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gnu.java.security.hash

Class Sha160

Implemented Interfaces:
Cloneable, IMessageDigest
public class Sha160
extends BaseHash
The Secure Hash Algorithm (SHA-1) is required for use with the Digital Signature Algorithm (DSA) as specified in the Digital Signature Standard (DSS) and whenever a secure hash algorithm is required for federal applications. For a message of length less than 2^64 bits, the SHA-1 produces a 160-bit condensed representation of the message called a message digest. The message digest is used during generation of a signature for the message. The SHA-1 is also used to compute a message digest for the received version of the message during the process of verifying the signature. Any change to the message in transit will, with very high probability, result in a different message digest, and the signature will fail to verify.

The SHA-1 is designed to have the following properties: it is computationally infeasible to find a message which corresponds to a given message digest, or to find two different messages which produce the same message digest.

References:

  1. SECURE HASH STANDARD
    Federal Information, Processing Standards Publication 180-1, 1995 April 17.

Field Summary

Fields inherited from class gnu.java.security.hash.BaseHash

blockSize, buffer, count, hashSize, name

Constructor Summary

Sha160()
Trivial 0-arguments constructor.

Method Summary

static int[]
G(int hh0, int hh1, int hh2, int hh3, int hh4, byte[] in, int offset)
Object
clone()
Returns a clone copy of this instance.
protected byte[]
getResult()
Constructs the result from the contents of the current context.
protected byte[]
padBuffer()
Returns the byte array to use as padding before completing a hash operation.
protected void
resetContext()
Resets the instance for future re-use.
boolean
selfTest()
A basic test.
protected void
transform(byte[] in, int offset)
The block digest transformation per se.

Methods inherited from class gnu.java.security.hash.BaseHash

blockSize, clone, digest, getResult, hashSize, name, padBuffer, reset, resetContext, selfTest, transform, update, update, update

Methods inherited from class java.lang.Object

clone, equals, extends Object> getClass, finalize, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

Sha160

public Sha160()
Trivial 0-arguments constructor.

Method Details

G

public static final int[] G(int hh0,
                            int hh1,
                            int hh2,
                            int hh3,
                            int hh4,
                            byte[] in,
                            int offset)

clone

public Object clone()
Returns a clone copy of this instance.
Specified by:
clone in interface IMessageDigest
Overrides:
clone in interface BaseHash
Returns:
a clone copy of this instance.

getResult

protected byte[] getResult()
Constructs the result from the contents of the current context.
Overrides:
getResult in interface BaseHash
Returns:
the output of the completed hash operation.

padBuffer

protected byte[] padBuffer()
Returns the byte array to use as padding before completing a hash operation.
Overrides:
padBuffer in interface BaseHash
Returns:
the bytes to pad the remaining bytes in the buffer before completing a hash operation.

resetContext

protected void resetContext()
Resets the instance for future re-use.
Overrides:
resetContext in interface BaseHash

selfTest

public boolean selfTest()
A basic test. Ensures that the digest of a pre-determined message is equal to a known pre-computed value.
Specified by:
selfTest in interface IMessageDigest
Overrides:
selfTest in interface BaseHash
Returns:
true if the implementation passes a basic self-test. Returns false otherwise.

transform

protected void transform(byte[] in,
                         int offset)
The block digest transformation per se.
Overrides:
transform in interface BaseHash
Parameters:
in - the blockSize long block, as an array of bytes to digest.
offset - the index where the data to digest is located within the input buffer.
Sha160.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.

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