package com.trilead.ssh2.crypto.cipher;

import java.util.Vector;

/**
 * BlockCipherFactory.
 *
 * @author Christian Plattner, plattner@trilead.com
 * @version $Id: BlockCipherFactory.java,v 1.2 2008/04/01 12:38:09 cplattne Exp $
 */
public class BlockCipherFactory {
    static class CipherEntry {
        String type;
        int blocksize;
        int keysize;
        String cipherClass;

        public CipherEntry(String type, int blockSize, int keySize, String cipherClass) {
            this.type = type;
            this.blocksize = blockSize;
            this.keysize = keySize;
            this.cipherClass = cipherClass;
        }
    }

    static Vector<CipherEntry> ciphers = new Vector<CipherEntry>();

    static {
        /* Higher Priority First */
        ciphers.addElement(new CipherEntry("aes256-ctr", 16, 32, "com.trilead.ssh2.crypto.cipher.AES"));
        ciphers.addElement(new CipherEntry("aes192-ctr", 16, 24, "com.trilead.ssh2.crypto.cipher.AES"));
        ciphers.addElement(new CipherEntry("aes128-ctr", 16, 16, "com.trilead.ssh2.crypto.cipher.AES"));
        ciphers.addElement(new CipherEntry("blowfish-ctr", 8, 16, "com.trilead.ssh2.crypto.cipher.BlowFish"));
        ciphers.addElement(new CipherEntry("aes256-cbc", 16, 32, "com.trilead.ssh2.crypto.cipher.AES"));
        ciphers.addElement(new CipherEntry("aes192-cbc", 16, 24, "com.trilead.ssh2.crypto.cipher.AES"));
        ciphers.addElement(new CipherEntry("aes128-cbc", 16, 16, "com.trilead.ssh2.crypto.cipher.AES"));
        ciphers.addElement(new CipherEntry("blowfish-cbc", 8, 16, "com.trilead.ssh2.crypto.cipher.BlowFish"));
        ciphers.addElement(new CipherEntry("3des-ctr", 8, 24, "com.trilead.ssh2.crypto.cipher.DESede"));
        ciphers.addElement(new CipherEntry("3des-cbc", 8, 24, "com.trilead.ssh2.crypto.cipher.DESede"));
    }

    public static String[] getDefaultCipherList() {
        String list[] = new String[ciphers.size()];

        for (int i = 0; i < ciphers.size(); i++) {
            CipherEntry ce = ciphers.elementAt(i);
            list[i] = new String(ce.type);
        }

        return list;
    }

    public static void checkCipherList(String[] cipherCandidates) {
        for (int i = 0; i < cipherCandidates.length; i++)
            getEntry(cipherCandidates[i]);
    }

    public static BlockCipher createCipher(String type, boolean encrypt, byte[] key, byte[] iv) {
        try {
            CipherEntry ce = getEntry(type);
            Class cc = Class.forName(ce.cipherClass);
            BlockCipher bc = (BlockCipher) cc.newInstance();

            if (type.endsWith("-cbc")) {
                bc.init(encrypt, key);
                return new CBCMode(bc, iv, encrypt);
            }
            else if (type.endsWith("-ctr")) {
                bc.init(true, key);
                return new CTRMode(bc, iv, encrypt);
            }

            throw new IllegalArgumentException("Cannot instantiate " + type);
        }
        catch (Exception e) {
            throw new IllegalArgumentException("Cannot instantiate " + type);
        }
    }

    private static CipherEntry getEntry(String type) {
        for (int i = 0; i < ciphers.size(); i++) {
            CipherEntry ce = ciphers.elementAt(i);

            if (ce.type.equals(type))
                return ce;
        }

        throw new IllegalArgumentException("Unkown algorithm " + type);
    }

    public static int getBlockSize(String type) {
        CipherEntry ce = getEntry(type);
        return ce.blocksize;
    }

    public static int getKeySize(String type) {
        CipherEntry ce = getEntry(type);
        return ce.keysize;
    }
}