Providing and receiving medical data records

A computer-implemented method for sending a request for a requested medical data record of a patient, comprising:

• receiving a request patient identifier corresponding to the patient;
• receiving a set of joint data indices by querying a distributed ledger storing the set of joint data indices, each respective joint data index of the set of joint data indices respectively corresponding to a respective providing entity from a group of providing entities, wherein each respective joint data index of the set of joint data indices is based on a plurality of hash functions and each respective joint data index is stored in the distributed ledger by the respective providing entity, the distributed ledger being accessible by a receiving entity;
• determining a hash vector by applying the plurality of hash functions to the request patient identifier;
• determining a selected providing entity of the group of providing entities based on the hash vector and based on the joint data indices;
• and
• sending a request for the requested medical data record to the selected providing entity.

A providing system for providing a requested medical data record to a receiving entity, comprising:

• an interface, configured to receive a set of medical data records stored in a database of a providing entity;
• and
• a computation unit, wherein the interface or the computation unit is configured to receive or initialize a joint data index and wherein the computation unit is, for each respective medical data record of the set of medical data records,
• configured to apply a plurality of hash functions to a patient identifier corresponding to the respective medical data record to determine a respective hash vector, the patient identifier corresponding to the respective medical data record identifying a patient being subject of the respective medical data record, and
• configured to update the joint data index based on the respective hash vector;
• wherein the interface is furthermore configured to provide the joint data index to the receiving entity by storing, by the providing entity, the joint data index in a distributed ledger that is accessible by the receiving entity,
• wherein the interface is furthermore configured to receive a request for the requested medical data record of the set of medical data records from the receiving entity,
• wherein the requested medical data record corresponds to a requested patient identifier, and
• wherein the interface is furthermore configured to provide the requested medical data record to the receiving entity via a secure communication channel.