Cisco Cyber Security Practice Exam

What is the characteristic of the output of a hash function?

1. Variable length

2. Fixed length

3. Random length

4. None of the above

The correct answer is: Fixed length

The output of a hash function is characterized by being of fixed length. Regardless of the size of the input data, whether it is a small string or a very large file, the hash function produces a hash value that is always the same size. For example, the widely used SHA-256 hash function always generates a 256-bit (or 32-byte) output, no matter how large the input is. This fixed length is crucial as it allows for consistent and predictable processing, ease of comparison, and enhances security by reducing the potential for data collisions where two different inputs produce the same hash value. It also facilitates efficient storage and indexing in various applications such as digital signatures, password storage, and integrity verification. In contrast, options indicating variable or random lengths do not align with the fundamental properties of hash functions, which are specifically designed to provide a predictable, fixed-size output.