receiving, by one or more processors and from an entity device associated with an entity, a request to execute a transaction between a blockchain of a computing system corresponding to an organization associated with the one or more processors and the entity device;

extracting by the one or more processors and from a digital certificate in response to a determination that the blockchain is restricted to predetermined members, a component including a first entity identifier identifying the entity device;

extracting, by the one or more processors and from the digital certificate in response to a determination that the blockchain is compatible with a request from an anonymous entity device, the component including the first key identifier and a first public key;

maintaining, by the one or more processors and in a sanctioned list storage, a sanctioned entity blacklist having one or second key identifiers, second entity identifiers and second public keys each indicating that a respective entity has a sanctioned entity status prohibiting the respective entity from performing a transaction with the blockchain of the computing system;

authenticating, by the one or more processors, the entity device to the blockchain by identifying one or more of a first match between the first key identifier and one of the second key identifiers, a second match between the first public key and one of the second public keys, and a third match between the first entity identifier and one or more the second entity identifiers;

generating, by the one or more processors responsive to one or more of the first match, the second match and the third match, an error condition indicating that the digital certificate failed validation;

blocking, by the one or more processors responsive to the generating the error condition, the transaction between the entity device and the blockchain of the computing system, system; and

inserting, by the one or more processors into a smart contract linked to the entity device responsive to the generating the error condition, code to prevent execution of the smart contract.