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caesar cipher.py
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import caesar_data
#logo
print(caesar_data.logo)
#===========================>> ENCRYPTION <<===========================
def encode(text, shift_amount):
encoded_text = ""
if len(text) == 0:
print("\nNothing to encode")
else:
for letter in text:
# for lower-case alphabets =========================================================================
if letter in caesar_data.lower_alphabets:
index_of_letter = caesar_data.lower_alphabets.index(letter)
result_index = index_of_letter + shift_amount
if -27 < result_index <26:
encoded_text = encoded_text + caesar_data.lower_alphabets[result_index]
elif result_index > 25:
result_index = result_index % 26
encoded_text = encoded_text + caesar_data.lower_alphabets[result_index]
else:
result_index = ((result_index * -1) % 26) * -1
encoded_text = encoded_text + caesar_data.lower_alphabets[result_index]
#for upper-case alphabets ===========================================================================
elif letter in caesar_data.upper_alphabets:
index_of_letter = caesar_data.upper_alphabets.index(letter)
result_index = index_of_letter + shift_amount
if -27 < result_index < 26:
encoded_text = encoded_text + caesar_data.upper_alphabets[result_index]
elif result_index > 25:
result_index = result_index % 26
encoded_text = encoded_text + caesar_data.upper_alphabets[result_index]
else:
result_index = ((result_index * -1) % 26) * -1
encoded_text = encoded_text + caesar_data.upper_alphabets[result_index]
#for numbers alphabets ==============================================================================
elif letter in caesar_data.numbers:
index_of_letter = caesar_data.numbers.index(letter)
result_index = index_of_letter + shift_amount
if -11 < result_index < 10:
encoded_text = encoded_text + caesar_data.numbers[result_index]
elif result_index > 9:
result_index = result_index % 10
encoded_text = encoded_text + caesar_data.numbers[result_index]
else:
result_index = ((result_index * -1) % 10) * -1
encoded_text = encoded_text + caesar_data.numbers[result_index]
#for special characters alphabets ===================================================================
elif letter in caesar_data.special_characters:
index_of_letter = caesar_data.special_characters.index(letter)
result_index = index_of_letter + shift_amount
if -32 < result_index < 31:
encoded_text = encoded_text + caesar_data.special_characters[result_index]
elif result_index > 31:
result_index = result_index % 31
encoded_text = encoded_text + caesar_data.special_characters[result_index]
else:
result_index = ((result_index * -1) % 31) * -1
encoded_text = encoded_text + caesar_data.special_characters[result_index]
#for unrecognized characters alphabets ==============================================================
else:
encoded_text = encoded_text + letter
print(f"\nEncoded text = {encoded_text}")
#===========================>> DECRYPTION <<===========================
def decode(text, shift_amount):
decoded_text = ""
if len(text) == 0:
print("\nNothing to decode")
else:
for letter in text:
# for lower-case alphabets =========================================================================
if letter in caesar_data.lower_alphabets:
index_of_letter = caesar_data.lower_alphabets.index(letter)
result_index = index_of_letter - shift_amount
if -27 < result_index <26:
decoded_text = decoded_text + caesar_data.lower_alphabets[result_index]
elif result_index > 25:
result_index = result_index % 26
decoded_text = decoded_text + caesar_data.lower_alphabets[result_index]
else:
result_index = ((result_index * -1) % 26) * -1
decoded_text = decoded_text + caesar_data.lower_alphabets[result_index]
#for upper-case alphabets ===========================================================================
elif letter in caesar_data.upper_alphabets:
index_of_letter = caesar_data.upper_alphabets.index(letter)
result_index = index_of_letter - shift_amount
if -27 < result_index < 26:
decoded_text = decoded_text + caesar_data.upper_alphabets[result_index]
elif result_index > 25:
result_index = result_index % 26
decoded_text = decoded_text + caesar_data.upper_alphabets[result_index]
else:
result_index = ((result_index * -1) % 26) * -1
decoded_text = decoded_text + caesar_data.upper_alphabets[result_index]
#for numbers alphabets ==============================================================================
elif letter in caesar_data.numbers:
index_of_letter = caesar_data.numbers.index(letter)
result_index = index_of_letter - shift_amount
if -11 < result_index < 10:
decoded_text = decoded_text + caesar_data.numbers[result_index]
elif result_index > 9:
result_index = result_index % 10
decoded_text = decoded_text + caesar_data.numbers[result_index]
else:
result_index = ((result_index * -1) % 10) * -1
decoded_text = decoded_text + caesar_data.numbers[result_index]
#for special characters alphabets ===================================================================
elif letter in caesar_data.special_characters:
index_of_letter = caesar_data.special_characters.index(letter)
result_index = index_of_letter - shift_amount
if -32 < result_index < 31:
decoded_text = decoded_text + caesar_data.special_characters[result_index]
elif result_index > 31:
result_index = result_index % 31
decoded_text = decoded_text + caesar_data.special_characters[result_index]
else:
result_index = ((result_index * -1) % 31) * -1
decoded_text = decoded_text + caesar_data.special_characters[result_index]
#for unrecognized characters alphabets ==============================================================
else:
decoded_text = decoded_text + letter
print(f"\nDecoded text = {decoded_text}")
while 1 == 1 :
function = input("\nEnter 'encode' to encrypt message\nEnter 'decode' to decrypt message\n"
"Enter anything else to exit program\nEnter Choice: \n").lower()
if function != 'encode' and function != 'decode':
print("\nProgram 'Caesar cipher' exited....!!!\n")
print(caesar_data.credit_of_project)
exit()
message = input("Enter your message: \n")
shift = int(input("Enter shift value: \n"))
if function == "encode":
encode(text= message, shift_amount=shift)
else:
decode(text= message, shift_amount=shift)