java.security
Class MessageDigestSpi
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.
Object | clone()- Returns a clone of this class.
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protected abstract byte[] | engineDigest()- Computes the final digest of the stored bytes and returns
them.
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protected int | engineDigest(byte[] buf, int offset, int len)- Computes the final digest of the stored bytes and returns
them.
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protected int | engineGetDigestLength()- Returns the length of the digest.
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protected abstract void | engineReset()- Resets the digest engine.
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protected abstract void | engineUpdate(byte input)- Updates the digest with the specified byte.
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protected abstract void | engineUpdate(byte[] input, int offset, int len)- Updates the digest with the specified bytes starting with the
offset and proceeding for the specified length.
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protected void | engineUpdate(ByteBuffer input)- Updates this digest with the remaining bytes of a byte buffer.
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clone, equals, extends Object> getClass, finalize, hashCode, notify, notifyAll, toString, wait, wait, wait |
MessageDigestSpi
public MessageDigestSpi()
Default constructor of the MessageDigestSpi class
clone
public Object clone()
throws CloneNotSupportedExceptionReturns 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.
- clone in interface Object
engineDigest
protected abstract 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.
- An array of bytes containing the digest
engineDigest
protected int engineDigest(byte[] buf,
int offset,
int len)
throws DigestExceptionComputes 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.
buf - An array of bytes to store the digestoffset - An offset to start storing the digest atlen - The length of the buffer
- 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.
- Length of Digest in Bytes
engineReset
protected abstract void engineReset()
Resets the digest engine. Reinitializes internal variables
and clears sensitive data.
engineUpdate
protected abstract void engineUpdate(byte input)
Updates the digest with the specified byte.
input - the byte to update digest with
engineUpdate
protected abstract void engineUpdate(byte[] input,
int offset,
int len)Updates the digest with the specified bytes starting with the
offset and proceeding for the specified length.
input - the byte array to update digest withoffset - the offset of the byte to start withlen - the number of the bytes to update with
engineUpdate
protected void engineUpdate(ByteBuffer input)
Updates this digest with the remaining bytes of a byte buffer.
input - The input buffer.
MessageDigestSpi.java --- The message digest service provider interface.
Copyright (C) 1999, 2005 Free Software Foundation, Inc.
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