Blockchain Data Protection with Homomorphic Encryption

Glossary

Blockchain: A distributed database shared by participants that is secure and immutable and is used to record transaction information.

Consensus Node: A node in a blockchain network that is responsible for verifying and adding new blocks to ensure that all nodes are in the same state.

Homomorphic Encryption (HE): A special form of encryption that allows calculations to be performed on ciphertext, and the decrypted result is consistent with the result of the same calculation on the plaintext.

Commitment Scheme: A cryptographic protocol that allows one party (the committer) to commit to a value and prove certain properties of the value to another party (the verifier) without revealing the value.

Pedersen Commitment: A commonly used commitment scheme that is homomorphic and can be used to hide transaction amounts.

Okamoto-Uchiyama HE: A classic homomorphic encryption scheme.

Range Proof: A cryptographic proof used to prove that a value falls within a specified range, such as proving that the transaction amount is a positive number and is less than the account balance.

Digital Signature: An electronic signature used to verify the identity of the message sender and the integrity of the message.

Elliptic Curve Cryptography (ECC): A public key cryptography system based on elliptic curve mathematics, with the advantages of short key length and high security.

Short Answer Questions

Briefly describe the core features of blockchain technology.

Decentralization: There is no central authority to control, and data is distributed and stored on all participating nodes.

Tamper-proof: Once data is written to the blockchain, it cannot be modified or deleted.

Transparent and open: All transaction records are open and transparent and can be viewed by anyone.

Safe and reliable: Cryptography technology is used to ensure data security and prevent tampering and attacks.

Explain the role of homomorphic encryption in blockchain privacy protection.

Homomorphic encryption allows calculations on ciphertext without decrypting plaintext.

Using this feature, the validity of transactions can be verified without revealing transaction amounts and account balances, protecting user privacy.

Explain how the commitment scheme is used to hide transaction amounts.

The transaction sender uses the commitment scheme to commit to the transaction amount and generate a commitment value.

The commitment value does not reveal the specific information of the transaction amount, but can be used to verify whether the transaction amount is consistent.

List two common homomorphic encryption schemes.

Okamoto-Uchiyama Encryption Scheme (Okamoto-Uchiyama HE)

Boneh-Goh-Nissism Encryption Scheme (Boneh-Goh-Nissism HE)

Describe the use of digital signatures in blockchain transactions.

The transaction sender uses a digital signature to sign the transaction information to prove the authenticity and integrity of the transaction.

The receiver and consensus node can verify the digital signature to prevent the transaction from being tampered with or forged.

Explain the role of range proof in ensuring the legitimacy of the transaction amount.

Range proof can prove that the transaction amount is a positive number to prevent negative transaction attacks.

Range proof can also prove that the transaction amount is less than or equal to the sender's account balance to prevent double-spending attacks.

Briefly describe the basic process of the blockchain transaction verification method based on homomorphic encryption mentioned in the document.

The transaction sender uses the commitment scheme to commit to the transaction amount, and uses homomorphic encryption to encrypt the transaction amount and random number to generate a transaction proof.

The transaction sender sends the transaction proof to the consensus node.

The consensus node uses the properties of homomorphic encryption to verify the transaction proof, ensuring the consistency of the transaction amount without leaking the transaction amount.

What are the advantages of this method over traditional blockchain transaction verification methods?

Protect user privacy: The transaction amount and account balance are always encrypted and will not be leaked.

Improve transaction efficiency: Transactions can be verified without decrypting plaintext, reducing computing overhead.

What cryptographic technologies are used in the methods mentioned in the document?

Homomorphic encryption: used to encrypt transaction amounts and random numbers, while allowing calculations on ciphertext.

Commitment scheme: used to hide transaction amounts and allow verification of whether transaction amounts are consistent.

Digital signature: used to verify the identity of the transaction sender and the integrity of the message.

Range proof: used to prove the legitimacy of the transaction amount.

What are the application scenarios of this method?

Blockchain applications that need to protect user privacy, such as privacy coins, supply chain finance, etc.

Blockchain applications that need to improve transaction efficiency, such as high-frequency trading, the Internet of Things, etc.

Essay question

Detail the mechanism of homomorphic encryption and commitment scheme in protecting the privacy of blockchain transactions, and compare the advantages and disadvantages of the two.

Analyze the security of the blockchain transaction verification method based on homomorphic encryption mentioned in the document, explore the security risks and attack methods that this method may face, and propose corresponding defense measures.

Combined with actual application scenarios, discuss the applicability of this method in different types of blockchain platforms (such as public chains, consortium chains, and private chains), analyze its advantages and disadvantages and improvement directions.

Explore the possibility of combining this method with other privacy protection technologies (such as zero-knowledge proofs, ring signatures, etc.), analyze its advantages and challenges, and look forward to the development trend of blockchain privacy protection technology in the future.

Analyze the impact of this method on blockchain performance, such as transaction throughput, transaction delay, etc., and explore how to optimize this method to improve blockchain performance.