[工具类]AES加密和解密

[java] 
package innoview.itouchviewcivil.util; 
 
import java.security.SecureRandom; 
import javax.crypto.Cipher; 
import javax.crypto.KeyGenerator; 
import javax.crypto.SecretKey; 
import javax.crypto.spec.SecretKeySpec; 
 
/**
 * AES加密器
 * 
 * @author Eric_Ni
 * 
 */ 
public class AESEncryptor { 
    /**
     * AES加密
     */ 
    public static String encrypt(String seed, String cleartext) 
            throws Exception { 
        byte[] rawKey = getRawKey(seed.getBytes()); 
        byte[] result = encrypt(rawKey, cleartext.getBytes()); 
        return toHex(result); 
    } 
 
    /**
     * AES解密
     */ 
    public static String decrypt(String seed, String encrypted) 
            throws Exception { 
        if (seed == null || "".equals(seed) || encrypted == null || "".equals(encrypted)){ 
            return null; 
        } 
        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 { 
        if (raw == null || clear == null){ 
            return null; 
        } 
        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) { 
        if (hexString == null || "".equals(hexString)){ 
            return null; 
        } 
        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)); 
    } 
} 

补充：综合编程 , 安全编程 ,