catena: a Go implementation of the Catena memory consuming password scrambler

The Catena paper may be fetched from http://eprint.iacr.org/2013/525.pdf.


ROADMAP

This release currently has the basic password scrambling functions.
The next release will focus on the other components, particularly
client-independent updates and server relief.


PERFORMANCE NOTES

The benchmark uses the following parameters:
	garlic = 16
	initial garlic = 0
	tweak:
		mode: password hashing
		hash function: SHA256
		salt length: 16 bytes
		additional data: none

My test machine has the following specs:

	avail mem = 8049483776 (7676MB)
	cpu0: Intel(R) Core(TM) i5-3320M CPU @ 2.60GHz, 1197.50 MHz
	cpu1: Intel(R) Core(TM) i5-3320M CPU @ 2.60GHz, 1197.50 MHz
	cpu2: Intel(R) Core(TM) i5-3320M CPU @ 2.60GHz, 1197.50 MHz
	cpu3: Intel(R) Core(TM) i5-3320M CPU @ 2.60GHz, 1197.50 MHz

A garlic greater than 25 (with an initial garlic of 0) runs out of
memory; a garlic of 25 takes nearly 10 minutes to complete.

For faster SHA-256 hashing, take a look at github.com/conformal/fastsha256.
With the standard `crypto/sha256` package:

	BenchmarkBasicHash             1        1435149021 ns/op

With the `fastsha256` package:

	BenchmarkBasicHash             1        1083923404 ns/op

The `fastsha256` runs in just over 75% of the time as the standard library
SHA-256 pacakge.


LICENSE

Copyright (c) 2013 Kyle Isom <kyle@tyrfingr.is>

Permission to use, copy, modify, and distribute this software for any
purpose with or without fee is hereby granted, provided that the above 
copyright notice and this permission notice appear in all copies.

THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.