How can I prove that I have added a folder to IPFS no later than a certain date?

Question

I would like to be able to prove that a certain set of files was available through IPFS at a certain date.

How can I achieve that without resorting to centralized solutions or third party authorities?

Thanks!

Answer 1

您可以使用像opentimestamps这样的解决方案，使用比特币网络创建文档的时间戳。

Answer 2

You can use the current block timestamp block.timestamp store this value then compare it to the current time when adding a folder.

Note: The block time can be manipulated by the miners see the following links. If the stakes are very high and there is incentive for people to cheat the contract then i suggest exploring other methods otherwise it doesn't seem too risky.

Can a contract safely rely on block.timestamp? - https://ethereum.stackexchange.com/questions/413/can-a-contract-safely-rely-on-block-timestamp

Need help understanding block.timestamp and how time works in the blockchain - https://forum.ethereum.org/discussion/14634/need-help-understanding-block-timestamp-and-how-time-works-in-the-blockchain

Answer 3

You can create an Ethereum smart contract which takes in an IPFS hash and ties it with the current block timestamp.

Anyone will then be able to look up an IPFS hash and see if it's in the smart contract and the timestamp, as well the public address who submitted the transaction.

If you don't want to use Ethereum you can use any reliable blockchain such as Bitcoin.