com.smallfe.clerk.util.DigestUtil.java Source code

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Here is the source code for com.smallfe.clerk.util.DigestUtil.java

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package com.smallfe.clerk.util;

import java.nio.charset.Charset;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.apache.commons.lang3.StringUtils;

/**
 * Write short comment related with created class
 * @author mkucukdemir
 */
public class DigestUtil {
    public static String getSHA256(String message) {
        try {
            MessageDigest md = MessageDigest.getInstance("SHA-256");
            md.update(message.getBytes());

            byte byteData[] = md.digest();

            //convert the byte to hex format method 1
            StringBuffer sb = new StringBuffer();
            for (int i = 0; i < byteData.length; i++) {
                sb.append(Integer.toString((byteData[i] & 0xff) + 0x100, 16).substring(1));
            }
            return sb.toString();
        } catch (NoSuchAlgorithmException ex) {
            Logger.getLogger(DigestUtil.class.getName()).log(Level.SEVERE, null, ex);
            return null;
        }
    }

    private static String decryptionAlphabet = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";

    public static String encryptEGM(String plainText) {
        StringBuilder cypherText = new StringBuilder();
        try {
            plainText = StringUtils.rightPad(plainText, ((plainText.length() - 1) / 3 + 1) * 3, (char) 0);
        } catch (NullPointerException ex) {
            Logger.getLogger(DigestUtil.class.getName()).log(Level.SEVERE, null, ex);
            return null;
        }
        for (int i = 0; i < plainText.length(); i += 3) {
            byte[] partitions = plainText.substring(i, i + 3).getBytes(Charset.forName("iso-8859-9"));
            int c1 = (int) (partitions[0]);
            if (c1 < 0)
                c1 += 256;
            int c2 = (int) (partitions[1]);
            if (c2 < 0)
                c2 += 256;
            int c3 = (int) (partitions[2]);
            if (c3 < 0)
                c3 += 256;

            int k1 = (c1) / 4;
            int k2 = (c1) % 4;
            int k3 = (c2) / 16;
            int k4 = (c2) % 16;
            int k5 = (c3) / 64;
            int k6 = (c3) % 64;

            char ec1 = decryptionAlphabet.charAt(k1);
            char ec2 = decryptionAlphabet.charAt(k3 + k2 * 16);
            char ec3 = decryptionAlphabet.charAt(k5 + k4 * 4);
            char ec4 = decryptionAlphabet.charAt(k6);

            cypherText.append(ec1);
            cypherText.append(ec2);
            if (c2 != 0)
                cypherText.append(ec3);
            if (c3 != 0)
                cypherText.append(ec4);
        }
        return cypherText.toString();
    }

public static String decryptEGM(String cypherText){
    StringBuilder plainText = new StringBuilder();
    try {
        cypherText = StringUtils.rightPad(cypherText, ((cypherText.length() - 1) / 4 + 1) * 4, (char)0);
    } catch (NullPointerException ex) {
        Logger.getLogger(DigestUtil.class.getName()).log(Level.SEVERE, null, ex);
        return null;
    }
    for (int i = 0; i < cypherText.length(); i+=4) {
        String partition = cypherText.substring(i, i+4);
        int c1 = decryptionAlphabet.indexOf(partition.charAt(0));
        int c2 = decryptionAlphabet.indexOf(partition.charAt(1)) + (partition.charAt(0) == '/' ? 64 : 0);
        int c3 = decryptionAlphabet.indexOf(partition.charAt(2)) + (partition.charAt(1) == '/' ? 64 : 0);
        int c4 = decryptionAlphabet.indexOf(partition.charAt(3)) + (partition.charAt(2) == '/' ? 64 : 0);
            
        int r1 = (c2 * 16) / 255;
        int r2 = (c3 * 64) / 255;
            
        char dc1 = (char)(c1 * 4 + r1);
        char dc2 = (char)((c2 * 16 + r2) % 256);
        int r3 = Math.min(254,(c3 - dc2 % 16 * 4) % 64 * 64 + c4);
        char dc3 = c4 != -1 ? (char)r3 : (char)0;
        plainText.append((dc1));
        if (c3 != -1) plainText.append((dc2));
        if (c4 != -1) plainText.append((dc3));
    }
    return plainText.toString().toUpperCase().replace('?', '#').replace('', '$').replace('?', '').replace('', 'I').replace('', '');
}
}