The Hasty Pudding Cipher  --  A Tasty Morsel

<p>
Jun 12, 1999  added Tweak & Update; updated Spec <BR>
Dec 21, 1998  added Alpha times <p>

The Hasty Pudding Cipher is a variable length block cipher.  The block
size may be *any* number of bits, even fractional bit values are permitted.
The arbitrary block size means that anything can be encrypted without
expansion.  Arbitrary sets, such as dates, or the printable subset of ascii,
or the 20-bit primes, can be encrypted to themselves.<P>

The key size may be any (whole) number of bits.<P>

The Hasty Pudding Cipher has a 512-bit secondary key, the SPICE.  The spice
may be changed in one instruction.  Concealment of the spice is optional.<P>

I estimate the actual security level of the Hasty Pudding Cipher as 400 bits.
I am offering a token prize for successful cryptanalytic work.<P>

The Hasty Pudding Cipher is fast, achieving 247 megabits per second on
512-bit blocks on a 300 MHz DEC Alpha.<P>

The Hasty Pudding Cipher is in the public domain; there are no known patent
restrictions.<P>

<A href="hpc-oneyearlater"> Update on the Hasty Pudding Cipher</A>
http://www.cs.arizona.edu/~rcs/hpc/hpc-oneyearlater <BR>
Explains why HPC should be chosen as the AES: it's very very fast on
64-bit machines.  Includes new Pentium assembly language timings,
discusses the tweak to fix the equivalent key problem, and answers
various objections. <P>

<A href="tweak"> The Tweak</A>
http://www.cs.arizona.edu/~rcs/hpc/tweak <BR>
David Wagner found an equivalent key problem.  This is the fix.<P>

<A href="hpc-times-alpha.html"> Encryption Times for Alpha platform</A>
http://www.cs.arizona.edu/~rcs/hpc/hpc-times-alpha.html <p>

<A href="hpc-overview"> Overview of the Hasty Pudding Cipher (19KB)</A>
<A href="hpc-overview.gz"> (gzip 7KB)</A>
http://www.cs.arizona.edu/~rcs/hpc/hpc-overview <p>

<A href="hpc-nist-doc"> Specific Cipher Claims for NIST (14KB)</A>
<A href="hpc-nist-doc.gz"> (gzip 5KB)</A>
http://www.cs.arizona.edu/~rcs/hpc/hpc-nist-doc <P>

<A href="hpc-spec"> Specification for the Hasty Pudding Cipher (50KB)</A>
<A href="hpc-spec.gz"> (gzip 17KB)</A>
http://www.cs.arizona.edu/~rcs/hpc/hpc-spec <BR>
This version of the specification includes the one line tweak to fix
the Equivalent Key problem that David Wagner found. <P>

<A href="hpc.hlp"> Help File for the Hasty Pudding Cipher (12KB)</A>
<A href="hpc.hlp.gz"> (gzip 5KB)</A>
http://www.cs.arizona.edu/~rcs/hpc/hpc.hlp <P>

<A href="hpc-ov-cl-hl-sp"> Overview+Claims+Help+Spec (94K)</A>
<A href="hpc-ov-cl-hl-sp.gz"> (gzip 33K)</a>
http://www.cs.arizona.edu/~rcs/hpc/hpc-ov-cl-hl-sp <BR>
Note: Contains UNTWEAKED version of the Spec<P>

<A href="README"> Summmary of diskettes submitted to NIST</A>
http://www.cs.arizona.edu/~rcs/hpc/README <P>

<A href="README2"> Compiling and Testing the Hasty Pudding Cipher</A>
http://www.cs.arizona.edu/~rcs/hpc/README2 <P>

<A href="test-index.html"> Directory of Tests for the Hasty Pudding Cipher</A>
http://www.cs.arizona.edu/~rcs/hpc/test-index.html <BR>
Note: These tests are for the UNTWEAKED version of HPC. <P>


The code for the Hasty Pudding Cipher is freely available in the US and Canada.
Send me email with a phone number, the city where you will receive the reply message,
and stating your citizenship.
I will email you the program.  (You get to compile it).<P>

<PRE>
Five versions are available, each roughly 100KB.

hpc-gcc.c           Compilers with a 64-bit integer or long long data type.
hpc-ansi.c          Compilers restricted to 32-bit operations.  Slower.
HPC-standalone.java Standalone Java version.
HPC_Algorithm.java  NIST/Cryptix interface.

(new 12/21/98)  hpc-gcc-98dec21.c  includes fastest Alpha code
</PRE>

I'd like to acknowledge Peter Bigot for help with Java and Tex, Dave McGrew
and Trusted Information Systems (now part of Network Associates) for assistance
with the Borland C compiler, and Hilarie Orman for converting my collage of
sentence fragments into English prose.<P>

<A href="mailto:rcs@cs.arizona.edu"> email rcs@cs.arizona.edu</A><P>
<A href="http://www.cs.arizona.edu/~rcs"> Rich Schroeppel's home page
http://www.cs.arizona.edu/~rcs  </a><p>

Rich Schroeppel   rcs@cs.arizona.edu