Show HN: CryptoNote is an open source, encrypted, one time view message app

https://cryptonote.org/

by alainmeier • 13 years ago

55 41 13 years ago

cryptonote.org

jhorman• 13 years ago

Looks useful. I am seeing though

message[pre_encryption]

with my unencrypted message in the POST data?

alainmeier8• 13 years ago

Good catch, I'll take that out right now thanks.

Edit: fixed. If anybody thinks of anything else, please let me know. This is as much of a learning exercise as anything for me.

tptacek4• 13 years ago

This whole thread is like a textbook example of why people like me (breakers) have itchy trigger fingers when it comes to people building cryptography features.

I'm glad if this has been a good learning experience for you (may I suggest another?†), but real secure systems aren't, to steal a phrase from Richard Stallman, "debugged into existence": they start from a foundation of a secure, well-considered design and are verified piece by piece as the system is assembled.

† http://www.matasano.com/articles/crypto-challenges

effbott3• 13 years ago

The password is sent in plaintext in the POST body.

manish_gill4• 13 years ago

Also see: https://oneshar.es

I created a similar web application in Django as part of a College minor project last year. Best part was implementing the AES algorithm ourselves. :D

tptacek4• 13 years ago

You felt comfortable implementing AES yourself?

manish_gill4• 13 years ago

For learning purpose, why not? Taught me a lot more about crypto than I would have by simply reading about it. Of course, it wasn't meant for real-world use. :)

lawnchair_larry• 13 years ago

What role does AES serve in your application? Your site is just sending plaintext wrapped in SSL.

effbott3• 13 years ago

I'm confused by that as well. The POST data sends a nonce value but the message itself is in plaintext... not even Base64..

deepdog• 13 years ago

Why is the password stored in plain text "for now"? What is so hard about running bcrypt or pbkdf2 against the password before storing it in the database?

alainmeier8• 13 years ago

I was just getting this out as soon as possible. There's nothing hard about it, I just wanted to put it out there and keep working on it.

daeken5• 13 years ago

Good on you for having a list of known weaknesses, but here's the one that really makes this completely unsafe:

The server dictates what's run on the page, and thus can access the plaintext data in any way it sees fit. The trust model is fundamentally broken in client-side crypto of this nature.

Edit with two more thoughts: 1) Even if you trust the person running the service, how much do you trust the other users (who may be using stored XSS to compromise your data)? How much do you trust the hosting service behind it, if there is one? 2) Am I the only one that finds it massively irresponsible to not have a huge flashing "DO NOT TRUST THIS UNTIL IT'S BATTLE HARDENED" sign over it? This goes for just about every project of this nature.

Edit with a final thought: Most of the time, we think in terms of "relative goodness". A good car is better than a bad car, but a bad car is still better than no car at all. This logic completely breaks when it comes to crypto. Simply put, bad crypto (and bad implementations) when released on the world put lives at risk. This should be taken seriously.

It's one thing to build a project for learning (and please, please do!) but cover every friggin' surface you can with disclaimers.

alainmeier8• 13 years ago

Thanks, and that is absolutely true. That's why it's open source: I want people to host their own version if they don't trust me https://github.com/alainmeier/cryptonote

daeken5• 13 years ago

But if you need to trust the server (and you do), then the client-side encryption is 100% pointless. You might as well encrypt on the server with safe, sane, battle-hardened code.

At the end of the day, XSS, rogue hosts, etc can own this even if the person "running the show" doesn't want it to happen.

Edit: I note that you now link to nadim's response to http://www.matasano.com/articles/javascript-cryptography&#x2...; -- you reaaaaally should consider linking to the original, or perhaps to https://news.ycombinator.com/item?id=5768837 wherein that article is torn to shreds. JS cryptography is very, very dangerous.

alainmeier8• 13 years ago

Hm, yes, added a warning message, good idea. As for your other thoughts, I completely agree. It's a work-in-progress and I figured the best way to figure out what's wrong is to learn from others.

Edit: Also added a link to that discussion next to Nadim's post.

daeken5• 13 years ago

Awesome, glad to hear it!

rmrfrmrf• 13 years ago

If you're that paranoid, you shouldn't be using a hosted service at all. There could be a guy right outside your house intercepting your cable line and filtering all traffic to and from cryptonote.org and routing it to his own instance of the app. That doesn't mean that cryptonote is responsible for that happening.

daeken5• 13 years ago

This is everything that is wrong with cryptography and privacy. Simply put, if your data is important enough to use cryptography on it, why would you want to use crypto that is broken by design?

The whole point of a well-designed, well-implemented cryptosystem is that even if there is a dude sitting outside my house, he's not getting a single bit of my data. This is just as true for government secrets as it is sending a recipe to my mother. This service is broken, as all such services are. Bad crypto is never, ever, ever excusable.

uh_oh3• 13 years ago

No, he can't. Not without a valid SSL certificate for cryptonote.org. Sure, there are problems with CAs, but it would nevertheless be very difficult to obtain such a certificate.

tlrobinson• 13 years ago

Do you believe there is zero value to client-side JavaScript crypto?

There's a spectrum between "unencrypted webpage loaded over cafe WiFi" and "locally compiled open-source application". You don't always need the latter.

EDIT: Say you're using a web app that encrypts your data on the client. All the executable assets (html, js, css) are static and hosted on a CDN over HTTPS. The app stores your encrypted data to another server. Even if that server is compromised, it's still impossible to access your data without also compromising the CDN (assuming a correct implementation of the crypto and no XSS vulnerabilities, of course).

EDIT2: It would be interesting if you could sign a bundle of static assets that the browser could verify. Maybe as part of the HTML5 app cache. Like a lightweight version of a Chrome app. Add on a restrictive Content Security Policy and it sounds pretty good to me.

daeken5• 13 years ago

Client-side crypto in JS has value if and only if the following conditions are all met:

1) The application receives no HTML, CSS, Javascript, or code interpreted by plugins from a server in the same context (e.g. not an iframe) as the crypto code.

2) All assets that are run in the context of the crypto code are fixed and signed. No unsigned javascript code (generated at runtime, passed from a server or input to the app, whatever) is permitted to run in any way in that context.

3) The code as signed is completely transparent. It must be possible to audit the code as it would be run, and be able to 'quarantine' updates.

Without all of these things being met, client-side crypto in the browser is completely untrustable. These conditions have never been met.

ryandetzel• 13 years ago

Just use vanish.io

alainmeier8• 13 years ago

There are a lot of single view self destruct sites, but I wanted to make a new one because I wanted to let people host their own instead of relying on the site provider.

alfg• 13 years ago

This is neat, and the I really like the UI too.

I made something similar (except the one-time view part) not too long ago just to experiment with storing the base64 encoded message into the URL. It also has an option to add a key, which uses a javascript implementation of blowfish.

http://alfg.co/jot

https://github.com/alfg/jot

Since the message is stored within the URL, there's no backend needed, though that means the message needs to be short since most modern browsers can only support up to about 2000 characters in the URL and the messages can generate a long base64 string rather quickly.

alainmeier8• 13 years ago

I experimented with that too, but the character limitation was what made me go server-side. Cool project though, works really well

Show HN: CryptoNote is an open source, encrypted, one time view message app

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