org.bouncycastle.crypto.util.BasicAlphabetMapper Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of bcprov-ext-debug-jdk18on Show documentation

The Bouncy Castle Crypto package is a Java implementation of cryptographic algorithms. This jar contains JCE provider and lightweight API for the Bouncy Castle Cryptography APIs for Java 1.8 and later with debug enabled.

The newest version!

package org.bouncycastle.crypto.util;

import java.util.HashMap;
import java.util.Map;

import org.bouncycastle.crypto.AlphabetMapper;

/**
 * A basic alphabet mapper that just creates a mapper based on the
 * passed in array of characters.
 */
public class BasicAlphabetMapper
    implements AlphabetMapper
{
    private Map indexMap = new HashMap();
    private Map charMap = new HashMap();

    /**
     * Base constructor.
     *
     * @param alphabet a String of characters making up the alphabet.
     */
    public BasicAlphabetMapper(String alphabet)
    {
        this(alphabet.toCharArray());
    }

    /**
     * Base constructor.
     *
     * @param alphabet an array of characters making up the alphabet.
     */
    public BasicAlphabetMapper(char[] alphabet)
    {
        for (int i = 0; i != alphabet.length; i++)
        {
            if (indexMap.containsKey(alphabet[i]))
            {
                throw new IllegalArgumentException("duplicate key detected in alphabet: " + alphabet[i]);
            }
            indexMap.put(alphabet[i], i);
            charMap.put(i, alphabet[i]);
        }
    }

    public int getRadix()
    {
        return indexMap.size();
    }

    public byte[] convertToIndexes(char[] input)
    {
        byte[] out;

        if (indexMap.size() <= 256)
        {
            out = new byte[input.length];
            for (int i = 0; i != input.length; i++)
            {
                out[i] = indexMap.get(input[i]).byteValue();
            }
        }
        else
        {
            out = new byte[input.length * 2];
            for (int i = 0; i != input.length; i++)
            {
                int idx = indexMap.get(input[i]);
                out[i * 2] = (byte)((idx >> 8) & 0xff);
                out[i * 2  + 1] = (byte)(idx & 0xff);
            }
        }

        return out;
    }

    public char[] convertToChars(byte[] input)
    {
        char[] out;

        if (charMap.size() <= 256)
        {
            out = new char[input.length];
            for (int i = 0; i != input.length; i++)
            {
                out[i] = charMap.get(input[i] & 0xff);
            }
        }
        else
        {
            if ((input.length & 0x1) != 0)
            {
                throw new IllegalArgumentException("two byte radix and input string odd length");
            }
            
            out = new char[input.length / 2];
            for (int i = 0; i != input.length; i += 2)
            {
                out[i / 2] = charMap.get(((input[i] << 8) & 0xff00) | (input[i + 1] & 0xff));
            }
        }

        return out;
    }
}