## Description

It’s Prime Time!

(code60, solved by 388)Description: We all know that prime numbers are quite important in cryptography. Can you help me to find some?

Service: 188.166.133.53:11059

## Resolution

When we connect to the service we get the following:

laxa:Challenges:23:46:44$ nc 188.166.133.53 11059 Hi, you know that prime numbers are important, don't you? Help me calculating the next prime! Level 1.: Find the next prime number after 4:

So we make the following script:

#!/usr/bin/python import telnetlib def find_next_prime(n): return find_prime_in_range(n, 2*n) def find_prime_in_range(a, b): for p in range(a, b): for i in range(2, p): if p % i == 0: break else: return p return None t = telnetlib.Telnet("188.166.133.53", 11059) print t.read_until('\n'), while True: a = t.read_until('\n') print a, data = a.split(' ') prime = int(data[8].strip()[:-1]) nprime = find_next_prime(prime + 1) t.write(str(nprime) + '\n') a = t.read_until('\n') print a,

After solving 100 equations we get the flag:

IW{Pr1m3s_4r3_!mp0rt4nt}