caesar cipher encryption and decryption program in python code example

Example 1: python automatic caesar cipher decrypt

x = input()
NUM_LETTERS = 26
def SpyCoder(S, N):
   y = ""
   for i in S:
      if(i.isupper()):
         x = ord(i)
         x += N
         if x > ord('Z'):
            x -= NUM_LETTERS
         elif x < ord('A'):
            x += NUM_LETTERS
         y += chr(x)
      else:
         y += " "
   return y

def GoodnessFinder(S):
   y = 0
   for i in S:
      if i.isupper():
         x = ord(i)
         x -= ord('A')
         y += letterGoodness[x]
      else:
         y += 1
   return y

def GoodnessComparer(S):
   goodnesstocompare = GoodnessFinder(S)
   goodness = 0
   v = ''
   best_v = S
   for i in range(0, 26):
     v = SpyCoder(S, i)
     goodness = GoodnessFinder(v)
     if goodness > goodnesstocompare:
         best_v = v
         goodnesstocompare = goodness
   return best_v


print(GoodnessComparer(x))

Example 2: python caesar cipher

def caesar_encrypt():
    word = input('Enter the plain text: ')
    c = ''
    for i in word:
        if (i == ' '):
            c += ' '
        else:
            c += (chr(ord(i) + 3))
    return c

def caesar_decrypt():
    word = input('Enter the cipher text: ')
    c = ''
    for i in word:
        if (i == ' '):
            c += ' '
        else:
            c += (chr(ord(i) - 3))
    return c
  
plain = 'hello'
cipher = caesar_encrypt(plain)
decipher = caesar_decrypt(cipher)

Example 3: python caesar cipher

plaintext = input("Please enter your plaintext: ")
shift = input("Please enter your key: ")
alphabet = "abcdefghijklmnopqrstuvwxyz"
ciphertext = ""

# shift value can only be an integer
while isinstance(int(shift), int) == False:
  # asking the user to reenter the shift value
  shift = input("Please enter your key (integers only!): ")

shift = int(shift)
  
new_ind = 0 # this value will be changed later
for i in plaintext:
  if i.lower() in alphabet:
    new_ind = alphabet.index(i) + shift
    ciphertext += alphabet[new_ind % 26]
  else:
    ciphertext += i    
print("The ciphertext is: " + ciphertext)

Example 4: caesar cipher python

def cc_encrypt(msg: str,key: int) -> str:
    encrypted_msg = ''

    try:
        for char in msg:
            encrypted_msg += str(chr(ord(char)+int(key)))
    except:
        print(Exception)
        pass
    
    return encrypted_msg

def cc_decrypt(msg: str,key: int) -> str:
    decrypted_msg = ''

    try:
        for char in msg:
            decrypted_msg += chr(ord(char)-int(key))
    except:
        print(Exception)
        pass

    return decrypted_msg

  
message = 'Hello World!'
key = 9
print(f'Caesar Cipher:\nEncrypted: {cc_encrypt(message,key)}\nDecrypted: {cc_decrypt(cc_encrypt(message,key),key)}')

Example 5: caesar cipher in python

def encrypt(text,s):
result = ""
   # transverse the plain text
   for i in range(len(text)):
      char = text[i]
      # Encrypt uppercase characters in plain text
      
      if (char.isupper()):
         result += chr((ord(char) + s-65) % 26 + 65)
      # Encrypt lowercase characters in plain text
      else:
         result += chr((ord(char) + s - 97) % 26 + 97)
      return result
#check the above function
text = "CEASER CIPHER DEMO"
s = 4

print "Plain Text : " + text
print "Shift pattern : " + str(s)
print "Cipher: " + encrypt(text,s)