Secure key access with one-time programmable memory and applications thereof

• US 9,317,449 B2
• Filed: 10/08/2013
• Issued: 04/19/2016
• Est. Priority Date: 09/05/2008
• Status: Active Grant

• Current Assignee: Pixelworks Incorporated
• Original Assignee: VIXS Systems Incorporated (Pixelworks Incorporated)
• Inventors: Ducharme, Paul D., Cheung, Wendy Wai Yin, Wong, Albert Yunsang, Huang, Shijun, Stewart, Norman V. D.
• Primary Examiner(s): Turchen, James
• Application Number:
  US14/048,391
• Publication Number:
  US 20140136855A1
• Time in Patent Office: 924 Days
• US Class Current: 1/1
• CPC Class Codes: G06F 12/1408 by using cryptography for digital transmission H04L9/00
• CPC Class Codes: G06F 21/602 Providing cryptographic facilities or services
• CPC Class Codes: G06F 21/6209 to a single file or object, e.g. in a secure envelope, encrypted and accessed using a key, or with access control rules appended to the object itself
• CPC Class Codes: G06F 21/72 in cryptographic circuits
• CPC Class Codes: G06F 21/79 in semiconductor storage media, e.g. directly-addressable memories
• CPC Class Codes: G06F 2221/2123 Dummy operation
• CPC Class Codes: G06F 2221/2127 Bluffing
• CPC Class Codes: H04L 2209/12 Details relating to cryptographic hardware or logic circuitry
• CPC Class Codes: H04L 2209/60 Digital content management, e.g. content distribution
• CPC Class Codes: H04L 9/0822 using key encryption key
• 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 9/3247 involving digital signatures
• CPC Class Codes: H04N 21/4181 for conditional access
• CPC Class Codes: H04N 21/4183 providing its own processing capabilities, e.g. external module for video decoding
• CPC Class Codes: H04N 21/42623 involving specific decryption arrangements
• CPC Class Codes: H04N 21/42692 for reading from or writing on a volatile storage medium, e.g. Random Access Memory [RAM]
• CPC Class Codes: H04N 21/4431 characterized by the use of Application Program Interface [API] libraries
• CPC Class Codes: H04N 21/4435 Memory management allocation of memory to service a request G06F9/5016; addressing or allocating within memory systems or architectures G06F12/02
• CPC Class Codes: H04N 7/1675 Providing digital key or authorisation information for generation or regeneration of the scrambling sequence pseudo-random number generators in general G06F7/58

Abstract

A device includes a key store memory that stores one or more cryptographic keys. A rule set memory stores a set of rules for accessing the cryptographic keys. A key store arbitration module grants access to the cryptographic keys in accordance with the set of rules. The device can be used in conjunction with a key ladder. The device can include a one-time programmable memory and a load module that transfers the cryptographic keys from the one one-time programmable memory to the key store memory and the set of rules to the rule set memory. A validation module can validate the cryptographic keys and the set of rules stored in the key store and rule set memories, based on a signature defined by a signature rule.

Claims

1. A device for use in conjunction with a key ladder, the device comprises:

a key store memory operable to store at least one cryptographic key of the key ladder;

a rule set memory operable to store a set of rules for accessing the at least one cryptographic key in conjunction with the key ladder;

a key store arbitration module operable to;

interpret a request to retrieve the at least one cryptographic key stored in the key store memory to produce an interpreted request that indicates a type of cryptographic algorithm;

access the rule set memory based on the interpreted request to retrieve a rule of the set of rules; and

grant access to the at least one cryptographic key in accordance with the rule.

2. The device of claim 1, wherein the request to access the cryptographic key comprises:

a read/write indication;

an address of the at least one cryptographic key;

a destination in the key ladder for a cryptographic result; and

identification of the type of cryptographic algorithm.

3. The device of claim 1 wherein the set of rules includes a signature rule that defines at signature corresponding to at least one of:

the set of rules and the at least one cryptographic key.

4. The device of claim 3 further comprising:

at least one one-time programmable memory; and

a load module, coupled to the at least one one-time programmable memory and the key store memory, that transfers the at least one cryptographic key from the at least one one-time programmable memory to the key store memory.

5. The device of claim 4 further comprising:

a validation module, coupled to the key store memory, that validates the at least one cryptographic key stored in the key store memory, based on the signature.

6. The device of claim 3 further comprising:

at least one one-time programmable memory; and

a load module, coupled to the at least one one-time programmable memory and the rule set memory, that transfers the set of rules from the at least one one-time programmable memory to the rule set memory.

7. The device of claim 6 further comprising:

a validation module, coupled to the rule set memory, that validates the set of rules stored in the rule set memory, based on the signature.

8. The device of claim 1 wherein the set of rules includes at least one of:

a null rule; and

an end of rules rule.

9. The device of claim 1 wherein the key store memory is accessed in accordance with a plurality of constraints that include at least one of:

a type constraint;

an adjacency constraint;

a skip constraint; and

a repeat constraint.

10. A method for use in conjunction with a key ladder, the method comprises:

storing at least one cryptographic key of the key ladder in a key store memory;

storing a set of rules for accessing the at least one cryptographic key in conjunction with the key ladder in a rule set memory;

interpreting a request to retrieve the at least one cryptographic key stored in the key store memory the at least one cryptographic key to produce an interpreted request that indicates a type of cryptographic algorithm;

accessing the rule set memory based on the interpreted request to retrieve a rule of the set of rules; and

granting access to the at least one cryptographic key in accordance with the rule.

11. The method of claim 10, wherein the request to access the cryptographic key comprises:

a read/write indication;

an address of the at least one cryptographic key;

a destination in the key ladder for a cryptographic result; and

identification of the type of cryptographic algorithm.

12. The method of claim 10 wherein the set of rules includes a signature rule that defines at signature corresponding to at least one of:

the set of rules and the at least one cryptographic key.

13. The method of claim 12 further comprising:

loading the at least one cryptographic key from at least one one-time programmable memory to the key store memory.

14. The method of claim 13 further comprising:

validating the at least one cryptographic key stored in the key store memory, based on the signature.

15. The method of claim 12 further comprising:

loading the set of rules from at least one one-time programmable memory to the rule set memory.

16. The method of claim 15 further comprising:

validating the set of rules stored in the rule set memory, based on the signature.

17. The method of claim 10 wherein the set of rules includes at least one of:

a null rule; and

an end of rules rule.

18. The method of claim 10 wherein the key store memory is accessed in accordance with a plurality of constraints that include at least one of:

a type constraint;

an adjacency constraint;

a skip constraint; and

a repeat constraint.

19. A device comprises:

a key store memory operable to store at least one cryptographic key;

a rule set memory operable to store a set of rules for accessing the at least one cryptographic key, wherein the set of rules includes a signature rule that defines a signature corresponding to the set of rules and the at least one cryptographic key;

a key store arbitration module operable to grant access to the cryptographic key in accordance with the set of rules; and

a validation module, coupled to the key store memory, that validates the at least one cryptographic key stored in the key store memory and further validates the set of rules stored in the rule set memory, based on the signature and wherein the validation module erases the set of rules when validation of the set of rules fails.