android客户端加密代码

package com.devchina.scurity;import java.security.SecureRandom;import javax.crypto.Cipher;import javax.crypto.KeyGenerator;import javax.crypto.SecretKey;import javax.crypto.spec.SecretKeySpec;public class SecurityEnDe {private static final String defalutSeed = "devchina";private static final String algorithm = "AES";private final static String HEX = "0123456789ABCDEF";public static String encrypt(String cleartext) throws Exception {return encrypt(defalutSeed, cleartext);}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 encrypted) throws Exception {return decrypt(defalutSeed, encrypted);}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(algorithm);SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");sr.setSeed(seed);kgen.init(128, sr); // 192 and 256 bits may not be availableSecretKey skey = kgen.generateKey();byte[] raw = skey.getEncoded();return raw;}private static byte[] encrypt(byte[] raw, byte[] clear) throws Exception {SecretKeySpec skeySpec = new SecretKeySpec(raw, algorithm);Cipher cipher = Cipher.getInstance(algorithm);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, algorithm);Cipher cipher = Cipher.getInstance(algorithm);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 static void appendHex(StringBuffer sb, byte b) {sb.append(HEX.charAt((b >> 4) & 0x0f)).append(HEX.charAt(b & 0x0f));}}
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