Method, apparatus and electronic device for blockchain transactions

1. A computer-implemented method for implementing blockchain-based transactions, comprising:

determining, by a first computing device associated with a remitter, a transaction amount to be remitted from a blockchain account of the remitter into a blockchain account of a receiver, wherein the blockchain account of the remitter and the blockchain account of the receiver respectively record a homomorphic encryption ciphertext of the remitter's balance and a homomorphic encryption ciphertext of the receiver's balance in a blockchain;

generating, by the first computing device applying a homomorphic encryption algorithm, a homomorphic encryption ciphertext of the transaction amount with respect to the remitter based on a transaction amount random number with respect to the remitter, the transaction amount, and a public key of the remitter;

generating, by the first computing device applying the homomorphic encryption algorithm, a homomorphic encryption ciphertext of the transaction amount with respect to the receiver based on a transaction amount random number with respect to the receiver, the transaction amount, and a public key of the receiver;

sending, by the first computing device, the transaction amount random number with respect to the receiver to a second computing device associated with the receiver via a channel off the blockchain;

determining, by the first computing device, a difference between the transaction amount random number with respect to the remitter and the transaction amount random number with respect to the receiver;

generating, by the first computing device, a first verification random number and a second verification random number;

applying, by the first computing device, the homomorphic encryption algorithm to generate a random-number homomorphic encryption ciphertext based on the first verification random number, the second verification random number, and the public key of the receiver;

obtaining, by the first computing device, a hash digest by conducting a hash operation on the homomorphic encryption ciphertext of the transaction amount with respect to the receiver and the random-number homomorphic encryption ciphertext;

generating, by the first computing device, a first verification element associated with the first verification random number and a second verification element associated with the second verification random number according to the hash digest;

generating, by the first computing device, a public key proof associated with the receiver, wherein the public key proof comprises the first verification element and the second verification element; and

submitting, by the first computing device via a blockchain network, to the blockchain a transaction comprising information of the blockchain account of the remitter, information of the blockchain account of the receiver, the homomorphic encryption ciphertext of the transaction amount with respect to the remitter, the homomorphic encryption ciphertext of the transaction amount with respect to the receiver, the difference between the transaction amount random number with respect to the remitter and the transaction amount random number with respect to the receiver, and the public key proof.

2. The computer-implemented method of claim 1 , wherein the homomorphic encryption ciphertext of the remitter's balance is a commitment of the remitter's balance, and the homomorphic encryption ciphertext of the receiver's balance is a commitment of the receiver's balance.

3. The computer-implemented method of claim 1 , wherein the homomorphic encryption ciphertext of the remitter's balance is a Pedersen Commitment of the remitter's balance, and the homomorphic encryption ciphertext of the receiver's balance is a Pedersen Commitment of the remitter's balance.

4. The computer-implemented method of claim 1 , before submitting the transaction to the blockchain, further comprising:

generating, by the first computing device, a range proof related to the remitter's balance and the transaction amount with respect to the remitter, wherein the transaction further comprises the range proof.

5. The computer-implemented method of claim 1 , wherein the homomorphic encryption ciphertext of the transaction amount with respect to the remitter is a commitment of the transaction amount with respect to the remitter based on the public key of the remitter, and the homomorphic encryption ciphertext of the transaction amount with respect to the receiver is a commitment of the transaction amount with respect to the receiver based on the public key of the receiver.

6. The computer-implemented method of claim 1 , before submitting the transaction to the blockchain, further comprising:

generating, by the first computing device, a digital signature of the remitter endorsing the homomorphic encryption ciphertext of the transaction amount with respect to the remitter and the homomorphic encryption ciphertext of the transaction amount with respect to the receiver based on a private key of the remitter, wherein the transaction further comprises the digital signature.

7. An apparatus for implementing blockchain-based transactions, comprising: one or more processors and one or more non-transitory computer-readable memories coupled to the one or more processors and storing instructions that, when executed by the one or more processors, cause the apparatus to perform operations comprising:

determining a transaction amount to be remitted from a blockchain account of a remitter into a blockchain account of a receiver, wherein the blockchain account of the remitter and the blockchain account of the receiver respectively record a homomorphic encryption ciphertext of the remitter's balance and a homomorphic encryption ciphertext of the receiver's balance in a blockchain;

generating, by applying a homomorphic encryption algorithm, a homomorphic encryption ciphertext of the transaction amount with respect to the remitter based on a transaction amount random number with respect to the remitter, the transaction amount, and a public key of the remitter;

generating, by applying the homomorphic encryption algorithm, a homomorphic encryption ciphertext of the transaction amount with respect to the receiver based on a transaction amount random number with respect to the receiver, the transaction amount, and a public key of the receiver;

sending the transaction amount random number with respect to the receiver to a computing device associated with the receiver via a channel off the blockchain;

determining a difference between the transaction amount random number with respect to the remitter and the transaction amount random number with respect to the receiver;

generating a first verification random number and a second verification random number;

applying the homomorphic encryption algorithm to generate a random-number homomorphic encryption ciphertext based on the first verification random number, the second verification random number, and the public key of the receiver;

obtaining a hash digest by conducting a hash operation on the homomorphic encryption ciphertext of the transaction amount with respect to the receiver and the random-number homomorphic encryption ciphertext;

generating a first verification element associated with the first verification random number and a second verification element associated with the second verification random number according to the hash digest;

generating a public key proof associated with the receiver, wherein the public key proof comprises the first verification element and the second verification element; and

submitting, via a blockchain network, to the blockchain a transaction comprising information of the blockchain account of the remitter, information of the blockchain account of the receiver, the homomorphic encryption ciphertext of the transaction amount with respect to the remitter, the homomorphic encryption ciphertext of the transaction amount with respect to the receiver, the difference between the transaction amount random number with respect to the remitter and the transaction amount random number with respect to the receiver, and the public key proof.

8. The apparatus of claim 7 , wherein the homomorphic encryption ciphertext of the remitter's balance is a commitment of the remitter's balance, and the homomorphic encryption ciphertext of the receiver's balance is a commitment of the receiver's balance.

9. The apparatus of claim 7 , wherein the homomorphic encryption ciphertext of the remitter's balance is a Pedersen Commitment of the remitter's balance, and the homomorphic encryption ciphertext of the receiver's balance is a Pedersen Commitment of the remitter's balance.

10. The apparatus of claim 7 , wherein the homomorphic encryption ciphertext of the transaction amount with respect to the remitter is a commitment of the transaction amount with respect to the remitter based on the public key of the remitter, and the homomorphic encryption ciphertext of the transaction amount with respect to the receiver is a commitment of the transaction amount with respect to the receiver based on the public key of the receiver.

11. The apparatus of claim 7 , wherein the operations further comprise, before submitting the transaction to the blockchain:

generating a range proof related to the remitter's balance and the transaction amount with respect to the remitter, wherein the transaction further comprises the range proof.

12. A non-transitory computer-readable storage medium storing instructions that, when executed by one or more processors, cause the one or more processors to perform operations comprising:

determining a transaction amount to be remitted from a blockchain account of a remitter into a blockchain account of a receiver, wherein the blockchain account of the remitter and the blockchain account of the receiver respectively record a homomorphic encryption ciphertext of the remitter's balance and a homomorphic encryption ciphertext of the receiver's balance in a blockchain;

generating, by applying a homomorphic encryption algorithm, a homomorphic encryption ciphertext of the transaction amount with respect to the remitter based on a transaction amount random number with respect to the remitter, the transaction amount, and a public key of the remitter;

generating, by applying the homomorphic encryption algorithm, a homomorphic encryption ciphertext of the transaction amount with respect to the receiver based on a transaction amount random number with respect to the receiver, the transaction amount, and a public key of the receiver;

sending the transaction amount random number with respect to the receiver to a computing device associated with the receiver via a channel off the blockchain;

determining a difference between the transaction amount random number with respect to the remitter and the transaction amount random number with respect to the receiver;

generating a first verification random number and a second verification random number;

applying the homomorphic encryption algorithm to generate a random-number homomorphic encryption ciphertext based on the first verification random number, the second verification random number, and the public key of the receiver;

obtaining a hash digest by conducting a hash operation on the homomorphic encryption ciphertext of the transaction amount with respect to the receiver and the random-number homomorphic encryption ciphertext;

generating a first verification element associated with the first verification random number and a second verification element associated with the second verification random number according to the hash digest;

generating a public key proof associated with the receiver, wherein the public key proof comprises the first verification element and the second verification element; and

submitting, via a blockchain network, to the blockchain a transaction comprising information of the blockchain account of the remitter, information of the blockchain account of the receiver, the homomorphic encryption ciphertext of the transaction amount with respect to the remitter, the homomorphic encryption ciphertext of the transaction amount with respect to the receiver, the difference between the transaction amount random number with respect to the remitter and the transaction amount random number with respect to the receiver, and the public key proof.

13. The non-transitory computer-readable storage medium of claim 12 , wherein the homomorphic encryption ciphertext of the remitter's balance is a commitment of the remitter's balance, and the homomorphic encryption ciphertext of the receiver's balance is a commitment of the receiver's balance.

14. The non-transitory computer-readable storage medium of claim 12 , wherein the homomorphic encryption ciphertext of the remitter's balance is a Pedersen Commitment of the remitter's balance, and the homomorphic encryption ciphertext of the receiver's balance is a Pedersen Commitment of the remitter's balance.

15. The non-transitory computer-readable storage medium of claim 12 , wherein the operations further comprise, before submitting the transaction to the blockchain:

generating a range proof related to the remitter's balance and the transaction amount with respect to the remitter, wherein the transaction further comprises the range proof.

16. The non-transitory computer-readable storage medium of claim 12 , wherein the homomorphic encryption ciphertext of the transaction amount with respect to the remitter is a commitment of the transaction amount with respect to the remitter based on the public key of the remitter, and the homomorphic encryption ciphertext of the transaction amount with respect to the receiver is a commitment of the transaction amount with respect to the receiver based on the public key of the receiver.

17. The non-transitory computer-readable storage medium of claim 12 , wherein the operations further comprise, before submitting the transaction to the blockchain:

generating a digital signature of the remitter endorsing the homomorphic encryption ciphertext of the transaction amount with respect to the remitter and the homomorphic encryption ciphertext of the transaction amount with respect to the receiver based on a private key of the remitter, wherein the transaction further comprises the digital signature.

18. The apparatus of claim 7 , wherein the operations further comprise, before submitting the transaction to the blockchain:

generating a digital signature of the remitter endorsing the homomorphic encryption ciphertext of the transaction amount with respect to the remitter and the homomorphic encryption ciphertext of the transaction amount with respect to the receiver based on a private key of the remitter, wherein the transaction further comprises the digital signature.