Posts tagged Java

Download HashSum.java

/**
* A class for calculating hash sum in files or strings
* using all the hash algorithms supported by Java
*
* @author Olaf Reitmaier
* @version December, 2005
*/
import java.security.NoSuchAlgorithmException;
import java.security.MessageDigest;

import java.io.File;
import java.io.FileInputStream;
import java.io.BufferedInputStream;
import java.io.IOException;

public class HashSum{

public static final int BUFFER_SIZE = 1024; //The maximun buffer size

private MessageDigest msgDigest; //The message digest processor
private String hashStr; //The result sum of the digest commited with the hash algoritm

/**
* Creates a new hash processor
* @param algorithm The name of the algorithm (MD5, SHA-1, SHA-256, SHA-512, etc). See Java 2 documentacion.
*/
public HashSum(String algorithm) throws NoSuchAlgorithmException{
msgDigest = MessageDigest.getInstance(algorithm);
}

/**
* Calculate the hash sum of a file
* @param srcFile The file to be processed
* @return A byte array with the hash sum value (Must be converted to Hexadecimal)
*/
public byte [] calculate(File srcFile) throws IOException{
boolean ready = false;
int bytesOnBuffer = 0;
byte[] text = null;
FileInputStream fis = new FileInputStream(srcFile);
msgDigest.reset(); //Initialize the hashing proccessor
while(!ready){
bytesOnBuffer = fis.available(); //Available bytes on buffer
if (bytesOnBuffer >= BUFFER_SIZE){ // If there are too much bytes
text = new byte[BUFFER_SIZE]; //Create a new fixed buffer
fis.read(text, 0, BUFFER_SIZE);
msgDigest.update(text); //Hash
}else{
//If there are few bytes
if (bytesOnBuffer > 0){ //
text = new byte[bytesOnBuffer]; //Create a new fixed buffer
fis.read(text, 0, bytesOnBuffer); //Read all the last bytes
msgDigest.update(text); //Hash the last bytes
}
ready = true;
}
}
fis.close();
if (ready){
return msgDigest.digest(); //Final operations (padding)
}else{
return null; //No digest was done!!!
}
}

/**
* Calculate the hash sum of a string
* @param str The string to be processed
* @return A byte array with the hash sum value (Must be converted to Hexadecimal)
*/
public byte [] calculate(String str){
msgDigest.reset();
msgDigest.update(str.getBytes());
return msgDigest.digest();
}

/**
* Converts the byte array to string (Version #1)
* @param bytes The byte array
* @return A lower case string in hexadecimal notation
*/
public static String toHexString1(byte [] bytes) {
StringBuffer sb = new StringBuffer();
String s = null;
for (int i=0;i< s = "0"> 2) s = s.substring(s.length()-2);
sb.append(s);
}
return sb.toString();
}

/**
* Converts the byte array to string (Version #2)
* @param bytes The byte array
* @return A lower case string in hexadecimal notation
*/
public static String toHexString2(byte [] bytes) {
String HEX_DIGITS = "0123456789abcdef";
StringBuffer sb = new StringBuffer(bytes.length * 2);
int bValue = 0;
for (int i = 0; i < bvalue =" bytes[i]">>> 4))
.append(HEX_DIGITS.charAt(bValue & 0xF));
}
return sb.toString();
}
}