java.security
Class MessageDigestSpi
java.lang.Object
|
+--java.security.MessageDigestSpi
public abstract class
MessageDigestSpiextends
ObjectThis 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:- Mark Benvenuto <ivymccough@worldnet.att.net>
MessageDigestSpi
public MessageDigestSpi()
Default constructor of the MessageDigestSpi class
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:
- An array of bytes containing the digest
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:
- Returns the length of the buffer
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:
- Length of Digest in Bytes
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: