diff --git a/unit02_symmetric/lab/possible_ans.md b/unit02_symmetric/lab/possible_ans.md index 3844ae4..8f39553 100644 --- a/unit02_symmetric/lab/possible_ans.md +++ b/unit02_symmetric/lab/possible_ans.md @@ -332,6 +332,65 @@ print(" decrypt: ",plaintext.decode()) A sample is [here](https://replit.com/@billbuchanan/desdec#main.py). +If you want to pass as arguments: + +```Python +from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes +from cryptography.hazmat.primitives import padding +from cryptography.hazmat.backends import default_backend +import sys +import hashlib +import binascii + +val='hello' +password='hello' + +plaintext=val + +def encrypt(plaintext,key, mode): + method=algorithms.TripleDES(key) + cipher = Cipher(method,mode, default_backend()) + encryptor = cipher.encryptor() + ct = encryptor.update(plaintext) + encryptor.finalize() + return(ct) + +def decrypt(ciphertext,key, mode): + method=algorithms.TripleDES(key) + cipher = Cipher(method, mode, default_backend()) + decryptor = cipher.decryptor() + pl = decryptor.update(ciphertext) + decryptor.finalize() + return(pl) + +def pad(data,size=64): + padder = padding.PKCS7(size).padder() + padded_data = padder.update(data) + padded_data += padder.finalize() + return(padded_data) + +def unpad(data,size=64): + padder = padding.PKCS7(size).unpadder() + unpadded_data = padder.update(data) + unpadded_data += padder.finalize() + return(unpadded_data) + + + +if (len(sys.argv)>1): + digest=str(sys.argv[1]) +if (len(sys.argv)>2): + password=str(sys.argv[2]) + + +key = hashlib.sha256(password.encode()).digest()[:16] + +ciphertext=binascii.unhexlify(digest) + +plaintext = decrypt(ciphertext,key,modes.ECB()) + +plaintext = unpad(plaintext) +print(" decrypt: ",plaintext.decode()) +``` + ### E.3 In this case we will convert from Base-64 into a byte array and then try to decrypt: