There should be no password at all involved. You're doing key signing, not password authentication. You should have a tool, like OpenSSL or GPG, generating your key pair for you.
And people, STOP USING CRYPTOGRAPHIC PRIMITIVES FROM THINGS THAT ARE NOT OPENSSL.
Aroo? OpenSSL is usually a terrible place to pull crypto primitives from; the string "OpenSSL" in a Python or Ruby file is a decent predictor of crypto bugs. Also, OpenSSL has a relatively poor track record of algorithm-level bugs.
I'd like your sentence more if it read "STOP USING CRYPTOGRAPHIC PRIMITIVES" and then ended with a period.
I took that from cperciva when he did his crypto talk.
Edit: Found quote:
Website security: Use OpenSSL.
OpenSSL has a horrible track record for security; but it has the saving grace that because it is so widely used, vendors tend to be very good at making sure that OpenSSL vulnerabilities get fixed promptly. I wish there was a better alternative, but for now at least OpenSSL is the best option available.
UPDATE: For added security, terminate SSL connections in restricted environment and pass the raw HTTP over a loopback connection to your web server.
And yes, I'd always recommend using the highest-level possible API. If you have SHA in your code you are probably working at too low a level.
Do you have any recommendations for a better toolkit? Tarsnap uses Colin's own implementations so it's not a very good resource. There are other problems I've found with cryptlib, etc., (e.g., cryptlib is commercial).
I agree that one thing that is actually worse than directly pulling AES or SHA-2 out of OpenSSL and fucking with it in your code is actually implementing AES or SHA-2 yourself. :)
My inclination for doing this kind of thing would be to use PyOpenSSL or a similar wrapper to do an S/MIME sign/verify on each side. Encryption using AES if necessary. I'd be inclined to do this for a couple reasons:
1) If there's anything my grad crypto class taught me it's that RSA, specifically padding, is the most god-forsaken idea ever created by man and you will never, ever, ever, ever get it right. If the words RSA are in your code you are in deep shit.
2) S/MIME seems to be a simpler system than any certificate system I have seen. X.509 is an unholy mess. In fact, all PKI is just a complicated disaster waiting to happen.
3) Super simple API -- it can even be done on the command line.
Is there something different you'd recommend?
Edit: Actually, I just thought of another option. GPG has a --sign and --verify option. If GPG can be installed on the system it may be worth trying to integrate that.
And people, STOP USING CRYPTOGRAPHIC PRIMITIVES FROM THINGS THAT ARE NOT OPENSSL.