People aren't using shit crypto, virtually no one is using anything other than what is highly vetted or otherwise google/apple/ms/etc is telling them to.
What is the actual argument here? That some $randompeople play around with new cryptosystems and then share them with friends?
The sheer derision that my original comment has directed at it is astounding, let the kids play with cryptography, who the fuck cares, I hope they roll all of the crypto themselves, the world will be a better place, who exactly is saying it should replace current elliptical curves decided so wholesomely for us all by NIST?
The simple clear fact is that Western countries do not like and are actively campaigning against modern cryptography. Lets pretend we have some dignity left please as human beings. The West used to represent something, now it feels like we are taking notes from oppressive regimes and playing catch-up.
From Why You Should Stop Using Telegram Right Now (2016) (https://gizmodo.com/why-you-should-stop-using-telegram-right...):
According to interviews with leading encryption and security experts,
Telegram has a wide range of security issues and doesn’t live up to its
proclamations as a safe and secure messaging application. [...]
Telegram did what’s known as “rolling their own encryption,” which is
widely considered to be a fatal flaw when developing encrypted messaging apps.
1. Telegram's E2EE is not on by default, therefore 99% of users don't use it.
2. Telegram's E2EE is not advertising authentication, therefore ~90% of the people using it don't check for MITM attacks, therefore majority of E2EE is useless against active attackers.
3. Telegram's E2EE does not work across devices, therefore majority people who use secret chats also use non-secret chats because desktop client don't support it.
4. 100% of Telegram's group conversations can be eavesdropped by the server, because Telegram doesn't have E2EE for group chats.
Complaining about possible cribs in how Telegram implemented the protocol from cryptographic primitives is an insignificant problem compared to the fact the entire protocol is fundamentally FUBAR, how it's so glaringly obvious you can't even fill out a CVE form.
If Signal had vulnerability where 100% of group conversations were not properly end-to-end encrypted, every newspaper in the world would publish something about it. However, with Telegram it has been spun as a "feature".
Another big problem is Telegram has been mentioned by hundreds of publications as "Secure apps like Signal, WhatsApp and Telegram".
To experts it's like hearing news spout "Great writers like Leo Tolstoy, Paulo Coelho, and Stephanie Meyer", or "Great bunker materials like reinforced concrete, steel, and MDF".
Repeatedly claimed, anyone would make mental associations between the three, but when you actually find out what they're about you can't believe your ears.
My previous employer was encrypting customer data (in a project I didn't work on) with RSA. Yes, they were actually using RSA itself to encrypt the user data. If you're thinking "Oh, and that's bad because RSA right?" then "No", that's not actually why - again, I direct you to our main thesis: Stop hand-rolling crypto, this is dangerous and you are going to hurt yourself.
But even if we restrict "people" to just my mother and sister, ordinary users with common hardware and software then that's often still people using shit crypto.
Popular libraries like OpenSSL are full of garbage fire shit crypto. Lots of it is "optional" but did you turn off that option? Does my sister know where the option is? No. Some of it is because people are trying to do very hard things and there's no margin for error, but as this article suggests you can solve that by not doing the very hard things any more. Doing RSA Key Ex with TLS _safely_ is very, very hard. Not doing it at all is easy. So just don't do it.
Cryptography is not like folk dancing or pottery, where it's OK to be fairly bad at it so long as you had a good time.
This is like heart surgery. We don't encourage everybody to "have a go" at heart surgery and hope maybe some of them will do a good job, that would be crazy. People spend years acquiring enough skills to even _find out_ whether they'd actually be any good as a heart surgeon, and some don't make the cut.
What does that look like? Cryptanalysis. Probably starting with a Mathematics degree, but it is possible to get there from another numerate background and a LOT of study.
That's where anybody at all serious - certainly this century and arguably going back to the middle of the twentieth century - starts. They analyse existing crypto systems and they find new problems. They start out a bit shy, hey, did anybody notice that X is actually a member of a Boze-Lechstein inverted group here? Doesn't that mean we could use the Stross-Baxter formula to find X in O(n) time? And after a few successess (and maybe one or two setbacks where they made an embarrassing mistake) they get a reputation so that others in the field show them exciting new things. Hey, you're the guy who first saw Stross-Baxter-Watts, take a look at our SHA-4 contender which relies on a related approach, see any problems?
After you've got a few years in cryptanalysis, maybe, if you feel up to it, you can start to propose new ideas. Your colleagues will respect you enough to take a look, and the first few will definitely get shot down. Ha, you forgot that the Benford-Barnes hypothesis doesn't apply to correlated members, so your new cipher has vast swathes of hard-to-detect weak keys. Not good, better luck next time. But maybe, if you're good, you will eventually make something good enough that people remember it when it doesn't make the cut for a competition. You are now "famous".
Notice how none of this was just some random guy in his bedroom having an idea and inventing a brand new cryptosystem? That's because that doesn't work. It did two centuries ago. If your adversaries are from the late 18th century, you should definitely go try that approach. But the adversaries got a lot better.