Use PKCS5_PBKDF2_HMAC_SHA1 from widthin Lua to decrypt aes128 with several roundtrips

gistfile1.lua

functions = {}

aes = require("resty.aes")
local ffi = require "ffi"

ffi.cdef[[
int PKCS5_PBKDF2_HMAC_SHA1(const char *pass, int passlen,
			   const unsigned char *salt, int saltlen, int iter,
			   int keylen, unsigned char *out);
]]

local kCCKeySizeAES128 = 16
local kRoundTrips = 5000

function functions.decrypt_aes(password, salt, iv, payload)
   -- Generate the Key
   local buf = ffi.new("unsigned char[?]", 16)
   ffi.C.PKCS5_PBKDF2_HMAC_SHA1(password, #password, salt, #salt, kRoundTrips, kCCKeySizeAES128, buf)
   local key = ffi.string(buf, ffi.sizeof(buf))

   -- Decrypt the data
   local cipher = aes.cipher(128, nil)
   local data, err = aes.new(nil, key, nil, cipher, {iv = iv,}, nil)
   if err ~= nil then
      return nil, err
   end
   return aes.decrypt(data, payload)
end


return functions