OBJECTIVES: Compiling individual records coming from different sources is necessary for multi-center studies. Legal aspects can be satisfied by implementing anonymization procedures. When using these procedures with a different key for each study it becomes almost impossible to link records from separate data collections. METHODS: The originality of the method relies on the way the combination of hashing and enciphering techniques is performed: like in asymmetric encryption, two keys are used but the private key depends on the patient's identity. RESULTS: The combination of hashing and enciphering techniques provides a great improvement in the overall security of the proposed scheme. CONCLUSION: This methodology makes stored data available for use in the field of public health, while respecting legal security requirements.