CyberCertPrepSecurity FundamentalsCryptography FundamentalsEASYFree question
What is the key difference between a block cipher and a stream cipher?
- A.Block ciphers are faster than stream ciphers
- B.Stream ciphers use asymmetric keys
- C.Block ciphers cannot be used with modes of operation; a nonce must be reused across sessions for a stream cipher to stay secure
- D.Block ciphers encrypt fixed-size blocks of data; stream ciphers encrypt data one bit or byte at a time
Why D is correct
Block ciphers (like AES) encrypt data in fixed-size blocks (e.g., 128 bits). Stream ciphers (like ChaCha20) encrypt data continuously, one bit or byte at a time, by XORing plaintext with a pseudorandom keystream. Stream ciphers are often faster for real-time data.
Know someone studying for Security Fundamentals? Send them this one.