If symmetric cryptosystems have $C^2_n$ keys, and asymmetric systems have $2n$ keys, how many does a hybrid system have? This was in an online quiz from school
Company A is considering to adopt a cryptosystem for secure communications among its employees. Currently it has $5$ employees. Assume that every employee has used the adopted cryptosystem to communicate with all other employees once.
3) c. If the company adopts hybrid cryptosystem, how many keys would be used in this case? Show your working.
My answer was
$C_n^2$ symmetric session key + $2n$ asymmetric keys
$= C_5^2 + 2 \times 5$
$= 20$ keys
This was marked wrong. Where did i go wrong here? As far as i understand, in a hybrid system they make use of asymmetric keys to encrypt the symmetric session key, which is used to encrypt/decrypt the document.