DES加密工具

本工具采用的是DES SHA1PRNG 加密，如有兴趣，读者可由此自定义其他加密工具。具体可看代码注释

import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.security.InvalidKeyException;
import java.security.Key;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import javax.crypto.*;
import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;

/**
 * DESUtils 先采用BASE64Encoder对字符串进行处理，避免字符问题。
 * 再采用des 标准的SHA1PRNG加密方法进行加密
 */
public class DESUtils {
    private static Key key;
    private static String KEY_STR = "webapp";//加密秘钥,请自定义值
    private static String  charset = "UTF-8";
    private static String type = "DES";  //加密标准
    private static String  method="SHA1PRNG"; //加密方法
    private static Cipher cipher; //用于加解密操作的对象

    //初始化key  cipher
    static {
        try {
            KeyGenerator generator = KeyGenerator.getInstance(type); //获取秘钥对象
            SecureRandom secureRandom = SecureRandom.getInstance(method);//获取加密算法的强随机数对象
            secureRandom.setSeed(KEY_STR.getBytes());//根据key_str生成强随机数
            generator.init(secureRandom);//初始化秘钥对象
            key = generator.generateKey();//生成key
            generator = null;
            cipher= Cipher.getInstance(type);//获取cipher
            cipher.init(Cipher.ENCRYPT_MODE, key);//根据key初始化cipher
        } catch (NoSuchPaddingException e) {
            throw new RuntimeException(e);
        } catch (NoSuchAlgorithmException e) {
            throw new RuntimeException(e);
        } catch (InvalidKeyException e) {
            throw new RuntimeException(e);
        }
    }

    //获取加密后的字符串
    public static String getEncryptString(String str) {
        BASE64Encoder base64encoder = new BASE64Encoder();
        byte[] bytes = new byte[0];
        try {
            bytes = str.getBytes(charset);
            byte[] doFinal = new byte[0];
            doFinal = cipher.doFinal(bytes);
            return base64encoder.encode(doFinal);
        } catch (IllegalBlockSizeException e) {
            throw new RuntimeException(e);
        } catch (BadPaddingException e) {
            throw new RuntimeException(e);
        } catch (UnsupportedEncodingException e) {
            throw new RuntimeException(e);
        }
    }

    //获取加密后的字符串 将字符串解密
    public static String getDecryptString(String str) {
        BASE64Decoder base64decoder = new BASE64Decoder();
        try {
            byte[] bytes = base64decoder.decodeBuffer(str);
            byte[] doFinal = cipher.doFinal(bytes);
            return new String(doFinal, charset);
        } catch (IllegalBlockSizeException e) {
            throw new RuntimeException(e);
        } catch (BadPaddingException e) {
            throw new RuntimeException(e);
        } catch (UnsupportedEncodingException e) {
            throw new RuntimeException(e);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }
}

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