Method and a system for secure execution of workflow tasks in a distributed workflow management system within a decentralized network system

Abstract

There are provided a method, a system and an initiator server for a secure execution of workflow tasks of a workflow to be executed according to a given execution pattern in a distributed workflow management system within a decentralized network system with a plurality of servers (b, b, . . . , b) including at least an initiator server and at least a number of groups of servers of the plurality of servers. Each group satisfies a policy (pol) of a vertex, and thus, knows a corresponding policy key pair including a policy private key (SK) and a policy public key (PK), respectively. Each vertex denotes a set of workflow tasks to be executed in accord with the execution pattern and is assigned a vertex key pair including a vertex private key and a vertex public key. The vertex private keys and the policy public keys are jointly encrypted within a first onion structure, the first onion structure being built up of a number of onion layers representing the execution pattern which defines a succession of vertices such that each layer is decryptable by using the policy private key of exactly one vertex thus revealing the corresponding vertex private key.