/src/com/trilead/ssh2/crypto/cipher/BlockCipherFactory.java

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;

	}

}