Stream ciphers convert 1 bit or byte of plaintext directly into a ciphertext at a time.
- It relies on confusion only.
- It uses XOR for the encryption which can be easily reversed to the plain text.
- The algorithm modes which are used in stream cipher are: CFB (Cipher Feedback) and OFB (Output Feedback).
Advantages:
- Speed of transformation: algorithms are linear in time and constant in space.
- Low error propagation: an error in encrypting one symbol likely will not affect subsequent symbols.
Disadvantages:
- Low diffusion: all information of a plaintext symbol is contained in a single ciphertext symbol.
- Susceptibility to insertions/ modifications: an active interceptor who breaks the algorithm might insert spurious text that looks authentic.
Some popular stream ciphers are:
RC4 - RC4, which stands for Rivest Cipher 4, SALSA, SOSEMANUK, PANAMA
0 Comments