Apparatus and method for establishing a secure session with a device without exposing privacy-sensitive information

• US 20060117181A1
• Filed: 11/30/2004
• Published: 06/01/2006
• Est. Priority Date: 11/30/2004
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Brickell, Ernest F.
• Granted Patent: US 8,924,728 B2
• Time in Patent Office: Days
• US Class Current: 713/176
• CPC Class Codes: H04L 9/0844 with user authentication or key authentication, e.g. ElGamal, MTI, MQV-Menezes-Qu-Vanstone protocol or Diffie-Hellman protocols using implicitly-certified keys
• CPC Class Codes: H04L 9/3271 using challenge-response

Abstract

A method and apparatus for establishing a secure session with a device without exposing privacy-sensitive information are described. In one embodiment, the method includes the authentication of a digitally signed message received from a hardware device. In one embodiment, a digital signature, created by a private signature key of the hardware device, is authenticated according to a public key of an issuer without disclosure of an identity of the hardware device. The digital signature is a signature of an ephemeral DH public key, which the verifier is now assured comes from a trusted device. An encrypted and authenticated session (“secure session”) is established with the authenticated hardware device according to a key exchange using this signed ephemeral DH public key. Other embodiments are described and claimed.

Claims

1. A method comprising:

authenticating a digital signature of a hardware device according to a public key of an issuer of a private signature key used by the hardware device to sign a received message;

establishing a secure session with the authenticated hardware device according to a session key formed from a key exchange using the received message; and

using the same public key of the issuer to authenticate multiple hardware devices that use different private signature keys.

2. The method of claim 1, wherein authenticating comprises:

receiving the message from the hardware device including the digital signature formed according to the private signature key assigned to the hardware device by the issuer;

verifying the digital signature of the hardware device according to the public key of the issuer without disclosure of any unique, identification information of the hardware device; and

computing the session key according to a shared key formed from the key exchange using the received message.

3. The method of claim 1, wherein prior to authenticating, the method comprises:

selecting a random secret value y;

computing a public key k according to the random secret value y; and

transmitting the public key k to the hardware device.

4. The method of claim 1, wherein authenticating comprises:

identifying the issuer of the private signature key to the hardware device;

selecting a family public key from a family of members defined by the issuer; and

verifying, according to the selected family public key, that the hardware device is a member of the family defined by the issuer.

5. The method of claim 4, wherein identifying the issuer comprises:

determining a digital certificate for the hardware device; and

identifying the public key of the issuer according to the digital certificate.

6. The method of claim 2, wherein computing the session key comprises:

computing a shared key with the hardware device from the key exchange using the digitally signed message received from the hardware device; and

processing the shared key to form the session key.

7. The method of claim 1, wherein establishing the secure session comprises:

encrypting transmitted information to the hardware device with the session key; and

decrypting received information from the hardware device using the session key.

8. The method of claim 1, wherein authenticating further comprises:

denying authentication of the hardware device if the signature key of the device is compromised.

9. The method of claim 8, wherein denying authentication further comprises:

determining whether a digital signature attached to the digitally signed message was generated with a revoked private signing key; and

if the digital signature was created with a revoked key, rejecting the digital signature.

10. The method of claim 8, wherein denying authentication further comprises:

(a) selecting a revoked key from a revoked key list;

(b) verifying that the digital signature was not created with the revoked key; and

repeating (a)-(b) for each revoked key listed in the revoked key list.

11. A method comprising:

transmitting a message to a verifier in response to an authentication request, the message signed by a hardware device using a private signature key;

authenticating, by the verifier, a digital signature of the hardware device according to a public key of an issuer of the private signature key used by the hardware device to sign the message, without disclosing any unique identification information of the hardware device; and

establishing a secure session with the verifier according to a session key formed from a key exchange using a message received from the verifier.

12. The method of claim 11, wherein prior to transmitting the signed message, the method further comprises:

receiving a one-way authenticated key exchange request from the verifier;

computing a public key k according to a selected random value x; and

digitally signing the public key using the private signature key of the hardware device.

13. The method of claim 11, wherein prior to transmitting the signed message, the method further comprises:

generating, by the issuer, a family public/private key pair for a family of devices defined by the issuer;

computing the private signature key for the hardware device using the family private key without retaining a copy of the private signature key assigned to the hardware device; and

transmitting the private signature key to the hardware device.

14. The method of claim 11, wherein establishing the secure session comprises:

computing a shared secret key according to a public key received from the verifier; and

processing the shared key to form the session key.

15. The method of claim 11, wherein establishing the secure session comprises:

encrypting transmitted information to the verifier with the session key; and

decrypting received information from the verifier using the session key.

16. The method of claim 11, wherein prior to transmitting the signed message, the method further comprises:

receiving a platform family certificate for a family of devices defined by the issuer, the platform class certificate including at least cryptographic parameters defined by the issuer for the platform family, a public key of the issuer and a name of the issuer; and

transmitting the received platform family certificate to the verifier.

17. The method of claim 16, wherein transmitting the platform family certificate comprises:

signing, by a certifying authority, the platform family certificate; and

providing a public key of the certifying authority to the verifier to enable the verifier to authenticate the signed platform family certificate once received from the hardware device.

18. The method of claim 11, wherein prior to transmitting the digitally signed message, the method further comprises:

receiving a unique secret key pair (f,c), where F is the private signature key of the hardware device; and

digitally signing the message according to the private signature key f.

19. The method of claim 18, wherein the secret key pair includes the private signature key f of the form c^e mod n and private key c is of the form c=f^d mod n, where “

e”

, “

n”

is a public key and “

d”

is a private key of a certifying manufacturer of the hardware device.

20. An apparatus, comprising:

a flash memory to store cryptographic information received from certifying manufacturer of the apparatus; and

a trusted platform module to transmit a signed message to a verifier in response to an authentication request and to establish a secure session with the verifier according to a session key formed from a key exchange using a message received from the verifier without disclosing any unique identification information of the apparatus.

21. The apparatus of claim 20, wherein the trusted platform module further comprises:

one-way authentication logic to receive a one-way authenticated key exchange request from the verifier and to compute a public key k according to a selected random value x; and

digital signature logic to digitally sign the public key k using a private signature key of the apparatus.

22. The apparatus of claim 20, wherein the trusted platform module further comprises:

one-way authentication logic to compute a shared secret key with the verifier according to a public key received from the verifier and to process the shared key to form the session key to enable establishment of the secure session with the verifier.

23. The apparatus of claim 20, wherein the trusted platform module comprises:

secure session logic to encrypt transmitted information to the verifier using the session key and to decrypt received information from the verifier using the session key.

24. The apparatus of claim 20, wherein the apparatus is a graphics card.

25. The apparatus of claim 20, wherein the cryptographic information comprises:

a secret key pair (f, c), where f is a private signature key of the form c^e mod n and c is a private key of the form c=f^d mod n, where “

e”

, “

n”

is a public key and “

d”

is a private key of the certifying manufacturer.

26. A system comprising:

a processor to execute a trusted software module to issue a one-way authentication key exchange request to the hardware device;

a chipset coupled to the processor; and

a hardware device coupled to the chipset, the hardware device including a trusted platform module, the trusted platform module to transmit a signed message to the trusted software module in response to a one-way authentication request from the trusted software module and to establish a secure session with the trusted software module according to a session key formed from a key exchange using a message received from the trusted software module without disclosing any unique identification information of the hardware device.

27. The system of claim 26, wherein the chipset comprises a graphics controller.

28. The system of claim 26, wherein the hardware device comprises a graphics card.

29. The system of claim 26, wherein the trusted software module to authenticate a digital signature of a hardware device according to a public key of an issuer of a private signature key used by the hardware device to sign the message.

30. The system of claim 26, wherein the trusted software module is to receive a platform family certificate signed by a certifying authority, the platform family certificate to include cryptographic parameters defined by the certifying manufacturer for a platform family, and a public key of the certifying manufacturer to enable authentication of the digital signature of the hardware device.

31. An article of manufacture including a machine readable medium having stored thereon instructions which may be used to program a system to perform a method, comprising:

authenticating a digital signature of a hardware device according to a public key of an issuer of a private signature key used by the hardware device to sign a received message;

establishing a secure session with the authenticated hardware device according to a session key formed from a key exchange using the received message; and

using the same public key of the issuer to authenticate multiple hardware devices that use different private signature keys.

32. The article of manufacture of claim 31, wherein authenticating comprises:

receiving the message from the hardware device including the digital signature formed according to the private signature key assigned to the hardware device by the issuer;

verifying the digital signature of the hardware device according to the public key of the issuer without disclosure of any unique, identification information of the hardware device; and

computing the session key according to a shared key formed from key exchange using the received message.

33. The article of manufacture of claim 31, wherein prior to authenticating, the method comprises:

selecting a random secret value y;

computing a public key k according to the random secret value y; and

transmitting the public key k to the hardware device.

34. The article of manufacture of claim 31, wherein authenticating comprises:

identifying the issuer of the private signature key to the hardware device;

selecting a family public key from a family of members defined by the issuer; and

verifying, according to the selected family public key, that the hardware device is a member of the family defined by the issuer.

35. The article of manufacture of claim 34, wherein identifying the issuer comprises:

determining a digital certificate for the hardware device; and

identifying the public key of the issuer according to the digital certificate.

36. The article of manufacture of claim 32, wherein computing the session key comprises:

computing a shared key with the hardware device from the key exchange using the digitally signed message received from the hardware device; and

processing the shared key to form the session key.

37. The article of manufacture of claim 31, wherein establishing the secure session comprises:

encrypting transmitted information to the hardware device with the session key; and

decrypting received information from the hardware device using the session key.

38. The article of manufacture of claim 31, wherein authenticating further comprises:

denying authentication of the hardware device if the signature key of the device is compromised.

39. The article of manufacture of claim 38, wherein denying authentication further comprises:

determining whether a digital signature attached to the digitally signed message was generated with a revoked private signing key; and

if the digital signature was created with a revoked key, rejecting the digital signature.

40. The article of manufacture of claim 38, wherein denying authentication further comprises:

(a) selecting a revoked key from a revoked key list;

(b) verifying that the digital signature was not created with the revoked key; and

repeating (a)-(b) for each revoked key listed in the revoked key list.