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The Bouncy Castle Crypto package is a Java implementation of cryptographic algorithms. This jar contains JCE provider and lightweight API for the Bouncy Castle Cryptography APIs for JDK 1.8 and up.
package org.bouncycastle.util.encoders;
import java.io.IOException;
import java.io.OutputStream;
import org.bouncycastle.util.Arrays;
import org.bouncycastle.util.Strings;
/**
* A streaming Base32 encoder.
*/
public class Base32Encoder
implements Encoder
{
private static final byte[] DEAULT_ENCODING_TABLE =
{
(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)'2', (byte)'3', (byte)'4', (byte)'5', (byte)'6', (byte)'7'
};
private static final byte DEFAULT_PADDING = (byte)'=';
/*
* set up the decoding table.
*/
private final byte[] encodingTable;
private final byte padding;
private final byte[] decodingTable = new byte[128];
protected void initialiseDecodingTable()
{
for (int i = 0; i < decodingTable.length; i++)
{
decodingTable[i] = (byte)0xff;
}
for (int i = 0; i < encodingTable.length; i++)
{
decodingTable[encodingTable[i]] = (byte)i;
}
}
/**
* Base constructor for RFC 4648, Section 6.
*/
public Base32Encoder()
{
this.encodingTable = DEAULT_ENCODING_TABLE;
this.padding = DEFAULT_PADDING;
initialiseDecodingTable();
}
/**
* Constructor allowing the setting of an alternative alphabet.
*
* @param encodingTable a 32 entry encoding table to do the mapping.
* @param padding the padding value to use.
*/
public Base32Encoder(byte[] encodingTable, byte padding)
{
if (encodingTable.length != 32)
{
throw new IllegalArgumentException("encoding table needs to be length 32");
}
this.encodingTable = Arrays.clone(encodingTable);
this.padding = padding;
initialiseDecodingTable();
}
public int encode(byte[] inBuf, int inOff, int inLen, byte[] outBuf, int outOff) throws IOException
{
int inPos = inOff;
int inEnd = inOff + inLen - 4;
int outPos = outOff;
while (inPos < inEnd)
{
encodeBlock(inBuf, inPos, outBuf, outPos);
inPos += 5;
outPos += 8;
}
int extra = inLen - (inPos - inOff);
if (extra > 0)
{
byte[] in = new byte[5];
System.arraycopy(inBuf, inPos, in, 0, extra);
encodeBlock(in, 0, outBuf, outPos);
switch (extra)
{
case 1:
outBuf[outPos + 2] = padding;
outBuf[outPos + 3] = padding;
outBuf[outPos + 4] = padding;
outBuf[outPos + 5] = padding;
outBuf[outPos + 6] = padding;
outBuf[outPos + 7] = padding;
break;
case 2:
outBuf[outPos + 4] = padding;
outBuf[outPos + 5] = padding;
outBuf[outPos + 6] = padding;
outBuf[outPos + 7] = padding;
break;
case 3:
outBuf[outPos + 5] = padding;
outBuf[outPos + 6] = padding;
outBuf[outPos + 7] = padding;
break;
case 4:
outBuf[outPos + 7] = padding;
break;
}
outPos += 8;
}
return outPos - outOff;
}
private void encodeBlock(byte[] inBuf, int inPos, byte[] outBuf, int outPos)
{
int a1 = inBuf[inPos++];
int a2 = inBuf[inPos++] & 0xFF;
int a3 = inBuf[inPos++] & 0xFF;
int a4 = inBuf[inPos++] & 0xFF;
int a5 = inBuf[inPos] & 0xFF;
outBuf[outPos++] = encodingTable[(a1 >>> 3) & 0x1F];
outBuf[outPos++] = encodingTable[((a1 << 2) | (a2 >>> 6)) & 0x1F];
outBuf[outPos++] = encodingTable[(a2 >>> 1) & 0x1F];
outBuf[outPos++] = encodingTable[((a2 << 4) | (a3 >>> 4)) & 0x1F];
outBuf[outPos++] = encodingTable[((a3 << 1) | (a4 >>> 7)) & 0x1F];
outBuf[outPos++] = encodingTable[(a4 >>> 2) & 0x1F];
outBuf[outPos++] = encodingTable[((a4 << 3) | (a5 >>> 5)) & 0x1F];
outBuf[outPos] = encodingTable[a5 & 0x1F];
}
public int getEncodedLength(int inputLength)
{
return (inputLength + 4) / 5 * 8;
}
public int getMaxDecodedLength(int inputLength)
{
return inputLength / 8 * 5;
}
/**
* encode the input data producing a base 32 output stream.
*
* @return the number of bytes produced.
*/
public int encode(byte[] buf, int off, int len, OutputStream out)
throws IOException
{
if (len < 0)
{
return 0;
}
byte[] tmp = new byte[72];
int remaining = len;
while (remaining > 0)
{
int inLen = Math.min(45, remaining);
int outLen = encode(buf, off, inLen, tmp, 0);
out.write(tmp, 0, outLen);
off += inLen;
remaining -= inLen;
}
return (len + 2) / 3 * 4;
}
private boolean ignore(
char c)
{
return (c == '\n' || c =='\r' || c == '\t' || c == ' ');
}
/**
* decode the base 32 encoded byte data writing it to the given output stream,
* whitespace characters will be ignored.
*
* @return the number of bytes produced.
*/
public int decode(
byte[] data,
int off,
int length,
OutputStream out)
throws IOException
{
byte b1, b2, b3, b4, b5, b6, b7, b8;
byte[] outBuffer = new byte[55];
int bufOff = 0;
int outLen = 0;
int end = off + length;
while (end > off)
{
if (!ignore((char)data[end - 1]))
{
break;
}
end--;
}
// empty data!
if (end == 0)
{
return 0;
}
int i = 0;
int finish = end;
while (finish > off && i != 8)
{
if (!ignore((char)data[finish - 1]))
{
i++;
}
finish--;
}
i = nextI(data, off, finish);
while (i < finish)
{
b1 = decodingTable[data[i++]];
i = nextI(data, i, finish);
b2 = decodingTable[data[i++]];
i = nextI(data, i, finish);
b3 = decodingTable[data[i++]];
i = nextI(data, i, finish);
b4 = decodingTable[data[i++]];
i = nextI(data, i, finish);
b5 = decodingTable[data[i++]];
i = nextI(data, i, finish);
b6 = decodingTable[data[i++]];
i = nextI(data, i, finish);
b7 = decodingTable[data[i++]];
i = nextI(data, i, finish);
b8 = decodingTable[data[i++]];
if ((b1 | b2 | b3 | b4 | b5 | b6 | b7 | b8) < 0)
{
throw new IOException("invalid characters encountered in base32 data");
}
outBuffer[bufOff++] = (byte)((b1 << 3) | (b2 >> 2));
outBuffer[bufOff++] = (byte)((b2 << 6) | (b3 << 1) | (b4 >> 4));
outBuffer[bufOff++] = (byte)((b4 << 4) | (b5 >> 1));
outBuffer[bufOff++] = (byte)((b5 << 7) | (b6 << 2) | (b7 >> 3));
outBuffer[bufOff++] = (byte)((b7 << 5) | b8);
if (bufOff == outBuffer.length)
{
out.write(outBuffer);
bufOff = 0;
}
outLen += 5;
i = nextI(data, i, finish);
}
if (bufOff > 0)
{
out.write(outBuffer, 0, bufOff);
}
int e0 = nextI(data, i, end);
int e1 = nextI(data, e0 + 1, end);
int e2 = nextI(data, e1 + 1, end);
int e3 = nextI(data, e2 + 1, end);
int e4 = nextI(data, e3 + 1, end);
int e5 = nextI(data, e4 + 1, end);
int e6 = nextI(data, e5 + 1, end);
int e7 = nextI(data, e6 + 1, end);
outLen += decodeLastBlock(out,
(char)data[e0], (char)data[e1], (char)data[e2], (char)data[e3],
(char)data[e4], (char)data[e5], (char)data[e6], (char)data[e7]);
return outLen;
}
private int nextI(byte[] data, int i, int finish)
{
while ((i < finish) && ignore((char)data[i]))
{
i++;
}
return i;
}
/**
* decode the base 32 encoded String data writing it to the given output stream,
* whitespace characters will be ignored.
*
* @return the number of bytes produced.
*/
public int decode(
String data,
OutputStream out)
throws IOException
{
byte[] bytes = Strings.toByteArray(data);
return decode(bytes, 0, bytes.length, out);
}
private int decodeLastBlock(OutputStream out,
char c1, char c2, char c3, char c4,
char c5, char c6, char c7, char c8)
throws IOException
{
byte b1, b2, b3, b4, b5, b6, b7, b8;
if (c8 == padding)
{
if (c7 != padding)
{
b1 = decodingTable[c1];
b2 = decodingTable[c2];
b3 = decodingTable[c3];
b4 = decodingTable[c4];
b5 = decodingTable[c5];
b6 = decodingTable[c6];
b7 = decodingTable[c7];
if ((b1 | b2 | b3 | b4 | b5 | b6 | b7) < 0)
{
throw new IOException("invalid characters encountered at end of base32 data");
}
out.write((b1 << 3) | (b2 >> 2));
out.write((b2 << 6) | (b3 << 1) | (b4 >> 4));
out.write((b4 << 4) | (b5 >> 1));
out.write((b5 << 7) | (b6 << 2) | (b7 >> 3));
return 4;
}
if (c6 != padding)
{
throw new IOException("invalid characters encountered at end of base32 data");
}
if (c5 != padding)
{
b1 = decodingTable[c1];
b2 = decodingTable[c2];
b3 = decodingTable[c3];
b4 = decodingTable[c4];
b5 = decodingTable[c5];
if ((b1 | b2 | b3 | b4 | b5) < 0)
{
throw new IOException("invalid characters encountered at end of base32 data");
}
out.write((b1 << 3) | (b2 >> 2));
out.write((b2 << 6) | (b3 << 1) | (b4 >> 4));
out.write((b4 << 4) | (b5 >> 1));
return 3;
}
if (c4 != padding)
{
b1 = decodingTable[c1];
b2 = decodingTable[c2];
b3 = decodingTable[c3];
b4 = decodingTable[c4];
if ((b1 | b2 | b3 | b4) < 0)
{
throw new IOException("invalid characters encountered at end of base32 data");
}
out.write((b1 << 3) | (b2 >> 2));
out.write((b2 << 6) | (b3 << 1) | (b4 >> 4));
return 2;
}
if (c3 != padding)
{
throw new IOException("invalid characters encountered at end of base32 data");
}
b1 = decodingTable[c1];
b2 = decodingTable[c2];
if ((b1 | b2) < 0)
{
throw new IOException("invalid characters encountered at end of base32 data");
}
out.write((b1 << 3) | (b2 >> 2));
return 1;
}
else
{
b1 = decodingTable[c1];
b2 = decodingTable[c2];
b3 = decodingTable[c3];
b4 = decodingTable[c4];
b5 = decodingTable[c5];
b6 = decodingTable[c6];
b7 = decodingTable[c7];
b8 = decodingTable[c8];
if ((b1 | b2 | b3 | b4 | b5 | b6 | b7 | b8) < 0)
{
throw new IOException("invalid characters encountered at end of base32 data");
}
out.write((b1 << 3) | (b2 >> 2));
out.write((b2 << 6) | (b3 << 1) | (b4 >> 4));
out.write((b4 << 4) | (b5 >> 1));
out.write((b5 << 7) | (b6 << 2) | (b7 >> 3));
out.write((b7 << 5) | b8);
return 5;
}
}
}