What are symmetric and Asymmetric key encryptions?

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Let us understand the symmetric key encryption.

Symmetric Key encryption

Symmetric-key encryption algorithms in cryptography use a single key or the same cryptographic keys (secret key) shared between the two parties for both encrypting plain-text and decrypting cipher-text. The keys could be identical or there could be a simple change to go between the two keys.

It uses Diffie–Hellman key exchange or other public-key protocol to securely agree upon the sharing and usage of a fresh new secret key for each message.

Asymmetric Key encryption

Asymmetric key encryption is an encryption technique using a pair of public and private keys to encrypt and decrypt plain-text and cipher-text correspondingly when communicating.

Comparatively, asymmetric key encryption takes longer time than symmetric key encryption. It is also called public-key cryptography. Here, public keys are public and published and shared widely with everyone.

However, private keys are private and are known only to the owner. Both the keys are large numbers, paired together, however, are not identical (asymmetric).


The major differences between symmetric and asymmetric key encryption are as follows −

  • Symmetric key encryption is an old technique. Asymmetric key encryption is a new technique.

  • Asymmetric key encryption takes much time. Symmetric key encryption takes less time.

  • Symmetric key encryption is called secret-key cryptography. Asymmetric key encryption is called public-key cryptography.

  • Symmetric key encryption uses only one key for both encryption and decryption, whereas asymmetric key encryption uses two keys (public and private) for both, encryption and decryption.


The drawbacks of using symmetric and asymmetric key encryption are as follows −

  • Drawback of symmetric key encryption is that both parties should have access to the same secret key. However, asymmetric key encryption is advantageous as both parties have access to two different keys.

  • Asymmetric key encryption is a public key scheme which is susceptible to a "brute-force key search attack".

  • Asymmetric key encryption has the potential security vulnerability in using asymmetric keys were exposing it to a "man-in-the-middle" (MITM) attack, in which public keys communication is intercepted by an intruder (MITM) and modified by him/her providing different wrong/incorrect public keys instead.


The benefits of using the symmetric and asymmetric key encryption are as follows −

  • Benefit of symmetric key encryption is it prevents MITM attacks involving the use of a Public Key Infrastructure (PKI).

  • Symmetric key encryption is the simplest kind of encryption.

  • Asymmetric key encryption ensures malicious people do not misuse the keys using two related keys for additional security.

Published on 15-Sep-2021 07:46:06