Canister IDs lifecycle - can they be "lost" or "reused"?

While researching various patterns to enable users to “pay” for content via ICP on canisters, we got to some interesting lifecycle ideas that aren’t yet clear to me, so I thought it would be prudent to ask first, before jumping in :slight_smile:

  1. Is it possible to ever “lose” a canister, and thus it’s ID? (except issuing a dfx canister delete command)

  2. After issuing a dfx canister delete command, will that particular ID ever be re-used? In other words, can someone else gain control of a canister_id after it was used by someone else and deleted? Also, would it be possible for the original owner to re-issue the same ID after a delete, or is that ID lost forever?

  3. Does re-installing a canister guarantee that the ID will not change?

  4. Is there a way (now or planned) to “download” a canister’s private key so that one can ensure access to the ledger’s accounts for that canister? (example: some dapp requires a monthly transfer of 0.5 ICP to enable some functionality. Users setup their own flavor of recurrent payments. What happens if the canister gets deleted? Are the funds sent after the deletion of the canister irrecoverable?)

Please feel free to mention any other edge-cases in a canister’s life cycle that you can think of that would pose some problems with the ledger canister integration and ensuring proper access moving forward.

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  1. Depends on what you mean with lose. You can lose control if you set the set of controllers to be empty, or contain invalid entries etc.

  2. No, the system will not reuse ids. This is part of the Interface Specification.

  3. Yes, reinstall is like wipe+upgrade

  4. Canisters don’t have private keys, so no, not possible. To recover, you can reinstall canister code that does something useful with the funds again.

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Thanks a lot!