diff --git a/filters/gentoo-ldap-authentication.lua b/filters/gentoo-ldap-authentication.lua
new file mode 100644
index 0000000..fce5632
--- /dev/null
+++ b/filters/gentoo-ldap-authentication.lua
@@ -0,0 +1,320 @@
+-- This script may be used with the auth-filter. Be sure to configure it as you wish.
+--
+-- Requirements:
+-- 	luacrypto >= 0.3
+-- 	<http://mkottman.github.io/luacrypto/>
+-- 	lualdap >= 1.2
+-- 	<http://git.zx2c4.com/lualdap/about/>
+--
+
+
+--
+--
+-- Configure these variables for your settings.
+--
+--
+
+-- A list of password protected repositories, with which gentooAccess
+-- group is allowed to access each one.
+local protected_repos = {
+	glouglou = "infra",
+	portage = "dev"
+}
+
+
+-- All cookies will be authenticated based on this secret. Make it something
+-- totally random and impossible to guess. It should be large.
+local secret = "BE SURE TO CUSTOMIZE THIS STRING TO SOMETHING BIG AND RANDOM"
+
+
+
+--
+--
+-- Authentication functions follow below. Swap these out if you want different authentication semantics.
+--
+--
+
+-- Sets HTTP cookie headers based on post and sets up redirection.
+function authenticate_post()
+	local redirect = validate_value("redirect", post["redirect"])
+
+	if redirect == nil then
+		not_found()
+		return 0
+	end
+
+	redirect_to(redirect)
+	
+	local groups = gentoo_ldap_user_groups(post["username"], post["password"])
+	if groups == nil then
+		set_cookie("cgitauth", "")
+	else
+		-- One week expiration time
+		set_cookie("cgitauth", secure_value("gentoogroups", table.concat(groups, ","), os.time() + 604800))
+	end
+
+	html("\n")
+	return 0
+end
+
+
+-- Returns 1 if the cookie is valid and 0 if it is not.
+function authenticate_cookie()
+	local required_group = protected_repos[cgit["repo"]]
+	if required_group == nil then
+		-- We return as valid if the repo is not protected.
+		return 1
+	end
+	
+	local user_groups = validate_value("gentoogroups", get_cookie(http["cookie"], "cgitauth"))
+	if user_groups == nil or user_groups == "" then
+		return 0
+	end
+	for group in string.gmatch(user_groups, "[^,]+") do
+		if group == required_group then
+			return 1
+		end
+	end
+	return 0
+end
+
+-- Prints the html for the login form.
+function body()
+	html("<h2>Gentoo LDAP Authentication Required</h2>")
+	html("<form method='post' action='")
+	html_attr(cgit["login"])
+	html("'>")
+	html("<input type='hidden' name='redirect' value='")
+	html_attr(secure_value("redirect", cgit["url"], 0))
+	html("' />")
+	html("<table>")
+	html("<tr><td><label for='username'>Username:</label></td><td><input id='username' name='username' autofocus /></td></tr>")
+	html("<tr><td><label for='password'>Password:</label></td><td><input id='password' name='password' type='password' /></td></tr>")
+	html("<tr><td colspan='2'><input value='Login' type='submit' /></td></tr>")
+	html("</table></form>")
+
+	return 0
+end
+
+--
+--
+-- Gentoo LDAP support.
+--
+--
+
+local lualdap = require("lualdap")
+
+function gentoo_ldap_user_groups(username, password)
+	-- Ensure the user is alphanumeric
+	if username:match("%W") then
+		return nil
+	end
+
+	local who = "uid=" .. username .. ",ou=devs,dc=gentoo,dc=org"
+
+	local ldap, err = lualdap.open_simple {
+		uri = "ldap://ldap1.gentoo.org",
+		who = who,
+		password = password,
+		starttls = true,
+		certfile = "/var/www/uwsgi/cgit/gentoo-ldap/star.gentoo.org.crt",
+		keyfile = "/var/www/uwsgi/cgit/gentoo-ldap/star.gentoo.org.key",
+		cacertfile = "/var/www/uwsgi/cgit/gentoo-ldap/ca.pem"
+	}
+	if ldap == nil then
+		return nil
+	end
+
+	local group_suffix = ".group"
+	local group_suffix_len = group_suffix:len()
+	local groups = {}
+	for dn, attribs in ldap:search { base = who, scope = "subtree" } do
+		local access = attribs["gentooAccess"]
+		if dn == who and access ~= nil then
+			for i, v in ipairs(access) do
+				local vlen = v:len()
+				if vlen > group_suffix_len and v:sub(-group_suffix_len) == group_suffix then
+					table.insert(groups, v:sub(1, vlen - group_suffix_len))
+				end
+			end
+		end
+	end
+
+	ldap:close()
+
+	return groups
+end
+
+--
+--
+-- Wrapper around filter API, exposing the http table, the cgit table, and the post table to the above functions.
+--
+--
+
+local actions = {}
+actions["authenticate-post"] = authenticate_post
+actions["authenticate-cookie"] = authenticate_cookie
+actions["body"] = body
+
+function filter_open(...)
+	action = actions[select(1, ...)]
+
+	http = {}
+	http["cookie"] = select(2, ...)
+	http["method"] = select(3, ...)
+	http["query"] = select(4, ...)
+	http["referer"] = select(5, ...)
+	http["path"] = select(6, ...)
+	http["host"] = select(7, ...)
+	http["https"] = select(8, ...)
+
+	cgit = {}
+	cgit["repo"] = select(9, ...)
+	cgit["page"] = select(10, ...)
+	cgit["url"] = select(11, ...)
+	cgit["login"] = select(12, ...)
+
+end
+
+function filter_close()
+	return action()
+end
+
+function filter_write(str)
+	post = parse_qs(str)
+end
+
+
+--
+--
+-- Utility functions based on keplerproject/wsapi.
+--
+--
+
+function url_decode(str)
+	if not str then
+		return ""
+	end
+	str = string.gsub(str, "+", " ")
+	str = string.gsub(str, "%%(%x%x)", function(h) return string.char(tonumber(h, 16)) end)
+	str = string.gsub(str, "\r\n", "\n")
+	return str
+end
+
+function url_encode(str)
+	if not str then
+		return ""
+	end
+	str = string.gsub(str, "\n", "\r\n")
+	str = string.gsub(str, "([^%w ])", function(c) return string.format("%%%02X", string.byte(c)) end)
+	str = string.gsub(str, " ", "+")
+	return str
+end
+
+function parse_qs(qs)
+	local tab = {}
+	for key, val in string.gmatch(qs, "([^&=]+)=([^&=]*)&?") do
+		tab[url_decode(key)] = url_decode(val)
+	end
+	return tab
+end
+
+function get_cookie(cookies, name)
+	cookies = string.gsub(";" .. cookies .. ";", "%s*;%s*", ";")
+	return string.match(cookies, ";" .. name .. "=(.-);")
+end
+
+
+--
+--
+-- Cookie construction and validation helpers.
+--
+--
+
+local crypto = require("crypto")
+
+-- Returns value of cookie if cookie is valid. Otherwise returns nil.
+function validate_value(expected_field, cookie)
+	local i = 0
+	local value = ""
+	local field = ""
+	local expiration = 0
+	local salt = ""
+	local hmac = ""
+
+	if cookie == nil or cookie:len() < 3 or cookie:sub(1, 1) == "|" then
+		return nil
+	end
+
+	for component in string.gmatch(cookie, "[^|]+") do
+		if i == 0 then
+			field = component
+		elseif i == 1 then
+			value = component
+		elseif i == 2 then
+			expiration = tonumber(component)
+			if expiration == nil then
+				expiration = -1
+			end
+		elseif i == 3 then
+			salt = component
+		elseif i == 4 then
+			hmac = component
+		else
+			break
+		end
+		i = i + 1
+	end
+
+	if hmac == nil or hmac:len() == 0 then
+		return nil
+	end
+
+	-- Lua hashes strings, so these comparisons are time invariant.
+	if hmac ~= crypto.hmac.digest("sha1", field .. "|" .. value .. "|" .. tostring(expiration) .. "|" .. salt, secret) then
+		return nil
+	end
+
+	if expiration == -1 or (expiration ~= 0 and expiration <= os.time()) then
+		return nil
+	end
+
+	if url_decode(field) ~= expected_field then
+		return nil
+	end
+
+	return url_decode(value)
+end
+
+function secure_value(field, value, expiration)
+	if value == nil or value:len() <= 0 then
+		return ""
+	end
+
+	local authstr = ""
+	local salt = crypto.hex(crypto.rand.bytes(16))
+	value = url_encode(value)
+	field = url_encode(field)
+	authstr = field .. "|" .. value .. "|" .. tostring(expiration) .. "|" .. salt
+	authstr = authstr .. "|" .. crypto.hmac.digest("sha1", authstr, secret)
+	return authstr
+end
+
+function set_cookie(cookie, value)
+	html("Set-Cookie: " .. cookie .. "=" .. value .. "; HttpOnly")
+	if http["https"] == "yes" or http["https"] == "on" or http["https"] == "1" then
+		html("; secure")
+	end
+	html("\n")
+end
+
+function redirect_to(url)
+	html("Status: 302 Redirect\n")
+	html("Cache-Control: no-cache, no-store\n")
+	html("Location: " .. url .. "\n")
+end
+
+function not_found()
+	html("Status: 404 Not Found\n")
+	html("Cache-Control: no-cache, no-store\n\n")
+end