diff --git a/functions.lua b/functions.lua
index d72b9ed..7572dc5 100644
--- a/functions.lua
+++ b/functions.lua
@@ -1,65 +1,14 @@
 
--- https://stackoverflow.com/a/25594410
-local function bitxor(a,b)
-    local p,c=1,0
-    while a>0 and b>0 do
-        local ra,rb=a%2,b%2
-        if ra~=rb then c=c+p end
-        a,b,p=(a-ra)/2,(b-rb)/2,p*2
-    end
-    if a<b then a=b end
-    while a>0 do
-        local ra=a%2
-        if ra>0 then c=c+p end
-        a,p=(a-ra)/2,p*2
-    end
-    return c
-end
-
-local function bitor(a,b)
-    local p,c=1,0
-    while a+b>0 do
-        local ra,rb=a%2,b%2
-        if ra+rb>0 then c=c+p end
-        a,b,p=(a-ra)/2,(b-rb)/2,p*2
-    end
-    return c
-end
-
--- https://stackoverflow.com/a/32387452
-local function bitand(a, b)
-	local result = 0
-	local bitval = 1
-	while a > 0 and b > 0 do
-	  if a % 2 == 1 and b % 2 == 1 then -- test the rightmost bits
-		  result = result + bitval      -- set the current bit
-	  end
-	  bitval = bitval * 2 -- shift left
-	  a = math.floor(a/2) -- shift right
-	  b = math.floor(b/2)
-	end
-	return result
-end
-
--- https://gist.github.com/mebens/938502
-local function rshift(x, by)
-	return math.floor(x / 2 ^ by)
-end
-
-local function lshift(x, by)
-    return x * 2 ^ by
-end
-
 -- big-endian uint64 of a number
 function fediauth.write_uint64_be(v)
-	local b1 = bitand( rshift(v, 56), 0xFF )
-	local b2 = bitand( rshift(v, 48), 0xFF )
-	local b3 = bitand( rshift(v, 40), 0xFF )
-	local b4 = bitand( rshift(v, 32), 0xFF )
-	local b5 = bitand( rshift(v, 24), 0xFF )
-	local b6 = bitand( rshift(v, 16), 0xFF )
-	local b7 = bitand( rshift(v, 8), 0xFF )
-	local b8 = bitand( rshift(v, 0), 0xFF )
+	local b1 = bit.band( bit.rshift(v, 56), 0xFF )
+	local b2 = bit.band( bit.rshift(v, 48), 0xFF )
+	local b3 = bit.band( bit.rshift(v, 40), 0xFF )
+	local b4 = bit.band( bit.rshift(v, 32), 0xFF )
+	local b5 = bit.band( bit.rshift(v, 24), 0xFF )
+	local b6 = bit.band( bit.rshift(v, 16), 0xFF )
+	local b7 = bit.band( bit.rshift(v, 8), 0xFF )
+	local b8 = bit.band( bit.rshift(v, 0), 0xFF )
 	return string.char(b1, b2, b3, b4, b5, b6, b7, b8)
 end
 
@@ -76,13 +25,13 @@ end
 function fediauth.hmac(key, message)
     local i_key_pad = ""
     for i=1,64 do
-        i_key_pad = i_key_pad .. string.char(bitxor(string.byte(key, i) or 0x00, string.byte(i_pad, i)))
+        i_key_pad = i_key_pad .. string.char(bit.bxor(string.byte(key, i) or 0x00, string.byte(i_pad, i)))
     end
     assert(#i_key_pad == 64)
 
     local o_key_pad = ""
     for i=1,64 do
-        o_key_pad = o_key_pad .. string.char(bitxor(string.byte(key, i) or 0x00, string.byte(o_pad, i)))
+        o_key_pad = o_key_pad .. string.char(bit.bxor(string.byte(key, i) or 0x00, string.byte(o_pad, i)))
     end
     assert(#o_key_pad == 64)
 
@@ -129,12 +78,12 @@ function fediauth.generate_tfediauth(secret_b32, unix_time)
     local hmac = fediauth.hmac(key, counter)
 
     -- https://www.rfc-editor.org/rfc/rfc4226#section-5.4
-    local offset = bitand(string.byte(hmac, #hmac), 0xF)
+    local offset = bit.band(string.byte(hmac, #hmac), 0xF)
     local value = 0
-    value = bitor(value, string.byte(hmac, offset+4))
-    value = bitor(value, lshift(string.byte(hmac, offset+3), 8))
-    value = bitor(value, lshift(string.byte(hmac, offset+2), 16))
-    value = bitor(value, lshift(bitand(string.byte(hmac, offset+1), 0x7F), 24))
+    value = bit.bxor(value, string.byte(hmac, offset+4))
+    value = bit.bxor(value, bit.lshift(string.byte(hmac, offset+3), 8))
+    value = bit.bxor(value, bit.lshift(string.byte(hmac, offset+2), 16))
+    value = bit.bxor(value, bit.lshift(bit.band(string.byte(hmac, offset+1), 0x7F), 24))
     local code = value % 10^6
     local padded_code = left_pad("" .. code, "0", 6)