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package org.openslx.imagemaster.util;
import java.security.MessageDigest;
import java.nio.charset.Charset;
import java.security.NoSuchAlgorithmException;
public class Hash
{
/**
* Cache of md5 digesters
*/
private static final ThreadLocal<MessageDigest> md5hash = new ThreadLocal<MessageDigest>() {
@Override
public MessageDigest initialValue()
{
try {
return MessageDigest.getInstance( "MD5" );
} catch ( NoSuchAlgorithmException e ) {
e.printStackTrace();
System.exit( 1 );
return null;
}
}
};
/**
* Cache of sha256 digesters
*/
private static final ThreadLocal<MessageDigest> sha256hash = new ThreadLocal<MessageDigest>() {
@Override
public MessageDigest initialValue()
{
try {
return MessageDigest.getInstance( "SHA-256" );
} catch ( NoSuchAlgorithmException e ) {
e.printStackTrace();
System.exit( 1 );
return null;
}
}
};
/**
* For converting to hex string
*/
private static final char[] HEX_CHARS = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };
/**
* Constant for the utf-8 charset, saves repeated lookups
*/
private static final Charset UTF8 = Charset.forName( "UTF-8" );
// MD5
/**
* Compute md5 hash of given binary data.
*
* @param bytes the binary data in a byte array
* @return hex representation of the 128bit md5 hash
*/
public static String md5( final byte[] bytes )
{
return toHexString( md5hash.get().digest( bytes ) );
}
/**
* Compute md5 hash of the given string.
* The string will be converted to utf-8 before computation.
*
* @param text the text to hash
* @return hex representation of the 128bit md5 hash
*/
public static String md5( final String text )
{
return md5( text.getBytes( UTF8 ) );
}
// SHA-256
/**
* Compute sha256 hash of given binary data.
*
* @param bytes the binary data in a byte array
* @return hex representation of the 256bit sha256 hash
*/
public static String sha256( final byte[] bytes )
{
return toHexString( sha256hash.get().digest( bytes ) );
}
/**
* Compute sha256 hash of the given string.
* The string will be converted to utf-8 before computation.
*
* @param text the text to hash
* @return hex representation of the 256bit sha256 hash
*/
public static String sha256( final String text )
{
return sha256( text.getBytes( UTF8 ) );
}
// Helper
/**
* Convert given binary data to hex.
*
* @param bytes binary data in a byte array
* @return upper case hex representation of bytes
*/
private static String toHexString( final byte[] bytes )
{
final char[] hexChars = new char[ bytes.length * 2 ];
for ( int j = 0; j < bytes.length; ++j ) {
final int v = bytes[j] & 0xFF;
hexChars[j * 2] = HEX_CHARS[v >>> 4];
hexChars[j * 2 + 1] = HEX_CHARS[v & 0x0F];
}
return new String( hexChars );
}
}
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