Provides Base64 encoding and decoding as defined by RFC 2045
/*
* Copyright 2001-2004 The Apache Software Foundation.
*
* Licensed 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 as defined by RFC 2045.
*
* <p>This class implements section <cite>6.8. Base64 Content-Transfer-Encoding</cite>
* from RFC 2045 <cite>Multipurpose Internet Mail Extensions (MIME) Part One:
* Format of Internet Message Bodies</cite> by Freed and Borenstein.</p>
*
* @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>
* @author Apache Software Foundation
* @since 1.0-dev
* @version SourceVerion: Base64.java,v 1.20 2004/05/24 00:21:24 ggregory Exp
*/
public class CommonsCodecBase64 {
/**
* Chunk size per RFC 2045 section 6.8.
*
* <p>The {@value} character limit does not count the trailing CRLF, but counts
* all other characters, including any equal signs.</p>
*
* @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045 section 6.8</a>
*/
static final int CHUNK_SIZE = 76;
/**
* Chunk separator per RFC 2045 section 2.1.
*
* @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045 section 2.1</a>
*/
static final byte[] CHUNK_SEPARATOR = "\r\n".getBytes();
/**
* 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;
/**
* Byte used to pad output.
*/
static final byte PAD = (byte) '=';
// Create arrays to hold the base64 characters and a
// lookup for base64 chars
private static byte[] base64Alphabet = new byte[BASELENGTH];
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) '/';
}
private static boolean isBase64(byte octect) {
if (octect == PAD) {
return true;
} else if (base64Alphabet[octect] == -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 true 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;
}
/**
* Encodes binary data using the base64 algorithm but
* does not chunk the output.
*
* @param binaryData binary data to encode
* @return Base64 characters
*/
public static byte[] encodeBase64(byte[] binaryData) {
return encodeBase64(binaryData, false);
}
/**
* Encodes binary data using the base64 algorithm and chunks
* the encoded output into 76 character blocks
*
* @param binaryData binary data to encode
* @return Base64 characters chunked in 76 character blocks
*/
public static byte[] encodeBase64Chunked(byte[] binaryData) {
return encodeBase64(binaryData, 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 DecoderException if the parameter supplied is not
* of type byte[]
*/
public Object decode(Object pObject) {
if (!(pObject instanceof byte[])) {
throw new RuntimeException("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, optionally
* chunking the output into 76 character blocks.
*
* @param binaryData Array containing binary data to encode.
* @param isChunked if isChunked is true this encoder will chunk
* the base64 output into 76 character blocks
* @return Base64-encoded data.
*/
public static byte[] encodeBase64(byte[] binaryData, boolean isChunked) {
int lengthDataBits = binaryData.length * EIGHTBIT;
int fewerThan24bits = lengthDataBits % TWENTYFOURBITGROUP;
int numberTriplets = lengthDataBits / TWENTYFOURBITGROUP;
byte encodedData[] = null;
int encodedDataLength = 0;
int nbrChunks = 0;
if (fewerThan24bits != 0) {
//data not divisible by 24 bit
encodedDataLength = (numberTriplets + 1) * 4;
} else {
// 16 or 8 bit
encodedDataLength = numberTriplets * 4;
}
// If the output is to be "chunked" into 76 character sections,
// for compliance with RFC 2045 MIME, then it is important to
// allow for extra length to account for the separator(s)
if (isChunked) {
nbrChunks =
(CHUNK_SEPARATOR.length == 0 ? 0 : (int) Math.ceil((float) encodedDataLength / CHUNK_SIZE));
encodedDataLength += nbrChunks * CHUNK_SEPARATOR.length;
}
encodedData = new byte[encodedDataLength];
byte k = 0, l = 0, b1 = 0, b2 = 0, b3 = 0;
int encodedIndex = 0;
int dataIndex = 0;
int i = 0;
int nextSeparatorIndex = CHUNK_SIZE;
int chunksSoFar = 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;
// If we are chunking, let's put a chunk separator down.
if (isChunked) {
// this assumes that CHUNK_SIZE % 4 == 0
if (encodedIndex == nextSeparatorIndex) {
System.arraycopy(
CHUNK_SEPARATOR,
0,
encodedData,
encodedIndex,
CHUNK_SEPARATOR.length);
chunksSoFar++;
nextSeparatorIndex =
(CHUNK_SIZE * (chunksSoFar + 1)) +
(chunksSoFar * CHUNK_SEPARATOR.length);
encodedIndex += CHUNK_SEPARATOR.length;
}
}
}
// 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];
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;
}
if (isChunked) {
// we also add a separator to the end of the final chunk.
if (chunksSoFar < nbrChunks) {
System.arraycopy(
CHUNK_SEPARATOR,
0,
encodedData,
encodedDataLength - CHUNK_SEPARATOR.length,
CHUNK_SEPARATOR.length);
}
}
return encodedData;
}
/**
* Decodes Base64 data into octects
*
* @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 / 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;
}
/**
* 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 EncoderException if the parameter supplied is not
* of type byte[]
*/
public Object encode(Object pObject) {
if (!(pObject instanceof byte[])) {
throw new RuntimeException(
"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, false);
}
}
Related examples in the same category