Cryptography

2014-04-27

plaidCTF 2014 - rsa (for450)

By segher
Filed under plaidCTF2014 forensics cryptography rsa

For PlaidCTF2014, Eindbazen and fail0verflow joined forces as 0xffa, the Final Fail Alliance.
Don't miss out on other write-ups at Eindbazen's site!

rsa
Forensics (450 pts)
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Our archaeologists recovered a dusty and corrupted old hard drive used by
The Plague in his trips into the past. It contains a private key, but this
has long since been lost to bitrot. Can you recover the full key from the
little information we have recovered?

You can download the recovered information here.

2014-04-24

plaidCTF 2014 - graphs (crypto200)

By jix
Filed under plaidCTF2014 cryptography graphs sat

For PlaidCTF2014, Eindbazen and fail0verflow joined forces as 0xffa, the Final Fail Alliance.
Don't miss out on other write-ups at Eindbazen's site!

This challenge was about breaking a custom public key encryption system.

graphs
Cryptography (200 pts)
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In this era, block ciphers hadn't even been invented. The Plague created this
system based on problems he knew to be NP hard, but there must be something you
can do to decode his messages.

We were given a python implementation of the system, the Plague’s public key and an encrypted message. The implementation includes encryption, decryption (given a private key) and key generation.