COM-03 — Lesson 2 of 5

Physical Security and Key Management

Protecting the material COMSEC actually depends on

Lesson Objectives

Identify what counts as protected COMSEC material
Apply the core best practices for handling and storing that material
Explain why physical security is often the weakest link in an otherwise sound COMSEC system
Describe secure key exchange options in order of preference

Part A — What You Are Protecting

Physical security is often the weakest link

A group can have a well-designed cryptographic system, disciplined operators, and a solid authentication protocol — and still lose everything because a radio was left in an unlocked vehicle, or a printed key sheet was left on a table during a break. Physical security of COMSEC material is frequently the softest target in the whole system, because it does not require breaking any code. It only requires access.

Protected material includes

Radios and radio accessories capable of secure operation
Encryption keys and any key-loading devices
Codebooks, one-time pads, and authentication sheets
Written procedures, cheat sheets, and net rosters

Part B — Best Practices

Four rules that cover most of the risk

1

Restrict access on a strict need-to-know basis

Not every member of a group needs access to every piece of key material. The fewer hands that touch it, the smaller the compromise surface if something goes wrong. This is the same compartmentalization principle covered in more depth in SEC-02, OPSEC — need-to-know is not a COMSEC-specific idea, it is a general information-security discipline applied here to key material specifically.
2

Never leave crypto material unattended

A locked vehicle is not the same as attended material. Unattended means unattended, even for a few minutes.
3

Assume lost equals compromised

Do not wait to see if a lost key sheet or radio turns up. The moment you cannot account for it, treat everything it could expose as burned and act accordingly — which usually means rotating to the next key or authentication set immediately.
4

Destroy expired or used crypto material immediately

A used one-time pad page or an expired authentication table sitting in a drawer is a liability with no upside. Destroy it as soon as it is no longer needed, not at the next convenient cleaning day.

“Assume lost equals compromised” is the rule most groups skip. It is tempting to wait and see, especially when replacing key material is inconvenient. That hesitation is exactly the gap an adversary needs. Treat the loss as real the moment you notice it.

Part C — Secure Key Exchange

Getting new key material to people safely

Key material has to move from wherever it is generated to every operator who needs it, and that movement is its own point of risk. In order of preference:

Method	Notes
Hand-carry	The gold standard. A trusted person physically carries the material and hands it to the recipient. No transmission, no interception risk in transit.
Trusted encrypted channel with an out-of-band password	Acceptable secondary option. The password or key needed to open the file is communicated through a different channel than the file itself, so intercepting one does not give an adversary the other.
Electronic transmission of the key itself	Avoid whenever possible. Transmitting keys electronically — even over what looks like a secure service — multiplies the number of points where interception could occur.

Commercial encrypted email or file-sharing services may provide solid transport security, but that is not the same as protecting the key material itself. File-level encryption with an independent, separately-delivered password is strongly recommended even when the transport channel is already encrypted — it means a single compromised channel does not expose the key.

Knowledge Check

What is the recommended response the moment a piece of key material or a radio capable of secure operation is confirmed missing?

A. Assume it is compromised immediately and rotate to new key material without delay B. Wait roughly 24 hours to see if the missing item turns up before taking any action C. Only take action later, if and when the material is found in the wrong hands D. Simply make a note of it and report it at the next scheduled group meeting

Knowledge Check

Which method of getting new key material to an operator is the gold standard?

A. Emailing the key file through any commercial encrypted email service B. Hand-carrying the material directly to the recipient in person C. Transmitting the key itself over the radio net it is meant to protect D. Posting the key file to a private, password-protected webpage

Knowledge Check

A group uses a commercial encrypted file-sharing service to send a key file, and separately calls the recipient to give them the password over the phone. Why is this better than sending both the file and the password through the same service?

A. It is not actually better — splitting delivery across two channels only doubles the risk B. Because ordinary phone calls cannot be intercepted by any adversary at all C. Because it uses out-of-band delivery — intercepting one channel alone does not expose the key D. Because commercial encrypted file-sharing services are illegal to use for this purpose

Knowledge Check

Why is physical security often described as the weakest link even in an otherwise well-designed COMSEC system?

A. Because encryption algorithms are generally weaker than physical locks and safes B. Because most preparedness groups do not own any physical COMSEC material C. Because physical security measures are more expensive than cryptographic ones D. Because gaining physical access sidesteps the need to break any code at all

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Answer all questions to continue

Physical Security and Key Management

Lesson Objectives

Physical security is often the weakest link

Protected material includes

Four rules that cover most of the risk

Restrict access on a strict need-to-know basis

Never leave crypto material unattended

Assume lost equals compromised

Destroy expired or used crypto material immediately

Getting new key material to people safely