Android AES加密实现

AES:高级加密标准，是一种对称加密算法，加解密使用相同的口令。
以下是一个工具类，可以直接拿来使用。
package com.example.crypto;import java.security.SecureRandom;import javax.crypto.Cipher;import javax.crypto.KeyGenerator;import javax.crypto.SecretKey;import javax.crypto.spec.SecretKeySpec;/** * Created with IntelliJ IDEA. * User: zhangmin * Module: Safe * Date: 14-6-9 * Time: 下午3:13 */public class AESCrypto {    public static String encrypt(String seed, String cleartext) throws Exception {        byte[] rawKey = getRawKey(seed.getBytes());        byte[] result = encrypt(rawKey, cleartext.getBytes());        return toHex(result);    }    public static String decrypt(String seed, String encrypted) throws Exception {        byte[] rawKey = getRawKey(seed.getBytes());        byte[] enc = toByte(encrypted);        byte[] result = decrypt(rawKey, enc);        return new String(result);    }    private static byte[] getRawKey(byte[] seed) throws Exception {        KeyGenerator kgen = KeyGenerator.getInstance("AES");        SecureRandom sr =  SecureRandom.getInstance("SHA1PRNG", "Crypto");        sr.setSeed(seed);        kgen.init(128, sr); // 192 and 256 bits may not be available        SecretKey skey = kgen.generateKey();        byte[] raw = skey.getEncoded();        return raw;    }    private static byte[] encrypt(byte[] raw, byte[] clear) throws Exception {        SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");        Cipher cipher = Cipher.getInstance("AES/ECB/ZeroBytePadding");        cipher.init(Cipher.ENCRYPT_MODE, skeySpec);        byte[] encrypted = cipher.doFinal(clear);        return encrypted;    }    private static byte[] decrypt(byte[] raw, byte[] encrypted) throws Exception {        SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");        Cipher cipher = Cipher.getInstance("AES/ECB/ZeroBytePadding");        cipher.init(Cipher.DECRYPT_MODE, skeySpec);        byte[] decrypted = cipher.doFinal(encrypted);        return decrypted;    }    public static String toHex(String txt) {        return toHex(txt.getBytes());    }    public static String fromHex(String hex) {        return new String(toByte(hex));    }    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));    }}
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