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java.security

Class MessageDigestSpi

java.lang.Object
|
+--java.security.MessageDigestSpi


public abstract class MessageDigestSpi

extends Object

This is the Service Provider Interface (SPI) for MessageDigest class in java.security. It provides the back end functionality for the MessageDigest class so that it can compute message hashes. The default hashes are SHA-1 and MD5. A message hash takes data of arbitrary length and produces a unique number representing it. Cryptography service providers who want to implement their own message digest hashes need only to subclass this class. The implementation of a Cloneable interface is left to up to the programmer of a subclass.

Author:

Constructor Summary

MessageDigestSpi()

Default constructor of the MessageDigestSpi class

Method Summary

java.lang.Objectclone()

Returns a clone of this class.
byte[]engineDigest()

Computes the final digest of the stored bytes and returns them.
intengineDigest(byte[] , int offset, int len)

Computes the final digest of the stored bytes and returns them.
intengineGetDigestLength()

Returns the length of the digest.
voidengineReset()

Resets the digest engine.
voidengineUpdate(byte input)

Updates the digest with the specified byte.
voidengineUpdate(byte[] , int offset, int len)

Updates the digest with the specified bytes starting with the offset and proceeding for the specified length.

Constructor Details

MessageDigestSpi

public MessageDigestSpi()

Default constructor of the MessageDigestSpi class


Method Details

clone

public Object clone()

Returns a clone of this class. If cloning is not supported, then by default the class throws a CloneNotSupportedException. The MessageDigestSpi provider implementation has to overload this class in order to be cloneable.


engineDigest

protected byte[] engineDigest()

Computes the final digest of the stored bytes and returns them. It performs any necessary padding. The message digest should reset sensitive data after performing the digest.

Returns:


engineDigest

protected int engineDigest(byte[] , int offset, int len)

Computes the final digest of the stored bytes and returns them. It performs any necessary padding. The message digest should reset sensitive data after performing the digest. This method is left concrete for backwards compatibility with JDK1.1 message digest classes.

Since:Parameters:

Returns:


engineGetDigestLength

protected int engineGetDigestLength()

Returns the length of the digest. It may be overridden by the provider to return the length of the digest. Default is to return 0. It is concrete for backwards compatibility with JDK1.1 message digest classes.

Since:Returns:


engineReset

protected void engineReset()

Resets the digest engine. Reinitializes internal variables and clears sensitive data.


engineUpdate

protected void engineUpdate(byte input)

Updates the digest with the specified byte.

Parameters:


engineUpdate

protected void engineUpdate(byte[] , int offset, int len)

Updates the digest with the specified bytes starting with the offset and proceeding for the specified length.

Parameters: