(ISC)2 Certified in Cybersecurity Practice Exam

What is a one-way function that transforms a variable length input into a unique, fixed-length output called?

1. Hash Function

2. Encryption Function

3. Decoding Function

4. Symmetric Function

The correct answer is: Hash Function

A hash function is a one-way function that takes an input of any variable length and produces a unique output of fixed length, commonly known as a hash value or hash code. This process is crucial in various applications, including data integrity verification, digital signatures, and password storage. The key characteristic of a hash function is that it is computationally infeasible to reverse the process, meaning that it is extremely difficult to derive the original input from its hash output. Hash functions also have the property of producing a unique hash for different inputs, and even a small change in the input leads to a significantly different hash, which aids in detecting alterations to data. This functionality is widely leveraged in cybersecurity for ensuring the authenticity and integrity of data. In contrast, encryption functions are designed to reverse the process and recover the original data when provided with the correct key, making them fundamentally different from hash functions. Decoding functions serve the purpose of transforming encoded data back to its original form, which also does not align with the characteristics of a hash function. Symmetric functions typically refer to algorithms where two keys are used for encryption and decryption, further distinguishing them from the concept of a hash.