package com.android.vending.billing;
import android.annotation.SuppressLint;
import android.support.annotation.NonNull;
// This code was converted from code at http://iharder.sourceforge.net/base64/
// Lots of extraneous features were removed.
/*
* The original code said:
* <p>
* I am placing this code in the Public Domain. Do with it as you will.
* This software comes with no guarantees or warranties but with
* plenty of well-wishing instead!
* Please visit
* <a href="http://iharder.net/xmlizable">http://iharder.net/xmlizable</a>
* periodically to check for updates or to contribute improvements.
* </p>
*
* @author Robert Harder
*
* @author rharder@usa.net
*
* @version 1.3
*/
/**
* Base64 converter class. This code is not a complete MIME encoder; it simply converts binary data to base64 data and
* back.
*
* <p>Note CharBase64 is a GWT-compatible implementation of this class.
*/
public final class Base64 {
/**
* Specify encoding (value is {@code true}).
*/
public static final boolean ENCODE = true;
/**
* Specify decoding (value is {@code false}).
*/
public static final boolean DECODE = false;
/**
* The equals sign (=) as a byte.
*/
private static final byte EQUALS_SIGN = (byte) '=';
/**
* The new line character (\n) as a byte.
*/
private static final byte NEW_LINE = (byte) '\n';
/**
* The 64 valid Base64 values.
*/
private static final byte[] ALPHABET =
{(byte) 'A', (byte) 'B', (byte) 'C', (byte) 'D', (byte) 'E', (byte) 'F',
(byte) 'G', (byte) 'H', (byte) 'I', (byte) 'J', (byte) 'K',
(byte) 'L', (byte) 'M', (byte) 'N', (byte) 'O', (byte) 'P',
(byte) 'Q', (byte) 'R', (byte) 'S', (byte) 'T', (byte) 'U',
(byte) 'V', (byte) 'W', (byte) 'X', (byte) 'Y', (byte) 'Z',
(byte) 'a', (byte) 'b', (byte) 'c', (byte) 'd', (byte) 'e',
(byte) 'f', (byte) 'g', (byte) 'h', (byte) 'i', (byte) 'j',
(byte) 'k', (byte) 'l', (byte) 'm', (byte) 'n', (byte) 'o',
(byte) 'p', (byte) 'q', (byte) 'r', (byte) 's', (byte) 't',
(byte) 'u', (byte) 'v', (byte) 'w', (byte) 'x', (byte) 'y',
(byte) 'z', (byte) '0', (byte) '1', (byte) '2', (byte) '3',
(byte) '4', (byte) '5', (byte) '6', (byte) '7', (byte) '8',
(byte) '9', (byte) '+', (byte) '/'};
/**
* The 64 valid web safe Base64 values.
*/
private static final byte[] WEBSAFE_ALPHABET =
{(byte) 'A', (byte) 'B', (byte) 'C', (byte) 'D', (byte) 'E', (byte) 'F',
(byte) 'G', (byte) 'H', (byte) 'I', (byte) 'J', (byte) 'K',
(byte) 'L', (byte) 'M', (byte) 'N', (byte) 'O', (byte) 'P',
(byte) 'Q', (byte) 'R', (byte) 'S', (byte) 'T', (byte) 'U',
(byte) 'V', (byte) 'W', (byte) 'X', (byte) 'Y', (byte) 'Z',
(byte) 'a', (byte) 'b', (byte) 'c', (byte) 'd', (byte) 'e',
(byte) 'f', (byte) 'g', (byte) 'h', (byte) 'i', (byte) 'j',
(byte) 'k', (byte) 'l', (byte) 'm', (byte) 'n', (byte) 'o',
(byte) 'p', (byte) 'q', (byte) 'r', (byte) 's', (byte) 't',
(byte) 'u', (byte) 'v', (byte) 'w', (byte) 'x', (byte) 'y',
(byte) 'z', (byte) '0', (byte) '1', (byte) '2', (byte) '3',
(byte) '4', (byte) '5', (byte) '6', (byte) '7', (byte) '8',
(byte) '9', (byte) '-', (byte) '_'};
/**
* Translates a Base64 value to either its 6-bit reconstruction value or a negative number indicating some other
* meaning.
**/
private static final byte[] DECODABET = {-9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 0 - 8
-5, -5, // Whitespace: Tab and Linefeed
-9, -9, // Decimal 11 - 12
-5, // Whitespace: Carriage Return
-9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 14 - 26
-9, -9, -9, -9, -9, // Decimal 27 - 31
-5, // Whitespace: Space
-9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 33 - 42
62, // Plus sign at decimal 43
-9, -9, -9, // Decimal 44 - 46
63, // Slash at decimal 47
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, // Numbers zero through nine
-9, -9, -9, // Decimal 58 - 60
-1, // Equals sign at decimal 61
-9, -9, -9, // Decimal 62 - 64
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, // Letters 'A' through 'N'
14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, // Letters 'O' through 'Z'
-9, -9, -9, -9, -9, -9, // Decimal 91 - 96
26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, // Letters 'a' through 'm'
39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, // Letters 'n' through 'z'
-9, -9, -9, -9, -9 // Decimal 123 - 127
/*
* ,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 128 - 139 -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, //
* Decimal 140 - 152 -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 153 - 165
* -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 166 - 178 -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, //
* Decimal 179 - 191 -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 192 - 204
* -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 205 - 217 -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, //
* Decimal 218 - 230 -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 231 - 243
* -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9 // Decimal 244 - 255
*/
};
/**
* The web safe decodabet.
*/
private static final byte[] WEBSAFE_DECODABET =
{-9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 0 - 8
-5, -5, // Whitespace: Tab and Linefeed
-9, -9, // Decimal 11 - 12
-5, // Whitespace: Carriage Return
-9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 14 - 26
-9, -9, -9, -9, -9, // Decimal 27 - 31
-5, // Whitespace: Space
-9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 33 - 44
62, // Dash '-' sign at decimal 45
-9, -9, // Decimal 46-47
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, // Numbers zero through nine
-9, -9, -9, // Decimal 58 - 60
-1, // Equals sign at decimal 61
-9, -9, -9, // Decimal 62 - 64
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, // Letters 'A' through 'N'
14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, // Letters 'O' through 'Z'
-9, -9, -9, -9, // Decimal 91-94
63, // Underscore '_' at decimal 95
-9, // Decimal 96
26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, // Letters 'a' through 'm'
39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, // Letters 'n' through 'z'
-9, -9, -9, -9, -9 // Decimal 123 - 127
/*
* ,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 128 - 139 -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, //
* Decimal 140 - 152 -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 153 - 165
* -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 166 - 178 -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, //
* Decimal 179 - 191 -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 192 - 204
* -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 205 - 217 -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, //
* Decimal 218 - 230 -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 231 - 243
* -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9 // Decimal 244 - 255
*/
};
/**
* Indicates white space in encoding.
*/
private static final byte WHITE_SPACE_ENC = -5;
/**
* Indicates equals sign in encoding.
*/
private static final byte EQUALS_SIGN_ENC = -1;
/**
* Defeats instantiation.
*/
private Base64() {
}
/* ******** E N C O D I N G M E T H O D S ******** */
/**
* Encodes up to three bytes of the array <var>source</var> and writes the resulting four Base64 bytes to
* <var>destination</var>. The source and destination arrays can be manipulated anywhere along their length by
* specifying <var>srcOffset</var> and <var>destOffset</var>. This method does not check to make sure your arrays
* are large enough to accommodate <var>srcOffset</var> + 3 for the <var>source</var> array or <var>destOffset</var>
* + 4 for the <var>destination</var> array. The actual number of significant bytes in your array is given by
* <var>numSigBytes</var>.
*
* @param source the array to convert
* @param srcOffset the index where conversion begins
* @param numSigBytes the number of significant bytes in your array
* @param destination the array to hold the conversion
* @param destOffset the index where output will be put
* @param alphabet is the encoding alphabet
* @return the <var>destination</var> array
* @since 1.3
*/
private static byte[] encode3to4(final byte[] source, final int srcOffset,
final int numSigBytes, final byte[] destination, final int destOffset, final byte[] alphabet) {
// 1 2 3
// 01234567890123456789012345678901 Bit position
// --------000000001111111122222222 Array position from threeBytes
// --------| || || || | Six bit groups to index alphabet
// >>18 >>12 >> 6 >> 0 Right shift necessary
// 0x3f 0x3f 0x3f Additional AND
// Create buffer with zero-padding if there are only one or two
// significant bytes passed in the array.
// We have to shift left 24 in order to flush out the 1's that appear
// when Java treats a value as negative that is cast from a byte to an int.
int inBuff =
(numSigBytes > 0 ? ((source[srcOffset] << 24) >>> 8) : 0) // MAGIC_NUMBER
| (numSigBytes > 1 ? ((source[srcOffset + 1] << 24) >>> 16) : 0) // MAGIC_NUMBER
| (numSigBytes > 2 ? ((source[srcOffset + 2] << 24) >>> 24) : 0); // MAGIC_NUMBER
switch (numSigBytes) {
case 3: // MAGIC_NUMBER
destination[destOffset] = alphabet[inBuff >>> 18]; // MAGIC_NUMBER
destination[destOffset + 1] = alphabet[(inBuff >>> 12) & 0x3f]; // MAGIC_NUMBER
destination[destOffset + 2] = alphabet[(inBuff >>> 6) & 0x3f]; // MAGIC_NUMBER
destination[destOffset + 3] = alphabet[inBuff & 0x3f]; // MAGIC_NUMBER
return destination;
case 2:
destination[destOffset] = alphabet[inBuff >>> 18]; // MAGIC_NUMBER
destination[destOffset + 1] = alphabet[(inBuff >>> 12) & 0x3f]; // MAGIC_NUMBER
destination[destOffset + 2] = alphabet[(inBuff >>> 6) & 0x3f]; // MAGIC_NUMBER
destination[destOffset + 3] = EQUALS_SIGN; // MAGIC_NUMBER
return destination;
case 1:
destination[destOffset] = alphabet[inBuff >>> 18]; // MAGIC_NUMBER
destination[destOffset + 1] = alphabet[(inBuff >>> 12) & 0x3f]; // MAGIC_NUMBER
destination[destOffset + 2] = EQUALS_SIGN;
destination[destOffset + 3] = EQUALS_SIGN; // MAGIC_NUMBER
return destination;
default:
return destination;
} // end switch
} // end encode3to4
/**
* Encodes a byte array into Base64 notation. Equivalent to calling {@code encodeBytes(source, 0, source.length)}
*
* @param source The data to convert
* @return the encoded data.
* @since 1.4
*/
@NonNull
public static String encode(@NonNull final byte[] source) {
return encode(source, 0, source.length, ALPHABET, true);
}
/**
* Encodes a byte array into web safe Base64 notation.
*
* @param source The data to convert
* @param doPadding is {@code true} to pad result with '=' chars if it does not fall on 3 byte boundaries
* @return the encoded byte array.
*/
@NonNull
public static String encodeWebSafe(@NonNull final byte[] source, final boolean doPadding) {
return encode(source, 0, source.length, WEBSAFE_ALPHABET, doPadding);
}
/**
* Encodes a byte array into Base64 notation.
*
* @param source the data to convert
* @param off offset in array where conversion should begin
* @param len length of data to convert
* @param alphabet the encoding alphabet
* @param doPadding is {@code true} to pad result with '=' chars if it does not fall on 3 byte boundaries
* @return the encoded byte array.
* @since 1.4
*/
@NonNull
private static String encode(final byte[] source, final int off, final int len, final byte[] alphabet,
final boolean doPadding) {
byte[] outBuff = encode(source, off, len, alphabet, Integer.MAX_VALUE);
int outLen = outBuff.length;
// If doPadding is false, set length to truncate '='
// padding characters
while (!doPadding && outLen > 0) {
if (outBuff[outLen - 1] != '=') {
break;
}
outLen -= 1;
}
return new String(outBuff, 0, outLen);
}
/**
* Encodes a byte array into Base64 notation.
*
* @param source the data to convert
* @param off offset in array where conversion should begin
* @param len length of data to convert
* @param alphabet is the encoding alphabet
* @param maxLineLength maximum length of one line.
* @return the BASE64-encoded byte array
*/
@NonNull
@SuppressLint("Assert")
private static byte[] encode(final byte[] source, final int off, final int len, final byte[] alphabet,
final int maxLineLength) {
int lenDiv3 = (len + 2) / 3; // ceil(len / 3) - MAGIC_NUMBER
int len43 = lenDiv3 * 4; // MAGIC_NUMBER
byte[] outBuff = new byte[len43 // Main 4:3
+ (len43 / maxLineLength)]; // New lines
int d = 0;
int e = 0;
int len2 = len - 2;
int lineLength = 0;
for (; d < len2; d += 3, e += 4) { // MAGIC_NUMBER
// The following block of code is the same as
// encode3to4( source, d + off, 3, outBuff, e, alphabet );
// but inlined for faster encoding (~20% improvement)
int inBuff =
((source[d + off] << 24) >>> 8) // MAGIC_NUMBER
| ((source[d + 1 + off] << 24) >>> 16) // MAGIC_NUMBER
| ((source[d + 2 + off] << 24) >>> 24); // MAGIC_NUMBER
outBuff[e] = alphabet[inBuff >>> 18]; // MAGIC_NUMBER
outBuff[e + 1] = alphabet[(inBuff >>> 12) & 0x3f]; // MAGIC_NUMBER
outBuff[e + 2] = alphabet[(inBuff >>> 6) & 0x3f]; // MAGIC_NUMBER
outBuff[e + 3] = alphabet[inBuff & 0x3f]; // MAGIC_NUMBER
lineLength += 4; // MAGIC_NUMBER
if (lineLength == maxLineLength) {
outBuff[e + 4] = NEW_LINE; // MAGIC_NUMBER
e++;
lineLength = 0;
} // end if: end of line
} // end for: each piece of array
if (d < len) {
encode3to4(source, d + off, len - d, outBuff, e, alphabet);
lineLength += 4; // MAGIC_NUMBER
if (lineLength == maxLineLength) {
// Add a last newline
outBuff[e + 4] = NEW_LINE; // MAGIC_NUMBER
e++;
}
e += 4; // MAGIC_NUMBER
}
assert e == outBuff.length;
return outBuff;
}
/* ******** D E C O D I N G M E T H O D S ******** */
/**
* Decodes four bytes from array <var>source</var> and writes the resulting bytes (up to three of them) to
* <var>destination</var>. The source and destination arrays can be manipulated anywhere along their length by
* specifying <var>srcOffset</var> and <var>destOffset</var>. This method does not check to make sure your arrays
* are large enough to accommodate <var>srcOffset</var> + 4 for the <var>source</var> array or <var>destOffset</var>
* + 3 for the <var>destination</var> array. This method returns the actual number of bytes that were converted from
* the Base64 encoding.
*
* @param source the array to convert
* @param srcOffset the index where conversion begins
* @param destination the array to hold the conversion
* @param destOffset the index where output will be put
* @param decodabet the decodabet for decoding Base64 content
* @return the number of decoded bytes converted
* @since 1.3
*/
private static int decode4to3(final byte[] source, final int srcOffset,
final byte[] destination, final int destOffset, final byte[] decodabet) {
// Example: Dk==
if (source[srcOffset + 2] == EQUALS_SIGN) {
int outBuff =
((decodabet[source[srcOffset]] << 24) >>> 6) // MAGIC_NUMBER
| ((decodabet[source[srcOffset + 1]] << 24) >>> 12); // MAGIC_NUMBER
destination[destOffset] = (byte) (outBuff >>> 16); // MAGIC_NUMBER
return 1;
}
else if (source[srcOffset + 3] == EQUALS_SIGN) { // MAGIC_NUMBER
// Example: DkL=
int outBuff =
((decodabet[source[srcOffset]] << 24) >>> 6) // MAGIC_NUMBER
| ((decodabet[source[srcOffset + 1]] << 24) >>> 12) // MAGIC_NUMBER
| ((decodabet[source[srcOffset + 2]] << 24) >>> 18); // MAGIC_NUMBER
destination[destOffset] = (byte) (outBuff >>> 16); // MAGIC_NUMBER
destination[destOffset + 1] = (byte) (outBuff >>> 8); // MAGIC_NUMBER
return 2;
}
else {
// Example: DkLE
int outBuff =
((decodabet[source[srcOffset]] << 24) >>> 6) // MAGIC_NUMBER
| ((decodabet[source[srcOffset + 1]] << 24) >>> 12) // MAGIC_NUMBER
| ((decodabet[source[srcOffset + 2]] << 24) >>> 18) // MAGIC_NUMBER
| ((decodabet[source[srcOffset + 3]] << 24) >>> 24); // MAGIC_NUMBER
destination[destOffset] = (byte) (outBuff >> 16); // MAGIC_NUMBER
destination[destOffset + 1] = (byte) (outBuff >> 8); // MAGIC_NUMBER
destination[destOffset + 2] = (byte) outBuff;
return 3; // MAGIC_NUMBER
}
} // end decodeToBytes
/**
* Decodes data from Base64 notation.
*
* @param s the string to decode (decoded in default encoding)
* @return the decoded data
* @throws Base64DecoderException thrown if there is an exception while decoding.
* @since 1.4
*/
@NonNull
public static byte[] decode(@NonNull final String s) throws Base64DecoderException {
byte[] bytes = s.getBytes();
return decode(bytes, 0, bytes.length);
}
/**
* Decodes data from web safe Base64 notation. Web safe encoding uses '-' instead of '+', '_' instead of '/'
*
* @param s the string to decode (decoded in default encoding)
* @return the decoded data
* @throws Base64DecoderException thrown if there is an exception while decoding.
*/
@NonNull
public static byte[] decodeWebSafe(@NonNull final String s) throws Base64DecoderException {
byte[] bytes = s.getBytes();
return decodeWebSafe(bytes, 0, bytes.length);
}
/**
* Decodes Base64 content in byte array format and returns the decoded byte array.
*
* @param source The Base64 encoded data
* @return decoded data
* @throws Base64DecoderException thrown if there is an exception while decoding.
* @since 1.3
*/
@NonNull
public static byte[] decode(@NonNull final byte[] source) throws Base64DecoderException {
return decode(source, 0, source.length);
}
/**
* Decodes web safe Base64 content in byte array format and returns the decoded data. Web safe encoding uses '-'
* instead of '+', '_' instead of '/'
*
* @param source the string to decode (decoded in default encoding)
* @return the decoded data
* @throws Base64DecoderException thrown if there is an exception while decoding.
*/
@NonNull
public static byte[] decodeWebSafe(@NonNull final byte[] source)
throws Base64DecoderException {
return decodeWebSafe(source, 0, source.length);
}
/**
* Decodes Base64 content in byte array format and returns the decoded byte array.
*
* @param source the Base64 encoded data
* @param off the offset of where to begin decoding
* @param len the length of characters to decode
* @return decoded data
* @throws Base64DecoderException thrown if there is an exception while decoding.
* @since 1.3
*/
@NonNull
private static byte[] decode(final byte[] source, final int off, final int len)
throws Base64DecoderException {
return decode(source, off, len, DECODABET);
}
/**
* Decodes web safe Base64 content in byte array format and returns the decoded byte array. Web safe encoding uses
* '-' instead of '+', '_' instead of '/'
*
* @param source the Base64 encoded data
* @param off the offset of where to begin decoding
* @param len the length of characters to decode
* @return decoded data
* @throws Base64DecoderException thrown if there is an exception while decoding.
*/
@NonNull
private static byte[] decodeWebSafe(final byte[] source, final int off, final int len)
throws Base64DecoderException {
return decode(source, off, len, WEBSAFE_DECODABET);
}
/**
* Decodes Base64 content using the supplied decodabet and returns the decoded byte array.
*
* @param source the Base64 encoded data
* @param off the offset of where to begin decoding
* @param len the length of characters to decode
* @param decodabet the decodabet for decoding Base64 content
* @return decoded data
* @throws Base64DecoderException thrown if there is an exception while decoding.
*/
@NonNull
private static byte[] decode(final byte[] source, final int off, final int len, final byte[] decodabet)
throws Base64DecoderException {
int len34 = len * 3 / 4; // MAGIC_NUMBER
byte[] outBuff = new byte[2 + len34]; // Upper limit on size of output
int outBuffPosn = 0;
byte[] b4 = new byte[4]; // MAGIC_NUMBER
int b4Posn = 0;
byte sbiCrop;
byte sbiDecode;
for (int i = 0; i < len; i++) {
sbiCrop = (byte) (source[i + off] & 0x7f); // Only the low seven bits - MAGIC_NUMBER
sbiDecode = decodabet[sbiCrop];
if (sbiDecode >= WHITE_SPACE_ENC) { // White space Equals sign or better
if (sbiDecode >= EQUALS_SIGN_ENC) {
// An equals sign (for padding) must not occur at position 0 or 1
// and must be the last byte[s] in the encoded value
if (sbiCrop == EQUALS_SIGN) {
int bytesLeft = len - i;
byte lastByte = (byte) (source[len - 1 + off] & 0x7f); // MAGIC_NUMBER
if (b4Posn == 0 || b4Posn == 1) {
throw new Base64DecoderException(
"invalid padding byte '=' at byte offset " + i);
}
else if ((b4Posn == 3 && bytesLeft > 2) // MAGIC_NUMBER
|| (b4Posn == 4 && bytesLeft > 1)) { // MAGIC_NUMBER
throw new Base64DecoderException(
"padding byte '=' falsely signals end of encoded value "
+ "at offset " + i);
}
else if (lastByte != EQUALS_SIGN && lastByte != NEW_LINE) {
throw new Base64DecoderException(
"encoded value has invalid trailing byte");
}
break;
}
b4[b4Posn++] = sbiCrop;
if (b4Posn == 4) { // MAGIC_NUMBER
outBuffPosn += decode4to3(b4, 0, outBuff, outBuffPosn, decodabet);
b4Posn = 0;
}
}
}
else {
throw new Base64DecoderException("Bad Base64 input character at " + i
+ ": " + source[i + off] + "(decimal)");
}
}
// Because web safe encoding allows non padding base64 encodes, we
// need to pad the rest of the b4 buffer with equal signs when
// b4Posn != 0. There can be at most 2 equal signs at the end of
// four characters, so the b4 buffer must have two or three
// characters. This also catches the case where the input is
// padded with EQUALS_SIGN
if (b4Posn != 0) {
if (b4Posn == 1) {
throw new Base64DecoderException("single trailing character at offset "
+ (len - 1));
}
b4[b4Posn++] = EQUALS_SIGN;
outBuffPosn += decode4to3(b4, 0, outBuff, outBuffPosn, decodabet);
}
byte[] out = new byte[outBuffPosn];
System.arraycopy(outBuff, 0, out, 0, outBuffPosn);
return out;
}
}