보안|개인정보 보호 및 암호화

1. 단방향 암호화: SHA-512 알고리즘 사용     - 대상: 비밀번호 2. 양방향 암호화: AES256 알고리즘 사용     - 대상: 성명, 주소, 이메일, 핸드폰, 주민번호, 카드번호, 계좌번호 등

JAVA AES256 알고리즘

import sun.misc.BASE64Encoder; 
import sun.misc.BASE64Decoder; 
  
import javax.crypto.*; 
import javax.crypto.spec.SecretKeySpec; 
import java.io.*; 
import java.security.NoSuchAlgorithmException; 
  
public class AES256 { 
  public static SecretKeySpec getKeySpec() throws IOException, NoSuchAlgorithmException { 
        byte[] bytes = new byte[32]; 
        SecretKey key = null; 
        SecretKeySpec spec = null; 
/*  
        File f = new File("aes_key"); 
        if (f.exists()) { 
          new FileInputStream(f).read(bytes); 
        } else { 
           KeyGenerator kgen = KeyGenerator.getInstance("AES"); 
           kgen.init(256); 
           key = kgen.generateKey(); 
           bytes1 = key.getEncoded(); 
           new FileOutputStream(f).write(bytes1); 
        } 
*/
        String keyStr="암호화된 대칭키";
        bytes = Base64Utils.base64Decode(keyStr);

        spec = new SecretKeySpec(bytes,"AES"); 
        return spec; 
  } 


  public String encrypt(String text) throws Exception { 
        SecretKeySpec spec = getKeySpec(); 
        Cipher cipher = Cipher.getInstance("AES"); 
        cipher.init(Cipher.ENCRYPT_MODE, spec); 
        BASE64Encoder enc = new BASE64Encoder(); 

        return enc.encode(cipher.doFinal(text.getBytes())).toString(); 
  } 
  public String decrypt(String text) throws Exception { 
        SecretKeySpec spec = getKeySpec(); 
        Cipher cipher = Cipher.getInstance("AES"); 
        cipher.init(Cipher.DECRYPT_MODE, spec); 
        BASE64Decoder dec = new BASE64Decoder(); 
        return new String(cipher.doFinal(dec.decodeBuffer(text))); 
  } 
  public static void main(String[] args) throws Exception { 
        String mode = "encrypt"; 
        String text = "!mpluse0218"; 
        String encText = "";
        String decText = "";
        AES256 aes = new AES256();
        encText=aes.encrypt(text); 
        System.out.println("5ClhQFro0UAI+LrZkilamw==");
          System.out.println("enc::"+encText);
        decText = aes.decrypt(encText); 
        System.out.println("dec::"+decText);
  } 
}

SHA512 알고리즘

http://www.docjar.com/html/api/gnu/java/security/hash/Sha512.java.html
http://blog.fethilale.com/sha512-hashing-on-java/

JAVA MessageDigest Class 활용한 방법

http://java.sun.com/j2se/1.4.2/docs/api/java/security/MessageDigest.html (JavaTM 2 Platform Std. Ed. v1.4.2)

This MessageDigest class provides applications the functionality of a message digest algorithm, such as MD5 or SHA. Message digests are secure one-way hash functions that take arbitrary-sized data and output a fixed-length hash value.

import java.security.*;
 
public class cryptotest {
    public static void main(String[] args) throws NoSuchAlgorithmException {
        MessageDigest md;
        String message = "password";
        try {
            md= MessageDigest.getInstance("SHA-512");
 
            md.update(message.getBytes());
            byte[] mb = md.digest();
            String out = "";
            for (int i = 0; i < mb.length; i++) {
                byte temp = mb[i];
                String s = Integer.toHexString(new Byte(temp));
                while (s.length() < 2) {ㄴ
                    s = "0" + s;
                }
                s = s.substring(s.length() - 2);
                out += s;
            }
            System.out.println(out.length());
            System.out.println("CRYPTO: " + out);
 
        } catch (NoSuchAlgorithmException e) {
            System.out.println("ERROR: " + e.getMessage());
        }
    }
}

If you want to hash password with SHA256, you can change the line:

md= 


MessageDigest.getInstance("SHA-512");

to

md= MessageDigest.getInstance("SHA-256");

For others:

md= MessageDigest.getInstance("MD5");
md= MessageDigest.getInstance("SHA");
md= MessageDigest.getInstance("SHA-1");
md= MessageDigest.getInstance("SHA-384");