Rating: 3.2

# Organizer's Solution

The key is very hard to factor (it has actually more than two factors to generate it faster, there are a lot of 512 bit factors), but it doesn't matter.
RSA's basic math is :

ciphertext = message^exponent mod n

However, as n is very large, the modulus is useless and the ciphertext is only message^exponent. Since we have the ciphertext and the exponent, we only have to compute the 65537th root of c to get m !

alicio – April 9, 2017, 8:51 p.m.

nice task
i feel a bit wronged by "there are a lot of 512 bit factors" part though. would it be a 2-prime rsa n could be easily factorized by looking at the top 10 prime numbers list.