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Author: photon149

Cryptography/Caesar_Cipher.py

@@ -0,0 +1,50 @@
+from random import choice
+
+def decrypt(encrypted_string,key_val):
+    '''This is the decryption function
+    It takes in input encrypted string and key value
+    Prints nothing and return the decrypted string value'''
+    final = '"'
+    encrypted_string = encrypted_string.upper()
+    for i in range(len(encrypted_string)):
+        decrypt_char = ord(encrypted_string[i]) + key_val
+        if (decrypt_char > 90):
+            decrypt_char = 65 - ( 90 - decrypt_char)
+        decrypt_char = chr(decrypt_char)
+        final += decrypt_char
+    return final
+
+
+def encrypt(input_string,key_val):
+    '''This is the encryption function
+    It takes in input string and key value.
+    Prints nothing and return the Encrypted string value'''
+    final = ""
+    input_string = input_string.upper()
+    for i in range(len(input_string)):
+        encrypt_char = ord(input_string[i]) + key_val
+        if (encrypt_char > 90):
+            encrypt_char = 65 - ( 90 - encrypt_char)
+        encrypt_char = chr(encrypt_char)
+        final += encrypt_char
+    final = ''.join(choice((str.upper, str.lower))(char) for char in final)
+    return final
+
+#DRIVER CODE
+
+#This is the code for menu , chosing whether to encrypt or decrypt
+choose =int(input('CHOOSE FROM THE FOLLOWING : \n 1. Encrypt String \n 2. Decrypt String \n')) 
+
+#This is the code for encryption choice , it calls the function and prints the  encrypted value
+if (choose == 1):
+    input_string = input('Enter the input text ')
+    key_val = int(input('Enter the key value '))
+    print('Encrypted string is : ' + encrypt(input_string,key_val))
+    
+#This is the code for decryption choice , it calls the function and prints the decrypted value
+if (choose == 2):
+    encrypted_string = input('Enter the encrypted text ')
+    key_val = int(input('Enter the key value '))
+    print('Decrypted string is : ' + decrypt(encrypted_string,key_val))
+
+