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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 1.5 to JDK 1.8.
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package org.bouncycastle.util.encoders;
import java.io.IOException;
import java.io.OutputStream;
/**
* A streaming Base64 encoder.
*/
public class Base64Encoder
implements Encoder
{
protected final byte[] encodingTable =
{
(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)'/'
};
protected byte padding = (byte)'=';
/*
* set up the decoding table.
*/
protected 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;
}
}
public Base64Encoder()
{
initialiseDecodingTable();
}
public int encode(byte[] inBuf, int inOff, int inLen, byte[] outBuf, int outOff) throws IOException
{
int inPos = inOff;
int inEnd = inOff + inLen - 2;
int outPos = outOff;
while (inPos < inEnd)
{
int a1 = inBuf[inPos++];
int a2 = inBuf[inPos++] & 0xFF;
int a3 = inBuf[inPos++] & 0xFF;
outBuf[outPos++] = encodingTable[(a1 >>> 2) & 0x3F];
outBuf[outPos++] = encodingTable[((a1 << 4) | (a2 >>> 4)) & 0x3F];
outBuf[outPos++] = encodingTable[((a2 << 2) | (a3 >>> 6)) & 0x3F];
outBuf[outPos++] = encodingTable[a3 & 0x3F];
}
switch (inLen - (inPos - inOff))
{
case 1:
{
int a1 = inBuf[inPos++] & 0xFF;
outBuf[outPos++] = encodingTable[(a1 >>> 2) & 0x3F];
outBuf[outPos++] = encodingTable[(a1 << 4) & 0x3F];
outBuf[outPos++] = padding;
outBuf[outPos++] = padding;
break;
}
case 2:
{
int a1 = inBuf[inPos++] & 0xFF;
int a2 = inBuf[inPos++] & 0xFF;
outBuf[outPos++] = encodingTable[(a1 >>> 2) & 0x3F];
outBuf[outPos++] = encodingTable[((a1 << 4) | (a2 >>> 4)) & 0x3F];
outBuf[outPos++] = encodingTable[(a2 << 2) & 0x3F];
outBuf[outPos++] = padding;
break;
}
}
return outPos - outOff;
}
public int getEncodedLength(int inputLength)
{
return (inputLength + 2) / 3 * 4;
}
public int getMaxDecodedLength(int inputLength)
{
return inputLength / 4 * 3;
}
/**
* encode the input data producing a base 64 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(54, 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 64 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;
byte[] outBuffer = new byte[54]; // S/MIME standard
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 != 4)
{
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++]];
if ((b1 | b2 | b3 | b4) < 0)
{
throw new IOException("invalid characters encountered in base64 data");
}
outBuffer[bufOff++] = (byte)((b1 << 2) | (b2 >> 4));
outBuffer[bufOff++] = (byte)((b2 << 4) | (b3 >> 2));
outBuffer[bufOff++] = (byte)((b3 << 6) | b4);
if (bufOff == outBuffer.length)
{
out.write(outBuffer);
bufOff = 0;
}
outLen += 3;
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);
outLen += decodeLastBlock(out, (char)data[e0], (char)data[e1], (char)data[e2], (char)data[e3]);
return outLen;
}
private int nextI(byte[] data, int i, int finish)
{
while ((i < finish) && ignore((char)data[i]))
{
i++;
}
return i;
}
/**
* decode the base 64 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 b1, b2, b3, b4;
byte[] outBuffer = new byte[54]; // S/MIME standard
int bufOff = 0;
int length = 0;
int end = data.length();
while (end > 0)
{
if (!ignore(data.charAt(end - 1)))
{
break;
}
end--;
}
// empty data!
if (end == 0)
{
return 0;
}
int i = 0;
int finish = end;
while (finish > 0 && i != 4)
{
if (!ignore(data.charAt(finish - 1)))
{
i++;
}
finish--;
}
i = nextI(data, 0, finish);
while (i < finish)
{
b1 = decodingTable[data.charAt(i++)];
i = nextI(data, i, finish);
b2 = decodingTable[data.charAt(i++)];
i = nextI(data, i, finish);
b3 = decodingTable[data.charAt(i++)];
i = nextI(data, i, finish);
b4 = decodingTable[data.charAt(i++)];
if ((b1 | b2 | b3 | b4) < 0)
{
throw new IOException("invalid characters encountered in base64 data");
}
outBuffer[bufOff++] = (byte)((b1 << 2) | (b2 >> 4));
outBuffer[bufOff++] = (byte)((b2 << 4) | (b3 >> 2));
outBuffer[bufOff++] = (byte)((b3 << 6) | b4);
length += 3;
if (bufOff == outBuffer.length)
{
out.write(outBuffer);
bufOff = 0;
}
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);
length += decodeLastBlock(out, data.charAt(e0), data.charAt(e1), data.charAt(e2), data.charAt(e3));
return length;
}
private int decodeLastBlock(OutputStream out, char c1, char c2, char c3, char c4)
throws IOException
{
byte b1, b2, b3, b4;
if (c3 == padding)
{
if (c4 != padding)
{
throw new IOException("invalid characters encountered at end of base64 data");
}
b1 = decodingTable[c1];
b2 = decodingTable[c2];
if ((b1 | b2) < 0)
{
throw new IOException("invalid characters encountered at end of base64 data");
}
out.write((b1 << 2) | (b2 >> 4));
return 1;
}
else if (c4 == padding)
{
b1 = decodingTable[c1];
b2 = decodingTable[c2];
b3 = decodingTable[c3];
if ((b1 | b2 | b3) < 0)
{
throw new IOException("invalid characters encountered at end of base64 data");
}
out.write((b1 << 2) | (b2 >> 4));
out.write((b2 << 4) | (b3 >> 2));
return 2;
}
else
{
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 base64 data");
}
out.write((b1 << 2) | (b2 >> 4));
out.write((b2 << 4) | (b3 >> 2));
out.write((b3 << 6) | b4);
return 3;
}
}
private int nextI(String data, int i, int finish)
{
while ((i < finish) && ignore(data.charAt(i)))
{
i++;
}
return i;
}
}
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