## gnu.crypto.hash
Class BaseHashStandalone

    java.lang.Object
      gnu.crypto.hash.BaseHashStandalone

All Implemented Interfaces:
  IMessageDigestStandalone, Cloneable

Direct Known Subclasses:
  Sha256Standalone

    public abstract class BaseHashStandalone

extends Object
implements IMessageDigestStandalone

A base abstract class to facilitate hash implementations.

Version:
  $Revision: 1.1 $

Field Summary
`protected int` `blockSize` The hash (inner) block size in bytes.
`protected byte[]` `buffer` Temporary input buffer.
`protected long` `count` Number of bytes processed so far.
`protected int` `hashSize` The hash (output) size in bytes.
`protected String` `name` The canonical name prefix of the hash.

Constructor Summary
`protected` `BaseHashStandalone(String name, int hashSize, int blockSize)` Trivial constructor for use by concrete subclasses.

Method Summary
`int` `blockSize()` Returns the algorithm's (inner) block size in bytes.
`abstract Object` `clone()` Returns a clone copy of this instance.
`byte[]` `digest()` Completes the message digest by performing final operations such as padding and resetting the instance.
`protected abstract byte[]` `getResult()` Constructs the result from the contents of the current context.
`int` `hashSize()` Returns the output length in bytes of this message digest algorithm.
`String` `name()` Returns the canonical name of this algorithm.
`protected abstract byte[]` `padBuffer()` Returns the byte array to use as padding before completing a hash operation.
`void` `reset()` Resets the current context of this instance clearing any eventually cached intermediary values.
`protected abstract void` `resetContext()` Resets the instance for future re-use.
`abstract boolean` `selfTest()` A basic test.
`protected abstract void` `transform(byte[] in, int offset)` The block digest transformation per se.
`void` `update(byte b)` Continues a message digest operation using the input byte.
`void` `update(byte[] b)` Continues a message digest operation, by filling the buffer, processing data in the algorithm's HASH_SIZE-bit block(s), updating the context and count, and buffering the remaining bytes in buffer for the next operation.
`void` `update(byte[] b, int offset, int len)` Continues a message digest operation, by filling the buffer, processing data in the algorithm's HASH_SIZE-bit block(s), updating the context and count, and buffering the remaining bytes in buffer for the next operation.

Methods inherited from class java.lang.Object
`equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Field Detail

### name

    protected String name

  The canonical name prefix of the hash.

### hashSize

    protected int hashSize

  The hash (output) size in bytes.

### blockSize

    protected int blockSize

  The hash (inner) block size in bytes.

### count

    protected long count

  Number of bytes processed so far.

### buffer

    protected byte[] buffer

  Temporary input buffer.

Constructor Detail

### BaseHashStandalone

    protected BaseHashStandalone(String name,
                                 int hashSize,
                                 int blockSize)

  Trivial constructor for use by concrete subclasses.

  Parameters:
    `name` - the canonical name prefix of this instance.
    `hashSize` - the block size of the output in bytes.
    `blockSize` - the block size of the internal transform.

Method Detail

### name

    public String name()

  Description copied from interface: `IMessageDigestStandalone`

  Returns the canonical name of this algorithm.

  Specified by:
    `name` in interface `IMessageDigestStandalone`
  Returns:
    the canonical name of this instance.

### hashSize

    public int hashSize()

  Description copied from interface: `IMessageDigestStandalone`

  Returns the output length in bytes of this message digest algorithm.

  Specified by:
    `hashSize` in interface `IMessageDigestStandalone`
  Returns:
    the output length in bytes of this message digest algorithm.

### blockSize

    public int blockSize()

  Description copied from interface: `IMessageDigestStandalone`

  Returns the algorithm's (inner) block size in bytes.

  Specified by:
    `blockSize` in interface `IMessageDigestStandalone`
  Returns:
    the algorithm's inner block size in bytes.

### update

    public void update(byte b)

  Description copied from interface: `IMessageDigestStandalone`

  Continues a message digest operation using the input byte.

  Specified by:
    `update` in interface `IMessageDigestStandalone`
  Parameters:
    `b` - the input byte to digest.

### update

    public void update(byte[] b)

  Description copied from interface: `IMessageDigestStandalone`

  Continues a message digest operation, by filling the buffer, processing data in the algorithm's HASH_SIZE-bit block(s), updating the context and count, and buffering the remaining bytes in buffer for the next operation.

  Specified by:
    `update` in interface `IMessageDigestStandalone`
  Parameters:
    `b` - the input block.

### update

    public void update(byte[] b,
                       int offset,
                       int len)

  Description copied from interface: `IMessageDigestStandalone`

  Continues a message digest operation, by filling the buffer, processing data in the algorithm's HASH_SIZE-bit block(s), updating the context and count, and buffering the remaining bytes in buffer for the next operation.

  Specified by:
    `update` in interface `IMessageDigestStandalone`
  Parameters:
    `b` - the input block.
    `offset` - start of meaningful bytes in input block.
    `len` - number of bytes, in input block, to consider.

### digest

    public byte[] digest()

  Description copied from interface: `IMessageDigestStandalone`

  Completes the message digest by performing final operations such as padding and resetting the instance.

  Specified by:
    `digest` in interface `IMessageDigestStandalone`
  Returns:
    the array of bytes representing the hash value.

### reset

    public void reset()

  Description copied from interface: `IMessageDigestStandalone`

  Resets the current context of this instance clearing any eventually cached intermediary values.

  Specified by:
    `reset` in interface `IMessageDigestStandalone`

### clone

    public abstract Object clone()

  Description copied from interface: `IMessageDigestStandalone`

  Returns a clone copy of this instance.

  Specified by:
    `clone` in interface `IMessageDigestStandalone`
  Overrides:
    `clone` in class `Object`
  Returns:
    a clone copy of this instance.

### selfTest

    public abstract boolean selfTest()

  Description copied from interface: `IMessageDigestStandalone`

  A basic test. Ensures that the digest of a pre-determined message is equal to a known pre-computed value.

  Specified by:
    `selfTest` in interface `IMessageDigestStandalone`
  Returns:
    `true` if the implementation passes a basic self-test. Returns `false` otherwise.

### padBuffer

    protected abstract byte[] padBuffer()

  Returns the byte array to use as padding before completing a hash operation.

  Returns:
    the bytes to pad the remaining bytes in the buffer before completing a hash operation.

### getResult

    protected abstract byte[] getResult()

  Constructs the result from the contents of the current context.

  Returns:
    the output of the completed hash operation.

### resetContext

    protected abstract void resetContext()

  Resets the instance for future re-use.

### transform

    protected abstract void transform(byte[] in,
                                      int offset)

  The block digest transformation per se.

  Parameters:
    `in` - the blockSize long block, as an array of bytes to digest.
    `offset` - the index where the data to digest is located within the input buffer.