Method and electronic device for decrypting homomorphically encrypted data

A method comprising:

• generating, in an electronic device, result metadata and a keyed-hash message authentication code (HMAC) one time password (HOTP) token, wherein the result metadata specifies a size of homomorphically encrypted (HE) data to be decrypted;
• encrypting the result metadata with a metadata key;
• generating or collecting, by the electronic device, HE input data;
• transmitting the HE input data, the encrypted result metadata, and the HOTP token to a cloud server in a cloud environment to allow the cloud server to perform computations using the HE input data, and wherein the cloud server is enabled by the electronic device to send a result of the computations on the HE input data to a secure element for decryption;
• establishing a relatively secure online connection to the secure element in the cloud environment;
• and
• synchronizing a HE key, a shared secret, and a counter value between the secure element and the electronic device to enable the secure element to decrypt the result metadata and to decrypt the result of the computations on the HE input data as specified by the decrypted result metadata.

An electronic device comprising:

• a processor for generating encrypted result metadata, wherein the encrypted result metadata specifies a size of a homomorphically encrypted (HE) data to be decrypted;
• a data generator for generating HE input data;
• and
• a network interface for controlling transmission of the HE input data and the encrypted result metadata to a cloud server in a cloud environment,
• wherein the electronic device enables the cloud server to perform computations using the HE input data, and wherein the cloud server is enabled by the electronic device to send a result of the computations using the HE input data to a secure element in the cloud environment for decryption, and
• wherein the electronic device enables the secure element to decrypt the result of the computations using the HE input data according to the size specified by the result metadata.