This disclosure describes aspects of decentralized authorization and authentication for blockchain contracts. A permissioned blockchain includes requires decentralized approval of a particular number of users out of a specified set of users in order to approve permissioning rule updates for the permissioned blockchain. A signed blockchain request is received. The signed blockchain request specifies an action to perform with respect to the permissioned blockchain. Access to the permissioned blockchain is performed based at least in part on a confirmation that an action specified by the signed blockchain request approved according to permissioning rules of the permissioned blockchain.