Bartalog
commented
5 years ago Possible solution:
- mobile encrypts file with single-use random key P (see #371)
- mobile keeps a short-lived cache of (hash -> P) mappings
- for a file share having hash H, if mapping (H -> P) is found in mobile cache, and (P(H) -> F') is found in server cache, then generate a new download URL for F'
- otherwise, generate a new P, compute F'=P(F) and upload F'
Cache system thus works only when successives share actions are performed by the same user.
After #58
In a "simple" E2EE approach, the uploaded resource is encrypted with a single-use crypto key, and cannot be reused later even if the same user uploads the same file with the same filename.
Find a way to encrypt with some sort of secret K that would allow reuse, e.g. K=f(hash(resource)).