(ISC)2 Certified in Cybersecurity Practice Exam

In cybersecurity terms, what does a message digest refer to?

1. A summary of network activity

2. A unique identifier for a piece of data

3. A type of encryption algorithm

4. A measure of system performance

The correct answer is: A unique identifier for a piece of data

A message digest refers to a unique identifier for a piece of data and is generated through a process known as hashing. When data is run through a cryptographic hash function, the result is a fixed-size string of characters that uniquely represents the original data, regardless of its length. This unique identifier serves several purposes in cybersecurity: it ensures data integrity by allowing verification that the data has not been altered, facilitates efficient data retrieval and comparison, and enhances security measures like digital signatures. The hashing process inherently ensures that even the slightest change in the input data results in a drastically different message digest, which underlines its uniqueness. Thus, the primary function of a message digest in the context of cybersecurity is to provide a simple yet powerful means to positively identify and verify data without exposing the actual data itself, which is crucial for maintaining confidentiality and integrity in various security applications.