[comp.dcom.telecom] One Way Algorithm

konstan@elmer-fudd.berkeley.edu (Joe Konstan) (09/25/90)

In Telecom Digest #669 Steven King writes:

> A one way algorithm?  Pray, how does the bank decode it to verify you?

Just like Unix does.  Many (perhaps most) bank ATM systems do not
store your PIN but instead only store the encrypted version of your
PIN (the encryption scheme is designed to prevent many-to-one
mappings).

I recall that BayBanks in Boston had a problem when I was in college
where only the first four digits of the PIN (which could be four to
eight digits) were being used in the encrytion scheme.  I don't know
if they ever fixed it.

For better information on these schemes in general, consult a
reference on Unix passords, as this is a bit far out of Telecom
territory.

Joe Konstan