# Challenge : C is G ?Ez Camel


connecting the the server and we receive :


Refering to the title and server message its [ElGamal Encryption](https://en.wikipedia.org/wiki/ElGamal_encryption) . Taking a look for encryption option :


so we can give a message and a random number , that's interesting ! i will tell you why in a moment , lets see first get the cure option :


So we need the private key to get the cure , but how ? we don't have public keys , no g no y no p nothing ...
Back to the interesting thing , the encryption options allows us to give a message and a random

since :
**c1=pow(g,r,p) and c2=M*pow(y,r)[p]**

we send r=1 and M=1 , it gives us : **c1=g and c2=y**
we send r=1 and M=-1 , it gives us : **c1=g and c2=py**

now we have everything y,g and p , calculating the secret key x ! all we know is that y=pow(g,x,p) !
Discret log is solution !! we can use Pohlig_Hellman

Sending now the secret key to the server


flag is : Securinets{B4444d_3lG4m4l_system}

Original writeup (https://github.com/SemahBA/SecurinetsQuals20/tree/master/Cryptography/C%20is%20G%3FEz%20Camel).