test

uncrackable/decryptAESCBC.py

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+import sys
+import os
+import getpass
+
+from Crypto.Cipher import AES
+# from Crypto.Random import get_random_bytes, random
+# from Crypto.Util import Padding
+from Crypto.Hash import MD5, SHA256
+
+
+# generates key based on password
+def generatekey():
+    password = getpass.getpass('Password for decryption: ')
+
+    h = MD5.new()
+    h.update(''.join(password))
+
+    return h.digest()
+
+
+# calculates and return hash for message
+def calculatehash(message):
+    h = SHA256.new()
+    h.update(message)
+    # use hexdigest to prevent problems with control characters
+    # e.g. \r in charcter 5, appends 4, then overwrites beginning of message with rest of digest
+    return h.hexdigest()
+
+
+# check integrity and return cleartext or error message
+def checkintegrity(decryptedcontent):
+    return calculatehash(decryptedcontent[0:-64]) == decryptedcontent[-64:]
+
+
+# encrypts content in AES CBC mode
+def decrypt_AES_CBC(inputfilename, encryptedContent):
+    # create encrypted filename, keep extension
+    outputfilename = inputfilename[0:inputfilename.find('.', len(inputfilename) - 5)] + '_decrypted' + inputfilename[
+                                                                                                       inputfilename.find(
+                                                                                                           '.'):len(
+                                                                                                           inputfilename)]
+
+    key = generatekey()
+    decipher = AES.new(key, AES.MODE_CBC)
+    decryptedcontent = decipher.decrypt(encryptedContent)
+
+    ivlength = 16
+    # remove iv and padding
+    decryptedcontent = decryptedcontent[ivlength:-ord(decryptedcontent[-1])]
+
+    # check Integrity and retain cleartext
+    if checkintegrity(decryptedcontent):
+        cleartext = decryptedcontent[0:-64]
+    else:
+        cleartext = 'Integrity check error'
+
+    # useful only for decrypted text files
+    # print(cleartext)
+
+    # write to file
+    outputfile = open(outputfilename, 'wb')
+    outputfile.write(cleartext)
+    outputfile.close()
+
+
+for i in sys.argv[1:]:
+
+    inputfilename = i
+
+    try:
+        inputfile = open(inputfilename, 'rb')
+    except IOError:
+        print("File " + inputfilename + " not found, working directory: " + os.getcwd())
+        continue
+    else:
+        # if file opened, read content into variable
+        content = inputfile.read()
+        inputfile.close()
+
+    # apply symmetric encryption
+    decrypt_AES_CBC(inputfilename, content)
+    # encrypt_AES_ECB(inputfilename,content)

uncrackable/hash34.txt

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+084b8b05fae51beed25806aacf738fea

uncrackable/uitleg.txt

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+Gegeven is een md5 hash. Het is moeilijk te onthouden, maar het paswoord dat bij de hash hoort, is random gegenereerd op basis van de karakters in python<6F>s string.printable. Het paswoord is 10 karakters lang en is bruikbaar om met het meegeleverde script het eveneens meegeleverde png bestand te decrypteren.
+Dit script is hetzelfde script als wat bruikbaar was in de AES-CBC opgave.
+Om het script uit te voeren is python 2.7 met de pycryptodome library nodig (zoals in de installatie op de labo pc<70>s). De vlag staat in de gedecrypteerde afbeelding.