UUIDs can also be collided. Did you want some form of public key referencing that only a private key can answer, perhaps? As already pointed out by ivoras here

UUIDs can also be collided. Did you want some form of public key referencing that only a private key can answer, perhaps? As already pointed out by ivoras here, magnet: links are close to exactly what you're looking for. It also reminds me of, for example, the Freenet CHK/SSK/USK system, or several other things with similar designs. You should also not use SHA-1 hashes for uniqueness or checksumming anymore: they're too weak.