Android 加密解密字符串

Android 加密解密字符串：

package eoe.demo;
import java.security.SecureRandom;
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
/**
* Usage:
* <pre>
* String crypto = SimpleCrypto.encrypt（masterpassword, cleartext）
* ...
* String cleartext = SimpleCrypto.decrypt（masterpassword, crypto）
* </pre>
* @author ferenc.hechler
*/
public class SimpleCrypto {
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"）;
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"）;
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"）;
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））;
}
}