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Concepts

Authorization and Grant​

x/authz module defines interfaces and messages grant authorizations to perform actions on behalf of one account to other accounts. The design is defined in the ADR 030.

Grant is an allowance to execute a Msg by the grantee on behalf of the granter. Authorization is an interface which must be implemented by a concrete authorization logic to validate and execute grants. They are extensible and can be defined for any Msg service method even outside of the module where the Msg method is defined. See the SendAuthorization example in the next section for more details.

+++ https://github.com/cosmos/cosmos-sdk/blob/v0.43.0-beta1/x/authz/authorizations.go#L11-L25

Built-in Authorizations​

Cosmos-SDK x/authz module comes with following authorization types

SendAuthorization​

SendAuthorization implements the Authorization interface for the cosmos.bank.v1beta1.MsgSend Msg. It takes a SpendLimit that specifies the maximum amount of tokens the grantee can spend, which is updated as the tokens are spent.

+++ https://github.com/cosmos/cosmos-sdk/blob/v0.43.0-beta1/proto/cosmos/bank/v1beta1/authz.proto#L10-L19

+++ https://github.com/cosmos/cosmos-sdk/blob/v0.43.0-beta1/x/bank/types/send_authorization.go#L25-L40

  • spent_limit keeps track of how many coins are left in the authorization.

GenericAuthorization​

GenericAuthorization implements the Authorization interface, that gives unrestricted permission to execute the provided Msg on behalf of granter's account.

+++ https://github.com/cosmos/cosmos-sdk/blob/v0.43.0-beta1/proto/cosmos/authz/v1beta1/authz.proto#L14-L19

+++ https://github.com/cosmos/cosmos-sdk/blob/v0.43.0-beta1/x/authz/generic_authorization.go#L18-L31

  • msg stores Msg type URL.

Gas​

In order to prevent DoS attacks, granting StakeAuthorizaitons with x/authz incur gas. StakeAuthorizaiton allows you to authorize another account to delegate, undelegate, or redelegate to validators. The authorizer can define a list of validators they will allow and/or deny delegations to. The SDK will iterate over these lists and charge 10 gas for each validator in both of the lists.