Question: One uploads a file to the SAFE network that already exists on the network. Is that file a copy?

Like, if I were to create a file on my computer and make a copy of it, the bits and bytes of that file would be double the amount on my hard disk, but if I were to put a file on the SAFE network, I would imagine the network only needing to share extra links to the already existing file.

Yes, if it’s immutable data it will already be there at a fixed address on the network, so there’s no need to upload another copy.


Its an inherent feature of the self encryption process because 2 duplicate files encrypt to the same series of chunks. And as @JPL says the address is derived from the chunk itself and as such 2 identical chunks will have the same address and you cannot store it twice.

I have suggested before that someone will make an app to do the self encryption and check to see if each chunk already exists or not. Only if the chunk doesn’t exist will it attempt to store the chunk. The reason for this APP is that each attempt to store will incur a PUT cost whether its a duplicate or not. On a side note it is questionable if people would use this APP for small files (eg cat vids) since it requires running the APP specially for that upload.

Now there is a minor change now in that duplicates are only duplicates if both of the files are PUBLIC or both are PRIVATE. The reason being that PRIVATE files have an address created from both the contents hash and the owner of the chunk rather than just from the hash of the contents as for PUBLIC files. (@dirvine Did I get this bit right?)