Hasty Pudding (cipher)

The Hasty Pudding Cipher or HPC is a block cipher designed by Rich Schroeppel. It was, in some ways, the most interesting candidate in the AES competition. It did not make it into the finals.

Hasty Pudding is a variable size block cipher; blocks can be any size the application requires. It therefore might be ideal for things like encrypting disk blocks; see large block ciphers. Also, quoting the home page "Arbitrary sets, such as dates, or the printable subset of ascii, or the 20-bit primes, can be encrypted to themselves." Key size is also variable; any integer number of bits. For AES use, the block size would be fixed at 128 bits and key size at 128, 192 or 256 bits.

Hasty Pudding is also a tweakable block cipher, though it was designed before that term came into use. What is now called the "tweak" is called "spice" in Hasty Pudding.

The cipher is freely available for any use. It has a home page.