What is Stream cipher?

Understanding Stream cipher

When a cryptosystem performs its encryption on a bit-by-bit basis. A stream cipher is a symmetric encryption algorithm that encrypts data one bit or byte at a time by combining plaintext with a pseudorandom keystream. Unlike block ciphers that process fixed-size blocks stream ciphers are ideal for encrypting continuous data streams or when data size is unknown in advance. Stream ciphers like RC4 ChaCha20 and various modes of block ciphers are defined in cryptographic standards and publications. Organizations implement stream ciphers for applications requiring real-time encryption low latency or hardware efficiency following implementation guidance from NIST and other standards bodies. For example a secure video conferencing system might use a stream cipher to encrypt audio and video data in real-time providing confidentiality with minimal latency impact while ensuring proper initialization vector management to prevent keystream reuse attacks. Related terms Cryptography Symmetric encryption Block cipher Keystream XOR operation Initialization vector RC4 ChaCha20.