Accounts and Permissions

Overview

Account - A registered user on the XPR Network blockchain, that can send transactions to interact with smart contracts.

Contract - An account with a smart contract (WASM + ABI) deployed to it.

Permissions - A list of authorities associated with an account, with minimum thresholds to authorize a transaction.

Transaction (TX) - An array of actions submitted to the blockchain by an account.

Authority - A key or account that contributes X weight towards authorizing a permission.

Permission structure

1. Permission Name
   • account-level unique name
2. Parent
   • typically active/owner
   • parent is empty for owner permission
   • permissions can only use and modify authorizations of themselves and their nested child permissions
3. Required Authorities
   • list of keys and/or accounts
   • weight of authority
4. Threshold
   • The minimum aggregate authorities weight needed to authorize a permission

Default Account

New XPR Network accounts start with 2 permissions, the owner permission and it's child active.

Let's have a look at the permission structure of a brand new XPR Network account, alice:

Since both of alice's permissions have a threshold of 1 and PUB_K1_1... key has a weight of 1, signing with PUB_K1_1... would authorize both her owner and active permissions.

Advanced Account

Next, let's have a look at a more advanced permission structure, for bob:

Bob's active permission has 2 keys and 1 account and the threshold of the active permission is 2.

To submit a TX to the XPR Network blockchain using bob@active permission, the TX must be signed using by either:

• The PUB_K1_1... key

  OR

• Both the PUB_K1_2... key and alice@active

In the latter case, the blockchain would recursively require signing by the keys and accounts needed to authorize alice@active

Linked Account

By utilizing permission links, we can limit the actions a specific permission can take.

The 2 types of permission linking possible on XPR Network are:

1. Link to a specific contract
   • e.g. link to xtokens to perform any action on the xtokens contract
2. Link to a specific contract and action
   • e.g. link to xtokens::transfer to only perform transfer action on the xtokens contract

Lets have a look at eve's account:

By linking eve@send to xtokens::transfer, this permission can now only execute 2 tasks:

1. transfer action on the xtokens contract
2. Update the authorities for eve@send

Note the last point, permissions can always update their own authorities, even if linked to a specific action.

After linking, if eve tried executing a xtokens::abc or abc:transfer action signed with eve@send permission, it would fail.