Library · Devices
Safe offline licenses: signed tokens, short lives, untrusted clocks
Working without a network is convenient, but every offline day is a day a revoked license keeps running. Signed tokens, short lifetimes and rewind detection keep both promises.
A token, not a flag
Do not store "activated = true". Store a signed token naming the license, the device key, when it was issued and when it expires. The software checks the signature with the public key, no network needed.
Short lives
Tokens live days, not months. Each time the software is online it gets a fresh one. A revoked license stops when its last token expires.
Client clocks lie
Users can turn the clock back to stretch a token. Defences:
- Refuse a token issued in the future relative to the current clock.
- Remember the latest time ever seen; if the clock goes back further than allowed, require going online.
- Report rewinds to the server so they feed the risk score.
Bound to the device
A token is valid only on the machine holding the right device key. Copying it elsewhere is useless.
With ClavisAUH
Offline tokens are signed, device-bound and follow the plan's TTL: this is Signed Offline License, set on the license plan, and it needs Premium. In Advanced Protection, turn on Online-Only Mode when every revocation must land on the next connection.