[TriLUG] OT: RSA Securid - how does it work?

[Joseph Mack NA3T]

On Sat, 8 Mar 2008, Barry Gaskins wrote:

> Well only RSA knows for sure but they are not publishing 
> any details.

sure. I was just trying to estimate bounds on its 
functioning derived from simple physical principles.

> If I were writing the software then I would allow the last 
> number to work for a while after I knew it was supposed to 
> change. They could even make the window wider depending on 
> how long it was since the key was "activated".

That's testable. I found that it would only work for the 
time slot I had. If I saved the number and put it in after 
the RSA key had advanced to the next number, then I couldn't 
log in. This made me think that I had to be spot on, which 
is why I posted in the first place.

Kevin Flanagan also spoke

> The date on the back of the token is an expiration date.

ah. mine says

03/31/11

silly me. I thought that was a date in 2003. It's a date in 
2011. RSA didn't hear about Y2K.

> In reality the server knows 5 sets of numbers, the one it 
> believes it should be and two before and two after, so 
> that you could account for clock drift.

If that's true then my key must be running at the last of 
the 5 sets.

Thanks

Joe

-- 
Joseph Mack NA3T EME(B,D), FM05lw North Carolina
jmack (at) wm7d (dot) net - azimuthal equidistant map
generator at http://www.wm7d.net/azproj.shtml
Homepage http://www.austintek.com/ It's GNU/Linux!