[API] ChiffreVigenere

--cle = "chiffrement"
--a = "BaseOs est 100% secure!"
--at = {a:byte(1,#a)}
--clet = {cle:byte(1,#cle)}

function chiffre(cle,text)
  local retour = ""
  local retourT = {}
  local textT = {text:byte(1,#text)}
  local cleT = {cle:byte(1,#cle)}
  local ic = 1

  for i=1,#textT do
    if ic > #cleT-1 then
      ic = 1
    else
      ic = ic+1
    end

    retourT[i] = textT[i] + cleT[ic]
    --print(textT[i].."+"..cleT[ic].."="..retourT[i])
    if retourT[i] > 255 then

      retourT[i] = retourT[i] - 255
    end
    --print(i.." "..ic)
    retour = retour..string.char(retourT[i])
  end

  return retour

end

function dechiffre(cle,text)
  local retour = ""
  local retourT = {}
  local textT = {text:byte(1,#text)}
  local cleT = {cle:byte(1,#cle)}
  local ic = 1

  for i=1,#textT do
    if ic > #cleT-1 then
      ic = 1
    else
      ic = ic+1
    end

    retourT[i] = textT[i] - cleT[ic]
   --print(textT[i].."+"..cleT[ic].."="..retourT[i])
    if retourT[i] < 0 then

      retourT[i] = retourT[i] + 255
    end
    --print(i.." "..ic)
    retour = retour..string.char(retourT[i])
  end

  return retour

end