docdecoder.java

本软件使用Java语言提供的JavaMail包进行开发

package com.lanx.app.security.base64;

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;
import javax.crypto.spec.IvParameterSpec;

import sun.misc.BASE64Decoder;

/**
 * <p>解密类</p>
 * 
 * @author Ramboo Lan
 * @version 0.5
 * @Date: 2006-06-09
 */
public class DocDecoder extends AbstractDocCoder {
    public DocDecoder() {
        super();
    }

	/**
	 * 对字符串或者文件进行解密处理
	 * 
	 * @param str        需要解密的字符串或者文件路径
	 * */
    public String decode(String str) throws Exception {    	
        // Decode encryption data        
        BASE64Decoder base64 = new BASE64Decoder();
        byte[] sorData = base64.decodeBuffer(str);

        // Decrypting data
        byte[] retByte = decodeByteData(sorData);

        return new String(retByte);
    }

    private byte[] decodeByteData(byte[] sourceData) throws Exception {
        // Create SecretKey object
        byte[] encryptionByte = encryptionString.getBytes();
        DESKeySpec dks = new DESKeySpec(encryptionByte);
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
        SecretKey securekey = keyFactory.generateSecret(dks);

        // Create IvParameterSpec object with initialization vector
        IvParameterSpec spec=new IvParameterSpec(encryptionIV);
        Cipher cipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
        cipher.init(Cipher.DECRYPT_MODE, securekey, spec);

        return cipher.doFinal(sourceData);
    }
}