Non-repudiation protocol using time-based one-time password (totp)

A method of implementing a non-repudiation protocol, the method comprising:

• registering, with a first device, an application associated with the first device at a trusted third party, wherein the application registration is a one-time event;
• receiving, with the first device, a seed generated by the trusted third party based in part on a seed time;
• receiving, with the first device, a document from a second device;
• displaying, with the first device, the received document to a first user;
• in response to receiving an input from the first user indicating acceptance of the document:
• computing, with the first device, a time-based one-time password based in part on a current clock time of the first device and the seed;
• computing, with the first device, a first hash of the document using the time-based one-time password as an encryption key;
• and
• transmitting, with the first device, to the second device the first hash and the current clock time the first hash was computed by the first device.

A method of implementing a non-repudiation protocol, the method comprising:

• receiving, with a first device, a request for a document from a second device;
• transmitting, with the first device, the document to the second device;
• receiving, with the first device, a hash, and a current clock time the hash was computed by the second device, wherein, the second device computes a time-based one-time password based in part on the current clock time and a seed that was received from a trusted third party, and wherein, the second device computes the hash of the document using the time-based one-time password as an encryption key;
• verifying, with the first device, that the current clock time of the second device is within a threshold of a current clock time of the first device;
• and
• storing, with the first device, the document, the hash, and the current clock time the hash was computed by the second device.