So what is DeepVault? Quite simply, DeepVault is an information store that is held within the blockchain meaning that the data is immutable, forever! More specifically, DeepVault allows Onion members to store file validation credentials (hashes of files) within the blockchain. This has obvious benefits as it allows users to verify a file's integrity over time. Therefore, if the hash of the file changes, then the file has been altered or corrupted. This tool will be invaluable in checking whether your important documents are secure and have not been tampered with. Legal documents are an obvious use for this feature as it would enable a person to verify that the document, and thus content, has not been altered either maliciously, erroneously or through file corruption.
This is a very interesting development and I look forward to more information about it!
I wonder how large a file can be stored on the chain??
As described, DeepVault will store hashes of files on the blockchain, not the files themselves. Hash functions take an input of arbitrary size and turns them into the outputs of the same size. Cryptographic hash functions have one important characteristic: if you change your input even a little bit, the output changes entirely in the way that's impossible to predict. Use case looks like this:
- take a document of arbitrary size
- compute its hash
- record the hash on the blockchain (for example by using transaction with OP_RETURN locking script)
When you want to find out whether someone has tampered with your document, you just compute its hash again and compare it to the hash value stored on the blockchain. If both hash values are the same, you can safely assume, that the document has not changed even a tiny bit since its original hash value was recorded on blockchain. If current hash value differs from the hash value recorded on the blockchain, you're document has been modified in some way.
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