1. A method for accessing a memory space allocated to a virtual machine, the method comprises: receiving, by an intermediate entity, a request from the virtual machine to generate, for another virtual machine, a memory credential associated with a certain memory space allocated to the virtual machine, the request indicating an address range of the certain memory space; generating, by the intermediate entity, in response to access permissions defined by the virtual machine included in the request, a cryptographically signed credential; sending the cryptographically signed credential to the other virtual machine; receiving from the other virtual machine an access request to access at least one memory entry within the indicated address range of the certain memory space, the access request including both indication of a memory entry address in the certain memory space and the cryptographically signed credential; and accessing the at least one memory entry, if the access request complies with the memory credential, wherein sending the cryptographically signed credential to the other virtual machine comprises sending the cryptographically signed credential to a mapping module which stores the credential and forwards a mapping of the credential to the other virtual machine; and wherein receiving from the other virtual machine an access request comprises receiving a request from the other virtual machine by the mapping module, adding the cryptographically signed credential to the access request by the mapping module and forwarding the request, with the added credential to the intermediate entity.