Programming on-chip non-volatile memory in a secure processor using a sequence number
An improved secure programming technique involves reducing the size of bits programmed in on-chip secret non-volatile memory, at the same time enabling the typical secure applications supported by secure devices. A technique for secure programming involves de-coupling chip manufacture from the later process of connecting to ticket servers to obtain tickets. A method according to the technique may involve sending a (manufacturing) server signed certificate from the device prior to any communication to receive tickets. A device according to the technique may include chip-internal non-volatile memory to store the certificate along with the private key, in the manufacturing process.
1. A method comprising:
receiving, using a processor, a request for a device certificate;
initializing, using the processor, a state variable in an on-chip writable memory to an initial value in response to a power up event of a device containing the processor;
generating, using the processor and a function of a secret seed random number and a sequence number, a cryptographic key pair;
identifying a key in the cryptographic key pair, the key comprising one of a public key and a private key in the cryptographic key pair;
incrementing, using the processor, the sequence number;
generating, using the processor, a first random number as a function of the key and the state variable;
creating, using the processor, the device certificate based on the first random number and the request for the device certificate, the device certificate being configured to provide a security signature for accessing protected resources by a secure application.
2. The method of claim 1 , further comprising executing at least a portion of the secure application, the executing using at least a portion of the protected resources.
3. The method of claim 1 , further comprising clearing the state variable from the on-chip writable memory before a power down event of the device.
4. The method of claim 1 , wherein generating the cryptographic key pair comprises using a cryptographically strong encryption algorithm to generate the cryptographic key pair based on the seed random number and the sequence number.
5. The method of claim 1 , wherein generating the first random number comprises instructing, using the processor, a pseudorandom number generator to calculate the first random number.
6. The method of claim 1 , wherein the cryptographic key pair comprises an elliptic cryptographic key pair.
7. The method of claim 1 , wherein the on-chip writable memory comprises an on-chip non-volatile (NV) memory, and the seed random number is stored on the on-chip NV memory.
8. The method of claim 1 , wherein the sequence number is a stored sequence number included in the on-chip writable memory.
9. The method of claim 1 , wherein the processor comprises a secure processor, and the method is executed in one or more of a game console having the secure processor, a media player having the secure processor, an embedded secure device having the secure processor, or a digital device having the secure processor.
10. A system, comprising:
an on-chip non-volatile (NV) memory including a secret seed random number;
an on-chip writable memory including a stored sequence number;
a client-side interface associated with a registered client;
a certificate generation module;
wherein, in operation:
the client-side interface is configured to receive a request for a device certificate and to transmit a validated device certificate;
the certificate generation module is configured to:
initialize a state variable in the on-chip writable memory to an initial value in response to a power up event of a device containing the certificate generation module;
generate a cryptographic key pair using a function of the secret seed random number and the sequence number;
identify a key in the cryptographic key pair, the key comprising one of a public key and a private key in the cryptographic key pair;
increment the sequence number;
generate a first random number as a function of the key and the state variable;
create the validated device certificate based on the first random number and the request for the device certificate, the validated device certificate being configured to provide a security signature for accessing protected resources by a secure application.
11. The system of claim 10 , wherein the certificate generation module is configured to facilitate execution of at least a portion of the secure application on the system, the execution using at least a portion of the protected resources.
12. The system of claim 10 , wherein the certificate generation module is configured to clear the state variable from the on-chip writable memory before a power down event of the device.
13. The system of claim 10 , wherein, when generating the cryptographic key pair, the certificate generation module is configured to use a cryptographically strong encryption algorithm to generate the cryptographic key pair based on the seed random number and the sequence number.
14. The system of claim 10 , wherein, when generating the first random number, the certificate generation module is configured to use a cryptographically strong encryption algorithm to instruct a pseudorandom number generator to calculate the first random number.
15. The system of claim 10 , wherein the cryptographic key pair comprises an elliptic cryptographic key pair.
16. The system of claim 10 , wherein the on-chip writable memory comprises an on-chip non-volatile (NV) memory, and the seed random number is stored on the on-chip NV memory.
17. The system of claim 10 , wherein the processor comprises a secure processor, and the method is executed in one or more of a game console having the secure processor, a media player having the secure processor, an embedded secure device having the secure processor, or a digital device having the secure processor.
18. A system, comprising:
an on-chip non-volatile (NV) memory including a secret seed random number;
an on-chip writable memory including a stored sequence number;
a client-side interface associated with a registered client;
means for generating a certificate;
wherein, in operation:
the client-side interface is configured to receive a request for a device certificate and to transmit a validated device certificate;
the means for generating the certificate is configured to:
initialize a state variable in the on-chip writable memory to an initial value in response to a power up event of a device containing the certificate generation module;
generate a cryptographic key pair using a function of the secret seed random number and the sequence number;
identify a key in the cryptographic key pair, the key comprising one of a public key and a private key in the cryptographic key pair;
increment the sequence number;
generate a first random number as a function of the key and the state variable;
create the validated device certificate based on the first random number and the request for the device certificate, the validated device certificate being configured to provide a security signature for accessing protected resources by a secure application.