alvinalexander.com | career | drupal | java | mac | mysql | perl | scala | uml | unix  

Android example source code file (SystemKeyStore.java)

This example Android source code file (SystemKeyStore.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" TM.

Java - Android tags/keywords

android, crypto, file, fileinputstream, fileoutputstream, illegalargumentexception, io, ioexception, key_file_extension, keygenerator, nosuchalgorithmexception, os, securerandom, security, sha1prng, string, stringbuilder, system_keystore_directory, systemkeystore

The SystemKeyStore.java Android example source code

/*
 * Copyright (C) 2010 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.security;

import android.os.Environment;
import android.os.FileUtils;
import android.os.Process;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;

import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;

/**
 *@hide
 */
public class SystemKeyStore {

    private static final String SYSTEM_KEYSTORE_DIRECTORY = "misc/systemkeys";
    private static final String KEY_FILE_EXTENSION = ".sks";
    private static SystemKeyStore mInstance = new SystemKeyStore();

    private SystemKeyStore() { }

    public static SystemKeyStore getInstance() {
        return mInstance;
    }

    public static String toHexString(byte[] keyData) {
        if (keyData == null) {
            return null;
        }
        int keyLen = keyData.length;
        int expectedStringLen = keyData.length * 2;
        StringBuilder sb = new StringBuilder(expectedStringLen);
        for (int i = 0; i < keyData.length; i++) {
            String hexStr = Integer.toString(keyData[i] & 0x00FF, 16);
            if (hexStr.length() == 1) {
                hexStr = "0" + hexStr;
            }
            sb.append(hexStr);
        }
        return sb.toString();
    }

    public String generateNewKeyHexString(int numBits, String algName, String keyName)
            throws NoSuchAlgorithmException {
        return toHexString(generateNewKey(numBits, algName, keyName));
    }

    public byte[] generateNewKey(int numBits, String algName, String keyName)
            throws NoSuchAlgorithmException {

        // Check if key with similar name exists. If so, return null.
        File keyFile = getKeyFile(keyName);
        if (keyFile.exists()) {
            throw new IllegalArgumentException();
        }

        KeyGenerator skg = KeyGenerator.getInstance(algName);
        SecureRandom srng = SecureRandom.getInstance("SHA1PRNG");
        skg.init(numBits, srng);

        SecretKey sk = skg.generateKey();
        byte[] retKey = sk.getEncoded();

        try {
            // Store the key
            if (!keyFile.createNewFile()) {
                throw new IllegalArgumentException();
            }

            FileOutputStream fos = new FileOutputStream(keyFile);
            fos.write(retKey);
            fos.flush();
            fos.close();
            FileUtils.setPermissions(keyFile.getName(), (FileUtils.S_IRUSR | FileUtils.S_IWUSR),
                -1, -1);
        } catch (IOException ioe) {
            return null;
        }
        return retKey;
    }

    private File getKeyFile(String keyName) {
        File sysKeystoreDir = new File(Environment.getDataDirectory(),
                SYSTEM_KEYSTORE_DIRECTORY);
        File keyFile = new File(sysKeystoreDir, keyName + KEY_FILE_EXTENSION);
        return keyFile;
    }

    public String retrieveKeyHexString(String keyName) {
        return toHexString(retrieveKey(keyName));
    }

    public byte[] retrieveKey(String keyName) {

        File keyFile = getKeyFile(keyName);
        if (!keyFile.exists()) {
            return null;
        }

        try {
            FileInputStream fis = new FileInputStream(keyFile);
            int keyLen = fis.available();
            byte[] retKey = new byte[keyLen];
            fis.read(retKey);
            fis.close();
            return retKey;
        } catch (IOException ioe) { }
        throw new IllegalArgumentException();
    }

    public void deleteKey(String keyName) {

        // Get the file first.
        File keyFile = getKeyFile(keyName);
        if (!keyFile.exists()) {
            throw new IllegalArgumentException();
        }

        keyFile.delete();
    }
}

Other Android examples (source code examples)

Here is a short list of links related to this Android SystemKeyStore.java source code file:

... this post is sponsored by my books ...

#1 New Release!

FP Best Seller

 

new blog posts

 

Copyright 1998-2021 Alvin Alexander, alvinalexander.com
All Rights Reserved.

A percentage of advertising revenue from
pages under the /java/jwarehouse URI on this website is
paid back to open source projects.