# US 2021/0279727 A1 · Verifiably Unique Transfer of Exclusive Control of Data Units

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- Number: US 2021/0279727 A1
- Document ID: US20210279727A1
- Status: Published application
- Kind: A1
- Application number: 17/194,303
- Filed: 2021-03-07
- Published: 2021-09-09
- Earliest claimed: 2020-03-06
- Assignees: Guardtime SA
- Applicants: Guardtime SA
- Inventors: Ahto BULDAS; Mart SAAREPERA; Michael GAULT
- Web page: https://patentgrep.com/patent/US20210279727A1

## CPC

- G06F 21/64: Protecting data integrity, e.g. using checksums, certificates or signatures
- G06Q 20/401: {Transaction verification}
- G06Q 20/0655: {e-cash managed centrally}
- G06Q 20/363: {with the personal data of a user}
- G06Q 20/3823: {combining multiple encryption tools for a transaction}
- G06Q 20/3825: {Use of electronic signatures}
- G06Q 20/3827: {Use of message hashing}
- G06Q 20/3829: {involving key management}
- G06Q 20/389: {Keeping log of transactions for guaranteeing non-repudiation of a transaction}
- G06Q 20/405: {Establishing or using transaction specific rules}
- H04L 9/3236: {using cryptographic hash functions}
- H04L 9/3247: {involving digital signatures}
- H04L 9/3297: {involving time stamps, e.g. generation of time stamps}
- H04L 9/50: {using hash chains, e.g. blockchains or hash trees}
- H04L 63/126: {the source of the received data}
- G06Q 2220/00: Business processing using cryptography
- H04L 63/0442: {wherein the sending and receiving network entities apply asymmetric encryption, i.e. different keys for encryption and decryption (cryptographic mechanisms or cryptographic arrangements for public-key encryption H04L9/30)}
- H04L 2209/56: Financial cryptography, e.g. electronic payment or e-cash
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)
- G06Q: INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES; SYSTEMS OR METHODS SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES, NOT OTHERWISE PROVIDED FOR
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

Exclusive ownership of data units, such as monetary units, is transferred by inputting a request from a transferor, to transfer to a transferee at least a designated one of the data units, said request including an identifier of the transferor, an identifier of the designated data unit, and an identifier of a transferee. The identifier of the transferor is verified and the absence of any other request to transfer the designated data unit during an update period is confirmed. A designation of ownership of the designated data unit is then changed from the transferor to the transferee in a ledger, which is comprised of a group of subledgers, each configured as a blockchain. Ownership is thereby processed per-unit instead of per-account.

## Claims

### Claim 1

A method for transferring exclusive ownership of data units comprising:
inputting a request from a transferor to transfer to a transferee at least a designated one of the data units, said request including an identifier of the transferor, an identifier of the designated data unit, and an identifier of the transferee;
verifying the identifier of the transferor;
confirming the absence of any other request to transfer the designated data unit during an update period; and
in a ledger, changing a designation of ownership of the designated data unit from the transferor to the transferee.

### Claim 2 (depends on 1)

The method of claim 1, in the ledger comprises a plurality of sub-ledgers, each subledger comprising a ledger data structure having elements indicating the ownership of each of a respective subset of the of the data units.

### Claim 3 (depends on 2)

The method of claim 2, in which each subledger is structured as a blockchain.

### Claim 4 (depends on 3)

The method of claim 3, in which:
each subledger includes a bill ledger for each data unit associated with it;
for each transfer request received for a respective data unit, including selected data representing the transfer request in a respective digitally signed bill block, each bill block also including a cryptographic link from a previously created block;
each bill block is included in the corresponding bill ledger, along with an emission block including cryptographic proof of the emission of the data unit.

### Claim 5 (depends on 2)

The method of claim 2, in which, each of the data units has a respective unique identifier, further comprising associating each data unit with a respective one of the subledgers as a function of its unique identifier.

### Claim 6 (depends on 1, 5)

The method of claim 5, further comprising performing the steps of claim 1 per-subledger, whereby transfer requests for data units associated with different subledgers are processed in parallel.

### Claim 7 (depends on 5)

The method of claim 5, further comprising:
inputting each transfer request to a plurality of processing systems, each processing system having a respective copy of the respective subledger and separately performing the step of confirming the absence of any other request to transfer the designated data unit during the update period;
determining a Byzantine Fault Tolerant consensus state of the subledger at the end of the update period as a function of states of the copies of the subledger; and
updating the ledger according to the consensus state.

### Claim 8 (depends on 5)

The method of claim 5, further comprising entering into an emitter subledger identifiers of newly emitted data units.

### Claim 9 (depends on 5)

The method of claim 5, in which each data unit corresponds to a monetary unit having a nominal value.

### Claim 10 (depends on 9)

The method of claim 9, further comprising generating a cryptographic proof of at least one state by obtaining a digital signature for a state input by submitting a representation of the state input to a hash tree infrastructure, in which the digital signature comprises a vector of sibling values enabling recomputation upward through the hash tree infrastructure to a root value that represents an uppermost value of the hash tree infrastructure having a plurality of tree input values submitted during an accumulation period at a corresponding calendar time, said root value being included in the digital signature;
whereby a later purportedly authentic representation of the state input may be verified as being valid if, upon recomputing a hash tree path represented by the sibling values, from the purportedly authentic representation of the state input through the hash tree, the same root value is obtained as is contained in the digital signature.

### Claim 11 (depends on 10)

The method of claim 10, in which the state is the emission of the monetary unit and the state input is the identifier of the monetary unit.

### Claim 12 (depends on 10)

The method of claim 10, in which the state is ownership of the monetary unit, and the state input includes the identifier of the monetary unit and the identifier of the transferor.

### Claim 13 (depends on 10)

The method of claim 10, in which the state is the transfer of the monetary unit from the transferor to the transferee, and the state input is the identifier of the monetary unit and the identifier of the most recent transferee.

### Claim 14 (depends on 13)

The method of claim 13, further comprising sending a wallet of the transferee a reduced bill ledger containing transfer data corresponding to the transfer of the monetary unit, including at least the root value corresponding to the transfer of the monetary unit.

### Claim 15 (depends on 10)

The method of claim 10, in which the update period is the accumulation period of the hash tree infrastructure at the time of changing ownership.