Injection is not a problem if you use your data access correctly. You are not worried about maintaining your ownership model, so there are no problems. You have a green light to expose the model.
Confidentiality is not a problem if you tell the user that the data is publicly available. People open private information and photos on Facebook, so why not your system? Green light.
Random salt hashed data is, in theory, safe to download. A SHA512 with a random hash will probably never be broken. But who knows? Once MD5 was the "right way" for the hash, and now you detect a collision in less than 1 hour.
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