Authentication device, system and method

1. An authentication device comprising:

a light sensor;

a transmitter;

wherein the authentication device is configured to:

receive a unique identifier from a user device by sensing, with the light sensor, a visual element encoding the unique identifier that is displayed on a display of the user device;

transmit, to a server, the unique identifier;

receive, from the server, a cryptographic key corresponding to the unique identifier; and

transmit, with the transmitter to the user device, the cryptographic key for decryption of an electronic message corresponding to the unique identifier;

the authentication device further comprising:

a user input device for receiving biometric information and/or a secret code from a user, wherein the authentication device is configured to prevent transmission of the unique identifier to the server until a valid biometric information and/or a valid secret code is entered in the user input device.

2. The authentication device of claim 1 , wherein the transmitter is configured to establish a one way communication channel with the user device.

3. An authentication device comprising:

a light sensor; and

a transmitter;

wherein the authentication device is configured to:

receive a unique identifier from a user device by sensing, with the light sensor, a visual element encoding the unique identifier that is displayed on a display of the user device;

transmit, to a server, the unique identifier;

receive, from the server, a cryptographic key corresponding to the unique identifier;

transmit, with the transmitter to the user device, the cryptographic key for decryption of an electronic message corresponding to the unique identifier;

receive a sender's identification by scanning a second visual element encoding the sender's identification that is displayed on the display of the user device; and

transmit, to the server, the sender's identification.

4. The authentication device of claim 3 , wherein the authentication device and the user device are paired.

5. A computer-implemented method for encrypting an electronic message, comprising:

receiving a receiver's identification at an authentication device from a user device by sensing, with a light sensor of the authentication device, a visual element of the electronic message that is displayed on a display of the user device, the visual element encoding the receiver's identification;

generating, at the authentication device, a cryptographic key and a unique identifier;

transmitting, by the authentication device, the cryptographic key and the unique identifier to the user device for encryption of the electronic message;

transmitting, by the authentication device and over a secure channel, the cryptographic key, the unique identifier and the receiver's identification to a server;

receiving, by the user device, the cryptographic key and the unique identifier from the authentication device;

encrypting, by the user device and using the cryptographic key, a payload of the electronic message to generate an encrypted electronic message;

inserting, by the user device, a second visual element into the encrypted electronic message, the second visual element encoding the unique identifier; and

transmitting, by the user device, the encrypted electronic message to a receiver associated with the receiver's identification.

6. The computer-implemented method of claim 5 , wherein transmitting the cryptographic key and the unique identifier to the user device is over a one way channel.

7. A computer-implemented method for decrypting an electronic message, comprising:

(a) receiving a unique identifier from a user device by sensing, with a light sensor of an authentication device, a visual element of the electronic message that encodes the unique identifier and which is displayed on a display of the user device;

(b) transmitting the received unique identifier, by the authentication device, over a secure channel to a server;

(c) receiving, by the authentication device, a cryptographic key over the secure channel from the server, the cryptographic key corresponding to the unique identifier;

(d) transmitting, by the authentication device, the cryptographic key to the user device for decryption of the electronic message; and

before operation a) or operation b):

receiving, via a user input device of the authentication device, biometric information and/or a secret code from a user;

determining, by the authentication device, whether the biometric information and/or the secret code corresponds to an authorized user; and

in the negative, aborting the decryption of the electronic message.

8. The computer-implemented method of claim 7 , further comprising:

receiving, by the user device, the cryptographic key from the authentication device; and

decrypting an encrypted payload of the electronic message using the cryptographic key.

9. The computer-implemented method of claim 7 , further comprising:

receiving, by the server, the unique identifier from the authentication device;

identifying, in a database, a transaction block containing the unique identifier; and

transmitting, by the server and to the authentication device, the cryptographic key stored in the transaction block.