Public-key cryptography can be used for encryption (ElGamal for instance) and key exchange. Furthermore, it has some properties (such as nonrepudiation) which are not offered by secret key cryptography. So why do we still use symmetric cryptography in applications?

Advantage symmetric cryptography

Explanation:

1.The same key is used to both encrypt and decrypt messages.  

2.Symmetric key algorithms are widely applied in various types of computer systems to improve data security.

3.The security of symmetric encryption systems is based on the difficulty of randomly guessing the corresponding key to force them.

4.The Advanced Encryption Standard (AES) widely used in both secure messaging applications and cloud storage is a prominent example of symmetric encryption.

5.For every bit added to the length of a symmetric key, the difficulty of decrypting encryption using a brute force attack increases exponentially.

data security and user privacy

Explanation:Symmetric algorithms provide a fairly high level of security while at the same time allowing for messages to be encrypted and decrypted quickly. The relative simplicity of symmetric systems is also a logistical advantage, as they require less computing power than the asymmetric ones. In addition, the security provided by symmetric encryption can be scaled up simply by increasing key lengths. For every single bit added to the length of a symmetric key, the difficulty of cracking the encryption through a brute force attack increases exponentially.