I just added a zipfile into the CodeLibrary, containing three variants of the SkipJack cipher for '51 - a smaller but slower (skipjack.a51), a bigger but faster (skipfast.a51) and a somewhat smaller version of the skipfast, but using up all registers of a bank (skipregs.a51). Included are also the inverse versions (skipj_i.a51, skipf_i.a51 and skipr_i.a51; respectively).

http://www.8052.com/codelib/skipjack.zip

The faster variant encrypts/decrypts the 8-byte data block within 788/804 cycles, giving around 10kBytes/sec on the absolute vanilla '51 at 12MHz.

This, together with the TEA/XTEA implementations placed into CodeLibrary earlier this month, representing a slower but extremely small footprint block cipher (around 200 bytes of FLASH); and with the DES imlementation already present in the CodeLibrary (although said it is unvalidated) and the AES (Rijndael) implementation presumably by the Rijndael authors (together with '51 versions of a couple of other AES-candidates in http://www.cl.cam.ac.uk/~mgk25/do...051.tar.gz ) forms basis for some crypto-pseudo-library for the '51 platform.

Enjoy!

Jan Waclawek