Signal Protocol 也被 WhatsApp 及 Facebook Messenger 的 “Secret Chat” 使用。佢哋話就咁話,係咪真,無人知,closed-source 的 proprietary software 就係咁。Signal 係由個 501(c)(3) 非牟利機構運作, WhatsApp 的 co-founder Brian Acton 捐咗 US$50,000,000 俾 Signal Foundation 而且冇期望收得返。 Signal 冇 paid features,而且不賺用家錢。 Signal 冇廣告和不含 trackers。我引述 Signal 嘅網頁: “We've designed the Signal service to minimize the data we retain about Signal users, so the only information we can produce [...] is the date and time a user registered with Signal and the last date of a user's connectivity to the Signal service.
“Notably, things we don't have stored include anything about a user's contacts (such as the contacts themselves, a hash of the contacts, any other derivative contact information), anything about a user's groups (such as how many groups a user is in, which groups a user is in, the membership lists of a user's groups), or any records of who a user has been communicating with. All message contents are end-to-end encrypted, so we don't have that information either."