org.bouncycastle.util.encoders.HexEncoder.java Source code

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Here is the source code for org.bouncycastle.util.encoders.HexEncoder.java

Source

package org.bouncycastle.util.encoders;

import java.io.IOException;
import java.io.OutputStream;

/**
 * A streaming Hex encoder.
 */
public class HexEncoder implements Encoder {
    protected final byte[] encodingTable = { (byte) '0', (byte) '1', (byte) '2', (byte) '3', (byte) '4', (byte) '5',
            (byte) '6', (byte) '7', (byte) '8', (byte) '9', (byte) 'a', (byte) 'b', (byte) 'c', (byte) 'd',
            (byte) 'e', (byte) 'f' };

    /*
     * 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;
        }

        decodingTable['A'] = decodingTable['a'];
        decodingTable['B'] = decodingTable['b'];
        decodingTable['C'] = decodingTable['c'];
        decodingTable['D'] = decodingTable['d'];
        decodingTable['E'] = decodingTable['e'];
        decodingTable['F'] = decodingTable['f'];
    }

    public HexEncoder() {
        initialiseDecodingTable();
    }

    /**
     * encode the input data producing a Hex output stream.
     *
     * @return the number of bytes produced.
     */
    public int encode(byte[] data, int off, int length, OutputStream out) throws IOException {
        for (int i = off; i < (off + length); i++) {
            int v = data[i] & 0xff;

            out.write(encodingTable[(v >>> 4)]);
            out.write(encodingTable[v & 0xf]);
        }

        return length * 2;
    }

    private static boolean ignore(char c) {
        return c == '\n' || c == '\r' || c == '\t' || c == ' ';
    }

    /**
     * decode the Hex 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;
        int outLen = 0;

        int end = off + length;

        while (end > off) {
            if (!ignore((char) data[end - 1])) {
                break;
            }

            end--;
        }

        int i = off;
        while (i < end) {
            while (i < end && ignore((char) data[i])) {
                i++;
            }

            b1 = decodingTable[data[i++]];

            while (i < end && ignore((char) data[i])) {
                i++;
            }

            b2 = decodingTable[data[i++]];

            if ((b1 | b2) < 0) {
                throw new IOException("invalid characters encountered in Hex data");
            }

            out.write((b1 << 4) | b2);

            outLen++;
        }

        return outLen;
    }

    /**
     * decode the Hex 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;
        int length = 0;

        int end = data.length();

        while (end > 0) {
            if (!ignore(data.charAt(end - 1))) {
                break;
            }

            end--;
        }

        int i = 0;
        while (i < end) {
            while (i < end && ignore(data.charAt(i))) {
                i++;
            }

            b1 = decodingTable[data.charAt(i++)];

            while (i < end && ignore(data.charAt(i))) {
                i++;
            }

            b2 = decodingTable[data.charAt(i++)];

            if ((b1 | b2) < 0) {
                throw new IOException("invalid characters encountered in Hex string");
            }

            out.write((b1 << 4) | b2);

            length++;
        }

        return length;
    }

    byte[] decodeStrict(String str, int off, int len) throws IOException {
        if (null == str) {
            throw new NullPointerException("'str' cannot be null");
        }
        if (off < 0 || len < 0 || off > (str.length() - len)) {
            throw new IndexOutOfBoundsException("invalid offset and/or length specified");
        }
        if (0 != (len & 1)) {
            throw new IOException("a hexadecimal encoding must have an even number of characters");
        }

        int resultLen = len >>> 1;
        byte[] result = new byte[resultLen];

        int strPos = off;
        for (int i = 0; i < resultLen; ++i) {
            byte b1 = decodingTable[str.charAt(strPos++)];
            byte b2 = decodingTable[str.charAt(strPos++)];

            int n = (b1 << 4) | b2;
            if (n < 0) {
                throw new IOException("invalid characters encountered in Hex string");
            }

            result[i] = (byte) n;
        }
        return result;
    }
}