Symmetric-Key Cryptography consists of a key called symmetric key, with the help of which both encryption and decryption processes are carried out. The algorithms used in the Symmetric-key cryptography are often termed as symmetric key ciphers or private-key ciphers or secret-key ciphers or conventional ciphers etc. In Symmetric Key Cryptosystems, a single key is used to encrypt and decrypt data between two communicating hosts. In order to break the system, an attacker must discover the key through trail-and-error or discover the key during the initial key agreement. Symmetric Key Cryptography is used for authentication and exchange of secret data on the World Wide Web.

Modes Of Symmetric Key Cryptographic Algorithms

  • Electronic codebook mode
  • Cipher-Block Chaining mode
  • Cipher feedback mode
  • Output feedback mode

The characterization of Symmetric Key Ciphers in Symmetric-Key Cryptography is done by:

  • Choice of key-space.
  • Key identification within free space
  • Number of cycles involved in encryption and decryption process.
  • Role of Compression algorithms in adding security value.
  • Choice of operations that are used in encryption or decryption process of symmetric key cryptography

In symmetric Key cryptography, both the sender and receiver share a same key by making use of symmetric-key ciphers. Symmetric-key ciphers include block ciphers and stream ciphers. A block cipher takes a block of plain text as input and outputs a block of cipher text of same size. Since messages are almost always longer than a single block, successive blocks are required for Symmetric Key Cryptography.

Advantages of Symmetric-Key Cryptography

  • Symmetric key cryptographic algorithms are faster and easier to implement.
  • Symmetric key cryptography has lower overhead on system resources.
  • Security is dependent on the length of the key in symmetric key cryptography.
  • The encryption process of symmetric key cryptography is simple.
  • By using symmetric key cryptography, each trading partner can use the same publicly known encryption algorithm, there is no need to develop and exchange secret algorithms.

Drawbacks of Symmetric-Key Cryptography

  • In Symmetric encryption method, a shared secret key must be agreed upon by both parties.
  • Authenticity of origin or receipt cannot be proved because the secret key is shared in symmetric key cryptography.
  • Management of the symmetric keys becomes problematic.
  • If the share Symmetric key is compromised, then the attacker can easily decrypt any message that goes from the sender to the receiver.