Merge: Introduced xoring of String and a sequence of Bytes

Signed-off-by: Philippe Pepos Petitclerc <ppeposp@gmail.com>

Pull-Request: #1814
Reviewed-by: Alexis Laferrière <alexis.laf@xymus.net>
Reviewed-by: Lucas Bajolet <r4pass@hotmail.com>
Reviewed-by: Jean Privat <jean@pryen.org>

diff --git a/lib/crypto.nit b/lib/crypto.nit
index 011347d..357eb99 100644 (file)
--- a/lib/crypto.nit
+++ b/lib/crypto.nit
@@ -42,7 +42,7 @@ redef class Char
        end
 end
 
-redef class String
+redef class Text
        # Performs a Rotation of `x` on each letter of self
        #
        # Works by replacing every character in `self` by its
@@ -65,7 +65,7 @@ redef class String
        #
        # NOTE : Works on letters only
        # NOTE : This cipher is symmetrically decrypted with an `x` of 26-`x`
-       fun rot(x: Int): String do
+       fun rot(x: Int): Text do
                var rot = x % 26
                if rot < 0 then rot += 26
                var d = new FlatBuffer.with_capacity(length)
@@ -93,7 +93,7 @@ redef class String
        # Therefore, yielding the ciphertext : "fgounbmtcieehkh"
        #
        #     assert "fuckingbehemoth".railfence(4) == "fgounbmtcieehkh"
-       fun railfence(depth: Int): String do
+       fun railfence(depth: Int): Text do
                var lines = new Array[FlatBuffer].with_capacity(depth)
                var up = false
                for i in [0..depth[ do
@@ -127,10 +127,10 @@ redef class String
                return r.to_s
        end
 
-       # Transforms a rail-fence-encrypted String to its original
+       # Transforms a rail-fence-encrypted Text to its original
        #
        #     assert "fgounbmtcieehkh".unrail(4) == "fuckingbehemoth"
-       fun unrail(depth: Int): String do
+       fun unrail(depth: Int): Text do
                var dots = "." * length
                var arr = new FlatBuffer.from(dots)
                var start = 0
@@ -154,6 +154,33 @@ redef class String
                end
                return arr.to_s
        end
+
+       # Returns `self` xored with `key`
+       #
+       # The shortest of the two is cycled through until the longest has been
+       # completely xored.
+       #
+       #     assert "goodmorning".xor(" ".to_bytes) == "GOODMORNING"
+       fun xor(key: SequenceRead[Byte]): Text do
+               var xored = new Bytes.with_capacity(bytelen.max(key.length))
+
+               var shortest: SequenceRead[Byte]
+               var longest: SequenceRead[Byte]
+
+               if key.length > self.length then
+                       shortest = self.to_bytes
+                       longest = key
+               else
+                       shortest = key
+                       longest = self.to_bytes
+               end
+
+               for i in longest.length.times do
+                       xored.add(longest[i] ^ shortest[i % shortest.length])
+               end
+
+               return xored.to_s
+       end
 end
 
 redef class Int
@@ -188,7 +215,7 @@ redef class Int
        #
        # In the end, our string is read using the generated array
        #
-       # SEE: `String::unrail` for how the array is used
+       # SEE: `Text::unrail` for how the array is used
        private fun unrail_paces: Array[Couple[Int, Int]] do
                var ret = new Array[Couple[Int,Int]].with_capacity(self)
                var extremes = new Couple[Int, Int]((self - 1) * 2, (self - 1) * 2)