Cisco Cyber Security Practice Exam

What can be created to ensure a program file has not been changed during transit?

1. A firewall

2. A hash of the program file

3. Encryption of the file

4. A digital certificate

The correct answer is: A hash of the program file

Creating a hash of the program file is a reliable method to ensure that the file has not been altered during transit. A hash function takes an input (or 'message') and returns a fixed-size string of bytes that is unique to that specific input. Any modification to the original file, however minor, will result in an entirely different hash value. When a file is sent, its hash value can be calculated and sent alongside the file. The recipient can then compute the hash of the received file. If both hash values match, it confirms the integrity of the file, indicating that it has not changed during transit. This process is crucial for maintaining data integrity in communications, particularly in cybersecurity contexts where assurance against tampering is necessary. In contrast, while firewalls help protect data by controlling incoming and outgoing network traffic, they do not verify file integrity. Encryption secures data confidentiality but does not guarantee that the file remains unchanged. Digital certificates are used for authentication and can help ensure that a sender is legitimate, but they don't directly address file integrity.