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/*
* Copyright (C) 2014-2024 Philip Helger (www.helger.com)
* philip[at]helger[dot]com
*
* 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.
*/
package com.helger.commons.codec;
import java.io.IOException;
import java.io.OutputStream;
import javax.annotation.Nonnegative;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import javax.annotation.WillNotClose;
import com.helger.commons.exception.InitializationException;
import com.helger.commons.math.MathHelper;
/**
* Base32 encoder and decoder based on Apache Commons Codec Base32. Defined in
* RFC 4648. BASE32 characters are 5 bits in length. They are formed by taking a
* block of five octets to form a 40-bit string, which is converted into eight
* BASE32 characters.
* RFC 3548 and defines only the "regular encoding". RFC 4648 adds the "hex
* encoding". So when using the "regular encoding" it is compliant to both
* RFCs.
* Source: https://tools.ietf.org/html/rfc4648
* Source: https://tools.ietf.org/html/rfc3548
*
* @author Philip Helger
*/
public class Base32Codec implements IByteArrayCodec
{
/**
* This array is a lookup table that translates Unicode characters drawn from
* the "Base32 Alphabet" (as specified in Table 3 of RFC 4648) into their
* 5-bit positive integer equivalents. Characters that are not in the Base32
* alphabet but fall within the bounds of the array are translated to -1.
*/
private static final byte [] DECODE_TABLE = { // 00-0f
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
// 10-1f
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
// 20-2f
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
// 30-3f 2-7
-1,
-1,
26,
27,
28,
29,
30,
31,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
// 40-4f A-N
-1,
0,
1,
2,
3,
4,
5,
6,
7,
8,
9,
10,
11,
12,
13,
14,
// 50-5a O-Z
15,
16,
17,
18,
19,
20,
21,
22,
23,
24,
25 };
/**
* This array is a lookup table that translates 5-bit positive integer index
* values into their "Base32 Alphabet" equivalents as specified in Table 3 of
* RFC 4648.
*/
private static final byte [] ENCODE_TABLE = { 'A',
'B',
'C',
'D',
'E',
'F',
'G',
'H',
'I',
'J',
'K',
'L',
'M',
'N',
'O',
'P',
'Q',
'R',
'S',
'T',
'U',
'V',
'W',
'X',
'Y',
'Z',
'2',
'3',
'4',
'5',
'6',
'7' };
/**
* This array is a lookup table that translates Unicode characters drawn from
* the "Base32 |Hex Alphabet" (as specified in Table 3 of RFC 4648) into their
* 5-bit positive integer equivalents. Characters that are not in the Base32
* Hex alphabet but fall within the bounds of the array are translated to -1.
*/
private static final byte [] HEX_DECODE_TABLE = { // 00-0f
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
// 10-1f
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
// 20-2f
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
// 30-3f 2-7
0,
1,
2,
3,
4,
5,
6,
7,
8,
9,
-1,
-1,
-1,
-1,
-1,
-1,
// 40-4f A-N
-1,
10,
11,
12,
13,
14,
15,
16,
17,
18,
19,
20,
21,
22,
23,
24,
// 50-57 O-V
25,
26,
27,
28,
29,
30,
31,
32
};
/**
* This array is a lookup table that translates 5-bit positive integer index
* values into their "Base32 Hex Alphabet" equivalents as specified in Table 3
* of RFC 4648.
*/
private static final byte [] HEX_ENCODE_TABLE = { '0',
'1',
'2',
'3',
'4',
'5',
'6',
'7',
'8',
'9',
'A',
'B',
'C',
'D',
'E',
'F',
'G',
'H',
'I',
'J',
'K',
'L',
'M',
'N',
'O',
'P',
'Q',
'R',
'S',
'T',
'U',
'V' };
static
{
if (ENCODE_TABLE.length != 32)
throw new InitializationException ("ENCODE_TABLE");
if (HEX_ENCODE_TABLE.length != 32)
throw new InitializationException ("HEX_ENCODE_TABLE");
}
/** Mask used to extract 5 bits, used when encoding Base32 bytes */
private static final int MASK_5BITS = 0x1f;
/**
* Byte used to pad output.
*/
private static final byte DEFAULT_PAD = '=';
private byte m_nPad = DEFAULT_PAD;
private boolean m_bAddPadding = true;
/**
* Encode table to use.
*/
private byte [] m_aEncodeTable;
/**
* Decode table to use.
*/
private byte [] m_aDecodeTable;
/**
* Creates a Base32 codec used for decoding and encoding.
*/
public Base32Codec ()
{
this (false);
}
/**
* Creates a Base32 codec used for decoding and encoding.
*
* @param bUseHex
* true to use hex encoding, false to use
* regular encoding.
*/
public Base32Codec (final boolean bUseHex)
{
if (bUseHex)
{
m_aEncodeTable = HEX_ENCODE_TABLE;
m_aDecodeTable = HEX_DECODE_TABLE;
}
else
{
m_aEncodeTable = ENCODE_TABLE;
m_aDecodeTable = DECODE_TABLE;
}
}
public boolean isHexEncoding ()
{
return m_aEncodeTable == HEX_ENCODE_TABLE;
}
public byte getPad ()
{
return m_nPad;
}
/**
* Returns whether or not the {@code nOctet} is in the Base32 alphabet.
*
* @param nOctet
* The value to test
* @return {@code true} if the value is defined in the the Base32 alphabet
* {@code false} otherwise.
*/
private boolean _isInAlphabet (final byte nOctet)
{
return nOctet >= 0 && nOctet < m_aDecodeTable.length && m_aDecodeTable[nOctet] != -1;
}
/**
* Checks if a byte value is whitespace or not. Whitespace is taken to mean:
* space, tab, CR, LF
*
* @param nByte
* the byte to check
* @return true if byte is whitespace, false
* otherwise
*/
private static boolean _isWhiteSpace (final byte nByte)
{
return nByte == ' ' || nByte == '\n' || nByte == '\r' || nByte == '\t';
}
@Nonnull
public Base32Codec setPad (final byte nPad)
{
if (_isInAlphabet (nPad) || _isWhiteSpace (nPad))
throw new IllegalArgumentException ("pad must not be in alphabet or whitespace");
m_nPad = nPad;
return this;
}
public boolean isAddPadding ()
{
return m_bAddPadding;
}
@Nonnull
public Base32Codec setAddPaddding (final boolean bAddPadding)
{
m_bAddPadding = bAddPadding;
return this;
}
@Override
public int getMaximumEncodedLength (final int nLen)
{
return MathHelper.getRoundedUp (nLen * 8 / 5, 8);
}
public void encode (@Nullable final byte [] aDecodedBuffer,
@Nonnegative final int nOfs,
@Nonnegative final int nLen,
@Nonnull @WillNotClose final OutputStream aOS)
{
if (aDecodedBuffer == null || nLen == 0)
return;
// Save to local variables for performance reasons
final byte nPad = m_nPad;
final byte [] aEncodeTable = m_aEncodeTable;
int nRest = nLen;
int nIndex = nOfs;
while (nRest > 0)
{
try
{
switch (nRest)
{
case 1:
{
// Only 1 octet = 8 bits to use; 2 encoded and 6 padding bytes
final int nCur = aDecodedBuffer[nIndex] & 0xff;
nIndex += nRest;
// 8-1*5
aOS.write (aEncodeTable[(nCur >> 3) & MASK_5BITS]);
// 5-3=2
aOS.write (aEncodeTable[(nCur << 2) & MASK_5BITS]);
if (m_bAddPadding)
for (int i = 0; i < 6; ++i)
aOS.write (nPad);
nRest = 0;
break;
}
case 2:
{
// 2 octets = 16 bits to use; 4 encoded and 4 padding bytes
final int nCur = (aDecodedBuffer[nIndex] & 0xff) << 8 | (aDecodedBuffer[nIndex + 1] & 0xff);
nIndex += nRest;
// 16-1*5
aOS.write (aEncodeTable[(nCur >> 11) & MASK_5BITS]);
// 16-2*5
aOS.write (aEncodeTable[(nCur >> 6) & MASK_5BITS]);
// 16-3*5
aOS.write (aEncodeTable[(nCur >> 1) & MASK_5BITS]);
// 5-1
aOS.write (aEncodeTable[(nCur << 4) & MASK_5BITS]);
if (m_bAddPadding)
for (int i = 0; i < 4; ++i)
aOS.write (nPad);
nRest = 0;
break;
}
case 3:
{
// 3 octets = 24 bits to use; 5 encoded and 3 padding bytes
final int nCur = (aDecodedBuffer[nIndex] & 0xff) << 16 |
(aDecodedBuffer[nIndex + 1] & 0xff) << 8 |
(aDecodedBuffer[nIndex + 2] & 0xff);
nIndex += nRest;
// 24-1*5
aOS.write (aEncodeTable[(nCur >> 19) & MASK_5BITS]);
// 24-2*5
aOS.write (aEncodeTable[(nCur >> 14) & MASK_5BITS]);
// 24-3*5
aOS.write (aEncodeTable[(nCur >> 9) & MASK_5BITS]);
// 24-4*5
aOS.write (aEncodeTable[(nCur >> 4) & MASK_5BITS]);
// 5-4
aOS.write (aEncodeTable[(nCur << 1) & MASK_5BITS]);
if (m_bAddPadding)
for (int i = 0; i < 3; ++i)
aOS.write (nPad);
nRest = 0;
break;
}
case 4:
{
// 4 octets = 32 bits to use; 7 encoded and 1 padding byte
final int nCur = (aDecodedBuffer[nIndex] & 0xff) << 24 |
(aDecodedBuffer[nIndex + 1] & 0xff) << 16 |
(aDecodedBuffer[nIndex + 2] & 0xff) << 8 |
(aDecodedBuffer[nIndex + 3] & 0xff);
nIndex += nRest;
// 32-1*5
aOS.write (aEncodeTable[(nCur >> 27) & MASK_5BITS]);
// 32-2*5
aOS.write (aEncodeTable[(nCur >> 22) & MASK_5BITS]);
// 32-3*5
aOS.write (aEncodeTable[(nCur >> 17) & MASK_5BITS]);
// 32-4*5
aOS.write (aEncodeTable[(nCur >> 12) & MASK_5BITS]);
// 32-5*5
aOS.write (aEncodeTable[(nCur >> 7) & MASK_5BITS]);
// 32-6*5
aOS.write (aEncodeTable[(nCur >> 2) & MASK_5BITS]);
// 5-2
aOS.write (aEncodeTable[(nCur << 3) & MASK_5BITS]);
if (m_bAddPadding)
aOS.write (nPad);
nRest = 0;
break;
}
default:
{
// More than 5 octets = 40 bits to use; 8 encoded bytes
final long nCur = (long) (aDecodedBuffer[nIndex] & 0xff) << 32 |
(long) (aDecodedBuffer[nIndex + 1] & 0xff) << 24 |
(long) (aDecodedBuffer[nIndex + 2] & 0xff) << 16 |
(long) (aDecodedBuffer[nIndex + 3] & 0xff) << 8 |
(aDecodedBuffer[nIndex + 4] & 0xff);
nIndex += 5;
// 40-1*5
aOS.write (aEncodeTable[(int) (nCur >> 35) & MASK_5BITS]);
// 40-2*5
aOS.write (aEncodeTable[(int) (nCur >> 30) & MASK_5BITS]);
// 40-3*5
aOS.write (aEncodeTable[(int) (nCur >> 25) & MASK_5BITS]);
// 40-4*5
aOS.write (aEncodeTable[(int) (nCur >> 20) & MASK_5BITS]);
// 40-5*5
aOS.write (aEncodeTable[(int) (nCur >> 15) & MASK_5BITS]);
// 40-6*5
aOS.write (aEncodeTable[(int) (nCur >> 10) & MASK_5BITS]);
// 40-7*5
aOS.write (aEncodeTable[(int) (nCur >> 5) & MASK_5BITS]);
// 40-8*5
aOS.write (aEncodeTable[(int) nCur & MASK_5BITS]);
nRest -= 5;
break;
}
}
}
catch (final IOException ex)
{
throw new EncodeException ("Failed to encode Base32", ex);
}
}
}
@Override
public int getMaximumDecodedLength (final int nLen)
{
return MathHelper.getRoundedUp (nLen, 8) * 5 / 8;
}
public void decode (@Nullable final byte [] aEncodedBuffer,
@Nonnegative final int nOfs,
@Nonnegative final int nLen,
@Nonnull @WillNotClose final OutputStream aOS)
{
if (aEncodedBuffer == null || nLen == 0)
return;
// Save to local variables for performance reasons
final byte nPad = m_nPad;
final byte [] aDecodeTable = m_aDecodeTable;
final byte [] aDecodeBuf = new byte [8];
int nRest = nLen;
int nIndex = nOfs;
while (nRest > 0)
{
// Decode at maximum 8 bytes
int nBytesToDecode = Math.min (nRest, 8);
nRest -= nBytesToDecode;
for (int i = 0; i < nBytesToDecode; ++i)
{
final int n = aEncodedBuffer[nIndex++] & 0xff;
if (n == nPad)
{
// Padding means end of data
nBytesToDecode = i;
break;
}
final byte b = n >= aDecodeTable.length ? -1 : aDecodeTable[n];
if (b < 0)
throw new DecodeException ("Cannot Base32 decode char " + n);
aDecodeBuf[i] = b;
}
try
{
switch (nBytesToDecode)
{
case 0:
break;
case 2:
aOS.write (aDecodeBuf[0] << 3 | aDecodeBuf[1] >> 2);
break;
case 4:
aOS.write (aDecodeBuf[0] << 3 | aDecodeBuf[1] >> 2);
aOS.write (aDecodeBuf[1] << 6 | aDecodeBuf[2] << 1 | aDecodeBuf[3] >> 4);
break;
case 5:
aOS.write (aDecodeBuf[0] << 3 | aDecodeBuf[1] >> 2);
aOS.write (aDecodeBuf[1] << 6 | aDecodeBuf[2] << 1 | aDecodeBuf[3] >> 4);
aOS.write (aDecodeBuf[3] << 4 | aDecodeBuf[4] >> 1);
break;
case 7:
aOS.write (aDecodeBuf[0] << 3 | aDecodeBuf[1] >> 2);
aOS.write (aDecodeBuf[1] << 6 | aDecodeBuf[2] << 1 | aDecodeBuf[3] >> 4);
aOS.write (aDecodeBuf[3] << 4 | aDecodeBuf[4] >> 1);
aOS.write (aDecodeBuf[4] << 7 | aDecodeBuf[5] << 2 | aDecodeBuf[6] >> 3);
break;
case 8:
// At least 8 bytes
aOS.write (aDecodeBuf[0] << 3 | aDecodeBuf[1] >> 2);
aOS.write (aDecodeBuf[1] << 6 | aDecodeBuf[2] << 1 | aDecodeBuf[3] >> 4);
aOS.write (aDecodeBuf[3] << 4 | aDecodeBuf[4] >> 1);
aOS.write (aDecodeBuf[4] << 7 | aDecodeBuf[5] << 2 | aDecodeBuf[6] >> 3);
aOS.write (aDecodeBuf[6] << 5 | aDecodeBuf[7] & 0xff);
break;
default:
throw new DecodeException ("Unexpected number of Base32 bytes left: " + nBytesToDecode);
}
}
catch (final IOException ex)
{
throw new DecodeException ("Failed to decode Base32", ex);
}
}
}
}