When I think about generating unpredictable data from a predictable
source, I generally think about hashing a piece of data. You could take
the binary value of a data field, tweak it some with a bit-or or bit not
based on your application, then perform a SHA1 hash of the data. Then
BASE64 encoding that data would give you a case sensitive string of 40+
characters that you could make your password. The beauty of a SHA1 (or
MD5) hash is that a very small change in the source data makes large,
unpredictable changes to the hash output.
-----Original Message-----
From: security400-bounces@xxxxxxxxxxxx
[mailto:security400-bounces@xxxxxxxxxxxx] On Behalf Of Simon Coulter
Sent: Friday, June 11, 2010 6:06 PM
To: Security Administration on the AS400 / iSeries
Subject: [Security400] Password protection
Looking for suggestions:
I want to protect access to an application via a password. I want the
password to automatically change daily. I want the application to be
able to determine today's password without having to read it from an
external source (i.e., algorithmically/programmatically derived). This
last requirement means:
o no special profile with password changed daily
o no validation list use
o no encrypted password stored in external object such as *FILE
or
*DTAARA
I envisage:
o Application objects are *PUBLIC *EXCLUDE
o Application objects are authorised to a specific group profile
o Password generator is *PUBLIC *EXCLUDE
o Password generator is authorised to a specific profile
(different
from the above)
In actual use a user who is a member of the application group AND who
needs to use this particular application will request the password
from an authorised issuer. The issuer will use the password generator
to determine today's password. The user will then use the application.
The "automatic daily change" requirement means the password generation/
validation is tied to the date but obviously simple encryption linked
to the date will not be very secure nor will each daily password be
sufficiently different from the previous one.
I have some ideas but thought I would see what others suggest--always
presuming you think this sufficiently interesting to bother with :)
Regards,
Simon Coulter.
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