Android 加密解密字符串

加密和解密的字符串:

 

 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));
 }
 }