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Pokinator t1_je6qy6l wrote

Reply to comment by sethguy12 in ELI5: When a third party app says they offer "end to end encryption," what does that mean? by [deleted]

The answer is extremely dependent on the platform.

Generally, once a message has been encrypted with a doesn't-suck-ass encryption algorithm, the only way to read the message is by having the key or breaking the encryption algorithm to get the key. (most in-use algorithms are pretty break-proof at the moment). Without the key, the message in transit is just gibberish.

When it comes to back doors, it's pretty hard to implement them without severely weakening security. Any point where you say "okay but at this part you can use our magical master key to read it" becomes a gaping hole in the integrity of your encryption.

More commonly, if the platform wants a back-door they'll do it on the client ends instead of in the middle. Create a way to hack into a user account and get their keys. Even that is a major security hole though.

If you want reliable security, there can't be a back door at all.

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Blueroflmao t1_je8u99j wrote

For what its worth, AES (Advanced Encryption Standard) which is currently applied by default for nearly everything on the internet is the standard for a reason. A brute force attack (trying all combinations to find the right one) is... Impossible, with todays technology. The selection for AES was started in 2001 by the NSA, and in 2003, the Rjindael cipher was selected and it still remains the AES to this day.

As far as I know, several different attacks and methods have been found through cryptanalysis, the best of which was found in 2011. Named the "Biclique"-attack, it was further optimized in 2013.

Now heres the real kicker: there are generally three kinds of AES in use, all with slightly different designs depending on the size of the key used to encrypt (secret key/initial state, the key an attack is trying to find) These are AES-128, 192 and 256.

So using the most efficient attack that is publicly known, how long would it theoretically take to break one single instance of 128 (the simplest one)? Optimally, about 9007 Terabytes of storage is needed (down from the original version of the attack needing 38 TRILLION Terabytes) The time complexity remains the same, despite this improvement, at 2^126. (Simplified, theres some technicality involved here)

What this all means, TL; DR: The simplest form of AES in use (AES-128) would take billions of years to crack, taking ~ 2^126 operations to do so, requiring OVER 9000 terabytes of storage while executing.

As far as we can tell, AES is set to remain the standard until quantum computing comes far enough to actually be useful in Cryptanalysis (meaning we can actually extract the result of our computations, something we are unable to do today)

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famous_cat_slicer t1_je94s49 wrote

> (most in-use algorithms are pretty break-proof at the moment).

Your use of "most" in this context is slightly worrying. What are the exceptions?

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frzx1 t1_je99odh wrote

The exceptions fall in the experimental area of encryption. What I mean by that is that the most applications you use today, WhatsApp, Signal, Banking apps, are all encrypted with a military grade encryption, but if you go try out experimental encrypting algorithms then you are at risk. Note that the latter does not happen in your regular day to day life, encryption standards are extremely uniform.

Edit: also, be aware that the applications that have implemented an unbreakable encryption algorithm can still decrypt your files as they have the keys to decrypt them. They're bound to not do it going by the privacy agreement but they potentially can. There are exceptions to it, like Apple's advanced E2E standard where not even Apple has your keys.

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Dovaldo83 t1_jea3yqt wrote

Quantum computers are capable of taking encryptions that would normally take super computers 500 years to crack and crack them in minutes.

That said quantum computers are still so expensive and rare that you and I shouldn't be concerned about someone using them against us. They've already started development on encryption methods that use quantum phenomena to encrypt messages that even quantum computers have a hard time cracking.

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Pokinator t1_jea9qwz wrote

I used "Most" instead of "All" mainly for technicality.

TL;DR Rock-Solid encryptions exist, but that doesn't guarantee everyone is using them or using them correctly.

Firstly, just because there's options for solid encryption algorithms doesn't mean they're universally used. For example, the chat app that Bob down the street wrote could be using a very weak Caesar Shift encryption rather than something strong like AES or RSA.

Secondly, some encryptions are only as strong as their choice of key. For example, RSA uses prime numbers to generate keys in a way that's very not ELI5. Basically, 3 primes get used to generate an "encrypt" number, and a "decrypt" number.

If you follow guidelines, the secret "Decrypt" number is practically impossible to guess or calculate. However, if you choose irresponsibly bad starting numbers then a hacker can look at your public Encrypt number and go "hey, that looks like they might have..." and workshop the secret from there.

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nighthawk_something t1_jea15a5 wrote

Yup that's why there's no "make a back door just this one time so we can stop the terrorist".

It's all or nothing. The backdoor is wide open for everyone, or for no one.

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