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author | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
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committer | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
commit | 554fd8c5195424bdbcabf5de30fdc183aba391bd (patch) | |
tree | 976dc5ab7fddf506dadce60ae936f43f58787092 /libjava/classpath/gnu/javax/crypto/pad/TBC.java | |
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Diffstat (limited to 'libjava/classpath/gnu/javax/crypto/pad/TBC.java')
-rw-r--r-- | libjava/classpath/gnu/javax/crypto/pad/TBC.java | 118 |
1 files changed, 118 insertions, 0 deletions
diff --git a/libjava/classpath/gnu/javax/crypto/pad/TBC.java b/libjava/classpath/gnu/javax/crypto/pad/TBC.java new file mode 100644 index 000000000..5cd177058 --- /dev/null +++ b/libjava/classpath/gnu/javax/crypto/pad/TBC.java @@ -0,0 +1,118 @@ +/* TBC.java -- + Copyright (C) 2001, 2002, 2006 Free Software Foundation, Inc. + +This file is a part of GNU Classpath. + +GNU Classpath 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. + +GNU Classpath 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 GNU Classpath; if not, write to the Free Software +Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 +USA + +Linking this library statically or dynamically with other modules is +making a combined work based on this library. Thus, the terms and +conditions of the GNU General Public License cover the whole +combination. + +As a special exception, the copyright holders of this library give you +permission to link this library with independent modules to produce an +executable, regardless of the license terms of these independent +modules, and to copy and distribute the resulting executable under +terms of your choice, provided that you also meet, for each linked +independent module, the terms and conditions of the license of that +module. An independent module is a module which is not derived from +or based on this library. If you modify this library, you may extend +this exception to your version of the library, but you are not +obligated to do so. If you do not wish to do so, delete this +exception statement from your version. */ + + +package gnu.javax.crypto.pad; + +import gnu.java.security.Configuration; +import gnu.java.security.Registry; +import gnu.java.security.util.Util; + +import java.util.logging.Logger; + +/** + * The implementation of the Trailing Bit Complement (TBC) padding algorithm. + * <p> + * In this mode, "...the data string is padded at the trailing end with the + * complement of the trailing bit of the unpadded message: if the trailing bit + * is <tt>1</tt>, then <tt>0</tt> bits are appended, and if the trailing + * bit is <tt>0</tt>, then <tt>1</tt> bits are appended. As few bits are + * added as are necessary to meet the formatting size requirement." + * <p> + * References: + * <ol> + * <li><a + * href="http://csrc.nist.gov/encryption/modes/Recommendation/Modes01.pdf"> + * Recommendation for Block Cipher Modes of Operation Methods and + * Techniques</a>, Morris Dworkin.</li> + * </ol> + */ +public final class TBC + extends BasePad +{ + private static final Logger log = Logger.getLogger(TBC.class.getName()); + + /** + * Trivial package-private constructor for use by the <i>Factory</i> class. + * + * @see PadFactory + */ + TBC() + { + super(Registry.TBC_PAD); + } + + public void setup() + { + if (blockSize < 1 || blockSize > 256) + throw new IllegalArgumentException(); + } + + public byte[] pad(byte[] in, int offset, int length) + { + int padLength = blockSize; + if (length % blockSize != 0) + padLength = blockSize - length % blockSize; + byte[] result = new byte[padLength]; + int lastBit = in[offset + length - 1] & 0x01; + if (lastBit == 0) + for (int i = 0; i < padLength;) + result[i++] = 0x01; + // else it's already set to zeroes by virtue of initialisation + if (Configuration.DEBUG) + log.fine("padding: 0x" + Util.toString(result)); + return result; + } + + public int unpad(byte[] in, int offset, int length) + throws WrongPaddingException + { + int limit = offset + length - 1; + int lastBit = in[limit] & 0xFF; + int result = 0; + while (lastBit == (in[limit] & 0xFF)) + { + result++; + limit--; + } + if (result > length) + throw new WrongPaddingException(); + if (Configuration.DEBUG) + log.fine("padding length: " + result); + return result; + } +} |