[JAVA] 자바(JSP)를 이용한 암호화 기능 만들기

출처 : http://sunfuture.springnote.com/pages/3554173

● 관련내용 : http://www.okjsp.pe.kr/seq/62218

① 입력된 데이터를 암호화하는 서블릿 작성

파일명 : LocalEncrypter.java

package encrypt;

import java.security.InvalidKeyException;
import java.security.Key;
 
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.KeyGenerator;
 
import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;
 
public class LocalEncrypter{
    //DESede 는 암호화시 사용되는 최대 키 사이즈를 지정하는 키워드임 : 관련페이지 내용 링크
    private static String algorithm = "DESede";
    private static Key    key       = null;
    private static Cipher cipher    = null;
 
    public static String returnEncryptCode(String str) throws Exception {
        byte [] encryptionBytes = null;
       
        setUp();
              
        // 입력받은 문자열을 암호화 하는 부분
        encryptionBytes = encrypt( str );
        BASE64Encoder encoder = new BASE64Encoder();
         String encodeString = encoder.encode(encryptionBytes);
         //encoder.encode(encryptionBytes) 으로 encrypt 된 값 출력
        return encodeString;
    }

private static void setUp() throws Exception {
        key = KeyGenerator.getInstance( algorithm ).generateKey();
        cipher = Cipher.getInstance( algorithm );
    }

public static String returnDecryptCode(String str) throws Exception {
        BASE64Decoder decoder = new BASE64Decoder();
        String decode = decrypt( decoder.decodeBuffer(str) );
        return decode;
    }
 
    // encryptionBytes = encrypt( input ), input을 변조하여 encryptionBytes에 대입함.
    private static byte [] encrypt(String input) throws InvalidKeyException, BadPaddingException, IllegalBlockSizeException  {
        cipher.init( Cipher.ENCRYPT_MODE, key );
        byte [] inputBytes = input.getBytes();
        return cipher.doFinal( inputBytes );
    }
 
    //decrypt( decoder.decodeBuffer(encodeString) ) 처리부분.
    private static String decrypt(byte [] encryptionBytes) throws InvalidKeyException, BadPaddingException, IllegalBlockSizeException {
        cipher.init( Cipher.DECRYPT_MODE, key );
        byte [] recoveredBytes = cipher.doFinal( encryptionBytes );
        String recovered = new String( recoveredBytes );
        return recovered;
    }
 
}

② 간단한 입력폼 : InputCode.jsp

이 곳에서 문자열을 입력받아, InputCodeProc.jsp 에서 <jsp:useBean> 을 활용하여 암호화(변조, 복조)를 실시한다.

<%@ page language="java" contentType="text/html; charset=EUC-KR"
    pageEncoding="EUC-KR"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=EUC-KR">
<title>Insert title here</title>

.another_category h4 {
    font-size: 12px !important;
    margin: 0 !important;
    border-bottom: 1px solid #E5E5E5 !important;
    padding: 2px 0 6px !important;
}

.another_category h4 a {
    font-weight: bold !important;
}

.another_category table {
    table-layout: fixed;
    border-collapse: collapse;
    width: 100% !important;
    margin-top: 10px !important;
}

* html .another_category table {
    width: auto !important;
}

*:first-child + html .another_category table {
    width: auto !important;
}

.another_category th, .another_category td {
    padding: 0 0 4px !important;
}

.another_category th {
    text-align: left;
    font-size: 12px !important;
    font-weight: normal;
    word-break: break-all;
    overflow: hidden;
    line-height: 1.5;
}

.another_category td {
    text-align: right;
    width: 80px;
    font-size: 11px;
}

.another_category th a {
    font-weight: normal;
    text-decoration: none;
    border: none !important;
}

.another_category th a.current {
    font-weight: bold;
    text-decoration: none !important;
    border-bottom: 1px solid !important;
}

.another_category th span {
    font-weight: normal;
    text-decoration: none;
    font: 10px Tahoma, Sans-serif;
    border: none !important;
}

.another_category_color_gray, .another_category_color_gray h4 {
    border-color: #E5E5E5 !important;
}

.another_category_color_gray * {
    color: #909090 !important;
}

.another_category_color_gray th a.current {
    border-color: #909090 !important;
}

.another_category_color_gray h4, .another_category_color_gray h4 a {
    color: #737373 !important;
}

.another_category_color_red, .another_category_color_red h4 {
    border-color: #F6D4D3 !important;
}

.another_category_color_red * {
    color: #E86869 !important;
}

.another_category_color_red th a.current {
    border-color: #E86869 !important;
}

.another_category_color_red h4, .another_category_color_red h4 a {
    color: #ED0908 !important;
}

.another_category_color_green, .another_category_color_green h4 {
    border-color: #CCE7C8 !important;
}

.another_category_color_green * {
    color: #64C05B !important;
}

.another_category_color_green th a.current {
    border-color: #64C05B !important;
}

.another_category_color_green h4, .another_category_color_green h4 a {
    color: #3EA731 !important;
}

.another_category_color_blue, .another_category_color_blue h4 {
    border-color: #C8DAF2 !important;
}

.another_category_color_blue * {
    color: #477FD6 !important;
}

.another_category_color_blue th a.current {
    border-color: #477FD6 !important;
}

.another_category_color_blue h4, .another_category_color_blue h4 a {
    color: #1960CA !important;
}

.another_category_color_violet, .another_category_color_violet h4 {
    border-color: #E1CEEC !important;
}

.another_category_color_violet * {
    color: #9D64C5 !important;
}

.another_category_color_violet th a.current {
    border-color: #9D64C5 !important;
}

.another_category_color_violet h4, .another_category_color_violet h4 a {
    color: #7E2CB5 !important;
}
</style>

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</head>
<body>
    <form method=post action='InputCodeProc.jsp'>
    <table border='1'>
    <tr><th>키워드입력</th><td><input type='text' name='code'></td></tr>
    <tr><td colspan='2'><input type='submit'></td></tr>
    </form>

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③ 암호화처리 : InputCodeProc.jsp

InputCode.jsp 에서 code 파라메터를 받아내서 LocalEncrypter.java 에서 returnEncryptCode(code); 로 넣어준다.

<%@ page language="java" contentType="text/html; charset=EUC-KR"  pageEncoding="EUC-KR"%>
<jsp:useBean id="enc" class="encrypt.LocalEncrypter" />
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