Shift Cipher

#Shift cipher from keys 0 to 25
#Decipher program => http://pastebin.com/SaU5edKQ
#Display all possible deciphers => http://pastebin.com/Zn32AcxA
import random
print "CIPHER PROGRAM"
message=raw_input('Enter the message to be ciphered:')
message=message.lower()
key=raw_input('Enter a number:')
key=int(key)
flag=0
if key>26:
    key=int(key)%26
elif key==0:
    key=random.randrange(1,26)
    flag=1
num_equivalent={
' ':-int(key),'a':1,'b':2,'c':3,'d':4,'e':5,'f':6,'g':7,'h':8,'i':9,'j':10,'k':11,'l':12,'m':13,'n':14,'o':15,'p':16,'q':17,'r':18,'s':19,'t':20,'u':21,'v':22,'w':23,'x':24,'y':25,'z':26,
}
alpha_equivalent={
0:' ',1:'a',2:'b',3:'c',4:'d',5:'e',6:'f',7:'g',8:'h',9:'i',10:'j',11:'k',12:'l',13:'m',14:'n',15:'o',16:'p',17:'q',18:'r',19:'s',20:'t',21:'u',22:'v',23:'w',24:'x',25:'y',26:'z',
}
print "Ciphered message:"
for letter in message:
    x=num_equivalent[letter]+key
    if x>26:
        x=x%26
    y=alpha_equivalent[x]
    print y.upper(),
if flag==1:
    print "Your secret key is %s"%(key)
raw_input()