Write-Ups

EasyCTF IV – Not OTP

Posted on by ENOENT

Description

It seems we’ve intercepted 2 strings that were both encrypted with what looks like OTP! Is it possible to decrypt them?

c1 = 38445d4e5311544249005351535f005d5d0c575b5e4f481155504e495740145f4c505c5c0e196044454817564d4e12515a5f4f12465c4a45431245430050154b4d4d415c560c4f54144440415f595845494c125953575513454e11525e484550424941595b5a4b
c2 = 3343464b415550424b415551454b00405b4553135e5f00455f540c535750464954154a5852505a4b00455f5458004b5f430c575b58550c4e5444545e0056405d5f53101055404155145d5f0053565f59524c54574f46416c5854416e525e11506f485206554e51

Continue reading →

0
Write-Ups

EasyCTF IV – RSA V

Posted on by ENOENT

Description

Bob is extremely paranoid, so he decided that just one RSA encryption is not enough. Before sending his message to Alice, he forced her to create 5 public keys so he could encrypt his message 5 times! Show him that he still is not secure…

Here are the 5 public keys that Bob used, each in the format of (N, e):
(9247606623523847772698953161616455664821867183571218056970099751301682205123115716089486799837447397925308887976775994817175994945760278197527909621793469, 11)
(9247606623523847772698953161616455664821867183571218056970099751301682205123115716089486799837447397925308887976775994817175994945760278197527909621793469, 41)
(9247606623523847772698953161616455664821867183571218056970099751301682205123115716089486799837447397925308887976775994817175994945760278197527909621793469, 67623079903)
(9247606623523847772698953161616455664821867183571218056970099751301682205123115716089486799837447397925308887976775994817175994945760278197527909621793469, 5161910578063)
(9247606623523847772698953161616455664821867183571218056970099751301682205123115716089486799837447397925308887976775994817175994945760278197527909621793469, 175238643578591220695210061216092361657427152135258210375005373467710731238260448371371798471959129039441888531548193154205671)

Here is his encrypted message:
7117565509436551004326380884878672285722722211683863300406979545670706419248965442464045826652880670654603049188012705474321735863639519103720255725251120

Continue reading →

0
Write-Ups

Hackim18 – Web1

Posted on by ENOENT

Description

The objective of this challenge is to find a way to get logged in as the user “administrator”..

This is the demo application for our new session management system based on military cryptography (namely CBC-MAC). You can log in as any user (except ‘administrator’) with the password ‘Password1’. We blocked access to ‘administrator’ account for security reasons. Continue reading →

0