"Do-it-yourself" cryptography

New data communications services such as electronic data interchange, which allows companies to contract for goods and services by electronic mail, will bring increasing need for cryptographic privacy transformations that are unique to a group of participants. Participation of outsiders in supplying hardware or algorithms, or distributing keys may be regarded as unacceptable intrusion. This paper describes two ciphers: a block cipher, CRYPTO-MECCANO; and a stream cipher, CRYPTO-LEGGO. They exist in software and use so many keys that each implementation is a distinct cipher system. Tests suggest either one can provide stronger protection than the Data Encryption Standard (DES). CRYPTO-MECCANO has been submitted to the European RIPE/RACE Consortium as a candidate algorithm to replace DES as a cryptographic primitive for integrity assurance.