MUTUAL AUTHENTICATION WITH SYMMETRIC SECRETS AND SIGNATURES

• US 20160156626A1
• Filed: 01/21/2016
• Published: 06/02/2016
• Est. Priority Date: 06/26/2014
• Status: Active Grant

• Current Assignee: Amazon Technologies, Inc. (Amazon.com, Inc.)
• Original Assignee: Amazon Technologies, Inc. (Amazon.com, Inc.)
• Inventors: Roth, Gregory Branchek, Rubin, Gregory Alan
• Granted Patent: US 9,882,900 B2
• Time in Patent Office: Days
• 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 63/0869 for achieving mutual authentication cryptographic mechanisms or cryptographic arrangements for mutual authentication H04L9/3273
• CPC Class Codes: H04L 63/123 received data contents, e.g. message integrity
• CPC Class Codes: H04L 63/166 at the transport layer
• CPC Class Codes: H04L 9/0861 Generation of secret information including derivation or calculation of cryptographic keys or passwords
• CPC Class Codes: H04L 9/14 using a plurality of keys or algorithms
• CPC Class Codes: H04L 9/32 including means for verifying the identity or authority of a user of the system or for message authentication, e.g. authorization, entity authentication, data integrity or data verification, non-repudiation, key authentication or verification of credentials
• CPC Class Codes: H04L 9/321 involving a third party or a trusted authority
• CPC Class Codes: H04L 9/3247 involving digital signatures
• CPC Class Codes: H04L 9/3273 for mutual authentication network architectures or network communication protocols for achieving mutual authentication in a packet data network H04L63/0869

Abstract

A client and server negotiate a secure communication channel using a pre-shared key where the server, at the time the negotiation initiates, lacks access to the pre-shared key. The server obtains the pre-shared key from another server that shares a secret with the client. A digital signature or other authentication information generated by the client may be used to enable the other server to determine whether to provide the pre-shared key.

Claims

1. A computer-implemented method, comprising:

under the control of one or more computer systems configured with executable instructions,

receiving, from a client computer system and in accordance with a communication protocol for establishing a secure communication channel, a message and a digital signature, the message specifying a set of key derivation parameters, the communication protocol comprising a handshake protocol;

transmitting the message and the digital signature to an authentication server operable to verify authenticity of the message based at least in part on the digital signature and contingent on successful verification of the authenticity of the message, derive a pre-shared cryptographic key that is available to the client computer system and to provide the pre-shared cryptographic key;

receiving, from the authentication server, the pre-shared cryptographic key; and

using the pre-shared cryptographic key to establish, as part of the handshake protocol, the secure communication channel with the client computer system to result in an established secure communication channel.

2. The computer-implemented method of claim 1, wherein using the pre-shared cryptographic key to establish the secure communication channel with the client computer system comprises deriving an encryption key in accordance with a protocol used to establish the secure communication channel and using the encryption key to transmit encrypted messages to the client computer system.

3. The computer-implemented method of claim 1, wherein:

receiving the pre-shared key further comprises receiving, from the authentication server, a signing key; and

the method further comprises using the signing key to verify a digital signature of a request received, over the established secure communication channel, from the client computer system.

4. The computer-implemented method of claim 3, wherein using the pre-shared cryptographic key to establish the secure communication channel comprises using a set of additional key-derivation parameters to derive another cryptographic key from the pre-shared cryptographic key.

5. The computer-implemented method of claim 1, wherein the method further comprises:

storing a set of policies; and

determining, based at least in part on the set of policies, whether to fulfill a request received over the established secure communication channel.

6. A system, comprising a set of computing devices configured to implement at least:

a first server that negotiates, in accordance with a handshake protocol, a secure communication channel with a client computer system by executing executable code that causes the first server to;

provide a message and a digital signature received from a client computer system to a second server;

if the digital signature matches the message, receive, from the second server, a pre-shared key accessible to the client computer system and usable to transmit encrypted messages to the client computer system to communicate over the secure communication channel; and

if the digital signature fails to match the message, operate in accordance with the digital signature being unverified.

7. The system of claim 6, wherein:

the system further comprises the second server;

the second server and the client computer system both have access to a cryptographic key;

the message specifies a set of key derivation parameters; and

the second server is configured to derive, based at least in part on the key derivation parameters, the pre-shared key from the cryptographic key.

8. The system of claim 7, wherein the second server derives the pre-shared key iteratively where output of a first iteration is calculated based at least in part on a first key derivation parameter of the set of key derivation parameters and output of a second iteration is calculated based at least in part on the output of the first iteration and a second key derivation parameter of the set of key derivation parameters.

9. The system of claim 7, wherein:

the second server derives, based at least in part on the cryptographic key and a second set of key derivation parameters different from the set of key derivation parameters, second cryptographic key and provide the second cryptographic key with the with the pre-shared key; and

the first server receives the second cryptographic key and use the second cryptographic key to verify at least one digital signature generated by the client computer system.

10. The system of claim 7, wherein:

the message specifies a key path, the key path specifying an order of operations to be performed in deriving the pre-shared key; and

the second server derives the pre-shared key in accordance with the key path.

11. The system of claim 6, wherein the handshake protocol is part of a version of transport layer security.

12. The system of claim 6, wherein the pre-shared key is inaccessible to the first server until the pre-shared key is received from the second server.

13. The system of claim 6, wherein the first server provides, to the second server, information sufficient to enable the second server to verify the digital signature based at least in part on multiple messages transmitted between the client computer system and the first server.

14. The system of claim 6, wherein the first server digitally signs information comprising the message and the digital signature thereby generating a second digital signature verifiable by the second server.

15. A non-transitory computer-readable storage medium having stored thereon instructions that, as a result of execution by one or more processors of a computer system, cause the computer system to:

access a cryptographic key usable to derive a signing key, the signing key accessible to a second computer system and usable to generate a digital signature of a request to the second computer system such that the request and the digital signature of the request are collectively sufficient to cause the second computer system to fulfill the request;

derive, from the accessed cryptographic key, a session key; and

use the session key to encrypt at least a portion of one or more communications to the second computer system, the one or more communications comprising a first request that is digitally signed using the signing key.

16. The non-transitory computer-readable storage medium of claim 15, wherein the signing key is different from the session key.

17. The non-transitory computer-readable storage medium of claim 15, wherein the instructions that cause the computer system to derive the session key, as a result of execution by the one or more processors, cause the computer system to derive a pre-shared key from the cryptographic key and generate the session key from the pre-shared key.

18. The non-transitory computer-readable storage medium of claim 15, wherein the instructions further include instructions that, as a result of execution by the one or more processors, cause the computer system to provide parameters for deriving the session key to enable the second computer system to derive the session key.

19. The non-transitory computer-readable storage medium of claim 15, wherein the instructions further comprise instructions that, when executed by the one or more processors, cause the computer system to complete a handshake process in accordance with a secure communication protocol to cause the second computer system to utilize the session key.

20. The non-transitory computer-readable storage medium of claim 15, wherein the instructions further comprise instructions that, when executed by the one or more processors, cause the computer system to use the signing key to digitally sign information that is based at least in part on multiple messages transmitted between the computer system and the second computer system.