[darklajid]

Arguments as far as I'm aware (please correct me where I'm wrong):

- Crypto is 'home made' and - in spite of their crypto-challenges (or, as another school of thought states, related to the fact of trying to use these challenges to appear 'secure') unproven

- End to end encryption isn't the default

[SideburnsOfDoom]

I'm looking at this: https://core.telegram.org/techfaq#q-why-are-you-mostly-relyi...

While there seem to be "home made" elements, these are in how they are combining well-known cryptosystems.

So there may well be flaws in how they put it together or in the implementation, it doesn't appear to be a classic case of "home made" snake oil encryption. Also, it seems to be public, not the usual "trade secret" of snake oil.

[Nursie]

So to me a 'cryptosystem' is the way the elements are combined.

Block ciphers are used in a selection of modes and when combined into a protocol with integrity and authentication catered for, we have a cryptosystem.

Constructing these is hard, even with well-known algorithms, and is the source of many sneaky attack vectors. The fact that they have effectively invented their own mode is suspect, and the cryptosystem as a whole is not really well-validated either.

Their "$300,000 if you break it" contest is seen as a trust-gimmick as it provides no cryptographical or mathematical guarantees, it simply shows that nobody has yet broken it for whom 300k is more important than access to the data.

[SideburnsOfDoom]

You're right; that was poor wording. At the link they talk the "crypto algorithms" not cryptosystems that they combine.

[Aoyagi]

That's wrong in comparison to Viber/WhatsApp/Skype or just in general?