Download cyphercard-10a.hqx (150,387 KB)
From: Chris Westbury
Subject: CypherCard1.0a.sit.hqx
Cyphercard is a simple but effective tool (a
Hypercard stack) for encoding and decoding text
documents. It uses no complex math, but simply
encodes one document (the target) by using a second
document as a reference document or a 'one time
scratch pad', as they call it in the cypher biz.
Cyphercard does not just use simple pointers into the
reference document, but modulates those pointers
using offsets which are also taken from that
document. It uses various other encoding techniques
as well.
None of this is complicated or tricky. It doesn't
need to be. The security of the code is not
compromised at all by knowing exactly how it was
coded. All the security comes from the fact that the
code depends on the reference document and the
password. The upshot is that anyone who knows which
reference document and password to use can decode any
document that was encoded with that reference
document and password. Anyone who does not know that
document and password will not be able to decode the
target document.
Cyphercard requires a PowerPC Macintosh and Hypercard 2.4.