caeser_encrypt.py

A_ORD = ord('a')
E_ORD = ord('e')
Z_ORD = ord('z')

def count_char(text):
    res = {}
    for c in text.lower():
        if ord(c) not in range(A_ORD, Z_ORD+1):
            continue
        if c in res:
            res[c] += 1
        else:
            res[c] = 1
    return res

def encrypt_text(text, offset):
    res = []
    for c in text.lower():
        if ord(c) not in range(A_ORD, Z_ORD+1):
            res += c
        else:
            res += chr(A_ORD + (ord(c) - A_ORD + offset) % (Z_ORD - A_ORD))
    return "".join(res)

def decrypt_text(secret, count=0):
    char_table = count_char(secret.lower())
    key_char, key_count = sorted(char_table.items(), key=lambda x: x[1], reverse=True)[count]
    return encrypt_text(secret, -1 * (ord(key_char) - E_ORD))

text = """
Sorry but I already now those threats. Its more about those specifice sentences I mentioned before. I know that usally for questions which are not affimative any is used, but why is there some used
"""

secret = encrypt_text(text, 20)
for i in range(5):
    print decrypt_text(secret, i)

print("Cracking a Caesar cypher.")
print()
print()

text= input("Input cipherText: ")
A_ORD = ord('a') #the alphbeta range a--z
E_ORD = ord('e')#the most used letter in English
Z_ORD = ord('z')

def get_char(text): #get the most used letters
res = {}
for c in text.lower(): #using the lower letter to find
if ord(c) not in range(A_ORD, Z_ORD+1):#keep the space
continue
if c in res: #the most used letter
res[c] += 1
else:
res[c] = 1
return res

def encrypt_text(text, offset): #this function get the shift
res = []
for c in text.lower():
if ord(c) not in range(A_ORD, Z_ORD+1):
res += c
else:
res += chr(A_ORD + (ord(c) - A_ORD + offset) % (Z_ORD - A_ORD))
return "".join(res)

def output_plaintext(secret, count=0):# this function get the decrypte text
char_table = get_char(secret.lower()) #using the most used letter in plaintext
key_char, key_count = sorted(char_table.items(),
key=lambda x: x[1], reverse=True)[count]
return encrypt_text(secret, -1 * (ord(key_char) - E_ORD))
#try to get the decrypte letter

secret = encrypt_text(text, 20)

def main(): #the main function

 #run the project



for i in range(len(get_char(secret))):
    print(output_plaintext(secret, i).upper())
    result=input("Is the plaintext readable as English? (yes/no):")
#Judgement the if the plaintext readable
    if result.lower() == "yes":
       break
    else:
       i+= 1

if name == "main":
main()