Difference between Diffie Hellman and RSA

Diffie Hellman and RSA are both asymmetric key algorithms, also known as public-key cryptography system which uses two keys to encrypt a plain text.

Diffie Hellman(DH)
DH stands for Diffie Hellman RSA stands for Rivest, Shamir, Adleman.
First published in 1976 First published in 1977
Diffie Hellman was designed by Whitfield Diffie and Martin Hellman RSA was designed by Ron RIvest, Adi Shamir, and Leonard Adleman
Allows two parties to establish a connection over an insecure communication channel, a shared secret key that only the two parties know. In RSA, the sender encrypts the data using the public key and the receiver decrypts the data using his private key.
Generating ephemeral keys for Diffie Hellman is extremely easy Generating ephemeral keys for RSA is extremely difficult
Encryption is expensive Encryption is cheaper
Diffie Hellman 1024 bits is more robust than RSA RSA 1024 bits is less robust than Diffie Hellman
Public-key is bigger to encode Public-key is smaller to encode
Diffie Hellman is less secure than RSA RSA is more secure than Diffie Hellman


Also read: Difference between AES and DES in cryptography

Advantages and Disadvantages of Diffie Hellman

Advantages of Diffie Hellman

  • Sharing of secret-key is safe.
  • Sender and receiver don’t need any prior knowledge of each other.
  • Once the keys are exchanged the communication of data can be done through an insecure channel.

Disadvantages of Diffie Hellman

  • The algorithm cannot be used for signing digital signatures.
  • The Diffie Hellman key exchange is susceptible to man-in-the-middle attack. 
  • Only used for symmetric key exchange.

Advantages and Disadvantages of RSA

Advantages of RSA

  • Easier to implement and understand.
  • RSA is stronger than other symmetric key algorithms.
  • RSA has overcome the weakness of symmetric algorithms i.e. authenticity and confidentiality.
  • Very fast and simple encryption and verification.

Disadvantages of RSA

  • RSA has too much computation.
  • It requires a more computer power supply compared to single-key encryption.
Protocols that use Diffie-Hellman to enhance security
  • Transport Layer Security (TLS) / Secure Socket Layers (SSL)
  • Internet Protocol Security (IPSec)
  • Secure Shell (SSH)
What kind of attack is a standard Diffie-Hellman key exchange vulnerable to?
  • Man-in-the-middle attack

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