Explanation:
Key management is better in asymmetric key encryption as compare to symmetric key encryption. In fact, there is no key management built within Symmetric Crypto systems. You must use the sneaker net or a trusted courier to exchange the key securely with the person you wish to communicate with.
Key management is the major issue and challenge in symmetric key encryption.
In symmetric key encryption, a symmetric key is shared between two users who wish to communicate together. As the number of users grows, the number of keys required also increases very rapidly.
For example, if a user wants to communicate with 5 different users then total number of different keys required by the user are 10. The formula for calculating total number of key required is n(n-1)/2Or total number of users times total of users minus one divided by 2.
Where n is number of users communicating with each others securely.
In an asymmetric key encryption, every user will have only two keys, also referred to as a Key Pair.
Private Key – Only known to the user who initially generated the key pair
Public key – Known to everyone, can be distributed at large
The following were incorrect answers:
Performance – Symmetric key encryption performance is better than asymmetric key encryption
Bulk encryption – As symmetric key encryption gives better performance, symmetric key should be used for bulk data encryption
Number of keys grows very quickly – The number of keys under asymmetric grows very nicely.1000 users would need a total of only 2000 keys, or a private and a public key for each user. Under symmetric encryption, one thousand users would need 495,000 keys to communicate securely with each others.
Reference:
CISA review manual 2014 Page number 348