Implement `groupBytes`

tp/rsa/main.hs

@@ -30,3 +30,12 @@ subunpad (-1) ys (s:[]) = subunpad (s - 1) ys []
 subunpad (-1) ys (x:xs) = subunpad (-1) (x:ys) xs
 subunpad 0 ys _ = ys
 subunpad s (y:ys) _ = subunpad (s - 1) ys []
+
+groupBytes::Message -> Int
+groupBytes = subgroupBytes 1 0
+
+-- First arg : pow > Contains 256^n where n is the number of recursive calls
+-- Second arg : acc > contains the result of the block
+subgroupBytes::Int -> Int -> Message -> Int
+subgroupBytes _ acc [] = acc
+subgroupBytes pow acc (c:msg) = subgroupBytes (pow * 256) (acc + c * pow) msg