Mega Code Archive
Base64 encoding and decoding with URL and filename safe alphabet as defined by RFC 3548, section 4
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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
* Provides Base64 encoding and decoding with URL and filename safe alphabet as defined by RFC 3548,
* section 4. <p/> This Base64 encoder is modified to meet URL requirements. The changes are: '+' =>
* '*', '/' => '-', and no padding. <p/> This class is taken from the Apache commons-codec, and
* adjusted to fit the Wicket framework's needs, especially external dependencies have been removed.
* </p>
* <p/> This class implements section <cite>4. Base 64 Encoding with URL and Filename Safe Alphabet</cite>
* from RFC 3548 <cite>The Base16, Base32, and Base64 Data Encodings</cite> by Simon Josefsson.
* </p>
*
* @author Apache Software Foundation
* @author Juergen Donnerstag
*
* @since 1.2
*/
public class Base64UrlSafe
{
/**
* The base length.
*/
static final int BASELENGTH = 255;
/**
* Lookup length.
*/
static final int LOOKUPLENGTH = 64;
/**
* Used to calculate the number of bits in a byte.
*/
static final int EIGHTBIT = 8;
/**
* Used when encoding something which has fewer than 24 bits.
*/
static final int SIXTEENBIT = 16;
/**
* Used to determine how many bits data contains.
*/
static final int TWENTYFOURBITGROUP = 24;
/**
* Used to get the number of Quadruples.
*/
static final int FOURBYTE = 4;
/**
* Used to test the sign of a byte.
*/
static final int SIGN = -128;
/**
* Contains the Base64 values <code>0</code> through <code>63</code> accessed by using
* character encodings as indices. <p/> For example, <code>base64Alphabet['+']</code> returns
* <code>62</code>.
* </p>
* <p/> The value of undefined encodings is <code>-1</code>.
* </p>
*/
private static byte[] base64Alphabet = new byte[BASELENGTH];
/**
* <p/> Contains the Base64 encodings <code>A</code> through <code>Z</code>, followed by
* <code>a</code> through <code>z</code>, followed by <code>0</code> through
* <code>9</code>, followed by <code>+</code>, and <code>/</code>.
* </p>
* <p/> This array is accessed by using character values as indices.
* </p>
* <p/> For example, <code>lookUpBase64Alphabet[62] </code> returns <code>'+'</code>.
* </p>
*/
private static byte[] lookUpBase64Alphabet = new byte[LOOKUPLENGTH];
// Populating the lookup and character arrays
static
{
for (int i = 0; i < BASELENGTH; i++)
{
base64Alphabet[i] = (byte)-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)'-';
}
/**
* Returns whether or not the <code>octet</code> is in the base 64 alphabet.
*
* @param octet
* The value to test
* @return <code>true</code> if the value is defined in the the base 64 alphabet,
* <code>false</code> otherwise.
*/
private static boolean isBase64(byte octet)
{
if (octet < 0 || base64Alphabet[octet] == -1)
{
return false;
}
else
{
return true;
}
}
/**
* Tests a given byte array to see if it contains only valid characters within the Base64
* alphabet.
*
* @param arrayOctect
* byte array to test
* @return <code>true</code> if all bytes are valid characters in the Base64 alphabet or if
* the byte array is empty; false, otherwise
*/
public static boolean isArrayByteBase64(byte[] arrayOctect)
{
arrayOctect = discardWhitespace(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 (!isBase64(arrayOctect[i]))
{
return false;
}
}
return true;
}
/**
* Decodes an Object using the base64 algorithm. This method is provided in order to satisfy the
* requirements of the Decoder interface, and will throw a DecoderException if the supplied
* object is not of type byte[].
*
* @param pObject
* Object to decode
* @return An object (of type byte[]) containing the binary data which corresponds to the byte[]
* supplied.
* @throws IllegalArgumentException
* if the parameter supplied is not of type byte[]
*/
public Object decode(Object pObject)
{
if (!(pObject instanceof byte[]))
{
throw new IllegalArgumentException(
"Parameter supplied to Base64 decode is not a byte[]");
}
return decode((byte[])pObject);
}
/**
* Decodes a byte[] containing containing characters in the Base64 alphabet.
*
* @param pArray
* A byte array containing Base64 character data
* @return a byte array containing binary data
*/
public byte[] decode(byte[] pArray)
{
return decodeBase64(pArray);
}
/**
* Encodes binary data using the base64 algorithm.
*
* @param binaryData
* Array containing binary data to encode.
* @return Base64-encoded data.
*/
public static byte[] encodeBase64(byte[] binaryData)
{
int lengthDataBits = binaryData.length * EIGHTBIT;
int fewerThan24bits = lengthDataBits % TWENTYFOURBITGROUP;
int numberTriplets = lengthDataBits / TWENTYFOURBITGROUP;
byte encodedData[] = null;
int encodedDataLength = 0;
if (fewerThan24bits != 0)
{
// data not divisible by 24 bit
encodedDataLength = (numberTriplets + 1) * 4;
}
else
{
// 16 or 8 bit
encodedDataLength = numberTriplets * 4;
}
if (fewerThan24bits == EIGHTBIT)
{
encodedDataLength -= 2;
}
else if (fewerThan24bits == SIXTEENBIT)
{
encodedDataLength -= 1;
}
encodedData = new byte[encodedDataLength];
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);
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];
encodedIndex += 4;
}
// form integral number of 6-bit groups
dataIndex = i * 3;
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];
}
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];
}
return encodedData;
}
/**
* Decodes Base64 data into octets
*
* @param base64Data
* Byte array containing Base64 data
* @return Array containing decoded data.
*/
public static byte[] decodeBase64(byte[] base64Data)
{
// RFC 2045 requires that we discard ALL non-Base64 characters
base64Data = discardNonBase64(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 + 3) / FOURBYTE;
byte decodedData[] = new byte[base64Data.length - numberQuadruple];
byte b1 = 0, b2 = 0, b3 = 0, b4 = 0;
// Throw away anything not in base64Data
int encodedIndex = 0;
int dataIndex = 0;
for (int i = 0; i < numberQuadruple; i++)
{
dataIndex = i * 4;
b1 = base64Alphabet[base64Data[dataIndex]];
b2 = base64Alphabet[base64Data[dataIndex + 1]];
if ((dataIndex + 3) < base64Data.length)
{
// No PAD e.g 3cQl
b3 = base64Alphabet[base64Data[dataIndex + 2]];
b4 = base64Alphabet[base64Data[dataIndex + 3]];
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 ((dataIndex + 2) < base64Data.length)
{
// One PAD e.g. 3cQ[Pad]
b3 = base64Alphabet[base64Data[dataIndex + 2]];
decodedData[encodedIndex] = (byte)(b1 << 2 | b2 >> 4);
decodedData[encodedIndex + 1] = (byte)(((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
}
else if ((dataIndex + 1) < base64Data.length)
{
// Two PAD e.g. 3c[Pad][Pad]
decodedData[encodedIndex] = (byte)(b1 << 2 | b2 >> 4);
}
encodedIndex += 3;
}
return decodedData;
}
/**
* Discards any whitespace from a base-64 encoded block.
*
* @param data
* The base-64 encoded data to discard the whitespace from.
* @return The data, less whitespace (see RFC 2045).
*/
static byte[] discardWhitespace(byte[] data)
{
byte groomedData[] = new byte[data.length];
int bytesCopied = 0;
for (int i = 0; i < data.length; i++)
{
switch (data[i])
{
case (byte)' ' :
case (byte)'\n' :
case (byte)'\r' :
case (byte)'\t' :
break;
default :
groomedData[bytesCopied++] = data[i];
}
}
byte packedData[] = new byte[bytesCopied];
System.arraycopy(groomedData, 0, packedData, 0, bytesCopied);
return packedData;
}
/**
* Discards any characters outside of the base64 alphabet, per the requirements on page 25 of
* RFC 2045 - "Any characters outside of the base64 alphabet are to be ignored in base64 encoded
* data."
*
* @param data
* The base-64 encoded data to groom
* @return The data, less non-base64 characters (see RFC 2045).
*/
static byte[] discardNonBase64(byte[] data)
{
byte groomedData[] = new byte[data.length];
int bytesCopied = 0;
for (int i = 0; i < data.length; i++)
{
if (isBase64(data[i]))
{
groomedData[bytesCopied++] = data[i];
}
}
byte packedData[] = new byte[bytesCopied];
System.arraycopy(groomedData, 0, packedData, 0, bytesCopied);
return packedData;
}
// Implementation of the Encoder Interface
/**
* Encodes an Object using the base64 algorithm. This method is provided in order to satisfy the
* requirements of the Encoder interface, and will throw an EncoderException if the supplied
* object is not of type byte[].
*
* @param pObject
* Object to encode
* @return An object (of type byte[]) containing the base64 encoded data which corresponds to
* the byte[] supplied.
* @throws IllegalArgumentException
* if the parameter supplied is not of type byte[]
*/
public Object encode(Object pObject)
{
if (!(pObject instanceof byte[]))
{
throw new IllegalArgumentException(
"Parameter supplied to Base64 encode is not a byte[]");
}
return encode((byte[])pObject);
}
/**
* Encodes a byte[] containing binary data, into a byte[] containing characters in the Base64
* alphabet.
*
* @param pArray
* a byte array containing binary data
* @return A byte array containing only Base64 character data
*/
public byte[] encode(byte[] pArray)
{
return encodeBase64(pArray);
}
}
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