Cipher for LuaBank (meant for ComputerCraft)

function string:split( inSplitPattern, outResults )
  if not outResults then
    outResults = { }
  end
  local theStart = 1
  local theSplitStart, theSplitEnd = string.find( self, inSplitPattern, theStart )
  while theSplitStart do
    table.insert( outResults, string.sub( self, theStart, theSplitStart-1 ) )
    theStart = theSplitEnd + 1
    theSplitStart, theSplitEnd = string.find( self, inSplitPattern, theStart )
  end
  table.insert( outResults, string.sub( self, theStart ) )
  return outResults
end

Crypto = {}

function Crypto.DEC_HEXX(IN)
    local B,K,OUT,I,D=16,"0123456789ABCDEF","",0
    while IN>0 do
        I=I+1
        IN,D=math.floor(IN/B),math.mod(IN,B)+1
        OUT=string.sub(K,D,D)..OUT
    end
    return OUT
end

function Crypto.BYTE_HEX(Bytes)
    local HexBytes = {}
    for k,v in ipairs(Bytes) do
        HexBytes[k] = Crypto.DEC_HEXX(v)
    end
    return table.concat(HexBytes,'-')
end

function Crypto.HEX_BYTE(HexString)
    local Bytes = {}
    local SplitHex = HexString:split("-")
    for k,v in pairs(SplitHex) do
        Bytes[k] = tonumber("0x" .. v)
    end
    return Bytes
end

function Crypto.Xor(x, y) --Made by Arno Wagner <arno@wagner.name>
   local z = 0
   for i = 0, 31 do
      if (x % 2 == 0) then                      -- x had a '0' in bit i
         if ( y % 2 == 1) then                  -- y had a '1' in bit i
            y = y - 1
            z = z + 2 ^ i                       -- set bit i of z to '1'
         end
      else                                      -- x had a '1' in bit i
         x = x - 1
         if (y % 2 == 0) then                  -- y had a '0' in bit i
            z = z + 2 ^ i                       -- set bit i of z to '1'
         else
            y = y - 1
         end
      end
      y = y / 2
      x = x / 2
   end
   return z
end

function Crypto.Compare(t)
local key, min = 1, t[1]
for k, v in ipairs(t) do
    if t[k] < min then
        key, min = k, v
    end
end
    return key
end

function Crypto.BytesToString(bytes) --Made by Philippe Lhoste
  local s = ""
  for i = 1, table.getn(bytes) do
    s = s .. string.char(bytes[i])
  end
  return s
end

function Crypto.StringToBytes(string)
    local bytes = {}
    for i = 1, string.len(string) do
    bytes[i] = string.byte(string,i)
    end
    return bytes
end

function Crypto.Encrypt(string,key,airbag)
    local msg = {}
    msg.Bytes = {}
    msg.Bytes = Crypto.StringToBytes(string)
    local keyBytes = Crypto.StringToBytes(key)
    for i in ipairs(msg.Bytes) do
        msg.Bytes[i] = Crypto.Xor(msg.Bytes[i],keyBytes[(i-1) % table.maxn(keyBytes)+1])
    end
    local key2 = Crypto.Compare(msg.Bytes)
    if airbag == true then
        msg.Airbag = msg.Bytes[key2] - 1
    else
        msg.Airbag = 0
    end
    for i in ipairs(msg.Bytes) do
        msg.Bytes[i] = msg.Bytes[i] - msg.Airbag
    end
    msg.Hex = Crypto.BYTE_HEX(msg.Bytes)
    return msg
end

function Crypto.Decrypt(string,key,airbag)
    local Bytes = {}
    Bytes = Crypto.HEX_BYTE(string)
    local keyBytes = Crypto.StringToBytes(key)
    for i in ipairs(Bytes) do
        Bytes[i] = Crypto.Xor(Bytes[i] + airbag,keyBytes[(i-1) % table.maxn(keyBytes)+1])
    end
    return Bytes
end

Test = {}
function Test.FullTest(string,key,airbag)
    print("Original string: " .. string)
    print("Encryption key: " .. key .. "\n")
    local msg = {}
    msg = Crypto.Encrypt(string,key,airbag)
    print("Encrypted String: " .. msg.Hex)
    print("Encryption Airbag: " .. msg.Airbag .. "\n")
    local decrypted = Crypto.BytesToString(Crypto.Decrypt(msg.Hex,key,msg.Airbag))
    print("Decrypted string: " .. decrypted .. "\n")
end
function Test.Decrypt(string,key,airbag)
    print(Crypto.BytesToString(Crypto.Decrypt(string,key,airbag)))
end
function Test.HexTest(string)
    local hex = Crypto.BYTE_HEX(Crypto.StringToBytes(string))
    print("Encrypted: " .. hex)
    local dec = Crypto.BytesToString(Crypto.HEX_BYTE(hex))
    print("Decrypted: " .. dec)
end