| Cryptography and Information Security Group Research Project: Pseudo-Randomness in Cryptographic Applications |
Randomness is a key ingredient for cryptography. Random bits are necessary
not only for generating cryptographic keys, but are also often an integral
part of steps of cryptographic algorithms. In practice, the random bits
will be generated by a pseudo random number generation process. When this
is done, the security of the scheme of course depends in a crucial way
on the quality of the random bits produced by the generator. Thus, an evaluation
of the overall security of a cryptographic algorithm should consider and
take into account the choice of the pseudorandom generator. We started
a combined study of pseudo-random number generators and cryptographic applications.
The intent is to illustrate the extreme care with which one should choose
a pseudo random number generator to use within a particular cryptographic
algorithm. Specifically, in [BGM97]
Mihir Bellare from UCSD and CIS members Shafi Goldwasser and Daniele Micciancio
consider a concrete algorithm, the Digital Signature Standard, and a concrete
pseudo random number generator, the linear congruential generator (or truncated
linear congruential pseudo random generators) and show that if a LCG or
truncated LCG is used to produce the pseudo random choices called for in
DSS, then DSS becomes completely breakable. Slides
on this work are available online.