android典型程式碼系列(三十)------DES加密演算法

DES加密演算法

import java.security.InvalidKeyException;
import java.security.Key;
import java.security.NoSuchAlgorithmException;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.SecretKeySpec;
import org.apache.commons.codec.binary.Base64;
public class DES {
    public DES() {}
    public static DES getInstance(String key) throws NoSuchPaddingException,
            NoSuchAlgorithmException {
        return getInstance(getKeyByStr(key));
    }
    public static DES getInstance(byte key[]) throws NoSuchPaddingException,
            NoSuchAlgorithmException {
        DES des = new DES();
        if (des.key == null) {
            SecretKeySpec spec = new SecretKeySpec(key, "DES");
            des.key = spec;
        }
        des.cipher = Cipher.getInstance("DES/ECB/PKCS5Padding");
        return des;
    }
    public byte[] encrypt(byte b[]) throws InvalidKeyException,
            BadPaddingException, IllegalBlockSizeException,
            IllegalStateException {
        byte byteFina[] = null;
        cipher.init(1, key);
        byteFina = cipher.doFinal(b);
        return byteFina;
    }
    public byte[] decrypt(byte b[]) throws InvalidKeyException,
            BadPaddingException, IllegalBlockSizeException,
            IllegalStateException {
        byte byteFina[] = null;
        cipher.init(2, key);
        byteFina = cipher.doFinal(b);
        return byteFina;
    }
    public static byte[] getKeyByStr(String str) {
        byte bRet[] = new byte[str.length() / 2];
        for (int i = 0; i < str.length() / 2; i++) {
            Integer itg = new Integer(16 * getChrInt(str.charAt(2 * i))
                    + getChrInt(str.charAt(2 * i + 1)));
            bRet[i] = itg.byteValue();
        }
        return bRet;
    }
    private static int getChrInt(char chr) {
        int iRet = 0;
        if (chr == "0".charAt(0))
            iRet = 0;
        if (chr == "1".charAt(0))
            iRet = 1;
        if (chr == "2".charAt(0))
            iRet = 2;
        if (chr == "3".charAt(0))
            iRet = 3;
        if (chr == "4".charAt(0))
            iRet = 4;
        if (chr == "5".charAt(0))
            iRet = 5;
        if (chr == "6".charAt(0))
            iRet = 6;
        if (chr == "7".charAt(0))
            iRet = 7;
        if (chr == "8".charAt(0))
            iRet = 8;
        if (chr == "9".charAt(0))
            iRet = 9;
        if (chr == "A".charAt(0))
            iRet = 10;
        if (chr == "B".charAt(0))
            iRet = 11;
        if (chr == "C".charAt(0))
            iRet = 12;
        if (chr == "D".charAt(0))
            iRet = 13;
        if (chr == "E".charAt(0))
            iRet = 14;
        if (chr == "F".charAt(0))
            iRet = 15;
        return iRet;
    }
    private Key key;
    private Cipher cipher;

    /**
     * @interpret 進行base64加密操作
     * @param text
     * @param keyString
     * @return String
     */
    public String encrypt(String text, String keyString) {
        String body = null;
        try {
            DES des = DES.getInstance(keyString);

            byte[] b = des.encrypt(text.getBytes("UTF8"));
            body = new String(Base64.encodeBase64(b));
        } catch (Exception ex) {

        }
        return body;
    }
    /**
     * @interpret 進行base64進行解密
     * @param text
     * @param keyString
     * @return String
     */
    public String decrypt(String text, String keyString) {
        String body = null;
        try {
            DES des = DES.getInstance(keyString);

            byte[] b = Base64.decodeBase64(text.getBytes());

            body = new String(des.decrypt(b), "UTF8");
        } catch (Exception e) {
            e.printStackTrace();
        }
        return body;
    }
    public String authcode(String content, String operation, String key){

        String encontent = null;
        if (operation != null && operation.equals("DECODE")) {
            encontent = encrypt(content,key);
        } else if (operation != null && operation.equals("ENCODE")) {
            encontent = decrypt(content,key);
        }
        return encontent;
    }
    public static void main(String[] args) {
        DES des = new DES();
        System.out.println(des.authcode("wewweewewew=","DECODE","0102030405060708"));
        System.out.println(des.authcode("d8fPhfd9JkW99p8aqhtVIA==","ENCODE","0102030405060708"));
    }
}