Authenticating secure channel establishment messages based on shared-secret
Systems and processes are described for establishing and using a secure channel. A shared secret may be used for authentication of session initiation messages as well as for generation of a private/public key pair for the session. A number of ways of agreeing on the shared secret are described and include pre-sharing the keys, reliance on a key management system, or via a token mechanism that uses a third entity to manage authentication, for example. In some instances, the third party may also perform endpoint selection by providing a particular endpoint along with the token. The particular cipher suite applied in a particular implementation may be configurable. The process is applicable to either implicit key confirmation (e.g., handshake negotiation) or explicit key confirmation (e.g., full negotiation).
1. A system, comprising:
a computing device including at least one hardware processor and configured to:
authenticate a secure channel establishment message based at least in part on a shared secret key shared between the computing device and another computing device that sent the secure channel establishment message; and
generate, based at least in part on contents of the secure channel establishment message and the shared secret key, a data communication key block for performance of cryptographic operations on data received or to be sent over the secure channel between the computing device and the other computing device, wherein the shared secret key used for authentication of the secure channel establishment message is the same shared secret key used in generation of the data communication key block;
generate a key confirmation code using a key based at least in part on a private key of a private-public key pair of the computing device, a public key of a private-public key pair of the other computing device, and the shared secret key to encrypt data known to the other computing device; and
send the key confirmation code to the other computing device.
2. The system of claim 1 , wherein, to authenticate the secure channel establishment message, the computing device is further configured to:
apply a key derivation function to at least the shared secret key to generate an initiator authentication key,
apply a message authentication code function with the initiator authentication key and initiation message body as inputs to generate an initiation message authentication code, and
compare the initiation message authentication code generated by the computing device with an initiation message authentication code received in the secure channel establishment message.
3. The system of claim 1 , further comprising:
the other computing device, configured to:
verify the key confirmation code using a key based at least in part on the private key of the other computing device, the public key of the computing device, and the shared secret key to decrypt the data, wherein verification of the key confirmation code verifies that the other computing device can decrypt data communications from the computing device on the secure channel.
4. The system of claim 3 , wherein the other computing device is further configured to:
generate another key confirmation code using a key based at least in part on the private key of the other computer device, the public key of the computing device, and the shared secret key to encrypt data known to the computing device; and
send a key confirmation message to the computing device including the other key confirmation code.
5. The system of claim 4 , wherein the computing device is further configured to:
verify the other key confirmation code from the key confirmation message using a key based at least in part on the private key of the computing device, the public key of the other computing device, and the shared secret key to decrypt the data, wherein verification of the other key confirmation code verifies that the computing device can decrypt data communications from the other computing device on the secure channel.
6. The system of claim 1 , wherein:
an identifier for a cipher suite is indicated in one of the messages from the other computing device; and
the computing device is further configured to verify the indicated cipher suite as acceptable.
7. The system of claim 6 , wherein the indicated cipher suite specifies:
a particular scheme for generation of the private-public key pair of the other computing device and the private-public key pair of the computing device,
a particular scheme for generating an initiation message authentication code and response message authentication code, and
a key derivation function for use in generation of the data communication key blocks for the computing device and the other computing device.
8. A method, comprising:
performing, by a computing device comprising at least one hardware processor:
authenticating a secure channel establishment message based at least in part on a shared secret key shared between the computing device and another computing device that sent the secure channel establishment message; and
generating, based at least in part on contents of the secure channel establishment message and the shared secret key, a data communication key block for performing cryptographic operations on data received or to be sent over the secure channel between the computing device and the other computing device, wherein the shared secret key used for authenticating the secure channel establishment message is the same shared secret key used in generating the data communication key block;
generating a key confirmation code using a key based at least in part on a private key of a private-public key pair of the computing device, a public key of a private-public key pair of the other computing device, and the shared secret key to encrypt data known to the other computing device; and
sending the key confirmation code to the other computing device.
9. The method of claim 8 , wherein authenticating the secure channel establishment message comprises:
applying a key derivation function to at least the shared secret key to generate an initiator authentication key,
applying a message authentication code function with the initiator authentication key and initiation message body as inputs to generate an initiation message authentication code, and
comparing the initiation message authentication code generated by the computing device with an initiation message authentication code received in the secure channel establishment message.
10. The method of claim 8 , further comprising:
verifying, by the computing device, the key confirmation code using a key based at least in part on the private key of the other computing device, the public key of the computing device, and the shared secret key to decrypt the data, wherein verifying the key confirmation code verifies that the other computing device can decrypt data communications from the computing device on the secure channel.
11. The method of claim 10 , further comprising:
generating, by the other computing device, another key confirmation code using a key based at least in part on the private key of the other computing device, the public key of the computing device, and the shared secret key to encrypt data known to the computing device; and
sending a key confirmation message to the computing device including the other key confirmation code.
12. The method of claim 11 , further comprising:
verifying, by the computing device the other key confirmation code from the key confirmation message using a key based at least in part on the private key of the computing device, the public key of the other computing device, and the shared secret key to decrypt the data, wherein verifying the other key confirmation code verifies that the computing device can decrypt data communications from the other computing device on the secure channel.
13. The method of claim 8 , wherein:
an identifier for a cipher suite is indicated in one of the messages from the other computing device; and
the method further comprises verifying, by the computing device, the indicated cipher suite as acceptable.
14. The method of claim 13 , wherein the indicated cipher suite specifies:
a particular scheme for generation of the private-public key pair of the other computing device and the private-public key pair of the computing device,
a particular scheme for generating an initiation message authentication code and response message authentication code, and
a key derivation function for use in generation of the data communication key blocks for the computing device and the other computing device.
15. One or more non-transitory, computer-readable storage media storing program instructions that when executed on or across one or more processors cause at least one hardware processor to perform:
authenticating a secure channel establishment message based at least in part on a shared secret key shared between a computing device and another computing device that sent the secure channel establishment message; and
generating, based at least in part on contents of the secure channel establishment message and the shared secret key, a data communication key block for performing cryptographic operations on data received or to be sent over the secure channel between the computing device and the other computing device, wherein the shared secret key used for authenticating the secure channel establishment message is the same shared secret key used in generating the data communication key block;
generating a key confirmation code using a key based at least in part on a private key of a private-public key pair of the computing device, a public key of a private-public key pair of the other computing device, and the shared secret key to encrypt data known to the other computing device; and
sending the key confirmation code to the other computing device.
16. The one or more non-transitory, computer-readable storage media of claim 15 , wherein to perform said authenticating the secure channel establishment message, the one or more media store program instructions cause the at least one hardware processor to perform:
applying a key derivation function to at least the shared secret key to generate an initiator authentication key,
applying a message authentication code function with the initiator authentication key and initiation message body as inputs to generate an initiation message authentication code, and
comparing the initiation message authentication code generated by the computing device with an initiation message authentication code received in the secure channel establishment message.
17. The one or more non-transitory, computer-readable storage media of claim 15 , wherein the one or more media store program instructions that cause the at least one hardware processor to perform:
verifying, by the computing device, the key confirmation code using a key based at least in part on the private key of the other computing device, the public key of the computing device, and the shared secret key to decrypt the data, wherein verifying the key confirmation code verifies that the other computing device can decrypt data communications from the computing device on the secure channel.
18. The one or more non-transitory, computer-readable storage media of claim 17 , wherein the one or more media store program instructions that cause the at least one hardware processor to perform:
verifying, by the computing device, another key confirmation code from key confirmation message from the other computing device using a key based at least in part on the private key of the computing device, the public key of the other computing device, and the shared secret key to decrypt the data, wherein verifying the other key confirmation code verifies that the computing device can decrypt data communications from the other computing device on the secure channel.
19. The one or more non-transitory, computer-readable storage media of claim 15 , wherein:
an identifier for a cipher suite is indicated in one of the messages from the other computing device; and
the one or more media store program instructions that cause the at least one hardware processor to perform:
verifying, by the computing device, the indicated cipher suite as acceptable.
20. The one or more non-transitory, computer-readable storage media of claim 19 , wherein the indicated cipher suite specifies:
a particular scheme for generation of the private-public key pair of the other computing device and the private-public key pair of the computing device,
a particular scheme for generating an initiation message authentication code and response message authentication code, and
a key derivation function for use in generation of the data communication key blocks for the computing device and the other computing device.