Thank you for your response. Sorry it took me so long to reply, I've been swamped lately.
Actually, I am a developer and I am trying to write my own file encryption tool into a Python program that I'm working on. That's why I was asking about this on StackExchange (specifically StackOverflow). Sorry, I should have clarified that.
I don't necessarily want to build one from scratch, because I'm just learning about cryptography. And I don't feel that I have a good enough understanding about cryptography to build one from scratch, let alone build one that is safe to use. Which is why I've been looking for libraries to help me get started.
Basically, my program is an automated tool that generates a particular report from a set of data and then sends it some end-point. Now I need to implement a feature to encrypt the file before sending it to the end-point. Then the entity receiving the encrypted file needs to be able to decrypt the file using the tools in their system.
The problem I'm running into is that I'm not sure what information the other person needs to successfully decrypt the file. Being new to cryptography, I thought all they would need to know is the form of encryption used (AES-256, RSA-2048, etc) and the appropriate key to decrypt but I was completely wrong. So now I'm stuck because I'm not sure how to implement a solution that will enable me to encrypt the file and have the receiving entity be able to decrypt the file on their side. I was hoping to use Keyczar because it's a solid tool and it's simple to use but that is no longer an option because the receiving party cannot use it.
What would you suggest? What info about the encryption process does the receiving entity need to know so they can decrypt?