Господа, мне нужно написать раскодировщик сабжа. Не подскажет ли кто, где найти описание формата base64, а еще лучше алгоритмы раскодирования сего дела?
С уважением, Сергей
/*
* $Header: /home/cvspublic/jakarta-tomcat-4.0/catalina/src/share/org/apache/catalina/util/Base64.java,v 1.4 2001/09/04 21:49:55 craigmcc Exp $
* $Revision: 1.4 $
* $Date: 2001/09/04 21:49:55 $
*
* ====================================================================
*
* The Apache Software License, Version 1.1
*
* Copyright (c) 1999 The Apache Software Foundation. All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. The end-user documentation included with the redistribution, if
* any, must include the following acknowlegement:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowlegement may appear in the software itself,
* if and wherever such third-party acknowlegements normally appear.
*
* 4. The names "The Jakarta Project", "Tomcat", and "Apache Software
* Foundation" must not be used to endorse or promote products derived
* from this software without prior written permission. For written
* permission, please contact apache@apache.org.
*
* 5. Products derived from this software may not be called "Apache"
* nor may "Apache" appear in their names without prior written
* permission of the Apache Group.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
* <http://www.apache.org/>.
*
* [Additional notices, if required by prior licensing conditions]
*
*/package org.apache.catalina.util;
/**
* This class provides encode/decode for RFC 2045 Base64 as defined by
* RFC 2045, N. Freed and N. Borenstein. <a
* href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>:
* Multipurpose Internet Mail Extensions (MIME) Part One: Format of
* Internet Message Bodies. Reference 1996
*
* @author Jeffrey Rodriguez
* @version $Id: Base64.java,v 1.4 2001/09/04 21:49:55 craigmcc Exp $
*/
public final class Base64
{
static private final int BASELENGTH = 255;
static private final int LOOKUPLENGTH = 64;
static private final int TWENTYFOURBITGROUP = 24;
static private final int EIGHTBIT = 8;
static private final int SIXTEENBIT = 16;
static private final int SIXBIT = 6;
static private final int FOURBYTE = 4;
static private final int SIGN = -128;
static private final byte PAD = (byte) '=';
static private byte [] base64Alphabet = new byte[BASELENGTH];
static private byte [] lookUpBase64Alphabet = new byte[LOOKUPLENGTH];
//static private final Log log = LogSource.getInstance("org.apache.commons.util.Base64");static
{
for (int i = 0; i < BASELENGTH; i++ )
{
base64Alphabet[i] = -1;
}
for (int i = 'Z'; i >= 'A'; i--)
{
base64Alphabet[i] = (byte) (i - 'A');
}
for (int i = 'z'; i>= 'a'; i--)
{
base64Alphabet[i] = (byte) (i - 'a' + 26);
}
for (int i = '9'; i >= '0'; i--)
{
base64Alphabet[i] = (byte) (i - '0' + 52);
}base64Alphabet['+'] = 62;
base64Alphabet['/'] = 63;for (int i = 0; i <= 25; i++ )
lookUpBase64Alphabet[i] = (byte) ('A' + i);for (int i = 26, j = 0; i <= 51; i++, j++ )
lookUpBase64Alphabet[i] = (byte) ('a'+ j);for (int i = 52, j = 0; i <= 61; i++, j++ )
lookUpBase64Alphabet[i] = (byte) ('0' + j);lookUpBase64Alphabet[62] = (byte) '+';
lookUpBase64Alphabet[63] = (byte) '/';
}public static boolean isBase64( String isValidString )
{
return isArrayByteBase64(isValidString.getBytes());
}public static boolean isBase64( byte octect )
{
//shall we ignore white space? JEFF??
return (octect == PAD || base64Alphabet[octect] != -1);
}public static boolean isArrayByteBase64( byte[] arrayOctect )
{
int length = arrayOctect.length;
if (length == 0)
{
// shouldn't a 0 length array be valid base64 data?
// return false;
return true;
}
for (int i=0; i < length; i++)
{
if ( !Base64.isBase64(arrayOctect[i]) )
return false;
}
return true;
}/**
* Encodes hex octects into Base64.
*
* @param binaryData Array containing binary data to encode.
* @return Base64-encoded data.
*/
public static byte[] encode( byte[] binaryData )
{
int lengthDataBits = binaryData.length*EIGHTBIT;
int fewerThan24bits = lengthDataBits%TWENTYFOURBITGROUP;
int numberTriplets = lengthDataBits/TWENTYFOURBITGROUP;
byte encodedData[] = null;
if (fewerThan24bits != 0)
{
//data not divisible by 24 bit
encodedData = new byte[ (numberTriplets + 1 ) * 4 ];
}
else
{
// 16 or 8 bit
encodedData = new byte[ numberTriplets * 4 ];
}byte k = 0, l = 0, b1 = 0, b2 = 0, b3 = 0;
int encodedIndex = 0;
int dataIndex = 0;
int i = 0;
//log.debug("number of triplets = " + numberTriplets);
for ( i = 0; i<numberTriplets; i++ )
{
dataIndex = i*3;
b1 = binaryData[dataIndex];
b2 = binaryData[dataIndex + 1];
b3 = binaryData[dataIndex + 2];//log.debug("b1= " + b1 +", b2= " + b2 + ", b3= " + b3);
l = (byte)(b2 & 0x0f);
k = (byte)(b1 & 0x03);encodedIndex = i * 4;
byte val1 = ((b1 & SIGN)==0)?(byte)(b1>>2):(byte)((b1)>>2^0xc0);
byte val2 = ((b2 & SIGN)==0)?(byte)(b2>>4):(byte)((b2)>>4^0xf0);
byte val3 = ((b3 & SIGN)==0)?(byte)(b3>>6):(byte)((b3)>>6^0xfc);encodedData[encodedIndex] = lookUpBase64Alphabet[ val1 ];
//log.debug( "val2 = " + val2 );
//log.debug( "k4 = " + (k<<4) );
//log.debug( "vak = " + (val2 | (k<<4)) );
encodedData[encodedIndex+1] =
lookUpBase64Alphabet[ val2 | ( k<<4 )];
encodedData[encodedIndex+2] =
lookUpBase64Alphabet[ (l <<2 ) | val3 ];
encodedData[encodedIndex+3] = lookUpBase64Alphabet[ b3 & 0x3f ];
}// form integral number of 6-bit groups
dataIndex = i*3;
encodedIndex = i*4;
if (fewerThan24bits == EIGHTBIT )
{
b1 = binaryData[dataIndex];
k = (byte) ( b1 &0x03 );
//log.debug("b1=" + b1);
//log.debug("b1<<2 = " + (b1>>2) );
byte val1 = ((b1 & SIGN)==0)?(byte)(b1>>2):(byte)((b1)>>2^0xc0);
encodedData[encodedIndex] = lookUpBase64Alphabet[ val1 ];
encodedData[encodedIndex + 1] = lookUpBase64Alphabet[ k<<4 ];
encodedData[encodedIndex + 2] = PAD;
encodedData[encodedIndex + 3] = PAD;
}
else if (fewerThan24bits == SIXTEENBIT)
{b1 = binaryData[dataIndex];
b2 = binaryData[dataIndex +1 ];
l = (byte) (b2 & 0x0f);
k = (byte) (b1 & 0x03);byte val1 = ((b1 & SIGN) == 0)?(byte)(b1>>2):(byte)((b1)>>2^0xc0);
byte val2 = ((b2 & SIGN) == 0)?(byte)(b2>>4):(byte)((b2)>>4^0xf0);encodedData[encodedIndex] = lookUpBase64Alphabet[ val1 ];
encodedData[encodedIndex + 1] =
lookUpBase64Alphabet[ val2 | ( k<<4 )];
encodedData[encodedIndex + 2] = lookUpBase64Alphabet[ l<<2 ];
encodedData[encodedIndex + 3] = PAD;
}return encodedData;
}/**
* Decodes Base64 data into octects
*
* @param binaryData Byte array containing Base64 data
* @return Array containing decoded data.
*/
public static byte[] decode( byte[] base64Data )
{
// handle the edge case, so we don't have to worry about it later
if(base64Data.length == 0) { return new byte[0]; }int numberQuadruple = base64Data.length/FOURBYTE;
byte decodedData[] = null;
byte b1=0,b2=0,b3=0, b4=0, marker0=0, marker1=0;// Throw away anything not in base64Data
int encodedIndex = 0;
int dataIndex = 0;
{
// this sizes the output array properly - rlw
int lastData = base64Data.length;
// ignore the '=' padding
while (base64Data[lastData-1] == PAD)
{
if (--lastData == 0)
{
return new byte[0];
}
}
decodedData = new byte[ lastData - numberQuadruple ];
}for (int i = 0; i < numberQuadruple; i++)
{
dataIndex = i * 4;
marker0 = base64Data[dataIndex + 2];
marker1 = base64Data[dataIndex + 3];b1 = base64Alphabet[base64Data[dataIndex]];
b2 = base64Alphabet[base64Data[dataIndex +1]];if (marker0 != PAD && marker1 != PAD)
{
//No PAD e.g 3cQl
b3 = base64Alphabet[ marker0 ];
b4 = base64Alphabet[ marker1 ];decodedData[encodedIndex] = (byte)( b1 <<2 | b2>>4 ) ;
decodedData[encodedIndex + 1] =
(byte)(((b2 & 0xf)<<4 ) |( (b3>>2) & 0xf) );
decodedData[encodedIndex + 2] = (byte)( b3<<6 | b4 );
}
else if (marker0 == PAD)
{
//Two PAD e.g. 3c[Pad][Pad]
decodedData[encodedIndex] = (byte)( b1 <<2 | b2>>4 ) ;
}
else if (marker1 == PAD)
{
//One PAD e.g. 3cQ[Pad]
b3 = base64Alphabet[ marker0 ];decodedData[encodedIndex] = (byte)( b1 <<2 | b2>>4 );
decodedData[encodedIndex + 1] =
(byte)(((b2 & 0xf)<<4 ) |( (b3>>2) & 0xf) );
}
encodedIndex += 3;
}
return decodedData;
}
}
>Господа, мне нужно написать раскодировщик сабжа. Не подскажет ли кто, где найти
>описание формата base64, а еще лучше алгоритмы раскодирования сего дела?
>С уважением, Сергей
мне кажется ваш вопрос решается легко на перловке:#!/usr/local/bin/perl -w
use MIME::Base64;my $normaltext="Normal text";
my $encoded=encode_base64($normaltext);#кодируем
my $decoded=decode_base64($encoded);#декодируем
>Господа, мне нужно написать раскодировщик сабжа. Не подскажет ли кто, где найти
>описание формата base64, а еще лучше алгоритмы раскодирования сего дела?
>С уважением, Сергей
и еще... в портах БСД-шных лежит утилка base64 - кодирует/декодирует, в принципе если тебе надо узнать алгоритм - возьми сырцы порта и все
>Господа, мне нужно написать раскодировщик сабжа. Не подскажет ли кто, где найти
>описание формата base64, а еще лучше алгоритмы раскодирования сего дела?
>С уважением, Сергей
// This function takes a BASE64 encoded string pointed by *text
// and returns appropriate string in plain ASCII.
// You should always free() the result string when
// you are done with it.
char *base64_to_ascii(char *text)
{
char *c, *new, *out;
char chunk[4];
int count;count = strlen(text);
new = (char *)malloc(count + 1);
if(!new) return NULL;out = new;
count = 0;
while(*text) {
c = strchr(base64, (int)*text);
if(c) {
chunk[count] = (char)(c - base64);
count++;
if(count == 4) {
out[0] = (chunk[0] << 2) | (chunk[1] >> 4);
out[1] = (chunk[1] << 4) | (chunk[2] >> 2);
out[2] = (chunk[2] << 6) | (chunk[3]);
out += 3;
count = 0;
}
}
text++;
}*out = 0;
return new;
}