email-gravatar-hover.lua

local crypto = require("crypto")

function filter_open(email, page)
        buffer = ""
        hexdigest = crypto.digest("md5", email:sub(2, -2):lower())
end

function filter_close()
        html("<span class='gravatar'><img class='inline' src='//www.gravatar.com/avatar/" .. hexdigest .. "?s=13&amp;d=retro' /><img class='onhover' src='//www.gravatar.com/avatar/" .. hexdigest .. "?s=128&amp;d=retro' /></span>" .. buffer)
        return 0
end

function filter_write(str)
        buffer = buffer .. str
end

gistfile1.txt

local openssl = require("openssl")
local digest = require("openssl.digest")
local function tohex(b)
	local x = ""
	for i = 1, #b do
		x = x .. string.format("%.2x", string.byte(b, i))
	end
	return x
end

local function hexdigest(algo, input)
  local hash = algo
  local data = digest.new(hash)
  local digest_output = data:final(input)
  return tohex(digest_output)
end

function filter_open(email, page)
        buffer = ""
        hexdigest = crypto.digest("md5", email:sub(2, -2):lower())
		hexdigest = hexdigest('md5', email:sub(2, -2):lower())
end

function filter_close()
        html("<span class='gravatar'><img class='inline' src='//www.gravatar.com/avatar/" .. hexdigest .. "?s=13&amp;d=retro' /><img class='onhover' src='//www.gravatar.com/avatar/" .. hexdigest .. "?s=128&amp;d=retro' /></span>" .. buffer)
        return 0
end

function filter_write(str)
        buffer = buffer .. str
end