java.security
Class MessageDigestSpi

java.lang.Object sample code for java.lang.Object definition code for java.lang.Object 
  extended by java.security.MessageDigestSpi
Direct Known Subclasses:
MessageDigest sample code for java.security.MessageDigest definition code for java.security.MessageDigest

public abstract class MessageDigestSpi
extends Object sample code for java.lang.Object definition code for java.lang.Object

This class defines the Service Provider Interface (SPI) for the MessageDigest class, which provides the functionality of a message digest algorithm, such as MD5 or SHA. Message digests are secure one-way hash functions that take arbitrary-sized data and output a fixed-length hash value.

All the abstract methods in this class must be implemented by a cryptographic service provider who wishes to supply the implementation of a particular message digest algorithm.

Implementations are free to implement the Cloneable interface.

See Also:
MessageDigest sample code for java.security.MessageDigest definition code for java.security.MessageDigest

Constructor Summary
MessageDigestSpi sample code for java.security.MessageDigestSpi.MessageDigestSpi() definition code for java.security.MessageDigestSpi.MessageDigestSpi() ()
           
 
Method Summary
 Object sample code for java.lang.Object definition code for java.lang.Object clone sample code for java.security.MessageDigestSpi.clone() definition code for java.security.MessageDigestSpi.clone() ()
          Returns a clone if the implementation is cloneable.
protected abstract  byte[] engineDigest sample code for java.security.MessageDigestSpi.engineDigest() definition code for java.security.MessageDigestSpi.engineDigest() ()
          Completes the hash computation by performing final operations such as padding.
protected  int engineDigest sample code for java.security.MessageDigestSpi.engineDigest(byte[], int, int) definition code for java.security.MessageDigestSpi.engineDigest(byte[], int, int) (byte[] buf, int offset, int len)
          Completes the hash computation by performing final operations such as padding.
protected  int engineGetDigestLength sample code for java.security.MessageDigestSpi.engineGetDigestLength() definition code for java.security.MessageDigestSpi.engineGetDigestLength() ()
          Returns the digest length in bytes.
protected abstract  void engineReset sample code for java.security.MessageDigestSpi.engineReset() definition code for java.security.MessageDigestSpi.engineReset() ()
          Resets the digest for further use.
protected abstract  void engineUpdate sample code for java.security.MessageDigestSpi.engineUpdate(byte) definition code for java.security.MessageDigestSpi.engineUpdate(byte) (byte input)
          Updates the digest using the specified byte.
protected abstract  void engineUpdate sample code for java.security.MessageDigestSpi.engineUpdate(byte[], int, int) definition code for java.security.MessageDigestSpi.engineUpdate(byte[], int, int) (byte[] input, int offset, int len)
          Updates the digest using the specified array of bytes, starting at the specified offset.
protected  void engineUpdate sample code for java.security.MessageDigestSpi.engineUpdate(java.nio.ByteBuffer) definition code for java.security.MessageDigestSpi.engineUpdate(java.nio.ByteBuffer) (ByteBuffer sample code for java.nio.ByteBuffer definition code for java.nio.ByteBuffer  input)
          Update the digest using the specified ByteBuffer.
 
Methods inherited from class java.lang.Object sample code for java.lang.Object definition code for java.lang.Object
equals sample code for java.lang.Object.equals(java.lang.Object) definition code for java.lang.Object.equals(java.lang.Object) , finalize sample code for java.lang.Object.finalize() definition code for java.lang.Object.finalize() , getClass sample code for java.lang.Object.getClass() definition code for java.lang.Object.getClass() , hashCode sample code for java.lang.Object.hashCode() definition code for java.lang.Object.hashCode() , notify sample code for java.lang.Object.notify() definition code for java.lang.Object.notify() , notifyAll sample code for java.lang.Object.notifyAll() definition code for java.lang.Object.notifyAll() , toString sample code for java.lang.Object.toString() definition code for java.lang.Object.toString() , wait sample code for java.lang.Object.wait() definition code for java.lang.Object.wait() , wait sample code for java.lang.Object.wait(long) definition code for java.lang.Object.wait(long) , wait sample code for java.lang.Object.wait(long, int) definition code for java.lang.Object.wait(long, int)
 

Constructor Detail

MessageDigestSpi sample code for java.security.MessageDigestSpi() definition code for java.security.MessageDigestSpi()

public MessageDigestSpi()
Method Detail

engineGetDigestLength sample code for java.security.MessageDigestSpi.engineGetDigestLength() definition code for java.security.MessageDigestSpi.engineGetDigestLength()

protected int engineGetDigestLength()
Returns the digest length in bytes.

This concrete method has been added to this previously-defined abstract class. (For backwards compatibility, it cannot be abstract.)

The default behavior is to return 0.

This method may be overridden by a provider to return the digest length.

Returns:
the digest length in bytes.
Since:
1.2

engineUpdate sample code for java.security.MessageDigestSpi.engineUpdate(byte) definition code for java.security.MessageDigestSpi.engineUpdate(byte)

protected abstract void engineUpdate(byte input)
Updates the digest using the specified byte.

Parameters:
input - the byte to use for the update.

engineUpdate sample code for java.security.MessageDigestSpi.engineUpdate(byte[], int, int) definition code for java.security.MessageDigestSpi.engineUpdate(byte[], int, int)

protected abstract void engineUpdate(byte[] input,
                                     int offset,
                                     int len)
Updates the digest using the specified array of bytes, starting at the specified offset.

Parameters:
input - the array of bytes to use for the update.
offset - the offset to start from in the array of bytes.
len - the number of bytes to use, starting at offset.

engineUpdate sample code for java.security.MessageDigestSpi.engineUpdate(java.nio.ByteBuffer) definition code for java.security.MessageDigestSpi.engineUpdate(java.nio.ByteBuffer)

protected void engineUpdate(ByteBuffer sample code for java.nio.ByteBuffer definition code for java.nio.ByteBuffer  input)
Update the digest using the specified ByteBuffer. The digest is updated using the input.remaining() bytes starting at input.position(). Upon return, the buffer's position will be equal to its limit; its limit will not have changed.

Parameters:
input - the ByteBuffer
Since:
1.5

engineDigest sample code for java.security.MessageDigestSpi.engineDigest() definition code for java.security.MessageDigestSpi.engineDigest()

protected abstract byte[] engineDigest()
Completes the hash computation by performing final operations such as padding. Once engineDigest has been called, the engine should be reset (see engineReset sample code for java.security.MessageDigestSpi.engineReset() definition code for java.security.MessageDigestSpi.engineReset() ). Resetting is the responsibility of the engine implementor.

Returns:
the array of bytes for the resulting hash value.

engineDigest sample code for java.security.MessageDigestSpi.engineDigest(byte[], int, int) definition code for java.security.MessageDigestSpi.engineDigest(byte[], int, int)

protected int engineDigest(byte[] buf,
                           int offset,
                           int len)
                    throws DigestException sample code for java.security.DigestException definition code for java.security.DigestException 
Completes the hash computation by performing final operations such as padding. Once engineDigest has been called, the engine should be reset (see engineReset sample code for java.security.MessageDigestSpi.engineReset() definition code for java.security.MessageDigestSpi.engineReset() ). Resetting is the responsibility of the engine implementor. This method should be abstract, but we leave it concrete for binary compatibility. Knowledgeable providers should override this method.

Parameters:
buf - the output buffer in which to store the digest
offset - offset to start from in the output buffer
len - number of bytes within buf allotted for the digest. Both this default implementation and the SUN provider do not return partial digests. The presence of this parameter is solely for consistency in our API's. If the value of this parameter is less than the actual digest length, the method will throw a DigestException. This parameter is ignored if its value is greater than or equal to the actual digest length.
Returns:
the length of the digest stored in the output buffer.
Throws:
DigestException sample code for java.security.DigestException definition code for java.security.DigestException - if an error occurs.
Since:
1.2

engineReset sample code for java.security.MessageDigestSpi.engineReset() definition code for java.security.MessageDigestSpi.engineReset()

protected abstract void engineReset()
Resets the digest for further use.


clone sample code for java.security.MessageDigestSpi.clone() definition code for java.security.MessageDigestSpi.clone()

public Object sample code for java.lang.Object definition code for java.lang.Object  clone()
             throws CloneNotSupportedException sample code for java.lang.CloneNotSupportedException definition code for java.lang.CloneNotSupportedException 
Returns a clone if the implementation is cloneable.

Overrides:
clone sample code for java.lang.Object.clone() definition code for java.lang.Object.clone() in class Object sample code for java.lang.Object definition code for java.lang.Object
Returns:
a clone if the implementation is cloneable.
Throws:
CloneNotSupportedException sample code for java.lang.CloneNotSupportedException definition code for java.lang.CloneNotSupportedException - if this is called on an implementation that does not support Cloneable.
See Also:
Cloneable sample code for java.lang.Cloneable definition code for java.lang.Cloneable