aboutsummaryrefslogtreecommitdiffstats
path: root/gcc-4.4.3/libjava/classpath/gnu/javax/crypto/mode/CTR.java
diff options
context:
space:
mode:
Diffstat (limited to 'gcc-4.4.3/libjava/classpath/gnu/javax/crypto/mode/CTR.java')
-rw-r--r--gcc-4.4.3/libjava/classpath/gnu/javax/crypto/mode/CTR.java168
1 files changed, 168 insertions, 0 deletions
diff --git a/gcc-4.4.3/libjava/classpath/gnu/javax/crypto/mode/CTR.java b/gcc-4.4.3/libjava/classpath/gnu/javax/crypto/mode/CTR.java
new file mode 100644
index 000000000..0c856b483
--- /dev/null
+++ b/gcc-4.4.3/libjava/classpath/gnu/javax/crypto/mode/CTR.java
@@ -0,0 +1,168 @@
+/* CTR.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.mode;
+
+import gnu.java.security.Registry;
+import gnu.java.security.util.Sequence;
+import gnu.javax.crypto.cipher.IBlockCipher;
+
+import java.util.Arrays;
+import java.util.Iterator;
+
+/**
+ * The implementation of the Counter Mode.
+ * <p>
+ * The algorithm steps are formally described as follows:
+ *
+ * <pre>
+ * CTR Encryption: O[j] = E(K)(T[j]); for j = 1, 2...n;
+ * C[j] = P[j] &circ; O[j]; for j = 1, 2...n.
+ * CTR Decryption: O[j] = E(K)(T[j]); for j = 1, 2...n;
+ * P[j] = C[j] &circ; O[j]; for j = 1, 2...n.
+ * </pre>
+ *
+ * <p>
+ * where <code>P</code> is the plaintext, <code>C</code> is the ciphertext,
+ * <code>E(K)</code> is the underlying block cipher encryption function
+ * parametrised with the session key <code>K</code>, and <code>T</code> is
+ * the <i>Counter</i>.
+ * <p>
+ * This implementation, uses a standard incrementing function with a step of 1,
+ * and an initial value similar to that described in the NIST document.
+ * <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 class CTR
+ extends BaseMode
+ implements Cloneable
+{
+ private int off;
+ private byte[] counter, enc;
+
+ /**
+ * Trivial package-private constructor for use by the Factory class.
+ *
+ * @param underlyingCipher the underlying cipher implementation.
+ * @param cipherBlockSize the underlying cipher block size to use.
+ */
+ CTR(IBlockCipher underlyingCipher, int cipherBlockSize)
+ {
+ super(Registry.CTR_MODE, underlyingCipher, cipherBlockSize);
+ }
+
+ /**
+ * Private constructor for cloning purposes.
+ *
+ * @param that the instance to clone.
+ */
+ private CTR(CTR that)
+ {
+ this((IBlockCipher) that.cipher.clone(), that.cipherBlockSize);
+ }
+
+ public Object clone()
+ {
+ return new CTR(this);
+ }
+
+ public void setup()
+ {
+ if (modeBlockSize > cipherBlockSize)
+ throw new IllegalArgumentException("mode size exceeds cipher block size");
+ off = 0;
+ counter = new byte[cipherBlockSize];
+ int i = cipherBlockSize - 1;
+ int j = iv.length - 1;
+ while (i >= 0 && j >= 0)
+ counter[i--] = iv[j--];
+ enc = new byte[cipherBlockSize];
+ cipher.encryptBlock(counter, 0, enc, 0);
+ }
+
+ public void teardown()
+ {
+ if (counter != null)
+ Arrays.fill(counter, (byte) 0);
+ if (enc != null)
+ Arrays.fill(enc, (byte) 0);
+ }
+
+ public void encryptBlock(byte[] in, int i, byte[] out, int o)
+ {
+ ctr(in, i, out, o);
+ }
+
+ public void decryptBlock(byte[] in, int i, byte[] out, int o)
+ {
+ ctr(in, i, out, o);
+ }
+
+ public Iterator blockSizes()
+ {
+ return new Sequence(1, cipherBlockSize).iterator();
+ }
+
+ private void ctr(byte[] in, int inOffset, byte[] out, int outOffset)
+ {
+ for (int i = 0; i < modeBlockSize; i++)
+ {
+ out[outOffset++] = (byte)(in[inOffset++] ^ enc[off++]);
+ if (off == cipherBlockSize)
+ {
+ int j;
+ for (j = cipherBlockSize - 1; j >= 0; j--)
+ {
+ counter[j]++;
+ if ((counter[j] & 0xFF) != 0)
+ break;
+ }
+ if (j == 0)
+ counter[cipherBlockSize - 1]++;
+ off = 0;
+ cipher.encryptBlock(counter, 0, enc, 0);
+ }
+ }
+ }
+}