Management canister API for threshold key derivation (vetKD)

[mraszyk]

Proposes two new system APIs for the prospective threshold key derivation (vetKD) feature in the management canister.

Notes

• The API is designed so that it allows for implementing the scheme referred to as An aggregatable vetBLS scheme (2) in the related talk at the Real World Crypto Symposium (RWC) 2023.
• The APIs are designed to be similar to the ones for threshold ECDSA.
• Information regarding usage of vetKD keys is not included in the interface spec on purpose. The idea is that the relevant information will later be provided in the Internet Computer Developer Docs.

Alternatives considered

We considered the following alternative API, where one would have two sets of API pairs: one pair for threshold key derivation, and a second one for threshold BLS signatures.

  // Threshold key derivation
  vetkd_public_key : (record {
    canister_id : opt canister_id;
    key_id : record { curve : vetkd_curve; name : text };
  }) -> (record { public_key : blob; });
  vetkd_encrypted_key : (record {
    derivation_id : blob;
    key_id : record { curve : vetkd_curve; name : text };
    encryption_public_key : blob;
  }) -> (record { encrypted_key : blob; });

  // Threshold BLS signature
  bls_public_key : (record {
    canister_id : opt canister_id;
    derivation_path : vec blob;
    key_id : record { curve : vetkd_curve; name : text };
  }) -> (record { public_key : blob; });
  sign_with_bls : (record {
    message : blob;
    derivation_path : vec blob;
    key_id : record { curve : vetkd_curve; name : text };
  }) -> (record { signature : blob; });

This alternative was discarded, however, because there is a concern that not all possible future use cases can be covered with this split API approach.

TODOs

• Determine if we should specify further constraints on input data (e.g., max size of derivation_id, etc.)

[lwshang]

The merged PR #4110 introduced the system API for vetKD cost, including a reference to the management canister endpoint.

I noticed that the names for both the system API and the management canister endpoint were updated in this PR. Could you please ensure the documentation reflects these changes to avoid any inconsistencies?

https://github.com/dfinity/portal/blame/d21d728fce42875832202d46c4410172514dfe3d/docs/references/ic-interface-spec.md#L1549 https://github.com/dfinity/portal/blame/d21d728fce42875832202d46c4410172514dfe3d/docs/references/ic-interface-spec.md#L2140-L2147 https://github.com/dfinity/portal/blame/d21d728fce42875832202d46c4410172514dfe3d/docs/references/ic-interface-spec.md#L7985-L7989

[mraszyk]

The merged PR #4110 introduced the system API for vetKD cost, including a reference to the management canister endpoint.

I noticed that the names for both the system API and the management canister endpoint were updated in this PR. Could you please ensure the documentation reflects these changes to avoid any inconsistencies?

https://github.com/dfinity/portal/blame/d21d728fce42875832202d46c4410172514dfe3d/docs/references/ic-interface-spec.md#L1549 https://github.com/dfinity/portal/blame/d21d728fce42875832202d46c4410172514dfe3d/docs/references/ic-interface-spec.md#L2140-L2147 https://github.com/dfinity/portal/blame/d21d728fce42875832202d46c4410172514dfe3d/docs/references/ic-interface-spec.md#L7985-L7989

@fspreiss It seems you renamed the API from derive_encrypted_key to derive_key in this PR incl. the system API to get the cost. Could you please perform this renaming in this spec PR, too?

[fspreiss]

@fspreiss It seems you renamed the API from derive_encrypted_key to derive_key in this PR incl. the system API to get the cost. Could you please perform this renaming in this spec PR, too?

Done.