Base64 Encoder
//http://www.bouncycastle.org/
//MIT X11 License
using System;
using System.IO;
namespace Org.BouncyCastle.Utilities.Encoders
{
public class Base64Encoder
{
protected readonly 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 readonly byte[] decodingTable = new byte[128];
protected void InitialiseDecodingTable()
{
for (int i = 0; i < encodingTable.Length; i++)
{
decodingTable[encodingTable[i]] = (byte)i;
}
}
public Base64Encoder()
{
InitialiseDecodingTable();
}
/**
* encode the input data producing a base 64 output stream.
*
* @return the number of bytes produced.
*/
public int Encode(
byte[] data,
int off,
int length,
Stream outStream)
{
int modulus = length % 3;
int dataLength = (length - modulus);
int a1, a2, a3;
for (int i = off; i < off + dataLength; i += 3)
{
a1 = data[i] & 0xff;
a2 = data[i + 1] & 0xff;
a3 = data[i + 2] & 0xff;
outStream.WriteByte(encodingTable[(int) ((uint) a1 >> 2) & 0x3f]);
outStream.WriteByte(encodingTable[((a1 << 4) | (int) ((uint) a2 >> 4)) & 0x3f]);
outStream.WriteByte(encodingTable[((a2 << 2) | (int) ((uint) a3 >> 6)) & 0x3f]);
outStream.WriteByte(encodingTable[a3 & 0x3f]);
}
/*
* process the tail end.
*/
int b1, b2, b3;
int d1, d2;
switch (modulus)
{
case 0: /* nothing left to do */
break;
case 1:
d1 = data[off + dataLength] & 0xff;
b1 = (d1 >> 2) & 0x3f;
b2 = (d1 << 4) & 0x3f;
outStream.WriteByte(encodingTable[b1]);
outStream.WriteByte(encodingTable[b2]);
outStream.WriteByte(padding);
outStream.WriteByte(padding);
break;
case 2:
d1 = data[off + dataLength] & 0xff;
d2 = data[off + dataLength + 1] & 0xff;
b1 = (d1 >> 2) & 0x3f;
b2 = ((d1 << 4) | (d2 >> 4)) & 0x3f;
b3 = (d2 << 2) & 0x3f;
outStream.WriteByte(encodingTable[b1]);
outStream.WriteByte(encodingTable[b2]);
outStream.WriteByte(encodingTable[b3]);
outStream.WriteByte(padding);
break;
}
return (dataLength / 3) * 4 + ((modulus == 0) ? 0 : 4);
}
private bool 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,
Stream outStream)
{
byte b1, b2, b3, b4;
int outLen = 0;
int end = off + length;
while (end > off)
{
if (!ignore((char)data[end - 1]))
{
break;
}
end--;
}
int i = off;
int finish = end - 4;
i = nextI(data, i, 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++]];
outStream.WriteByte((byte)((b1 << 2) | (b2 >> 4)));
outStream.WriteByte((byte)((b2 << 4) | (b3 >> 2)));
outStream.WriteByte((byte)((b3 << 6) | b4));
outLen += 3;
i = nextI(data, i, finish);
}
outLen += decodeLastBlock(outStream, (char)data[end - 4], (char)data[end - 3], (char)data[end - 2], (char)data[end - 1]);
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 DecodeString(
string data,
Stream outStream)
{
// Platform Implementation
// byte[] bytes = Convert.FromBase64String(data);
// outStream.Write(bytes, 0, bytes.Length);
// return bytes.Length;
byte b1, b2, b3, b4;
int length = 0;
int end = data.Length;
while (end > 0)
{
if (!ignore(data[end - 1]))
{
break;
}
end--;
}
int i = 0;
int finish = end - 4;
i = nextI(data, i, 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++]];
outStream.WriteByte((byte)((b1 << 2) | (b2 >> 4)));
outStream.WriteByte((byte)((b2 << 4) | (b3 >> 2)));
outStream.WriteByte((byte)((b3 << 6) | b4));
length += 3;
i = nextI(data, i, finish);
}
length += decodeLastBlock(outStream, data[end - 4], data[end - 3], data[end - 2], data[end - 1]);
return length;
}
private int decodeLastBlock(
Stream outStream,
char c1,
char c2,
char c3,
char c4)
{
if (c3 == padding)
{
byte b1 = decodingTable[c1];
byte b2 = decodingTable[c2];
outStream.WriteByte((byte)((b1 << 2) | (b2 >> 4)));
return 1;
}
if (c4 == padding)
{
byte b1 = decodingTable[c1];
byte b2 = decodingTable[c2];
byte b3 = decodingTable[c3];
outStream.WriteByte((byte)((b1 << 2) | (b2 >> 4)));
outStream.WriteByte((byte)((b2 << 4) | (b3 >> 2)));
return 2;
}
{
byte b1 = decodingTable[c1];
byte b2 = decodingTable[c2];
byte b3 = decodingTable[c3];
byte b4 = decodingTable[c4];
outStream.WriteByte((byte)((b1 << 2) | (b2 >> 4)));
outStream.WriteByte((byte)((b2 << 4) | (b3 >> 2)));
outStream.WriteByte((byte)((b3 << 6) | b4));
return 3;
}
}
private int nextI(string data, int i, int finish)
{
while ((i < finish) && ignore(data[i]))
{
i++;
}
return i;
}
}
}
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