Which term describes a cryptographic operation that operates on a bit or character at a time?

• A. Trusted Path
• B. Stream-based Ciphers
• C. Virtual Machines
• D. Provisioning Identities

Answer: (B)

Stream-based ciphers operate on a bit or character at a time. They generate a keystream and combine it with the plaintext as the data flows, typically by XORing each bit or byte. This per-bit/byte processing is what distinguishes stream ciphers from block ciphers, which encrypt fixed-size blocks and may require padding. Because they work continuously, stream ciphers are often fast for real-time or streaming data. They rely on a secret key and a nonce or IV to ensure the keystream is unique for each message; reusing the same keystream across messages is a critical vulnerability. The other terms describe different concepts (secure input/output paths, computing environments, or identity provisioning) and are not about the way cryptographic data is processed.