Introduction to Asymmetric Cryptography

November 23, 2020 by Nitesh Malviya

Encryption and Decryption

Encryption is the process of converting plaintext to encrypted text. Since encrypted text cannot be read by anyone, encrypted text hides the original data from unauthorized users. The process entailing encryption and decryption together is called cryptography. The unencrypted data is called plaintext, while the encrypted data is called ciphertext. The algorithms used to encrypt and decrypt messages are called encryption algorithms.

Decryption is the process of converting encrypted data to plaintext. Basically, it is the reverse of encryption. It is used to decrypt the encrypted data so that only an authorized user can access and read the data. The authorized user uses a pre-shared secret key for converting encrypted data to plaintext.

Private and Public Keys in Cryptography

A key is a bit valued string which is used to convert the plaintext into cipher text and vice-versa. A key can be a word, number or phrase. Cryptography makes use of public and private keys. A public key is issued publicly by the organization and it is used by the end user to encrypt the data. The encrypted data, once received by the organization, is decrypted by using a private key and the data is converted to plaintext.

Encryption Types  Cryptography uses symmetric and asymmetric encryption for encryption and decryption of data. If the sender and the recipient of the data use the same key to encrypt and decrypt the data, it’s called symmetric encryption and if the keys are different for encryption and decryption then its asymmetric encryption. 

In this post, we will be focusing on and discussing Asymmetric Encryption in detail. 

Asymmetric Encryption – Asymmetric Encryption is the one in which the sender and the recipient of the data use different keys to encrypt and decrypt the data. 

Asymmetric Encryption makes use of 2 keys – one for encryption and other for decryption. Key use for encrypting the data is called a public key and the other key for decrypting the data is called a private key. 

Public key is distributed publicly to the involved parties for encryption and the private key is stored on the server for decrypting the encrypted data. Private Key must be stored securely on the server and should not be accessible to anyone. Anyone having access to the key can decrypt encrypted data and read the data in plain text.

Asymmetric encryption makes use of 2 keys, thus it is more complex and time consuming and requires more computational power as compared to symmetric encryption. Asymmetric encryption ensures authentication and non-repudiation along with encryption. The usual key size involved in Asymmetric encryption is 1024-4096 bit in length. Asymmetric encryption is ideal for applications where a small amount of data needs to be encrypted.

Asymmetric Encryption Algorithms

Following algorithms uses Asymmetric encryption for encrypting the data – 

  1. RSA (Ron Rivest, Adi Shamir, and Leonard Adleman)
  2. DSA (Digital Signature Algorithm)
  3. ECC (Elliptic Curve Cryptography)
  4. Diffie-Hellman
  5. El Gamal 

Asymmetric Encryption Applications

1) Confidentiality of Data

2) Authenticity using Digital Signatures 

3) Integrity of Information Exchange 

4) Non-repudiation



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Posted: November 23, 2020
Articles Author
Nitesh Malviya
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Nitesh Malviya is a Security Consultant. He has prior experience in Web Appsec, Mobile Appsec and VAPT. At present he works on IoT, Radio and Cloud Security and open to explore various domains of CyberSecurity. He can be reached on his personal blog – and Linkedin –