I encrypted a secret message with RSA but I lost the modulus. Can you help me recover it?
Nuclear Sale
Plutonium Labs is a private laboratory experimenting with plutonium products. A huge sale is going to take place and our intelligence agency is interested in learning more about it. We have managed to intercept the traffic of their mail server. Can you find anything interesting?
LostKey
Mustard Brightpants is an archaeologist who has been excavating ruins in Egypt for the past 25 years. In one of his discoveries, he found a sphere-shaped trinket that has a strange combination of letters and numbers printed around it. Alongside it was a scroll containing a riddle in a strange language, and a keypad. The sphere’s contents might finally solve the mystery behind the downfall of the mythical city of Outlandis. Could you help Mr. Brightpants solve the riddle and find the correct key to unlock the sphere?
Optimus Prime
Optimus Prime has returned to Earth, choose an historical character and overcome this threat.
https://en.wikipedia.org/wiki/Extended_Euclidean_algorithm
https://en.wikipedia.org/wiki/Modular_multiplicative_inverse
RLotto
Are you ready to win lottery? Guess the Random Lotto Numbers. It’s TIME you become a millionaire.
BabyEncryption
You are after an organised crime group which is responsible for the illegal weapon market in your country. As a secret agent, you have infiltrated the group enough to be included in meetings with clients. During the last negotiation, you found one of the confidential messages for the customer. It contains crucial information about the delivery. Do you think you can decrypt it?
Composition
The more the merrier, right? We decided to mash two of the best cryptosytems together for the best product. Our new encryption scheme is up and running and this time it is unbreakable! To prove that, we have also released its source code and a test center where you can test it out!
RsaCtfTool
Crypto is fun 😉
TwoForOne
Alice sent two times the same message to Bob.
Common Modulus Attack (RsaCtfTool)
xorxorxor
Who needs AES when you have XOR?