| package org.bouncycastle.util.encoders; |
| |
| import java.io.IOException; |
| import java.io.OutputStream; |
| |
| 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(); |
| } |
| |
| /** |
| * 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, |
| OutputStream out) |
| throws IOException |
| { |
| 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; |
| |
| out.write(encodingTable[(a1 >>> 2) & 0x3f]); |
| out.write(encodingTable[((a1 << 4) | (a2 >>> 4)) & 0x3f]); |
| out.write(encodingTable[((a2 << 2) | (a3 >>> 6)) & 0x3f]); |
| out.write(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; |
| |
| out.write(encodingTable[b1]); |
| out.write(encodingTable[b2]); |
| out.write(padding); |
| out.write(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; |
| |
| out.write(encodingTable[b1]); |
| out.write(encodingTable[b2]); |
| out.write(encodingTable[b3]); |
| out.write(padding); |
| break; |
| } |
| |
| return (dataLength / 3) * 4 + ((modulus == 0) ? 0 : 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; |
| 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++]]; |
| |
| if ((b1 | b2 | b3 | b4) < 0) |
| { |
| throw new IOException("invalid characters encountered in base64 data"); |
| } |
| |
| out.write((b1 << 2) | (b2 >> 4)); |
| out.write((b2 << 4) | (b3 >> 2)); |
| out.write((b3 << 6) | b4); |
| |
| outLen += 3; |
| |
| i = nextI(data, i, finish); |
| } |
| |
| outLen += decodeLastBlock(out, (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 decode( |
| String data, |
| OutputStream out) |
| throws IOException |
| { |
| byte b1, b2, b3, b4; |
| int length = 0; |
| |
| int end = data.length(); |
| |
| while (end > 0) |
| { |
| if (!ignore(data.charAt(end - 1))) |
| { |
| break; |
| } |
| |
| end--; |
| } |
| |
| int i = 0; |
| int finish = end - 4; |
| |
| i = nextI(data, i, 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"); |
| } |
| |
| out.write((b1 << 2) | (b2 >> 4)); |
| out.write((b2 << 4) | (b3 >> 2)); |
| out.write((b3 << 6) | b4); |
| |
| length += 3; |
| |
| i = nextI(data, i, finish); |
| } |
| |
| length += decodeLastBlock(out, data.charAt(end - 4), data.charAt(end - 3), data.charAt(end - 2), data.charAt(end - 1)); |
| |
| 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) |
| { |
| 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; |
| } |
| } |