CSE 127: Lecture 8
The topics covered in this lecture are
Differential Power Analysis and
Using a different statistical characteristic -- the amount of
electrical power used by a modular multiply operation -- the same idea
used in Differential Timing Analysis is used to extract the RSA
private key exponent one bit at a time.
A much stronger timing signal is available in an attack on the Tenex
operating system's system call to verify a user's password.
In Tenex, the operating system kernel has all users' passwords in
cleartext; no encryption is done, as is on most more modern operating
systems. When a user-level application wishes to switch to another
user account, it makes a system call, providing the user account name
and password in string buffers. The kernel looks up the correct
password corresponding to the account in its internal database, and
performs a character-at-a-time string comparison with the provided
password. This is the standard string compare function and terminates
with a unequal return status as soon as a mismatch is seen.
These are links additional security-related information. Exploring
them is optional unless otherwise stated.
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firstname.lastname@example.org, last updated Sat Feb 8 16:55:32 PST 2003. Copyright 2003 Bennet Yee.