rsa padding done
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GPG Key ID:
25B4ACF7D88186CC
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@ -6,7 +6,7 @@ Since this (auth) hash did not have a name before, I gave it the name 'authur1'
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@author: Christoph J. Scherr <software@cscherr.de>
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@license: MIT
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@source: https://git.cscherr.de/PlexSheep/plexcryptool/src/branch/master/plexcryptool/authur1.py
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@source: https://git.cscherr.de/PlexSheep/plexcryptool/
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"""
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import argparse
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import random
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@ -5,7 +5,7 @@ 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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@source: https://git.cscherr.de/PlexSheep/plexcryptool/src/branch/master/plexcryptool/basic-decrypt.py
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@source: https://git.cscherr.de/PlexSheep/plexcryptool/
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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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@ -7,6 +7,7 @@ Common tools that may be used by many
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"""
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from math import floor
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from typing import Literal
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def byte_xor(ba0: bytearray, ba1: bytearray) -> bytearray:
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"""
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@ -27,3 +28,19 @@ def calc_byte_len(n: int) -> int:
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return 1 + floor(len)
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else:
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return floor(len)
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def int_to_bytearray(n: int, size: int|None = None, endianness = 'big') -> bytearray:
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"""
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convert an integer to a bytearray
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you can specify a size if you want, if the number is too big an Exception will be raised.
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size is in bytes
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"""
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brepr: bytes = n.to_bytes(calc_byte_len(n), endianness)
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ba: bytearray = bytearray(brepr)
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if size is not None and len(ba) > size:
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raise Exception("Number is larger than requested")
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while size is not None and size > len(ba):
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ba: bytearray = bytearray(1) + ba
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return ba
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@ -4,8 +4,7 @@ A small script to help analyze the md5 hash function.
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@author: Christoph J. Scherr <software@cscherr.de>
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@license: MIT
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@source: https://git.cscherr.de/PlexSheep/plexcryptool/src/branch/master/plexcryptool/md5-analyzer.py
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TODO do I need to implement md5 by myself for the assignment?
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@source: https://git.cscherr.de/PlexSheep/plexcryptool/
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"""
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import argparse
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import hashlib
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@ -1 +0,0 @@
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0976f89569d94414fed4f7714cd85c840dbf338781926f5d1f6284688c97eaeef7f42b3d844c70468cfb960092235855da5d5c66107dfee4204c1a78512ee00306da957a856a085affe40b2ab32fc90a8c8e059feea9a83e753618aeae04884aa1658afe59a69c30ec5c014a5da06ff484143ca1ea884b44a3f92d063db8503f
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@ -4,7 +4,7 @@ Perform RSA-OAEP
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@author: Christoph J. Scherr <software@cscherr.de>
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@license: MIT
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@source: https://git.cscherr.de/PlexSheep/plexcryptool/src/branch/master/plexcryptool/trash-hash.py
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@source: https://git.cscherr.de/PlexSheep/plexcryptool/
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"""
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import argparse
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@ -0,0 +1,104 @@
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"""
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Rsa padding script for croptology lectures
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@author: Christoph J. Scherr <software@cscherr.de>
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@license: MIT
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@source: https://git.cscherr.de/PlexSheep/plexcryptool/
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"""
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import argparse
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import plexcryptool
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import common
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# predefined constants
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P = 2**206 - 5
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Q = 2**226 -5
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N = P*Q
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D = 0xaffe0815
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CIPHERTEXTS: list[int] = [
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0x78766a52455329b486aaa414c3a029834a7e4b6ed87019dce4056f4d8999b137404d9ec4df28da201c9b0bc142deb1d86ff94d83becc,
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0x670b865216dfd0aacd5f7fa8802e704fa82f3fb9c7dbe3eb5a9ec308a1a2288648b15d5cc8ba2f54b245a972aea977932c9c84cf6422,
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0x61d5f2a4298bff3d6ebcd78830fb9181d97235623819eb7c60b92dcdf836a6cf731c60187e72f471c05d1c6eab216c3f6032af3c5370,
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0x3651009d02a0c72b9bc206c57d12277594d9eaad28bb3de5d661670b42f1cfafe688b9674e34d4ad79db898205417086e7e1877b9ef1,
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0x96e51d4675c6be5b14ec0cf2a9e9a9610a99d632723b3f1fcfc6b36806f5d74045f47622817cc35f6ffe9afe29f0aa236cbe12371651,
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]
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def padding_check(cihpertext: int, private_key: tuple[int, int], verbose: bool = False) -> bool:
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"""
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Check the padding of a given cihpertext
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"""
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decrypted: int = pow(cihpertext, private_key[0], private_key[1])
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# the ciphertexts seem to all be 54B long, so I have just hardcoded that
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cleartext: bytearray = common.int_to_bytearray(decrypted, 54)
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if verbose:
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print(f"original:\t{cihpertext:054x}")
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print(f"decrypted:\t{cleartext.hex()}")
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index: int = 0
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padding_active: bool = False
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for b in cleartext:
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if index == 0 and b != 0:
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# the first byte has to be 0x00
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if verbose:
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print(f"error:\t\tThe first byte is not 00: {b:02x}")
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return False
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elif index == 1:
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# the second byte is the padding type, we only accept 01 and 02 type padding
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if b == 1:
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padding_active = True
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pad_type = b
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if verbose:
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print(f"type:\t\t01 deterministic padding")
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elif b == 2:
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padding_active = True
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pad_type = b
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if verbose:
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print(f"type:\t\t02 nondeterministic padding")
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else:
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if verbose:
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print(f"error:\t\tThe second byte is not 01 or 02 (block type): {b:02x}")
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return False
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elif padding_active:
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if b == 0:
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# padding has ended
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padding_active = False
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continue
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if pad_type == 1 and b != 0xff:
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if verbose:
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print(f"error:\t\tPadding of type 01 contains non ff byte: {b:02x}")
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return False
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elif pad_type == 2:
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if b == 0:
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# must be random non 00
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if verbose:
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print(f"error:\t\tPadding of type 02 contains 00 byte: {b:02x}")
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return False
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index += 1
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if padding_active:
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if verbose:
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print(f"error:\t\tPadding has not been ended with 00 byte")
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return True
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def main():
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parser = argparse.ArgumentParser(prog="rsa-padding", description='validates a rsa padding')
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parser.add_argument('-v', '--verbose', action="store_true",
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help='append some auth hashed stuff')
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args = parser.parse_args()
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results: list[bool] = []
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for c in CIPHERTEXTS:
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b = padding_check(c, (D, N), args.verbose)
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print(f"Passed:\t\t{b}")
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plexcryptool.cplex.printing.seperator()
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if __name__ == "__main__":
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main()
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@ -4,7 +4,7 @@ Dirty hash we covered in an excercise for Week 16 of 2023 in cryptography
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@author: Christoph J. Scherr <software@cscherr.de>
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@license: MIT
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@source: https://git.cscherr.de/PlexSheep/plexcryptool/src/branch/master/plexcryptool/trash-hash.py
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@source: https://git.cscherr.de/PlexSheep/plexcryptool/
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"""
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import math
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import argparse
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