The only one I can find so far is bcrypt at GitHub C files

Maybe for Key passing to clients you could email them the key. That may open another can of worms. As for scrypt are you all sure it exist, can't find it any where.

Can I take the red pill now, Opening the lid on internet security, talk about pandora's box.

This here is a must read long. A link to more things to read.

Thanks for the links. I found a library called "Botan" which seems to have bunch of useful crypto/algorithm. Its' bcrypt_generate function doesn't let you create/store your own salt since it's doing it somewhere in function but it has bcrypt_check function which gets the job done. Another useful information i came across was to use a public key exchange algorithm on top of tls for decent amount of security.

a public key exchange algorithm on top of tls for decent amount of security

Unfortunately, unless you use full end-to-end certificate validation, public key exchange doesn't add any security.

The reason is that man-in-the-middle can insert himself between client and server, and send one PKX to the client, and run another to the server, and have the decrypted data in the middle.

Use TLS, if you can. The worry more about endpoint security than potential snoopers in the middle.