auth: lua string comparisons are time invariant

By default, strings are compared by hash, so we can remove this comment.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/filters/simple-authentication.lua b/filters/simple-authentication.lua
index 5935d08..5c4f074 100644
--- a/filters/simple-authentication.lua
+++ b/filters/simple-authentication.lua
@@ -45,7 +45,7 @@ function authenticate_post()
 
         redirect_to(redirect)
 
-        -- TODO: Implement time invariant string comparison function to mitigate timing attack.
+        -- Lua hashes strings, so these comparisons are time invariant.
         if password == nil or password ~= post["password"] then
                 set_cookie("cgitauth", "")
         else
@@ -222,7 +222,7 @@ function validate_value(cookie)
                 return nil
         end
 
-        -- TODO: implement time invariant comparison to prevent against timing attack.
+        -- Lua hashes strings, so these comparisons are time invariant.
         if hmac ~= crypto.hmac.digest("sha1", value .. "|" .. tostring(expiration) .. "|" .. salt, secret) then
                 return nil
         end