> I wouldn't say this is bad or anything

I would.

The idea might not be bad, but the implementation is.

They use a pure software AES implementation that, due to its reliance on S-boxes, opens the door for cache-timing attacks.

Offending file: https://github.com/keybase/triplesec/blob/master/src/aes.ice...

Permalink: https://github.com/keybase/triplesec/blob/bb0b2f449cc28ca402...

Issue: https://github.com/keybase/triplesec/issues/47 (opened March 17, still collecting dust)

Reference: http://cr.yp.to/antiforgery/cachetiming-20050414.pdf

AES-NI or bust.

> The FAQ says something about plans for a future streaming API. Please do not do this, at least for the decrypt operation. Streaming decryption APIs expose application developers to not-yet-authenticated plaintext.

I've written a streaming PoC to encrypt/decrypt file handles in PHP. During the decryption process, it first recalculates the HMAC over the entire file then verifies it with the one stored before decrypting. (Yes, in constant time too.) It's slower than just blindly decrypting, but more trustworthy.

Not quite the same as streaming network resources, but I figured that bit of nuance is worth mentioning.

The experiment lives here if you're interested in schooling me on some matter I overlooked, though I'm going to significantly rewrite it before I propose it to the project I was PoCing it for:

https://github.com/paragonie-scott/php-crypto-stream

(For starters, the actual pull request won't be using CBC.)

I was mainly commenting on the design. I actually haven't looked at the implementation.

Also, I would put AES side channels somewhat low on the list of practical vulnerabilities.

> Also, I would put AES side channels somewhat low on the list of practical vulnerabilities.

Sure, but if they're concerned about weaknesses in AES enough to cascade it with other ciphers, ignoring the side-channel inherent to the AES design is pretty silly and indicates a lack of research or foresight.

Combine that with no response from their team for threee months after I opened the issue, and I think we can safely conclude that this library is not currently trustworthy.

(in b4 "TripleSec Considered Harmful")

Just commented on that issue. As you point out, most pure software implementations of AES still use S-Boxes, for better or worse. It's a risk to switch to a less standard and more complicated implementation to mitigate these attacks. Of course if you did TripleSec your data, the cache-timing attack is mitigated by the independent Salsa20 stream.

Exactly, this will fail just as fast as a single cipher when your users inevitably use 'password123' for their password.

This is like saying, "A self driving car is a bad idea, because the user might enter the bottom of the ocean as their destination.".

This is like saying "adding triple redundant GPS to a self driving car is a bad idea because the GPS is the component least likely to cause you to end up at the bottom of the ocean."

There's no a priori need for password-derived key material in a library like this. To require it unilaterally is to introduce a security risk, since people have proven to be poor sources of entropy.

I don't really understand the self-driving car analogy. A better analogy would probably be three cars hitched together.

If the user enters the bottom of the ocean as their destination, it would be bad for a self-driving car to take them there. "The user is an idiot and so we killed him" is not going to be such a great defense in court...

In all seriousness, if a man puts a GLOCK 21 in his mouth and pulls the trigger, is it GLOCK that "killed him"?

If I take my car and intentionally drive into the ocean, I expect it to continue until the engine dies, and then I do shortly after. Why should machines start prohibiting me from doing stupid things, if I want to do them? I think Isaac Asimov wrote a parable about such a future.

None of the mistakes people make in crypto are intentional. We need better interfaces to help them not make those mistakes.

Except this also adds very little benefit. Sure, 3 ciphers might be better than one, but as the top comment said the cipher is already the strongest part of the entire process.

That's why you do password strengthening, which helps quite a bit.