A modified version of the AWS SDK for Android sample code which fetches credentials from awskeyserver.

AWSDemo.java

package com.amazon.aws.demo;

import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.io.Writer;
import java.net.URL;
import java.net.URLConnection;
import java.net.URLEncoder;
import java.util.Properties;

import com.amazon.aws.demo.R;
import com.amazon.aws.demo.s3.S3Menu;
import com.amazon.aws.demo.sdb.SdbMenu;
import com.amazon.aws.demo.sns.SnsMenu;
import com.amazon.aws.demo.sqs.SqsMenu;
import com.amazonaws.auth.BasicAWSCredentials;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.DialogInterface.OnClickListener;
import android.content.Intent;
import android.content.SharedPreferences;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.os.Handler;
import android.text.Html;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.TextView;

public class AWSDemo extends Activity {
    
	private Handler mHandler;
	private static final String success = "Welcome to The AWS Browser Demo!";
	private static final String fail = "Load Failed. Please Try Restarting the Application.";
	
	public static BasicAWSCredentials credentials = null;
	protected Button snsButton;
	protected Button sqsButton;
	protected Button s3Button;
	protected Button sdbButton;
	protected TextView welcomeText;
	
	private boolean credentials_found;
	
	private final Runnable postResults = new Runnable() {
		@Override
		public void run(){
			updateUi();
		}
	};
	
	/** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        mHandler = new Handler();
        snsButton = (Button) findViewById(R.id.main_notify_button);
        sqsButton = (Button) findViewById(R.id.main_queue_button);
        s3Button = (Button) findViewById(R.id.main_storage_button);
        sdbButton = (Button) findViewById(R.id.main_sdb_button);
        welcomeText = (TextView) findViewById(R.id.main_into_text);
        startGetCredentials();

    }
    
    protected void updateUi(){
    	if(credentials_found == true){
    		welcomeText.setText(success);
    		snsButton.setVisibility(View.VISIBLE);
    		sqsButton.setVisibility(View.VISIBLE);
    		s3Button.setVisibility(View.VISIBLE);
    		sdbButton.setVisibility(View.VISIBLE);
    		wireButtons();
    	} else {
    		displayCredentialsIssueAndExit();
    		welcomeText.setText(fail);
    	}
    }
    
    private void wireButtons(){
        snsButton.setOnClickListener(new View.OnClickListener() {
			@Override
			public void onClick(View v) {
				startActivity(new Intent(AWSDemo.this, SnsMenu.class));
			}
		});
		
		sqsButton.setOnClickListener(new View.OnClickListener() {
			@Override
			public void onClick(View v) {
				startActivity( new Intent(AWSDemo.this, SqsMenu.class));
			}
		});
		
		s3Button.setOnClickListener(new View.OnClickListener() {
			@Override
			public void onClick(View v) {
				startActivity(new Intent(AWSDemo.this, S3Menu.class));
			}
		});
		
		sdbButton.setOnClickListener(new View.OnClickListener() {
			@Override
			public void onClick(View v) {
				startActivity(new Intent(AWSDemo.this, SdbMenu.class));
			}
		});
    }
    
    private void startGetCredentials() {
		final SharedPreferences settings = AWSDemo.this.getSharedPreferences("AWSCredentials", 0);
		if (!settings.contains("awsAccessKey")) {
			Log.i("Loading AWS Credentials", "No credentials found. Obtaining new ones...");
	        try {
	        	final String responseString = readStringFromUrl("http://awskeyserver.appspot.com/create_user?group=Users");
	        	if (!responseString.contains(":")) {
	        		// Must have received a reCaptcha code
	        		AlertDialog.Builder ab = new AlertDialog.Builder(AWSDemo.this);
	        		ImageView captchaImage = new ImageView(AWSDemo.this);
	        		captchaImage.setImageDrawable(
	        			Drawable.createFromStream((InputStream) new URL("http://www.google.com/recaptcha/api/image?c=" + responseString).getContent(), "reCaptcha"));
	        		final EditText captchaResponse = new EditText(AWSDemo.this);
	        		LinearLayout captchaView = new LinearLayout(AWSDemo.this);
	        		captchaView.addView(captchaImage);
	        		captchaView.addView(captchaResponse, LinearLayout.LayoutParams.FILL_PARENT);
	        		captchaView.setOrientation(LinearLayout.VERTICAL);
	        		ab.setView(captchaView);
	        		ab.setPositiveButton("Ok", new OnClickListener() {
						@Override
						public void onClick(DialogInterface dialog, int which) {
							String captchaResponseText = URLEncoder.encode(captchaResponse.getText().toString());
							try {
								String credentialString = readStringFromUrl(
										String.format("http://awskeyserver.appspot.com/create_user?"
												+ "group=Users"
												+ "&recaptcha_challenge_field=%s"
												+ "&recaptcha_response_field=%s",
												responseString, captchaResponseText));
								storeCredentials(credentialString.split(":")[0], credentialString.split(":")[1], settings);
							} catch (IOException e) {
								e.printStackTrace();
							}
						}});
	        		ab.show();
	        	} else {
	        		// No protection, just credentials
			        storeCredentials(responseString.split(":")[0], responseString.split(":")[1], settings);
	        	}
	        } catch (Exception exception) {
	        	Log.e("Loading AWS Credentials", "Message: " + exception.getMessage());
	        	credentials_found = false;
	        }
		} else {
			credentials = new BasicAWSCredentials(
				settings.getString("awsAccessKey", null),
				settings.getString("awsSecretKey", null));
			credentials_found = true;
			AWSDemo.this.mHandler.post(postResults);
		}
    }
    
    private void storeCredentials(String accessKey, String secretKey, SharedPreferences settings) {
    	SharedPreferences.Editor editor = settings.edit();
    	editor.putString("awsAccessKey", accessKey);
    	editor.putString("awsSecretKey", secretKey);
    	editor.commit();
    	
    	credentials = new BasicAWSCredentials(accessKey, secretKey);
    	credentials_found = true;
    	AWSDemo.this.mHandler.post(postResults);
    }
    
    private String readStringFromUrl(String urlString) throws IOException {
    	URL url = new URL(urlString);
    	URLConnection urlConnection = url.openConnection();
    	InputStream in = new BufferedInputStream(urlConnection.getInputStream());
    	String readString = "";
    	int byteRead = in.read();
    	while (byteRead >= 0) {
    		readString += new String(new byte[] { (byte) byteRead });
    		byteRead = in.read();
    	}
    	return readString;
    }

    
    protected void displayCredentialsIssueAndExit() {
        AlertDialog.Builder confirm = new AlertDialog.Builder( this );
        confirm.setTitle("Credential Problem!");
        confirm.setMessage( "AWS Credentials not configured correctly.  Please review the README file." );
        confirm.setNegativeButton( "OK", new DialogInterface.OnClickListener() {
                public void onClick( DialogInterface dialog, int which ) {
        AWSDemo.this.finish();
                }
        } );
        confirm.show().show();                
    }
    


}