I know that many will not like this 
I saw that if I sign a file with a private key, that the hex will take 65 bytes (that are less than 80 bytes, so it's ok)
By spreading signs on the Blockchain, than a service will be able to find how many data/files are signed by someone, by knowing his own Bitcoin address.
But it will not be able to know which files are signed by him.
If instead someone puts the hash (sha256 is 32 bytes) of his files on the Blockchain, then everyone (or a service) will be able to see that someone else has already claimed these files, but it will not be possible to know who is the owner.
Putting both sign + file_hash (65 + 32 = 97) in the OP_RETURN will give the possibility to a service, or even a dedicated full client, connected with a full node, to know everything.
It will know if a file is already claimed and who claimed it.
Just by adding these 17 bytes that we will get this great function
Anyway, do you know any cheaper way (with less bytes) to get the same result?
Is it possible to achieve the same with only 80 bytes?
I know that the easier way is just by making two chained transaction, but it would be cool to still be able to do with just one.
I saw that if I sign a file with a private key, that the hex will take 65 bytes (that are less than 80 bytes, so it's ok)
By spreading signs on the Blockchain, than a service will be able to find how many data/files are signed by someone, by knowing his own Bitcoin address.
But it will not be able to know which files are signed by him.
If instead someone puts the hash (sha256 is 32 bytes) of his files on the Blockchain, then everyone (or a service) will be able to see that someone else has already claimed these files, but it will not be possible to know who is the owner.
Putting both sign + file_hash (65 + 32 = 97) in the OP_RETURN will give the possibility to a service, or even a dedicated full client, connected with a full node, to know everything.
It will know if a file is already claimed and who claimed it.
Just by adding these 17 bytes that we will get this great function
Anyway, do you know any cheaper way (with less bytes) to get the same result?
Is it possible to achieve the same with only 80 bytes?
I know that the easier way is just by making two chained transaction, but it would be cool to still be able to do with just one.
Just take the first 15 bytes of the hash. To avoid collision, 120bits is already overkill
