Symmetric key Vs Asymmetric encryption
December 18, 2009
Symmetric encryption uses one shared key to encrypt and decrypt a document. This key is known to both the sender and receiver. While asymmetric encryption, each user has two keys one private only known to themselves and the other one public and known to everyone.
Symmetric encryption does not provide for non repudiation, since any person with access to the shared key can both encrypt and decrypt a message, so one cannot tell where it originated from, unlike asymmetric encryption where the use of a private key to sign a message allows for non repudiation of the message.
In symmetric encryption, key distribution is a problem since one has to find a secure means of exchanging the secret key unlike asymmetric encryption where people just need to make their public key known to anyone who wants to communicate with them.
Symmetric encryption provides for a fast method of communication and also lends itself to hardware implementation which provides for even higher operational speeds unlike asymmetric encryption which is slow because of the complicated math involved in generating the keys.
Symmetric key encryption algorithm is not scalable because it requires each potential pair of communicators to have a shared secret key thus making it hard for large groups to communicate e.g. two users would need one key, three users would need 3 keys, four users would need 6 keys etc unlike asymmetric encryption that that requires new users to only generate a pair of keys.
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