Data update

Task/Bifid-cipher/Lua/bifid-cipher.lua

@@ -0,0 +1,73 @@
+function transcipher (cipher, message, decipher)
+    local message = message:gsub("%s+", ""):upper()
+    local xStr, yStr, s, char = "", "", ""
+    for pos = 1, #message do
+        char = message:sub(pos, pos)
+        for x = 1, #cipher do
+            for y = 1, #cipher[x] do
+                if cipher[x][y] == char then
+                    s = s .. x .. y
+                    xStr = xStr .. x
+                    yStr = yStr .. y
+                end
+            end
+        end
+    end
+    if decipher then
+        xStr, yStr = s:sub(1, #s/2), s:sub(#s/2 + 1, #s)
+    else
+        s = xStr .. yStr
+    end
+    local result, x, y = ""
+    local limit = decipher and #s/2 or #s
+    local step = decipher and 1 or 2
+    for pos = 1, limit, step do
+        x = tonumber(s:sub(pos, pos))
+        y = decipher and
+            tonumber(s:sub(pos + #s/2, pos + #s/2)) or
+            tonumber(s:sub(pos + 1, pos + 1))
+        result = result .. cipher[x][y]
+    end
+    return result
+end
+
+local RCbifid = {
+    {"A", "B", "C", "D", "E"},
+    {"F", "G", "H", "I", "K"},
+    {"L", "M", "N", "O", "P"},
+    {"Q", "R", "S", "T", "U"},
+    {"V", "W", "X", "Y", "Z"}
+}
+
+local wikibifid = {
+    {"B", "G", "W", "K", "Z"},
+    {"Q", "P", "N", "D", "S"},
+    {"I", "O", "A", "X", "E"},
+    {"F", "C", "L", "U", "M"},
+    {"T", "H", "Y", "V", "R"}
+}
+
+local mybifid = {
+    {"A", "B", "C", "D", "E", "F"},
+    {"G", "H", "I", "J", "K", "L"},
+    {"M", "N", "O", "P", "Q", "R"},
+    {"S", "T", "U", "V", "W", "X"},
+    {"Y", "Z", "1", "2", "3", "4"},
+    {"5", "6", "7", "8", "9", "0"}
+}
+
+local testCases = {
+    {RCbifid, "ATTACKATDAWN"},
+    {wikibifid, "FLEEATONCE"},
+    {wikibifid, "ATTACKATDAWN",},
+    {mybifid, "The invasion will start on the first of January"}
+}
+
+local msg
+for task, case in pairs(testCases) do
+    print("\nTask " .. task)
+    msg = transcipher(case[1], case[2])
+    print("Encoded message: " .. msg)
+    msg = transcipher(case[1], msg, true)
+    print("Decoded message: " .. msg)
+end