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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/mode/CBC.java | |
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Diffstat (limited to 'libjava/classpath/gnu/javax/crypto/mode/CBC.java')
-rw-r--r-- | libjava/classpath/gnu/javax/crypto/mode/CBC.java | 123 |
1 files changed, 123 insertions, 0 deletions
diff --git a/libjava/classpath/gnu/javax/crypto/mode/CBC.java b/libjava/classpath/gnu/javax/crypto/mode/CBC.java new file mode 100644 index 000000000..31c445f4e --- /dev/null +++ b/libjava/classpath/gnu/javax/crypto/mode/CBC.java @@ -0,0 +1,123 @@ +/* CBC.java -- + Copyright (C) 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.mode; + +import gnu.java.security.Registry; +import gnu.javax.crypto.cipher.IBlockCipher; + +/** + * The Cipher Block Chaining mode. This mode introduces feedback into the cipher + * by XORing the previous ciphertext block with the plaintext block before + * encipherment. That is, encrypting looks like this: + * + * <pre> + * C<sub>i</sub> = E<sub>K</sub>(P<sub>i</sub>ˆ C<sub>i-1</sub>) + * </pre> + * <p> + * Similarly, decrypting is: + * <pre> + * P<sub>i</sub> = C<sub>i-1</sub> ˆ D<sub>K</sub>(C<sub>i</sub>) + * </pre> + */ +public class CBC + extends BaseMode + implements Cloneable +{ + /** The last (de|en)crypted block */ + private byte[] lastBlock; + /** An intermediate buffer. */ + private byte[] scratch; + + /** + * Package-private constructor for the factory class. + * + * @param underlyingCipher The cipher implementation. + * @param cipherBlockSize The cipher's block size. + */ + CBC(IBlockCipher underlyingCipher, int cipherBlockSize) + { + super(Registry.CBC_MODE, underlyingCipher, cipherBlockSize); + } + + /** Our constructor for cloning. */ + private CBC(CBC that) + { + this((IBlockCipher) that.cipher.clone(), that.cipherBlockSize); + } + + public Object clone() + { + return new CBC(this); + } + + public void setup() + { + if (modeBlockSize != cipherBlockSize) + throw new IllegalArgumentException(); + scratch = new byte[cipherBlockSize]; + lastBlock = new byte[cipherBlockSize]; + // lastBlock gets initialized to the initialization vector. + for (int i = 0; i < lastBlock.length && i < iv.length; i++) + lastBlock[i] = iv[i]; + } + + public void teardown() + { + lastBlock = null; + scratch = null; + } + + public void encryptBlock(byte[] in, int i, byte[] out, int o) + { + for (int k = 0; k < scratch.length; k++) + scratch[k] = (byte)(lastBlock[k] ^ in[k + i]); + cipher.encryptBlock(scratch, 0, out, o); + System.arraycopy(out, o, lastBlock, 0, cipherBlockSize); + } + + public void decryptBlock(byte[] in, int i, byte[] out, int o) + { + byte[] buf = new byte[cipherBlockSize]; + System.arraycopy(in, i, buf, 0, cipherBlockSize); + cipher.decryptBlock(in, i, scratch, 0); + for (int k = 0; k < scratch.length; k++) + out[o + k] = (byte)(lastBlock[k] ^ scratch[k]); + System.arraycopy(buf, 0, lastBlock, 0, cipherBlockSize); + } +} |