Encrypting and storing data

• US 9,992,017 B2
• Filed: 06/28/2013
• Issued: 06/05/2018
• Est. Priority Date: 06/28/2013
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Nslund, Mats, Melo De Brito Carvalho, Tereza Cristina, Iwaya, Leonardo Horn, Simplicio Junior, Marcos Antonio
• Primary Examiner(s): Simitoski, Michael
• Application Number:
  US14/900,557
• Publication Number:
  US 20160156464A1
• Time in Patent Office: 1,803 Days
• CPC Class Codes: H04L 2209/24 Key scheduling, i.e. generating round keys or sub-keys for block encryption
• CPC Class Codes: H04L 63/061 for key exchange, e.g. in peer-to-peer networks cryptographic mechanisms or cryptographic arrangements for key agreement H04L9/0838
• CPC Class Codes: H04L 9/0822 using key encryption key
• CPC Class Codes: H04L 9/0838 Key agreement, i.e. key establishment technique in which a shared key is derived by parties as a function of information contributed by, or associated with, each of these network architectures or network communication protocols for key exchange in a packet data network H04L63/061
• CPC Class Codes: H04L 9/0861 Generation of secret information including derivation or calculation of cryptographic keys or passwords
• CPC Class Codes: H04L 9/088 Usage controlling of secret information, e.g. techniques for restricting cryptographic keys to pre-authorized uses, different access levels, validity of crypto-period, different key- or password length, or different strong and weak cryptographic algorithms network architectures or network communication protocols for using time-dependent keys in a packet data network H04L63/068
• CPC Class Codes: H04L 9/0894 Escrow, recovery or storing of secret information, e.g. secret key escrow or cryptographic key storage
• CPC Class Codes: H04L 9/14 using a plurality of keys or algorithms

Abstract

Methods and apparatus for encrypting and storing data. The methods and apparatus provide different levels of security and usability. The methods and apparatus generate two or more keys based on a shared secret made available to a user equipment and a server. The two or more keys comprise at least one perfect forward secrecy key, and at least one limited forward secrecy key. The methods and apparatus encrypt data using at least one of the two or more keys. The methods and apparatus store the encrypted data in a memory of the user equipment and/or transmit the data from the user equipment to the server.

Claims

1. A user equipment that encrypts and stores data to communicate to a server of a communication network, the user equipment comprising:

a processor coupled to a first memory and configured to;

establish a session between the user equipment and the server of the communication network;

generate two or more keys based on a shared secret made available to the user equipment and the server, wherein the two or more keys comprise at least one perfect forward secrecy key, and at least one partial forward secrecy key, wherein the at least one partial forward secrecy key is generated based on a cryptographic function applied to the shared secret and a session identifier associated with the established session;

encrypt data using the at least one partial forward secrecy key;

store the encrypted data in the first memory of the user equipment;

generate an updated partial forward secrecy key based on an application of a one-way function to the partial forward secrecy key and the session identifier responsive to the encryption of the data using the at least one partial forward secrecy key; and

store the updated partial forward secrecy key in a second memory of the user equipment to encrypt future communications during the established session with the server; and

a transmitter configured to transmit the stored encrypted data in a communication to the server during the established session.

2. The user equipment according to claim 1, wherein the processor is configured to generate a master key based on the shared secret.

3. The user equipment according to claim 2, wherein the processor is further configured to generate a salt, and to generate the master key based on the shared secret and the salt.

4. The user equipment according to claim 2, wherein the processor is configured to generate the partial forward secrecy key based on a one-way function of the master key and the session identifier.

5. The user equipment according to claim 4, wherein the processor is configured to generate the session identifier.

6. The user equipment according to claim 2, wherein the processor is further configured to generate a salt, and to generate the master key based on the shared secret and the salt, and wherein the transmitter is further configured to transmit the salt to the server.

7. The user equipment according to claim 2, wherein the processor is configured to generate the at least one partial forward secrecy key based on a one-way function of the master key and the session identifier, and wherein the transmitter is further configured to transmit the session identifier to the server.

8. The user equipment according to claim 1, wherein processor is configured to select at least one of the two or more keys to encrypt the data based on a user input.

9. A method performed by a user equipment operable to communicate with a server of a communication network, the method comprising:

establishing a session between the user equipment and the server of the communication network;

generating, two or more keys based on a shared secret made available to the user equipment and the server, wherein the two or more keys comprise at least one perfect forward secrecy key, and at least one partial forward secrecy key, wherein the at least one partial forward secrecy key is generated based on a cryptographic function applied to the shared secret and a session identifier associated with the established session;

encrypting data using the at least one partial forward secrecy key;

storing the encrypted data in a first memory of the user equipment;

generating an updated partial forward secrecy key based on an application of a one-way function to the partial forward secrecy key and the session identifier responsive to the encryption of the data using the at least one partial forward secrecy key;

storing the updated partial forward secrecy key in a second memory of the user equipment to encrypt future communications during the established session with the server; and

transmitting the stored encrypted data in a communication to the server during the established session.

10. A computer program product comprising a non-transitory computer readable storage medium storing code configured, when executed by a computer, to carry out the method according to claim 9.

11. A server in communication with a user equipment operating in a communication network, the server comprising:

a receiver configured to receive encrypted data in a communication from the user equipment;

a processor and memory, the processor configured to;

establish a session between the user equipment and the server;

generate two or more keys based on a shared secret made available to the user equipment and the server, wherein the two or more keys comprise at least one perfect forward secrecy key, and at least one partial forward secrecy key, wherein the at least one partial forward secrecy key is generated based on a cryptographic function applied to the shared secret and a session identifier associated with the established session;

decrypt the received encrypted data using the at least one partial forward secrecy key;

store at least part of the decrypted data in the memory;

generate an updated partial forward secrecy key based on an application of a one-way function to the partial forward secrecy key and the session identifier responsive to the decryption of the data using the at least one partial forward secrecy key; and

store the updated partial forward secrecy key in the memory to decrypt future communications from the user equipment during the established session.

12. The server according to claim 11, wherein the processor is configured to generate a master key based on the shared secret, and wherein the key generator is further configured to generate the at least one perfect forward secrecy key by applying a one-way function on the master key and a seed value generated by the server.

13. The server according to claim 12, wherein the processor is configured to delete the seed value from the memory after the perfect forward secrecy key has been generated.

14. A method performed by a server in communication with a user equipment operating in a communication network, the method comprising:

establishing a session between the user equipment and the server;

receiving encrypted data in the established session from the user equipment;

generating two or more keys based on a shared secret made available to the user equipment and the server, wherein the two or more keys comprise at least one perfect forward secrecy key, and at least one partial forward secrecy key, wherein the at least one partial forward secrecy key is generated based on a cryptographic function applied to the shared secret and a session identifier associated with the established session;

decrypting the received encrypted data using the at least one partial forward secrecy key;

storing the decrypted data in a memory of the server;

generating an updated partial forward secrecy key based on an application of a one-way function to the partial forward secrecy key and the session identifier responsive to the decryption of the data using the at least one partial forward secrecy key; and

storing the updated partial forward secrecy key in the memory to decrypt future communications from the user equipment during the established session with.

15. A computer program product comprising a non-transitory computer readable storage medium storing code configured, when executed by a computer, to carry out the method according to claim 14.