SecurID and garage door openers

[Adam Shostack]

On Tue, Oct 18, 2005 at 03:25:40AM -0500, Travis H. wrote:
| Speaking of two-factor authentication, can anyone explain how servers
| validate the code from a SecurID token in the presence of clockskew? 
| Does it look backwards and forwards in time a few minutes?

Yes, it rolls forward and back 3-5 cycles.  The server maintains a
list of what time it thinks the token thinks it is.  So its not
testing what time it is, its testing what time the token thinks it is.


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