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Diffstat (limited to 'gnu/javax/crypto/pad/PKCS7.java')
| -rw-r--r-- | gnu/javax/crypto/pad/PKCS7.java | 149 |
1 files changed, 149 insertions, 0 deletions
diff --git a/gnu/javax/crypto/pad/PKCS7.java b/gnu/javax/crypto/pad/PKCS7.java new file mode 100644 index 000000000..5697aff27 --- /dev/null +++ b/gnu/javax/crypto/pad/PKCS7.java @@ -0,0 +1,149 @@ +/* PKCS7.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.Registry; +import gnu.java.security.util.Util; + +import java.io.PrintWriter; + +/** + * <p>The implementation of the PKCS7 padding algorithm.</p> + * + * <p>This algorithm is described for 8-byte blocks in [RFC-1423] and extended to + * block sizes of up to 256 bytes in [PKCS-7].</p> + * + * References:<br> + * <a href="http://www.ietf.org/rfc/rfc1423.txt">RFC-1423</a>: Privacy + * Enhancement for Internet Electronic Mail: Part III: Algorithms, Modes, and + * Identifiers.<br> + * <a href="http://www.ietf.org/">IETF</a>. + * <a href="http://www.rsasecurity.com/rsalabs/pkcs/pkcs-7/">[PKCS-7]</a>PKCS #7: + * Cryptographic Message Syntax Standard - An RSA Laboratories Technical Note.<br> + * <a href="http://www.rsasecurity.com/">RSA Security</a>.<p> + */ +public final class PKCS7 extends BasePad +{ + + // Debugging methods and variables + // ------------------------------------------------------------------------- + + private static final String NAME = "pkcs7"; + + private static final boolean DEBUG = false; + + private static final int debuglevel = 9; + + private static final PrintWriter err = new PrintWriter(System.out, true); + + private static void debug(String s) + { + err.println(">>> " + NAME + ": " + s); + } + + // Constants and variables + // ------------------------------------------------------------------------- + + // Constructor(s) + // ------------------------------------------------------------------------- + + /** + * Trivial package-private constructor for use by the <i>Factory</i> class.<p> + * + * @see gnu.crypto.pad.PadFactory + */ + PKCS7() + { + super(Registry.PKCS7_PAD); + } + + // Class methods + // ------------------------------------------------------------------------- + + // Implementation of abstract methods in BasePad + // ------------------------------------------------------------------------- + + public void setup() + { + if (blockSize < 2 || 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]; + for (int i = 0; i < padLength;) + { + result[i++] = (byte) padLength; + } + + if (DEBUG && debuglevel > 8) + { + debug("padding: 0x" + Util.toString(result)); + } + return result; + } + + public int unpad(byte[] in, int offset, int length) + throws WrongPaddingException + { + int limit = offset + length; + int result = in[limit - 1] & 0xFF; + for (int i = 0; i < result; i++) + { + if (result != (in[--limit] & 0xFF)) + { + throw new WrongPaddingException(); + } + } + + if (DEBUG && debuglevel > 8) + { + debug("padding length: " + String.valueOf(result)); + } + return result; + } +}
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