A system is provided for encoding user information. The system is configured to generate a random code pattern, assign the random code pattern to a user, assign a personal identifier of the user to the random code pattern, map a combination of the random code pattern and the personal identifier to user information associated with the user, and store an association of the random code pattern and the personal identifier to the user information in a mapping table. The system is further configured to receive from a decoder a query comprising the random code pattern and the personal identifier of the user, wherein the decoder is configured to decode the random code pattern. The system determines based on the mapping table, the user information mapped to the combination of the random code pattern and the personal identifier and transmits the user information to the decoder.