Implement cryptography algorithms in an ARM microcontroller

Question

Assume a situation in which you want do some encryption procedures in your ARM microcontroller. (Receive a file, encrypt with 3DES and some hash functions and returning it, for example.)

As far as I know we have two option here:

1. Reinventing the wheel! i.e. writing some functions to do described cryptography algorithms.
2. Adding already-written libraries in our project and using their methods simply.

Now I want to benefit from the second solution using OpenSSL libraries. But I'm not sure about it! Is it possible to add these libraries to the IAR IDE? Shall I recompile the OpenSSL source code before adding to my program?

I really appreciate a step-by-step solution.

• user17592: "Encrypt with ... and some hashes" -- multiple hashes does not provide security and may in fact introduce weaknesses. If you only plan to do different hashes on different inputs there's no problem though.

Answer 1

Yes, you will need to recompile the library in IAR to be able to use it in your project. You can find step-by-step instructions in this answer.

I suggest to take a look at mbedTLS or Tiny SSL instead of OpenSSL, as your project will probably benefit from using a smaller library.

• pjc50: Agreed - OpenSSL is a huge legacy package which is hard to work with. Consider also nacl.cr.yp.to . If you just want 3DES (obsolete!) and SHA-2, you can get those seperately as reference implementations. Don't forget to use the correct CBC mode, IV, key scheduling and padding modes!
• User1-St: @pjc50 Can I use NACL in my ARM programs also?
• User1-St: As I want to do some Signature generation and verification I think the OpenSSL is the only option, right?
• Dmitry Grigoryev: I believe you need SHA-2 for this. It is implemented in mbedTLS as well.
• pjc50: NaCl is targetted at ARM: hyperelliptic.org/tanja/vortraege/20121129.pdf and can do signatures, although only crypto_sign_edwards25519sha512batch and not PGP-compatible signatures.