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2021-csci-ga3205-midterm
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add decryption func

This commit is contained in:
Vicky Rampin 2021-10-24 14:26:19 -04:00
parent 56740c97f8
commit bc4d05361c
1 changed files with 13 additions and 5 deletions
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18
index.py
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@ -7,6 +7,11 @@ def caesar(ptextletter, keyletter):
return chr((ptextNum + keyletterNum) % 26 + ord('A')) return chr((ptextNum + keyletterNum) % 26 + ord('A'))
def caesar_reverse(ptextletter, keyletter):
ptextNum = ord(ptextletter) - ord('A')
keyletterNum = ord(keyletter) - ord('A')
return chr((ptextNum - keyletterNum) % 26 + ord('A'))
def encryption(plaintext, key): def encryption(plaintext, key):
ciphertext = '' ciphertext = ''
for i in range(len(plaintext)): for i in range(len(plaintext)):
@ -15,21 +20,24 @@ def encryption(plaintext, key):
def decryption(ciphertext, key): def decryption(ciphertext, key):
return ciphertext plaintext = ''
for i in range(len(ciphertext)):
plaintext += caesar_reverse(ciphertext[i], key[i % len(key)])
return plaintext
def main(): def main():
# parse command line argument # parse command line argument
parser = argparse.ArgumentParser() parser = argparse.ArgumentParser()
parser.add_argument('--ptext', type=str) parser.add_argument('--text', type=str)
parser.add_argument('--key', type=str) parser.add_argument('--key', type=str)
args = parser.parse_args() args = parser.parse_args()
key = args.key key = args.key
ciphertext = encryption(args.ptext, key) user_text = args.text
print("Ciphertext: " + ciphertext) print("Ciphertext: " + encryption(user_text, key))
print("Decrypted plaintext: " + decryption(ciphertext, key)) print("Decrypted plaintext: " + decryption(user_text, key))
if __name__ == '__main__': if __name__ == '__main__':