The FREE Cybersecurity Glossary by Thor Pedersen!

Subject: An active entity, typically a user, process, or device, which causes information to flow among objects or changes the system's state. The subject essentially initiates and controls these actions, making it a critical component of access control models and security protocols. It's crucial to verify the identity and permissions of a subject before allowing access to sensitive resources.

Subject security level: The classification level assigned to an individual or entity, determining their access to specific information or resources. This classification is crucial for safeguarding sensitive data and preventing unauthorized access, exemplified by categories such as top-secret clearance for government employees, confidential access to medical records, and unrestricted access to public content like news articles.

Subnet: A smaller network within a larger network that is used to divide a network into smaller, more efficient sections. It is used in network engineering and computer science to improve network performance and security. Examples include a subnet for a company's internal network, a subnet for a home network, and a subnet for a public Wi-Fi hotspot.

Substantive test: An audit procedure that is designed to assess the accuracy and completeness of financial statements. It involves reviewing and testing transactions, balances, and account balances to determine if they are properly recorded and presented. Examples of substantive tests include reviewing supporting documentation for transactions and testing the accuracy of calculations in financial statements.

Substantive testing: A type of testing that focuses on the accuracy and completeness of data rather than the technical functionality of a system. It is used in auditing and quality assurance to verify the integrity of financial records and other important data. Examples include testing the accuracy of financial statements, testing the completeness of inventory records, and testing the reliability of voter registration records.

Substitution: The process of replacing one element with another. In cryptography, substitution is a fundamental method used in various types of ciphers where units of plaintext are replaced with the corresponding units of ciphertext according to a fixed system. The "units" may be single letters, pairs of letters, triplets of letters, mixtures of the above, and so forth.