gecko-dev/mobile/android/base/sync/jpake/BigIntegerHelper.java

78 lines
2.8 KiB
Java

/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Android Sync Client.
*
* The Initial Developer of the Original Code is
* the Mozilla Foundation.
* Portions created by the Initial Developer are Copyright (C) 2011
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Chenxia Liu <liuche@mozilla.com>
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
package org.mozilla.gecko.sync.jpake;
import java.math.BigInteger;
public class BigIntegerHelper {
public static byte[] BigIntegerToByteArrayWithoutSign(BigInteger value) {
byte[] bytes = value.toByteArray();
if (bytes[0] == (byte) 0) {
bytes = copyArray(bytes, 1, bytes.length - 1);
}
return bytes;
}
private static byte[] copyArray(byte[] original, int start, int length) {
byte[] copy = new byte[length];
System.arraycopy(original, start, copy, 0,
Math.min(original.length - start, length));
return copy;
}
/**
* Convert an array of bytes to a non-negative big integer.
*/
public static BigInteger ByteArrayToBigIntegerWithoutSign(byte[] array) {
return new BigInteger(1, array);
}
/**
* Convert a big integer into hex string. If the length is not even, add an
* '0' character in the beginning to make it even.
*/
public static String toEvenLengthHex(BigInteger value) {
String result = value.toString(16);
if (result.length() % 2 != 0) {
result = "0" + result;
}
return result;
}
}