liste = ['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']
for x in range(len(liste)):    #Dédouble la liste
    liste.append(liste[x])

message = 'RTSXNJZW' #input('Entrez votre message : ')

def dechiffrage_lettre(lettre,liste,cle):

    for i in range(len(liste)):
        if lettre==' ':
            return ' '
        elif liste[i]==lettre:
            return str(liste[i-cle])

message_dechiffre = str()

cle = 0

for n in range(25):
    cle = cle + 1
    for lettre in message:
        message_dechiffre += dechiffrage_lettre(lettre,liste,cle)
    print(cle)
    print(message_dechiffre)