassword returns 1 if the password matched, 0 if it did not match, and -1 if the
    //  verification could not be performed.  Always test for a match with == 1.
    int verifyResult = crypt.Argon2VerifyPassword(password,json.emit(),phcHash);
    if (verifyResult == 1) {
        Log.i(TAG, "The password is verified.");
        }
    else {
        if (verifyResult == 0) {
            Log.i(TAG, "The password does not match.");
            }
        else {
            Log.i(TAG, "The verification could not be performed: " + crypt.lastErrorText());
            }

        }


  }

  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."
  }
}