SSCP Systems Security Certified PractitionerCryptographyEasy
A small business is implementing a secure communication channel for its online transactions. They are considering a cryptographic algorithm that offers both confidentiality and integrity for streamed data, where data is processed bit by bit or byte by byte. Which of the following best describes such an algorithm?
- ABlock Cipher
- BAsymmetric Algorithm
- CStream Cipher
- DHash Function
Show answer & explanationAnswer & explanation
Correct answer: C. Stream Cipher
A stream cipher encrypts data continuously, bit by bit or byte by byte, making it suitable for streaming data. It maintains a state that changes with each encryption operation, unlike block ciphers.
Why the other options are wrong
- A. Block ciphers operate on fixed-size blocks of data, not continuous streams.
- B. Asymmetric algorithms use different keys for encryption and decryption and are typically slower, not ideal for bulk data encryption like streaming.
- D. Hash functions provide integrity but not confidentiality and are not used for encryption.
Stream Cipher
A symmetric key cipher that encrypts plaintext digits (bits or bytes) one at a time, and whose transformation of successive digits depends on the internal state of the cipher.
- Encrypts data bit by bit or byte by byte.
- Ideal for streaming data, real-time communication, and data of unknown length.
- Requires a keystream generator to produce a pseudo-random sequence.
Memory trick: Stream flows like a river, bit by bit.