encryptdec.md

Encrypt / Decrypt Strings in Android

Third-party Lib

A better and more secure way is implemented in this library.

Encrypt Strings

Please copy the AESUtils class in your project first and then you can use it like this.

String encrypted = "";
String sourceStr = "This is any source string";
try {
    encrypted = AESUtils.encrypt(sourceStr);
    Log.d("TEST", "encrypted:" + encrypted);
} catch (Exception e) {
    e.printStackTrace();
}

Decrypt Strings

Please copy the AESUtils class in your project first and then you can use it like this.

String encrypted = "ANY_ENCRYPTED_STRING_HERE";
String decrypted = "";
try {
    decrypted = AESUtils.decrypt(encrypted);
    Log.d("TEST", "decrypted:" + decrypted);
} catch (Exception e) {
    e.printStackTrace();
}

AESUtils Class

The easiest way of implementing AES Encryption and Decryption in Android is to copy this class in your projects.

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

public class AESUtils 
{

    private static final byte[] keyValue =
            new byte[]{'c', 'o', 'd', 'i', 'n', 'g', 'a', 'f', 'f', 'a', 'i', 'r', 's', 'c', 'o', 'm'};


    public static String encrypt(String cleartext)
            throws Exception {
        byte[] rawKey = getRawKey();
        byte[] result = encrypt(rawKey, cleartext.getBytes());
        return toHex(result);
    }

    public static String decrypt(String encrypted)
            throws Exception {

        byte[] enc = toByte(encrypted);
        byte[] result = decrypt(enc);
        return new String(result);
    }

    private static byte[] getRawKey() throws Exception {
        SecretKey key = new SecretKeySpec(keyValue, "AES");
        byte[] raw = key.getEncoded();
        return raw;
    }

    private static byte[] encrypt(byte[] raw, byte[] clear) throws Exception {
        SecretKey skeySpec = new SecretKeySpec(raw, "AES");
        Cipher cipher = Cipher.getInstance("AES");
        cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
        byte[] encrypted = cipher.doFinal(clear);
        return encrypted;
    }

    private static byte[] decrypt(byte[] encrypted)
            throws Exception {
        SecretKey skeySpec = new SecretKeySpec(keyValue, "AES");
        Cipher cipher = Cipher.getInstance("AES");
        cipher.init(Cipher.DECRYPT_MODE, skeySpec);
        byte[] decrypted = cipher.doFinal(encrypted);
        return decrypted;
    }

    public static byte[] toByte(String hexString) {
        int len = hexString.length() / 2;
        byte[] result = new byte[len];
        for (int i = 0; i < len; i++)
            result[i] = Integer.valueOf(hexString.substring(2 * i, 2 * i + 2),
                    16).byteValue();
        return result;
    }

    public static String toHex(byte[] buf) {
        if (buf == null)
            return "";
        StringBuffer result = new StringBuffer(2 * buf.length);
        for (int i = 0; i < buf.length; i++) {
            appendHex(result, buf[i]);
        }
        return result.toString();
    }

    private final static String HEX = "0123456789ABCDEF";

    private static void appendHex(StringBuffer sb, byte b) {
        sb.append(HEX.charAt((b >> 4) & 0x0f)).append(HEX.charAt(b & 0x0f));
    }
}