308 lines
6.4 KiB
C#
308 lines
6.4 KiB
C#
using System;
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using System.IO;
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namespace Org.BouncyCastle.Utilities.Encoders
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{
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public class Base64Encoder
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: IEncoder
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{
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protected readonly byte[] encodingTable =
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{
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(byte)'A', (byte)'B', (byte)'C', (byte)'D', (byte)'E', (byte)'F', (byte)'G',
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(byte)'H', (byte)'I', (byte)'J', (byte)'K', (byte)'L', (byte)'M', (byte)'N',
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(byte)'O', (byte)'P', (byte)'Q', (byte)'R', (byte)'S', (byte)'T', (byte)'U',
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(byte)'V', (byte)'W', (byte)'X', (byte)'Y', (byte)'Z',
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(byte)'a', (byte)'b', (byte)'c', (byte)'d', (byte)'e', (byte)'f', (byte)'g',
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(byte)'h', (byte)'i', (byte)'j', (byte)'k', (byte)'l', (byte)'m', (byte)'n',
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(byte)'o', (byte)'p', (byte)'q', (byte)'r', (byte)'s', (byte)'t', (byte)'u',
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(byte)'v',
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(byte)'w', (byte)'x', (byte)'y', (byte)'z',
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(byte)'0', (byte)'1', (byte)'2', (byte)'3', (byte)'4', (byte)'5', (byte)'6',
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(byte)'7', (byte)'8', (byte)'9',
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(byte)'+', (byte)'/'
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};
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protected byte padding = (byte)'=';
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/*
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* set up the decoding table.
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*/
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protected readonly byte[] decodingTable = new byte[128];
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protected void InitialiseDecodingTable()
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{
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for (int i = 0; i < encodingTable.Length; i++)
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{
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decodingTable[encodingTable[i]] = (byte)i;
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}
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}
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public Base64Encoder()
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{
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InitialiseDecodingTable();
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}
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/**
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* encode the input data producing a base 64 output stream.
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*
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* @return the number of bytes produced.
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*/
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public int Encode(
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byte[] data,
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int off,
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int length,
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Stream outStream)
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{
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int modulus = length % 3;
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int dataLength = (length - modulus);
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int a1, a2, a3;
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for (int i = off; i < off + dataLength; i += 3)
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{
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a1 = data[i] & 0xff;
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a2 = data[i + 1] & 0xff;
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a3 = data[i + 2] & 0xff;
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outStream.WriteByte(encodingTable[(int) ((uint) a1 >> 2) & 0x3f]);
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outStream.WriteByte(encodingTable[((a1 << 4) | (int) ((uint) a2 >> 4)) & 0x3f]);
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outStream.WriteByte(encodingTable[((a2 << 2) | (int) ((uint) a3 >> 6)) & 0x3f]);
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outStream.WriteByte(encodingTable[a3 & 0x3f]);
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}
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/*
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* process the tail end.
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*/
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int b1, b2, b3;
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int d1, d2;
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switch (modulus)
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{
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case 0: /* nothing left to do */
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break;
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case 1:
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d1 = data[off + dataLength] & 0xff;
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b1 = (d1 >> 2) & 0x3f;
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b2 = (d1 << 4) & 0x3f;
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outStream.WriteByte(encodingTable[b1]);
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outStream.WriteByte(encodingTable[b2]);
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outStream.WriteByte(padding);
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outStream.WriteByte(padding);
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break;
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case 2:
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d1 = data[off + dataLength] & 0xff;
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d2 = data[off + dataLength + 1] & 0xff;
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b1 = (d1 >> 2) & 0x3f;
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b2 = ((d1 << 4) | (d2 >> 4)) & 0x3f;
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b3 = (d2 << 2) & 0x3f;
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outStream.WriteByte(encodingTable[b1]);
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outStream.WriteByte(encodingTable[b2]);
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outStream.WriteByte(encodingTable[b3]);
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outStream.WriteByte(padding);
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break;
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}
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return (dataLength / 3) * 4 + ((modulus == 0) ? 0 : 4);
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}
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private bool ignore(
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char c)
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{
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return (c == '\n' || c =='\r' || c == '\t' || c == ' ');
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}
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/**
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* decode the base 64 encoded byte data writing it to the given output stream,
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* whitespace characters will be ignored.
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*
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* @return the number of bytes produced.
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*/
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public int Decode(
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byte[] data,
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int off,
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int length,
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Stream outStream)
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{
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byte b1, b2, b3, b4;
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int outLen = 0;
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int end = off + length;
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while (end > off)
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{
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if (!ignore((char)data[end - 1]))
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{
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break;
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}
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end--;
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}
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int i = off;
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int finish = end - 4;
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i = nextI(data, i, finish);
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while (i < finish)
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{
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b1 = decodingTable[data[i++]];
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i = nextI(data, i, finish);
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b2 = decodingTable[data[i++]];
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i = nextI(data, i, finish);
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b3 = decodingTable[data[i++]];
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i = nextI(data, i, finish);
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b4 = decodingTable[data[i++]];
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outStream.WriteByte((byte)((b1 << 2) | (b2 >> 4)));
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outStream.WriteByte((byte)((b2 << 4) | (b3 >> 2)));
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outStream.WriteByte((byte)((b3 << 6) | b4));
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outLen += 3;
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i = nextI(data, i, finish);
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}
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outLen += decodeLastBlock(outStream, (char)data[end - 4], (char)data[end - 3], (char)data[end - 2], (char)data[end - 1]);
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return outLen;
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}
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private int nextI(
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byte[] data,
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int i,
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int finish)
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{
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while ((i < finish) && ignore((char)data[i]))
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{
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i++;
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}
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return i;
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}
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/**
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* decode the base 64 encoded string data writing it to the given output stream,
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* whitespace characters will be ignored.
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*
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* @return the number of bytes produced.
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*/
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public int DecodeString(
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string data,
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Stream outStream)
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{
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// Platform Implementation
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// byte[] bytes = Convert.FromBase64String(data);
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// outStream.Write(bytes, 0, bytes.Length);
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// return bytes.Length;
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byte b1, b2, b3, b4;
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int length = 0;
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int end = data.Length;
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while (end > 0)
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{
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if (!ignore(data[end - 1]))
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{
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break;
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}
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end--;
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}
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int i = 0;
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int finish = end - 4;
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i = nextI(data, i, finish);
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while (i < finish)
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{
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b1 = decodingTable[data[i++]];
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i = nextI(data, i, finish);
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b2 = decodingTable[data[i++]];
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i = nextI(data, i, finish);
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b3 = decodingTable[data[i++]];
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i = nextI(data, i, finish);
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b4 = decodingTable[data[i++]];
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outStream.WriteByte((byte)((b1 << 2) | (b2 >> 4)));
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outStream.WriteByte((byte)((b2 << 4) | (b3 >> 2)));
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outStream.WriteByte((byte)((b3 << 6) | b4));
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length += 3;
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i = nextI(data, i, finish);
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}
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length += decodeLastBlock(outStream, data[end - 4], data[end - 3], data[end - 2], data[end - 1]);
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return length;
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}
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private int decodeLastBlock(
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Stream outStream,
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char c1,
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char c2,
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char c3,
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char c4)
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{
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if (c3 == padding)
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{
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byte b1 = decodingTable[c1];
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byte b2 = decodingTable[c2];
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outStream.WriteByte((byte)((b1 << 2) | (b2 >> 4)));
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return 1;
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}
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if (c4 == padding)
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{
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byte b1 = decodingTable[c1];
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byte b2 = decodingTable[c2];
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byte b3 = decodingTable[c3];
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outStream.WriteByte((byte)((b1 << 2) | (b2 >> 4)));
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outStream.WriteByte((byte)((b2 << 4) | (b3 >> 2)));
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return 2;
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}
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{
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byte b1 = decodingTable[c1];
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byte b2 = decodingTable[c2];
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byte b3 = decodingTable[c3];
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byte b4 = decodingTable[c4];
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outStream.WriteByte((byte)((b1 << 2) | (b2 >> 4)));
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outStream.WriteByte((byte)((b2 << 4) | (b3 >> 2)));
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outStream.WriteByte((byte)((b3 << 6) | b4));
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return 3;
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}
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}
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private int nextI(string data, int i, int finish)
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{
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while ((i < finish) && ignore(data[i]))
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{
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i++;
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}
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return i;
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}
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}
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}
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