Unfortunately, hashing provides no meaningful protection here. The preimage space (i.e. the set of all possible phone numbers) is just too small. See https://wh

Unfortunately, hashing provides no meaningful protection here. The preimage space (i.e. the set of all possible phone numbers) is just too small. See https://whispersystems.org/blog/contact-discovery/ https://whispersystems.org/blog/contact-discovery/