The field guide · rule 07 of 16
Give each part only the power it needs
Keep keys out of the code, and design so that one broken part cannot do much damage.
What it means
Give every part of a system the smallest set of powers it needs to do its job. Keep passwords and keys out of the code. Then, if one part is broken into, the damage stays small. The parts that face the internet should have no power to move money.
What goes wrong without it
A website is hacked. Because the website holds the keys to the wallet, the money goes too.
How I build it
- My chain-intelligence service creates payment addresses from a public key only. The keys that can spend stay offline, so a hacked server cannot move funds.
- In my AI agent system, people sign in with a password and a one-time code. The agents get limited access and see records with account and tax numbers removed.
- My background services each run as their own restricted user, and only accept connections from the machine they run on.
Ask your team
- Could anyone outside your team still get in with an old key or account?
- If your web server were hacked, could it move money?
- Are passwords and keys kept out of the code?
How a review checks this
A review lists who and what holds each key and account, and what each one could do if it were misused.
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