Package java.security

Class MessageDigestSpi

java.lang.Object
java.security.MessageDigestSpi
Direct Known Subclasses:
MessageDigest, SHA1_MessageDigestImpl
public abstract class MessageDigestSpi
extends Object
MessageDigestSpi is the Service Provider Interface (SPI) definition for MessageDigest. Examples of digest algorithms are MD5 and SHA. A digest is a secure one way hash function for a stream of bytes. It acts like a fingerprint for a stream of bytes.
See Also:
MessageDigest

  • Constructor Summary

    Constructors
    Constructor Description
    MessageDigestSpi()  

  • Method Summary

    Modifier and Type Method Description
    Object clone()
    Creates and returns a copy of this Object.
    protected abstract byte[] engineDigest()
    Computes and returns the final hash value for this MessageDigestSpi.
    protected int engineDigest​(byte[] buf, int offset, int len)
    Computes and stores the final hash value for this MessageDigestSpi.
    protected int engineGetDigestLength()
    Returns the engine digest length in bytes.
    protected abstract void engineReset()
    Puts this MessageDigestSpi back in an initial state, such that it is ready to compute a one way hash value.
    protected abstract void engineUpdate​(byte input)
    Updates this MessageDigestSpi using the given byte.
    protected abstract void engineUpdate​(byte[] input, int offset, int len)
    Updates this MessageDigestSpi using the given byte[].
    protected void engineUpdate​(ByteBuffer input)
    Updates this MessageDigestSpi using the given input.

    Methods inherited from class java.lang.Object

    equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

    • MessageDigestSpi

      public MessageDigestSpi()

  • Method Details

    • engineGetDigestLength

      protected int engineGetDigestLength()
      Returns the engine digest length in bytes. If the implementation does not implement this function 0 is returned.
      Returns:
      the digest length in bytes, or 0.

    • engineUpdate

      protected abstract void engineUpdate​(byte input)
      Updates this MessageDigestSpi using the given byte.
      Parameters:
      input - the byte to update this MessageDigestSpi with.
      See Also:
      engineReset()

    • engineUpdate

      protected abstract void engineUpdate​(byte[] input, int offset, int len)
      Updates this MessageDigestSpi using the given byte[].
      Parameters:
      input - the byte array.
      offset - the index of the first byte in input to update from.
      len - the number of bytes in input to update from.
      Throws:
      IllegalArgumentException - if offset or len are not valid in respect to input.

    • engineUpdate

      protected void engineUpdate​(ByteBuffer input)
      Updates this MessageDigestSpi using the given input.
      Parameters:
      input - the ByteBuffer.

    • engineDigest

      protected abstract byte[] engineDigest()
      Computes and returns the final hash value for this MessageDigestSpi. After the digest is computed the receiver is reset.
      Returns:
      the computed one way hash value.
      See Also:
      engineReset()

    • engineDigest

      protected int engineDigest​(byte[] buf, int offset, int len) throws DigestException
      Computes and stores the final hash value for this MessageDigestSpi. After the digest is computed the receiver is reset.
      Parameters:
      buf - the buffer to store the result in.
      offset - the index of the first byte in buf to store in.
      len - the number of bytes allocated for the digest.
      Returns:
      the number of bytes written to buf.
      Throws:
      DigestException - if an error occures.
      IllegalArgumentException - if offset or len are not valid in respect to buf.
      See Also:
      engineReset()

    • engineReset

      protected abstract void engineReset()
      Puts this MessageDigestSpi back in an initial state, such that it is ready to compute a one way hash value.

    • clone

      public Object clone() throws CloneNotSupportedException
      Description copied from class: Object
      Creates and returns a copy of this Object. The default implementation returns a so-called "shallow" copy: It creates a new instance of the same class and then copies the field values (including object references) from this instance to the new instance. A "deep" copy, in contrast, would also recursively clone nested objects. A subclass that needs to implement this kind of cloning should call super.clone() to create the new instance and then create deep copies of the nested, mutable objects.
      Overrides:
      clone in class Object
      Returns:
      a copy of this object.
      Throws:
      CloneNotSupportedException - if this object's class does not implement the Cloneable interface.