Abstract: System for performing a cryptographic operation, comprising a client system and a server system; said server comprising a multi-repository manager, repositories of cryptographic keys, a processor and a memory; and said client comprising a processor and a memory; wherein said two memories store computer executable instructions that, when executed, cause the client and the server to perform a method comprising: the client sending a request of the cryptographic operation to the server; the multi-repository manager obtaining a set of references to cryptographic keys allowed to the request from the repositories of cryptographic keys; the multi-repository manager establishing a cryptographic key referenced in said set of references as the cryptographic key to be used; the multi-repository manager requesting performance of the cryptographic operation to the repository wherein the cryptographic key to be used is stored; the multi-repository manager obtaining the result of the cryptographic operation from the reposito