Embedded systems file encryption library

Question

I've got a project and a part of it is incorporating encryption into a FAT file system.

The goal of the project is not the encryption, so I'm free to use open-source pre-done libraries.

Ideally what I'm after is a C library which uses RSA, that already has the methods for computing keys and encrypting/decrypting files.

Answer 1

You might want to check out NaCl (pronounced as "salt"), especially since this is for an embedded system.

It has CPU-specific tunings and doesn't require any dynamic memory allocation.

As for licensing, the page (linked above) says "All of the NaCl software is in the public domain".

Answer 2

Regarding library - check Cryptlib . It has dual license and includes quite a lot of functionality.

However, capability to encrypt files right depends on how you write the data and how you expect to do encryption.

Streaming encryption for streams with random access (i.e. when you need to encrypt-decrypt file data on the fly when it's written or read) is not a trivial task and requires certain knowledge of cryptography to employ correct encryption mode and do this right.

On the other hand if you have a file and want it encrypted, CryptLib has PKCS7/CMS implementation to do the job.

Answer 3

You might want to give blowfish a try. It's royalty free and there are several open source C implementations. It was created by Bruce Schneier. Here is an article about using it with embedded systems.