PasswordGenerator.java

/*
 * Copyright 2010 Tolga Onbay, Brian Pellin.
 *     
 * This file is part of KeePassDroid.
 *
 *  KeePassDroid is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  KeePassDroid is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with KeePassDroid.  If not, see <http://www.gnu.org/licenses/>.
 *
 */
package com.keepassdroid.password;

import java.security.SecureRandom;

import android.content.Context;

import com.android.keepass.R;

public class PasswordGenerator {
	private static final String UPPERCASE_CHARS	= "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
	private static final String LOWERCASE_CHARS 	= "abcdefghijklmnopqrstuvwxyz";
	private static final String DIGIT_CHARS 	= "0123456789";
	private static final String MINUS_CHAR	 	= "-";
	private static final String UNDERLINE_CHAR 	= "_";
	private static final String SPACE_CHAR 		= " ";
	private static final String SPECIAL_CHARS 	= "!\"#$%&'*+,./:;=?@\\^`";
	private static final String BRACKET_CHARS 	= "[]{}()<>";

	
	private Context cxt;
	
	public PasswordGenerator(Context cxt) {
		this.cxt = cxt;
	}
	
	public String generatePassword(int length, boolean upperCase, boolean lowerCase, boolean digits, boolean minus, boolean underline, boolean space, boolean specials, boolean brackets) throws IllegalArgumentException{
		// Desired password length is 0 or less
		if (length <= 0) {
			throw new IllegalArgumentException(cxt.getString(R.string.error_wrong_length));
		}
		
		// No option has been checked
		if (!upperCase && !lowerCase && !digits && !minus && !underline && !space && !specials && !brackets) {
			throw new IllegalArgumentException(cxt.getString(R.string.error_pass_gen_type));
		}
		
		String characterSet = getCharacterSet(upperCase, lowerCase, digits, minus, underline, space, specials, brackets);
		
		int size = characterSet.length();
		
		StringBuffer buffer = new StringBuffer();

		SecureRandom random = new SecureRandom(); // use more secure variant of Random!
		if (size > 0) {
			for (int i = 0; i < length; i++) {
				char c = characterSet.charAt((char) random.nextInt(size));
				buffer.append(c);
			}
		}
		return buffer.toString();
	}
	
	public String getCharacterSet(boolean upperCase, boolean lowerCase, boolean digits, boolean minus, boolean underline, boolean space, boolean specials, boolean brackets) {
		StringBuffer charSet = new StringBuffer();
		
		if (upperCase) {
			charSet.append(UPPERCASE_CHARS);
		}
		
		if (lowerCase) {
			charSet.append(LOWERCASE_CHARS);
		}
		
		if (digits) {
			charSet.append(DIGIT_CHARS);
		}
		
		if (minus) {
			charSet.append(MINUS_CHAR);
		}
		
		if (underline) {
			charSet.append(UNDERLINE_CHAR);
		}
		
		if (space) {
			charSet.append(SPACE_CHAR);
		}
		
		if (specials) {
			charSet.append(SPECIAL_CHARS);
		}
		
		if (brackets) {
			charSet.append(BRACKET_CHARS);
		}
		
		return charSet.toString();
	}
}