Digest::Keccak
==============

This Ruby extension implements the [Keccak](http://keccak.noekeon.org/)
(draft version of SHA-3) cryptographic hash function. It is based on
the reference C implementation, version 3.2. The exposed interface
is almost identical to that of the `digest` standard library.



Table of contents
-----------------

* [Usage](#usage)
* [Development](#development)



Usage
-----

Keccak supports 5 hash lengths: 224-bit, 256-bit, 384-bit, 512-bit
and variable length. Variable length is not supported by this Ruby extension.
Unless the user specifies otherwise, this Ruby extension assumes 512-bit.

```ruby
require 'digest/keccak'

# Generate 512-bit digest.
Digest::Keccak.digest    'foo' #=> "\x15\x97\x84*\xACR\xBC\x9D..."
Digest::Keccak.hexdigest 'foo' #=> "1597842aac52bc9d..."

# Generate 224-bit digest.
Digest::Keccak.digest    'foo', 224 #=> "\xDA\xA9M\xA7\xF6\x80k\xF5..."
Digest::Keccak.hexdigest 'foo', 224 #=> "daa94da7f6806bf5..."

# Use this interface to feed data in chunks. 512-bit by default.
digest = Digest::Keccak.new
digest.update 'f'
digest.update 'o'
digest.update 'o'
digest.digest    #=> "\x15\x97\x84*\xACR\xBC\x9D..."
digest.hexdigest #=> "1597842aac52bc9d..."

# You can pass a hash length to the constructor.
digest = Digest::Keccak.new 224
```



Development
-----------

Run the test suite as follows:

```
make test
```

A part of the test suite is automatically generated from Keccak's reference
test suite.