caesar cypher decryption python code example

Example 1: 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 2: 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)