About

Below are some problems related to computer security (specifically poorly implemented security). Do Them. You are free to use any language and environment you like to complete them. The problems require familiarity with programming, but not necessarily with applied cryptography or computer security in general. An understanding of how some of the algorithms and tools in the problems work will be of use, so as a starting point you can find some resources to help you begin here. If this topic is new to you, you may want to start with the Tutorial Problems.

Problems

HÃ¥stad's Broadcast Attack

RSA with a small exponent is fast to compute but it has a serious weakness.

Solved by 102
Monoalphabetic Cipher

Monoalphabetic ciphers leak information. Can you recover it?

Solved by 133
Playfair

This bigram cipher is a bit trickier...

Solved by 46
Bleichenbacher's CCA2 on RSA

A server is giving feedback it's not supposed to. Can you stage an online attack?

Solved by 35
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