Method for securely transferring data elements values

A method for securely transferring data element values (Dei_Val) in a first device to a second device comprising:

• encrypting each of the data element values with a storage key (KSi) using a commutative cryptographic algorithm to obtain a plurality of encrypted data values, wherein each of storage keys (KSi) is different from one another and is derived from a long-term key (LTK) of the first device and an initialization value (IVi),
• storing the plurality of the encrypted data values at the first device;
• in response to receiving a request from the second device to access the plurality of the encrypted data element values, mutually agreeing by the first and the second device on a short-term session key (STK) via a secure channel;
• determining, by the first device, a plurality of ephemeral keys for the plurality of the encrypted data values, each of the plurality of the ephemeral keys is a sub-sequence of a pseudorandom sequence (bsi) derived from the short-term session key (STK);
• encrypting, by the first device, using the commutative cryptographic algorithm, each of the plurality of the encrypted data element values with one of the plurality of the ephemeral keys data to obtain a plurality of doubly encrypted data element values;
• decrypting, by the first device, each of the plurality of the doubly encrypted data element values, using a corresponding storage key (KSi) from the storage keys, to obtain KSi-decrypted data element values;
• transferring said KSi-decrypted data element values from the first device to the second device;
• obtaining, by the second device, from the short-term session key (STK), for each of the KSi-decrypted data element values, a corresponding ephemeral key;
• and
• decrypting, by the second device, each of the KSi-decrypted data element values using the corresponding ephemeral key obtained.