A minimal openSSL engine for offloading sha256 functions to a hardware accelerator in FPGA logic

1. You are running linux on the Xilinx ZYNQ-7000 development board, with the necessary design instantiated in PL [link to final design goes here]
2. Ensure you have openSSL using the command $ openssl version. If you have lower than version 1.0.2, you must upgrade to this version.
3. Check out the repository using git $ git clone https://github.com/bigbrett/wssha256engine.git
4. You must have the wssha256kern kernel module loaded (source to come...)

$ cd wssha256engine
$ make

You can verify that the engine can be loaded using:

$ openssl engine -t -c `pwd`/bin/libwssha256engine.so
(/home/brett/wssha256engine/bin/libwssha256engine.so) A test engine for the ws sha256 hardware encryption module, on the Xilinx ZYNQ7000
Loaded: (wssha256engine) A test engine for the ws sha256 hardware encryption module, on the Xilinx ZYNQ7000
    [ available ]

A quick and easy test goes like this, where the resultant digest values should be identical:

$ teststr="OpenSSL has poor documentation!"

$ echo -n $teststr | openssl dgst -engine /full/path/to/libwssha256engine.so -sha256
  (stdin)= b6264baa6804978da052f91344621c81fe7653847012481ddb5567376dec2839

$ echo -n $teststr | openssl dgst -sha256
  (stdin)= b6264baa6804978da052f91344621c81fe7653847012481ddb5567376dec2839

A more advanced test, using a c test program, can be conducted like this (see test/wssha256engine_test.c for implementation):

$ make test
$ source test/runtest.sh

NOTE: the runtest.sh script must remain in the test directory, but should be able to be called from anywhere

The speed of the engine's digest computation can be tested using the built-in openSSL speed command (making sure to explicitly specify using the EVP API for the message digest)

$ openssl speed -evp sha256 -engine /path/to/libwssha256engine.so