Using virtual blockchain protocols to implement a fair electronic exchange

Abstract

Methods for a virtual blockchain protocol include generating a public key and a private key for transmitting a message from a sender to a recipient. The sender encrypts the message using the public key and a cryptographic key of the recipient to generate a first data package. The sender signs a hash function of the first data package using a cryptographic key of the sender to generate a third data package. The sender transmits the first data package and the third data package to the recipient. The sender receives a signed version of the third data package signed using the cryptographic key of the recipient. The sender determines that the signed version of the third data package has been posted to a blockchain. The sender posts the private key to the blockchain.

1 - 20 . (canceled) 
     
     
         21 . A method comprising:
 generating, by a first computer device, a keypair comprising a public key and a private key, the public key for transmitting a message from a sender to a recipient;   encrypting, by the first computer device, the message using the public key and a cryptographic key of the recipient to generate a first data package;   signing, by the first computer device, a hash function of the first data package using a cryptographic key of the sender to generate a second data package;   transmitting, by the first computer device, the first data package and the second data package to a second computer device;   receiving, by the first computer device, a signed version of the second data package from the second computer device, wherein the signed version of the second data package is signed by the recipient; and   determining, by the first computer device, whether to provide, to the recipient, the private key of the keypair.   
     
     
         22 . The method of  claim 21 , wherein the second data package comprises information representing the identity of the sender, information representing the identity of the recipient, the public key of the keypair, and the hash function of the first data package. 
     
     
         23 . The method of  claim 21 , wherein the second data package indicates a deadline for the first computer device to receive the signed version of the second data package from the second computer device. 
     
     
         24 . The method of  claim 21 , wherein the second data package indicates a deadline for the second computer device to post the signed version of the second data package to the blockchain, and wherein the first computer device posts the private key of the keypair to the blockchain responsive to determining that the signed version of the second data package is posted to the blockchain at a time earlier than the deadline. 
     
     
         25 . The method of  claim 21 , wherein the hash function is a collision-resistant hash function, and wherein a first size of the first data package is larger than a second size of the signed version of the second data package. 
     
     
         26 . The method of  claim 21 , wherein the signed version of the second data package indicates a deadline for the first computer device to post the private key to the blockchain after the signed version of the second data package is posted to the blockchain by the second computer device. 
     
     
         27 . The method of  claim 21 , wherein the first data package further comprises the cryptographic key of the recipient and the cryptographic key of the sender. 
     
     
         28 . The method of  claim 21 , wherein determining whether to provide, to the recipient, the private key of the keypair comprises determining that the signed version of the second data package has been posted to a blockchain. 
     
     
         29 . The method of  claim 21 , comprising posting, by the first computer device, the private key to the blockchain. 
     
     
         30 . The method of  claim 21 , wherein the cryptographic key of the recipient comprises a public key of the recipient. 
     
     
         31 . The method of  claim 21 , wherein the cryptographic key of the sender comprises a private key of the sender. 
     
     
         32 . The method of  claim 21 , wherein the first computer device is associated with the sender. 
     
     
         33 . The method of  claim 21 , wherein the second computer device associated with the recipient.