openresty/lua-resty-string — pull request #18 by ddragosd (2014-05-16 22:38:20+00:00)
Title: Added support for HMAC-SHA256 and other SHA* algorithms 

I've added a wrapper on top of openssl libraries to bring support in ngx lua for HMAC-SHA* algorithms.
The supported algorithms are: sha1, sha224, sha256, sha384 and sha512.