Which class of cipher is typically used in software and has reusable keys?

Block ciphers are a class of cryptographic algorithms that encrypt data in fixed-size blocks, typically 64 or 128 bits at a time. They use reusable symmetric keys, meaning the same key is used for both the encryption and decryption processes. This characteristic makes block ciphers efficient for software implementations where data needs to be processed securely in chunks.

Block ciphers also support various modes of operation, such as CBC (Cipher Block Chaining) or ECB (Electronic Codebook), which allow for greater flexibility in how the encryption is applied to data of arbitrary length. Since the keys can be reused across different encryptions, this makes block ciphers suitable for many software applications that need to secure large amounts of data while maintaining performance and security.

In contrast, while stream ciphers also use keys, they encrypt data one bit or byte at a time and are generally designed for scenarios requiring real-time encryption, such as in streaming applications. Hybrid ciphers combine both symmetric and asymmetric techniques but are not defined by the use of reusable keys alone. Asymmetric ciphers use a pair of keys (public and private) and are typically employed for secure key exchange rather than bulk data encryption.

Thus, the suitability of block ciphers for software applications and their