cantora / avr-crypto-lib Goto Github PK

I am trying to use the hmac sha256 in an Arduino project, but I have an issue, where if there are zeros in the hash value, the first zero gets omitted, resulting in a hash length of only 63 bytes. Otherwise the values correspond with online calculators. Has anyone encountered this issue? Any solutions?

Not sure if this makes a difference, but I am including the header with
extern "C"{ #include "hmac-sha256.h" };
because I am compiling with the Arduino IDE (C++).

edit. so for example if I try to hash "hello" with the key "key" I get
937B3B915EFB5171FF14D8CB55FBCC798C6C0EF1456D66DED1A6AA723A58B7B
instead of
9307b3b915efb5171ff14d8cb55fbcc798c6c0ef1456d66ded1a6aa723a58b7b

Hello.

I am using the library in a somewhat unconventional way. Note that I have not tried compiling with the stock Makefile utils that come bundled with the library. Basically I only need a few of the crypto methods, so I am extracting these couple of directories into my source, and compiling them with my project's own standalone Makefile.

This seems to work well, with the exception of a caveat I just ran into trying to compile this way: In the des/des.*{c,h} files, there is a discrepancy in a few of the functions with the way the key buffers are typed: sometimes it's void *key, others it's uint8_t *key. This caused avr-gcc to issue me an error, so I thought to pass it on to the developers.

Overall, the library seems to be very neatly coded and minimal enough that other crypto overhead can be built on top of it. Thanks.

Just tried the BIG_ENDIAN option in sha256.c (though I'm not sure why anyone would use it... it's there...), and suggest the following modifications:

line 197: *((uint64_t *)&(lb[56])) = state->length;
line 213: if ((void *) dest != (void *) &(state->h))

Hi!
Nice to see that AES-256 is working on AVR also. I want to implement AES-256 CBC technique for my application. So does it contain that implementation?
Can you please provide an example of these?