Last modification of this page: October 19, 2007

### About the Challenges

We plan to periodically publish some challenge related to cryptography. Most of the time, it will
show how to exploit some of the classical pitfalls one may find in cryptography. Needless to say,
some of these are already described in the exercise book. These challenges shall be a good way to
practice some of the exciting attacks presented in the book! We will also publish a sort of
*Hall of Fame* of the first undergraduate students who will break our challenges.

### Hall of Fame!

#### Challenge 1

*Nathalie Casati* and *Laurent Fasnacht* solved the
first challenge. Well done! They were able to
factor the RSA modulus within 280 hours on an
Athlon 2000+, using a modified p-1 factorization
algorithm (yes, some specials 1024 bit RSA modulus are "easy"
to factorize... check the book!).

### Challenge 1: A (weak) 1024-bit RSA modulus

The objective of this challenge is quite simple. You
are given an RSA modulus n of 1024 bits, which is
the product of two primes of about 512 bits
each. The goal of this challenge is to factorize n,
i.e., to recover the two prime numbers p and q such
that n = p*q. The value of n can be downloaded here.

If you manage to solve this challenge, send your
result to

so that your name appears in the Hall of Fame!

Good Luck!

#### Hall of Fame for Challenge 1

*Nathalie Casati* and *Laurent Fasnacht* solved the
first challenge. Well done! They were able to
factor the RSA modulus within 280 hours on an
Athlon 2000+, using a modified p-1 factorization
algorithm.

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