package org.spongycastle.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 < 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++]]; 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++)]; 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]; out.write((b1 << 2) | (b2 >> 4)); return 1; } else if (c4 == padding) { b1 = decodingTable[c1]; b2 = decodingTable[c2]; b3 = decodingTable[c3]; 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]; 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; } }