Under Requirement 3.5.1, how should access to cryptographic keys be restricted?

Under Requirement 3.5.1, how should access to cryptographic keys be restricted?

• A. Access should be restricted to the fewest number of custodians necessary.
• B. Access should be granted to all security staff.
• C. Access should be controlled by a single administrator.
• D. Access should be unrestricted for developers.

Answer: (A)

Access to cryptographic keys should follow the principle of least privilege for key management. Only the minimum number of custodians who truly need access to perform their duties should have it. This reduces the risk of misuse or leakage, supports accountability, and makes it easier to monitor and audit key usage. In practice, this often pairs with dual-control or multi-person authorization to prevent a single person from acting alone with sensitive keys. Why other approaches don’t fit: giving access to all security staff greatly widens the circle of people who can use the keys, increasing risk; letting a single administrator control access concentrates power and can create a single point of failure and drift from proper separation of duties; making keys unrestricted for developers exposes highly sensitive material to those who don’t need it, elevating the chance of mistakes or abuse. Therefore, restricting access to only the necessary custodians is the correct approach.

Access to cryptographic keys should follow the principle of least privilege for key management. Only the minimum number of custodians who truly need access to perform their duties should have it. This reduces the risk of misuse or leakage, supports accountability, and makes it easier to monitor and audit key usage. In practice, this often pairs with dual-control or multi-person authorization to prevent a single person from acting alone with sensitive keys.

Why other approaches don’t fit: giving access to all security staff greatly widens the circle of people who can use the keys, increasing risk; letting a single administrator control access concentrates power and can create a single point of failure and drift from proper separation of duties; making keys unrestricted for developers exposes highly sensitive material to those who don’t need it, elevating the chance of mistakes or abuse. Therefore, restricting access to only the necessary custodians is the correct approach.