Android通過AES128加密解密字符串

Android通過AES128加密解密字符串

import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
/** download from http://www.baiduhome.net/code

Usage:
<pre>
String crypto = SimpleCrypto.encrypt(masterpassword, cleartext)
...
String cleartext = SimpleCrypto.decrypt(masterpassword, crypto)
&lt;/pre&gt;
@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 &lt; 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 &lt; 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&gt;&gt;4)&amp;0x0f)).append(HEX.charAt(b&amp;0x0f));
}


}</pre>