Quick response (QR) secure shake

1. A method comprising, by a first computing device of a first user of a social-networking system:

acquiring a tag associated with a second computing device of a second user of the social-networking system, the social-networking system comprising a graph that comprises a plurality of nodes and edges connecting the nodes, at least one node in the graph corresponding to the first user, and at least one node in the graph corresponding to the second user;

processing the tag for user information comprising a time stamp, a signature, and a social action associated with the social-networking system;

sending the information to a computing device of the social-networking system for verification of the user information of the second user; and

receiving, in response to the verification, instructions for initiating the social action, the social action as initiated comprising a transaction between the at least one node corresponding to the first user and the at least one node corresponding to the second user,

wherein the signature is generated based at least in part on the time stamp and a social-networking access token of the second user.

2. The method of claim 1 , wherein the verification of the user information of the second user comprises verification of the social-networking access token of the second user by the social-networking system.

3. The method of claim 1 , wherein the tag comprises a Quick Response (QR) code, a Near Field Communication (NFC) tag, or a radio-frequency identification (RFID) tag.

4. The method of claim 1 , wherein the transaction between the at least one node corresponding to the first user and the at least one node corresponding to the second user comprises a payment action by the first user to the second user or by the second user to the first user via the social-networking system.

5. The method of claim 4 , wherein the payment comprises use of at least one of real currency, virtual currency, digital goods, and virtual goods.

6. The method of claim 1 , wherein the transaction between the at least one node corresponding to the first user and the at least one node corresponding to the second user comprises a payment action by the first user to the second user or by the second user to the first user via a third-party system associated with the social-networking system.

7. The method of claim 1 , wherein the social action further comprises creating an edge to or from the at least one node corresponding to the first user or the at least one node corresponding to the second user.

8. The method of claim 7 , wherein a payment action further comprises either creating an edge from the at least one node corresponding to the first user to the at least one node corresponding to the second user, or creating an edge from the at least one node corresponding to the second user to the at least one node corresponding to the first user.

9. The method of claim 1 , wherein the signature is generated with Secure Hash Algorithm 1 (SHA 1).

10. The method of claim 1 , wherein the tag further encodes a Uniform Resource Locator (URL).

11. The method of claim 10 , wherein the first computing device of a first user sends the information to the URL using Hypertext Transfer Protocol Secure (HTTPS) protocol.

12. The media of claim 11 , wherein the verification of the user information of the second user comprises verification of the social-networking access token of the second user by the social-networking system.

13. One or more computer-readable non-transitory storage media embodying software that is operable when executed by a computing device to:

acquire a tag associated with a second computing device of a second user of the social-networking system, the social-networking system comprising a graph that comprises a plurality of nodes and edges connecting the nodes, at least one node in the graph corresponding to the first user, and at least one node in the graph corresponding to the second user;

process the tag for user information comprising a time stamp, a signature, and a social action associated with the social-networking system;

send the information to a computing device of the social-networking system for verification of the user information of the second user; and

receive, in response to the verification, instructions for initiating the social action, the social action as initiated comprising a transaction between the at least one node corresponding to the first user and the at least one node corresponding to the second user,

wherein the signature is generated based at least in part on the time stamp and a social-networking access token of the second user.

14. The media of claim 13 , wherein the tag comprises a Quick Response (QR) code, a Near Field Communication (NFC) tag, or a radio-frequency identification (RFID) tag.

15. The media of claim 13 , wherein the transaction between the at least one node corresponding to the first user and the at least one node corresponding to the second user comprises a payment action by the first user to the second user or by the second user to the first user via the social-networking system.

16. The media of claim 13 , wherein the transaction between the at least one node corresponding to the first user and the at least one node corresponding to the second user comprises a payment action by the first user to the second user or by the second user to the first user via a third-party system associated with the social-networking system.

17. The media of claim 13 , wherein a payment action further comprises either creating an edge from the at least one node corresponding to the first user to the at least one node corresponding to the second user, or creating an edge from the at least one node corresponding to the second user to the at least one node corresponding to the first user.

18. A system comprising:

one or more processors; and

a memory coupled to the processors comprising instructions executed by the processors, the processors being operable when executing the instructions to:

acquire a tag associated with a second computing device of a second user of the social-networking system, the social-networking system comprising a graph that comprises a plurality of nodes and edges connecting the nodes, at least one node in the graph corresponding to the first user, and at least one node in the graph corresponding to the second user;

process the tag for user information comprising a time stamp, a signature, and a social action associated with the social-networking system;

send the information to a computing device of the social-networking system for verification of the user information of the second user; and

receive, in response to the verification, instructions for initiating the social action, the social action as initiated comprising a transaction between the at least one node corresponding to the first user and the at least one node corresponding to the second user,

wherein the signature is generated based at least in part on the time stamp and a social-networking access token of the second user.