Ethereum: Can I use Bitcoin to permanently prove that “there exists a file with content at this point of time”?

Using Bitcoin to Permanently Prove the Existence of a File

In the rapidly evolving world of blockchain technology, the concept of proof-of-work (PoW) has become synonymous with securing and validating transactions on the Ethereum network. However, this paradigm can be applied to a variety of other scenarios beyond cryptocurrency transactions. One such use case is proving the existence of a file at a specific point in time.

Problem:

Imagine that you have a digital archive containing sensitive information such as financial records, medical records, or even art collections. You want to prove that at a specific point in time (e.g. May 24, 2022), you had access to and created this archive. However, traditional proof-of-work methods are not suitable for this particular use case.

Solution:

Bitcoin’s consensus algorithm allows for the creation of unspent transaction inputs (UTIs) that can be used to prove the existence of a file at a specific point in time. This is achieved through the use of digital signatures and block headers, which contain a unique identifier for each block and its corresponding data.

How ​​it works:

• Digital signatures: You generate a pair of Bitcoin public keys using a cryptographic algorithm such as elliptic curve cryptography (ECC). These keys are used to create a digital signature for the file.

• UTI: Create a unique UTI that corresponds to the block containing the file’s data. This UTI is used to identify the specific transaction on the blockchain in which the file was created or modified.

• Proof of existence: Use your digital signature and UTI to create a new transaction that contains this proof. This transaction is then broadcast to the network, where it is verified by nodes around the world.

• Block header: The block header contains information about the new transaction, including its hash, timestamp, and other metadata.

Example:

Let’s say you have a 10MB file containing sensitive financial data. You generate a Bitcoin public key pair using ECC, create a UTI corresponding to the block containing the file’s data, and use this proof of existence to create a new transaction. This transaction is then broadcast to the network, where it is verified by nodes around the world.

Advantages:

• Scalability: Bitcoin’s consensus algorithm allows for high scalability, making it ideal for large-scale file archiving projects.

• Security: The use of digital signatures and UTIs ensures that any attempts to tamper with or change the proof of existence will be detectable by nodes around the world.

• Unconditional Provenance: The Bitcoin blockchain provides unconditional provenance, meaning you can prove the existence of your file at a specific point in time without having to worry about access control or permissions issues.

Conclusion:

Bitcoin’s consensus algorithm and use of digital signatures and UTIs make it an attractive solution for proving the existence of files at specific points in time. While this approach may not be suitable for all use cases, its scalability, security, and unconditional provenance make it a viable option for large-scale file archiving projects. As blockchain technology evolves, we can expect to see new applications that leverage these innovative features.