Secure key store derivation and management from a single secure root key

Patent metadata

Field	Value
Publication number	US-9838201-B2
Application number	US-201514882230-A
Country	US
Kind code	B2
Filing date	Oct 13, 2015
Priority date	Oct 13, 2015
Publication date	Dec 5, 2017
Grant date	Dec 5, 2017

Abstract

A root key of a computing device that is typically “burned” into the device hardware at time of manufacture is used to establish a master key and if desired a Transport Layer Security pre-shaped key, a WiFi configuration key, and application verification keys. The keys established from the root key are stored in a region of flash memory, and this region of flash memory is then encrypted using a random encryption code.

First claim

What is claimed is:

1. Device comprising:
at least one computer memory that is not a transitory signal or software per se and that comprises instructions executable by at least one processing circuitry to:
access a root key of a computing device;
use the root key of the computing device to establish at least one derived key selected from: a master key component SM, or a Transport Layer Security pre-shared key component ST, or a Wifi configuration key component SW, or an application verification key component SA;
store the at least one derived key in a first region of a memory, the first region being less than 100% of a total storage area of the memory; and
encrypt the first region using a random encryption code, wherein the random encryption code includes at least one of:
advanced encryption standard (AES) XEX encryption mode;
Liskov, Rivest, Wagner (LRW) encryption;
cipher block chaining-mask-cipher block chaining (CMC) encryption;
electronic codebook-mask-electronic codebook (EME) encryption.

2. The device of claim 1 , wherein the random encryption code includes advanced encryption standard (AES) XEX encryption mode.

3. The device of claim 2 , wherein the AES XEX encryption mode has tweak and ciphertext stealing (XTS) having a first tweak value equal to a key number of the derived key and a second tweak value equal to an AES block number.

4. The device of claim 1 , wherein the random encryption code includes Liskov, Rivest, Wagner (LRW) encryption.

5. The device of claim 1 , wherein the random encryption code includes cipher block chaining-mask-cipher block chaining (CMC) encryption.

6. The device of claim 1 , wherein the random encryption code includes electronic codebook-mask-electronic codebook (EME) encryption.

7. The device of claim 1 , wherein the instructions are executable to:
upon first boot or derived key reset, generate a mask L; and
establish an AES-XTS key using L, the AES-XTS key being used to encrypt the first region of the memory.

8. The device of claim 1 , comprising the at least one processing circuitry coupled to the at least one computer memory.

9. The device of claim 1 , wherein the first region has a memory size of thirty two kilobytes (32 kB).

10. The device of claim 1 , wherein the derived key includes at least two of: the master key component SM, the Transport Layer Security pre-shared key component ST, the Wifi configuration key component SW, the application verification key component SA.

11. The device of claim 1 , wherein the derived key includes the master key component SM.

12. The device of claim 1 , wherein the derived key includes the Transport Layer Security pre-shared key component ST.

13. The device of claim 1 , wherein the derived key includes the Wifi configuration key component SW.

14. The device of claim 1 , wherein the derived key includes the application verification key component SA.

15. Method comprising:
accessing a root key H of a computing device, the root key H being permanently stored on a secure hardware storage of the computing device;
using the root key H to establish a master key M by combining the root key H with a pseudorandom benign key split, represented as follows:
M=kdf (H, SM), where kdf=key derivation function, H=root key, SM=master key component;
using the master key to encrypt a Transport Layer Security pre-shared key (TLS_PSK) component ST;
using the TLS_PSK component ST to establish an encrypted communication channel with at least one paired device;
storing the master key component SM and the TLS_PSK component ST in an encrypted region of a memory; and
encrypting the first region using a random encryption code, wherein the random encryption code includes at least one of:
advanced encryption standard (AES) XEX encryption mode;
Liskov, Rivest, Wagner (LRW) encryption;
cipher block chaining-mask-cipher block chaining (CMC) encryption;
electronic codebook-mask-electronic codebook (EME) encryption.

16. The method of claim 15 , wherein the random encryption code includes advanced encryption standard (AES) XEX encryption mode.

17. The method of claim 16 , comprising:
upon first boot or derived key reset, generating a mask L; and
establishing an AES-XTS key using the mask L, the AES-XTS key being used to encrypt the first region of the memory.

18. Apparatus comprising:
at least one processing circuitry; and
at least one memory accessible to the at least one processing circuitry and comprising instructions executable by the at least one processing circuitry for:
deriving, from a hard-coded, unchangeable root key H, a master key M;
encrypting at least one communication key component using the master key M but not storing the master key M in an encrypted region of memory;
storing the communication key component encrypted by the master key M in the encrypted region of memory for use of the communication key component to establish a secure communication channel with a paired device;
storing a component SM of the master key M in the encrypted region of memory, the component SM of the master key M defined by: M=kdf (H, SM), where kdf=key derivation function;
encrypting the encrypted region of memory using a random encryption code wherein the random encryption code includes at least one of:
advanced encryption standard (AES) XEX encryption mode;
Liskov, Rivest, Wagner (LRW) encryption;
cipher block chaining-mask-cipher block chaining (CMC) encryption;
electronic codebook-mask-electronic codebook (EME) encryption.

Assignees

• Sony Computer Entertainment America Llc
• Sony Interactive Entertainment America Llc

Inventors

• Cotta Bryan

Classifications

• G06F2212/1052

  Security improvement · CPC title

• G06F21/00

  Security arrangements for protecting computers, components thereof, programs or data against unauthorised activity · CPC title

• G06F12/0246

  in block erasable memory, e.g. flash memory · CPC title

• G06F2212/7204

  Capacity control, e.g. partitioning, end-of-life degradation · CPC title

• G06F12/1408

  by using cryptography (for digital transmission H04L9/00) · CPC title