Yes that is correct that library won’t work because it is for the AVR. I’d recommend you to try the module HMAC included in Python 2.7 in the Linux side of Galileo. Take a look at these documents from the Python website on how to use it https://docs.python.org/2/library/hashlib.html https://docs.python.org/2/library/hmac.html . Let me know if it worked.
I'd say that would depend on what programming language you want to use.
For example, Galileo, being a normal Linux computer in this sense, has libgcrypt library, which has subroutines for HMAC calculation as far as I can see by googling. But then it probably only has bindings to C/C++ and not Pythin, at least out of the box. It also has OpenSSL, which has a lot of stuff as well. And so on - so start with the language and I think it'll be easier to narrow down the library you could use.
Thank you for your replies. However, I need to use the non-Linux side of the Intel Galileo, i.e., I shouldn't have to use Linux to achieve this. The idea is to have an equivalent solution on Arduino, which cannot have Linux. Could you please suggest any cryptography libraries available on out-of-the-box Galileo. I know best Python, however, I don't think I will be able to use it to achieve my goal.
Well, here goes the power of Galileo The sketch you write in the Arduino IDE is actually a normal Linux program and in addition to being able to use the Arduino API, objects and libraries, you can use the normal Linux functions as well. Just include necessary headers like "stdio.h" and so on and you are good to go. You'll most probably need to install the respective -dev package though, but this is true for any language I think - for Python you'll probably need to install modules and the same goes for Node.js - languages and runtimes available out of the box.
But if you want to have a sort of "cross-platform" (Arduino and Galileo) code, as your reply suggests, then the only way is to either re-implement everything yourself (which is ought to be complex with crypto) or to look for libraries someone has already (maybe) wrote. I don't know of any personally, so if that's indeed the case, let's see if someone else has anything to say. I assume you did the standard googling around for that.
Well, depending on the specific library you end up using, you may not need SD card to run your program. Galileo has a mini Linux image installed into the SPI flash, this is what is boots if no SD card is inserted. So if you pick the one installed into the image by default, then you will only need the SD card for development (with -dev packages) and for just running it the out-of-the-box image should be fine.
lenych, apologies for late reply.
This routine calculates the authorization code encrypted with HMAC to be authorized by twitter to post a tweet (using OAuth protocol authentication).
Original work comes from Markku Rossi firstname.lastname@example.org; I had to tune a bit the code to compile on galileo.
The important steps are marked with ************; forget about the rest.
Here you go:
Twitter::compute_authorization(const char *message)
char *cp = buffer;
/* Compute key and init HMAC. */
cp = url_encode_pgm(buffer, consumer_secret);
*cp++ = '&';
cp = url_encode_pgm(cp, token_secret.pgm);
cp = url_encode_eeprom(cp, token_secret.eeprom);
Sha1.initHmac((uint8_t *) buffer, cp - buffer); // ************
cp = hex_encode(buffer, nonce, sizeof(nonce));
auth_add_param(PSTR("oauth_nonce"), buffer, cp + 1);
auth_add_param(PSTR("oauth_signature_method"), "HMAC-SHA1", buffer);
sprintf(buffer, "%ld", timestamp);
auth_add_param(PSTR("oauth_timestamp"), buffer, cp + 1);
auth_add_param(PSTR("oauth_version"), "1.0", buffer);
cp = url_encode(buffer, message);
auth_add_param(PSTR("status"), buffer, cp + 1);
signature = Sha1.resultHmac(); // ************