org.xbib.net.security.signatures.Base64 Maven / Gradle / Ivy
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package org.xbib.net.security.signatures;
/**
* Provides Base64 encoding and decoding as defined by RFC 2045.
*
* This class implements section 6.8. Base64 Content-Transfer-Encoding
* from RFC 2045 Multipurpose Internet Mail Extensions (MIME) Part One:
* Format of Internet Message Bodies by Freed and Borenstein.
*
* @see RFC 2045
*/
public class Base64 {
/**
* Chunk size per RFC 2045 section 6.8.
*
* The {@value} character limit does not count the trailing CRLF, but counts
* all other characters, including any equal signs.
*
* @see RFC 2045 section 6.8
*/
static final int CHUNK_SIZE = 76;
/**
* Chunk separator per RFC 2045 section 2.1.
*
* @see RFC 2045 section 2.1
*/
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) '=';
/**
* Contains the Base64 values 0 through 63 accessed by using character encodings as
* indices.
*
* For example, base64Alphabet['+'] returns 62.
*
*
* The value of undefined encodings is -1.
*
*/
private static final byte[] base64Alphabet = new byte[BASELENGTH];
/**
*
* Contains the Base64 encodings A through Z, followed by a through
* z, followed by 0 through 9, followed by +, and
* /.
*
*
* This array is accessed by using character values as indices.
*
*
* For example, lookUpBase64Alphabet[62] returns '+'.
*
*/
private static final byte[] lookUpBase64Alphabet = new byte[LOOKUPLENGTH];
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 Base64() {
}
/**
* 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(final byte[] binaryData) {
return encodeBase64(binaryData, false);
}
/**
* 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 true this encoder will chunk
* the base64 output into 76 character blocks
* @return Base64-encoded data.
*/
public static byte[] encodeBase64(final byte[] binaryData, final boolean isChunked) {
final int lengthDataBits = binaryData.length * EIGHTBIT;
final int fewerThan24bits = lengthDataBits % TWENTYFOURBITGROUP;
final int numberTriplets = lengthDataBits / TWENTYFOURBITGROUP;
byte[] encodedData;
int encodedDataLength;
int nbrChunks = 0;
if (fewerThan24bits != 0) {
encodedDataLength = (numberTriplets + 1) * 4;
} else {
encodedDataLength = numberTriplets * 4;
}
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;
byte l;
byte b1;
byte b2;
byte b3;
int encodedIndex = 0;
int dataIndex;
int i;
int nextSeparatorIndex = CHUNK_SIZE;
int chunksSoFar = 0;
for (i = 0; i < numberTriplets; i++) {
dataIndex = i * 3;
b1 = binaryData[dataIndex];
b2 = binaryData[dataIndex + 1];
b3 = binaryData[dataIndex + 2];
l = (byte) (b2 & 0x0f);
k = (byte) (b1 & 0x03);
final byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) : (byte) ((b1) >> 2 ^ 0xc0);
final byte val2 = ((b2 & SIGN) == 0) ? (byte) (b2 >> 4) : (byte) ((b2) >> 4 ^ 0xf0);
final byte val3 = ((b3 & SIGN) == 0) ? (byte) (b3 >> 6) : (byte) ((b3) >> 6 ^ 0xfc);
encodedData[encodedIndex] = lookUpBase64Alphabet[val1];
encodedData[encodedIndex + 1] = lookUpBase64Alphabet[val2 | (k << 4)];
encodedData[encodedIndex + 2] = lookUpBase64Alphabet[(l << 2) | val3];
encodedData[encodedIndex + 3] = lookUpBase64Alphabet[b3 & 0x3f];
encodedIndex += 4;
if (isChunked) {
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;
}
}
}
dataIndex = i * 3;
if (fewerThan24bits == EIGHTBIT) {
b1 = binaryData[dataIndex];
k = (byte) (b1 & 0x03);
final 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);
final byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) : (byte) ((b1) >> 2 ^ 0xc0);
final 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) {
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) {
base64Data = discardNonBase64(base64Data);
if (base64Data.length == 0) {
return new byte[0];
}
final int numberQuadruple = base64Data.length / FOURBYTE;
byte[] decodedData;
byte b1;
byte b2;
byte b3;
byte b4;
byte marker0;
byte marker1;
int encodedIndex = 0;
int dataIndex;
{
int lastData = base64Data.length;
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) {
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) {
decodedData[encodedIndex] = (byte) (b1 << 2 | b2 >> 4);
} else {
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 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).
*/
private static byte[] discardNonBase64(final byte[] data) {
final byte[] groomedData = new byte[data.length];
int bytesCopied = 0;
for (byte datum : data) {
if (isBase64(datum)) {
groomedData[bytesCopied++] = datum;
}
}
final byte[] packedData = new byte[bytesCopied];
System.arraycopy(groomedData, 0, packedData, 0, bytesCopied);
return packedData;
}
/**
* Returns whether or not the octect is in the base 64 alphabet.
*
* @param octect The value to test
* @return true if the value is defined in the the base 64 alphabet, false otherwise.
*/
private static boolean isBase64(final byte octect) {
if (octect == PAD) {
return true;
} else return octect >= 0 && base64Alphabet[octect] != -1;
}
}