decrypted the cyphertext, basic-decrypt is a mess
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@ -1,5 +1,13 @@
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#!/usr/bin/env python3
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"""
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This script is really bad and hacky, don't expect it to do anything.
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you also need the chiffrat.txt file in the same directory.
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License: MIT
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author: Christoph J. Scherr <software@cscherr.de>
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"""
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MAX_IN_LINE = 16
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DE_MOST_COMMON = ['E', 'N', 'I', 'R', 'A']
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EN_MOST_COMMON = ['E', 'T', 'A', 'O', 'I']
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@ -23,7 +31,7 @@ def main():
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print('=' * 80)
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print("Trying to find key from frequencies")
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print('=' * 80)
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key = find_key(freq, DE_MOST_COMMON)
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key = find_key(freq, DE_MOST_COMMON, intarr)
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if not key:
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print("The key could not be determined.")
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if key:
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@ -42,7 +50,7 @@ def freq_analysis(intarr: list):
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freql[item] += 1
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return dict(sorted(freql.items(), key=lambda item: item[1], reverse=True))
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def find_key(freq: dict, language_reference: list):
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def find_key(freq: dict, language_reference: list, full_text: list):
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# caesar
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caesar_keys = [0] * len(language_reference)
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for index, common_char in enumerate(language_reference):
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@ -61,11 +69,30 @@ def find_key(freq: dict, language_reference: list):
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print("Caesar keys ambiguos: %s" % caesar_keys)
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# was not caesar encrypted, continue with XOR checks
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# XOR
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xor_keys = [0] * len(language_reference)
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for index, common_char in enumerate(language_reference):
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# this is probably garbage
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item = list(freq.values())[index]
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xor_keys[index] = item ^ ord(common_char)
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#for xor_key in range(0, 2**7):
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# decrypt = bytes(xor_key ^ common_char for common_char in full_text)
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# try:
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# print(("decry for kex %x:\t%s" % (xor_key, decrypt.decode(errors="backslashreplace"))).replace("\n", ""))
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# except:
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# print(("decry for kex %x:\t%s" % (xor_key, decrypt.hex())).replace("\n", ""))
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# -> manual review of the output of the above confirmed that the key for my cyphertext is 0x15
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THE_KEY = 0x15
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# dump the text:
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decrypted: list = []
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for c in full_text:
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decrypted.append((c ^ THE_KEY))
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print("dump of text repr:")
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output = ""
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for c in decrypted:
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output += chr(c)
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print(output)
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print("dumping decrypted with 0x15")
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print(dump_intarr(decrypted))
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exit()
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return THE_KEY
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all_same = False
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for i in range(1, len(xor_keys)):
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@ -79,6 +106,8 @@ def find_key(freq: dict, language_reference: list):
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# ????????
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print("xor keys ambiguos: %s" % xor_keys)
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return False
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def dump_frequencies(frequencies, chars_in_text: int = -1, print_top_x = 5):
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for i in range(print_top_x):
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@ -7,6 +7,7 @@ version control at: https://git.cscherr.de/PlexSheep/python-dhbw/src/branch/mast
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License: MIT
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"""
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import math
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import argparse
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import random
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DEFINED_INITIAL = bytearray(b'\xa5\xa5\xa5\xa5\x5a\x5a\x5a\x5a\x55\x55\x55\x55\xaa\xaa\xaa\xaa')
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@ -93,8 +94,21 @@ def first_preimage():
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trash_hash(input).hex(), trash_hash(THE_HASH_ORIGIN).hex())
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def main():
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parser = argparse.ArgumentParser(prog="trash hash", description='implements a bad hash and shows how to break it. No option for preimage attack, --hash to get a hash.')
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parser.add_argument('--hash', type=str,
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help='an input that should be hashed')
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args = parser.parse_args()
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if args.hash:
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my_bytes: bytearray = bytearray(str.encode(args.hash))
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hashed = trash_hash(my_bytes)
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print("hash for \"%s\" is:\n%s" % (args.hash, hashed.hex()))
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else:
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first_preimage()
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"""
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Don't use this, too inefficient
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"""
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def bruteForce() -> bool:
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payload_a = bytearray(b"AAAA")
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foundCollision = False
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