Combined authentication and encryption
View Patent ↗A system and methods are provided for establishing an authenticated and encrypted communication connection between two devices with at most two round-trip communications. During establishment of an initial authenticated, encrypted communication connection (or afterward), a first device (e.g., a server) provides the second device (e.g., a client) with a token (e.g., a challenge) that lives or persists beyond the current connection. After that connection is terminated and the second device initiates a new connection, it uses the token as part of the handshaking process to reduce the necessary round-trip communications to one.
1. A method of establishing an authenticated and encrypted communication connection between two devices, the method comprising, at a first device:
during a first communication connection with a second device, providing the second device with a first token; and
after termination of the first communication connection:
receiving from the second device encrypted authentication data;
generating a session key from the first token;
attempting to decrypt the encrypted authentication data with the session key;
if the encrypted authentication data can be decrypted with the session key, acknowledging to the second device establishment of a second communication connection as part of a single round trip that comprises the receiving of the second device encrypted authentication data and the acknowledging of the establishment of the second communication connection; and
if the encrypted authentication data cannot be decrypted with the session key:
providing the second device with a second token;
receiving from the second device new encrypted authentication data;
generating a new session key from the second token;
decrypting the new encrypted authentication data with the new session key; and
acknowledging to the second device establishment of a second communication connection.
2. The method of claim 1 , wherein the authentication data comprises:
an identifier of a user of the second device;
a token provided by the first device; and
device-specific data.
3. The method of claim 2 , wherein the authentication data further comprises:
a timestamp.
4. The method of claim 2 , wherein the user identifier is a telephone number of the user.
5. The method of claim 2 , wherein the device-specific data is a user agent operating on the second device.
6. The method of claim 2 , wherein the token is one of the first token and the second token.
7. The method of claim 1 , wherein generating the session key comprises applying a function to the first token and to a secret shared between the first device and the second device.
8. The method of claim 7 , wherein the shared secret is a password to an application hosted by the first device and executed on the second device.
9. A method of establishing an authenticated and encrypted communication connection between two devices, the method comprising, at a first device:
before termination of a first communication connection between the first device and a second device, providing the second device with a persistent challenge; and
after termination of the first communication connection, establishing a second communication connection with the second device with a single round-trip communication comprising:
receipt of a set of encrypted authentication data generated by the second device based in part on the persistent challenge and a secret shared by the first device and the second device; and
transmission of an acknowledgement of the second communication connection.
10. The method of claim 9 , further comprising, after receipt of the set of encrypted authentication data:
generating a session key based in part on the persistent challenge and the shared secret;
decrypting the encrypted authentication data with the session key; and
parsing the decrypted authentication data to verify its content.
11. The method of claim 9 , wherein the content of the decrypted authentication data includes:
a user identifier of a user of the second device; and
the persistent challenge.
12. The method of claim 11 , wherein the shared secret is a password for an application executed on the second device and hosted by the first device.
13. A system for establishing an authenticated and encrypted communication connection with a client device, the system comprising:
a processor; and
memory configured to store instructions that, when executed by the processor, cause the system to:
during a first connection with the client device, provide the client device with a temporary challenge;
after termination of the first connection, receive a set of authentication data encrypted with a key generated from the temporary challenge;
generate a session key based in part on the temporary challenge and a secret shared with the client device; and
if the encrypted authentication data can be decrypted with the session key, acknowledge establishment of a second connection with the client device in a single round trip without sending any other communications to the client device after receipt of the encrypted authentication data.
14. The system of claim 13 , wherein:
the shared secret is a password for an application executed on the client device and hosted by the system; and
the authentication data comprises a telephone number of the client device.
15. The system of claim 13 , wherein the memory is further configured to store instructions that, when executed by the processor, cause the system to:
if the encrypted authentication data cannot be decrypted with the session key:
provide the client device with a new challenge;
receive a new set of authentication data encrypted with a new key generated from the new challenge;
generate a new session key based in part on the new challenge and the secret shared with the client device;
decrypt the new encrypted authentication data with the new session key;
parse the decrypted authentication data to authenticate the client device; and
acknowledge establishment of the second connection with the client device.