Methods and systems for synchronizing a device with a blockchain

1 . A method performed by an RF broadcast station for allowing a device to maintain synchronization with a blockchain for security purposes, the blockchain being in a series of states S i , the method comprising:

receiving information about a first state S 1 of a blockchain;

encrypting the information about the first state S 1 of the blockchain with a session key;

generating a first RF broadcast signal encoding the encrypted information about the first state S 1 of the blockchain;

transmitting the first RF broadcast signal to the device at a first time t 1,0 ;

receiving information about a second state S 2 of the blockchain;

encrypting the information about the second state S 2 of the blockchain with the session key:

generating a second RF broadcast signal encoding the encrypted information about the second state S 2 of the blockchain;

transmitting the second RF broadcast signal to the device at a second time t 2,0 , the second time t 2,0 and the first time t 1,0 being separated by a first interval;

re-transmitting the first RF broadcast signal at a third time t 1,1 , the third time t 1,1 and the first time t 1,0 being separated by a second interval;

re-transmitting the second RF broadcast signal at a fourth time t 2,1 , the fourth time t 2,1 and the second time t 2,0 being separated by the second interval;

re-transmitting the first RF broadcast signal at a fifth time t 1,2 , the fifth time t 1,2 and the third time t 1,1 being separated by a third interval, the third interval being longer than the second interval; and

re-transmitting the second RF broadcast signal at a sixth time t 2,2 , the sixth time t 2,2 and the fourth time t 2,1 being separated by the third interval,

wherein:

a zeroth history H 0 comprises a plurality of transmissions at times t i,0 , which are first transmissions of respective RF broadcast signals representing i th states S i of the blockchain;

a j th history H j comprises a plurality of transmissions at times t i,j , which are j th retransmissions of respective RF broadcast signals representing i th states S i of the blockchain, and there are N histories in total; and

for all i:

distributions of time intervals Δt i,j =t i,j −t i,j(-1) between transmissions of signals encoding information about the i th states S i is such that the device is able eventually to resynchronize with the zeroth history H 0 after a period of loss of connectivity; and

a maximum time interval between an initial transmission of a signal encoding an i th state S i of the blockchain and a final retransmission of the signal encoding an i th state of the blockchain is equal to a maximum tolerable duration of a period of loss of connectivity of the device.

2 . The method of claim 1 , further comprising:

receiving a public encryption key from the device;

generating a broadcast encryption key based on at least the public encryption key of the device;

encrypting the session key with the broadcast encryption key; and

transmitting the encrypted session key to the device, the encrypted session key being decryptable using a private decryption key on the device, the private decryption key being complementary to the public encryption key.

3 . The method of claim 2 , further comprising:

receiving a plurality of registration requests from a respective plurality of devices, each registration request comprising a public encryption key associated with that device; and

determining whether each registration is a valid registration request;

wherein the broadcast encryption key is generated based only on the public encryption keys of those devices whose registration requests were determined to be valid registration requests.

4 . The method of claim 2 , wherein the session key is a rotating session key; and further comprising:

generating a new session key;

encrypting the new session key with the broadcast encryption key; and

transmitting the encrypted session key.

5 . A method performed by a device for maintaining synchronization between the device and a blockchain based on a plurality of RF broadcast signals, the method comprising:

receiving a first RF broadcast signal, the first RF broadcast signal encoding encrypted information about a first state S 1 of the blockchain;

decrypting the information about a first state S 1 of the blockchain using a session key:

storing the information about the first state S 1 of the blockchain in a memory of the device;

wherein after the device misses at least one transmission of an i th RF broadcast signal in a history H j at at least one time t i,j , the method further comprises:

receiving a retransmitted version of the i th RF broadcast signal from a subsequent history H k at a time t i,k where k>j, the retransmitted version of the i th RF broadcast signal encoding encrypted information about an i th state S i of the blockchain;

decrypting the information about the i th state S i of the blockchain using the session key; and

storing the information about the i th state S i of the blockchain in the memory of the device; and

wherein after the device has stored information about an i th state S i of the blockchain based on an RF broadcast signal from a subsequent history H k at a time t i,k , the method further comprises both:

at times t i,m receiving information about later states of the blockchain from an earlier history H m where m<k and storing the information to a buffer of the memory; and

receiving information about at least an (i+1) th state S i+1 of the blockchain from the subsequent history H k at times t n,k where n={i+1, i+2 . . . } and storing the information to the buffer of the memory; and

when all of the information resulting from missed transmissions has been obtained from history H k , combining the information received from the histories H k and H m , thereby restoring synchronization, and continuing to obtain information from RF broadcast signals in history H m .

6 . The method of claim 5 wherein the earlier history H m is an original history H 0 .

7 . The method of claim 5 , further comprising, after the device has regained connectivity:

(a) receiving a signal which arrives earlier of: a next signal from an original history H 0 , or a next signal containing information about a next unaccounted-for state of the blockchain, and storing that information to the memory, and repeating this step until a next signal from the original history H 0 has been received;

(b) determining whether information about states of the blockchain up to a most-recent state from the original history H 0 has been stored in the memory of the device;

(c) if so, re-synchronizing with the original history H 0 such that subsequent signals, preferably all subsequent signals, are received from the original history H 0 ; and

(d) if not, receiving the signal which arrives earlier of: a next signal from the original history H 0 , or a next signal containing information about the next unaccounted-for state of the blockchain, and storing that information to the memory, and repeating step (b) until a positive determination is returned.

8 . The method of claim 5 , further comprising:

when there is no internet connectivity:

generating data to be written to the blockchain, the data including a timestamp indicating the time at which the data was generated;

generating authentication data based on the information about the first state S 1 of the blockchain; and

storing the data and the authentication data in a temporary memory of the device; and

when there is internet connectivity:

transmitting the data and the authentication data to the blockchain via the internet.

9 . An apparatus for allowing a device to maintain synchronization with a blockchain for security purposes, the blockchain being in a series of states S i , the apparatus comprising:

at least one memory; and

at least one processor coupled to the at least one memory and configured to:

receive information about a first state S 1 of a blockchain;

encrypt the information about the first state S 1 of the blockchain with a session key;

generate a first RF broadcast signal encoding the encrypted information about the first state S 1 of the blockchain;

cause at least one transmitter to transmit the first RF broadcast signal to the device at a first time t 1,0 ;

receive information about a second state S 2 of the blockchain;

encrypt the information about the second state S 2 of the blockchain with the session key;

generate a second RF broadcast signal encoding the encrypted information about the second state S 2 of the blockchain;

cause the at least one transmitter to transmit the second RF broadcast signal to the device at a second time t 2,0 , the second time t 2,0 and the first time t 1,0 being separated by a first interval;

cause the at least one transmitter to re-transmit the first RF broadcast signal at a third time t 1,1 , the third time t 1,1 and the first time t 1,0 being separated by a second interval;

cause the at least one transmitter to re-transmit the second RF broadcast signal at a fourth time t 2,1 , the fourth time t 2,1 and the second time t 2,0 being separated by the second interval;

cause the at least one transmitter to re-transmit the first RF broadcast signal at a fifth time t 1,2 , the fifth time t 1,2 and the third time t 1,1 being separated by a third interval, the third interval being longer than the second interval; and

cause the at least one transmitter to re-transmit the second RF broadcast signal at a sixth time t 2,2 , the sixth time t 2,2 and the fourth time t 2,1 being separated by the third interval, wherein:

a zeroth history H 0 comprises a plurality of transmissions at times t i,0 , which are first transmissions of respective RF broadcast signals representing i th states S i of the blockchain;

a j th history H j comprises a plurality of transmissions at times t i,j , which are j th retransmissions of respective RF broadcast signals representing i th states S i of the blockchain, and there are N histories in total; and

for all i:

distributions of time intervals Δt i,j =t i,j −t i,(j-1) between transmissions of signals encoding information about the i th states S i is such that the device is able eventually to resynchronize with the zeroth history H 0 after a period of loss of connectivity; and

a maximum time interval between an initial transmission of a signal encoding an i th state S i of the blockchain and a final retransmission of the signal encoding an i th state of the blockchain is equal to a maximum tolerable duration of a period of loss of connectivity of the device.

10 . The apparatus of claim 9 , wherein the at least one processor is configured to:

receive a public encryption key from the device;

generate a broadcast encryption key based on at least the public encryption key of the device;

encrypt the session key with the broadcast encryption key; and

cause the at least one transmitter to transmit the encrypted session key to the device, the encrypted session key being decryptable using a private decryption key on the device, the private decryption key being complementary to the public encryption key.

11 . The apparatus of claim 10 , wherein the at least one processor is configured to:

receive a plurality of registration requests from a respective plurality of devices, each registration request comprising a public encryption key associated with that device; and

determine whether each registration is a valid registration request;

wherein the broadcast encryption key is generated based only on the public encryption keys of those devices whose registration requests were determined to be valid registration requests.

12 . The apparatus of claim 10 , wherein the session key is a rotating session key and wherein the at least one processor is configured to:

generate a new session key;

encrypt the new session key with the broadcast encryption key; and

cause the at least one transmitter to transmit the encrypted session key.

13 . The apparatus of claim 9 , wherein the apparatus comprises an RF broadcast station.

14 . The apparatus of claim 9 , wherein the apparatus comprises the at least one transmitter.