CS188 and CSCE580 reversed submission_autograder.py

CS188 Intro to AI is a course provided for free by UC Berkeley for use by other institutions. It is also in use at the University of South Carolina as CSCE580.

This project provides a useful discussion of client-side verification. It is very important to verify scores by rechecking the work that students submit. If the score in the reinforcement.token is trusted implicitly then it would be trivial to write a version of that token that erroneously states a higher than received score. Later in this document is a discussion of RSA keys. This is because it was found that the public key included in this project was laughably small.

Getting Started

These instructions will get you a copy of the program up and running on your local machine. See "Installing" for notes on what is required to run this on a live system.

Installing

Clone and cd into the directory

$ git clone https://github.com/brokencodebank/Berkeley-CS188-UofSC-CSCE580.git
$ cd Berkeley-CS188-UofSC-CSCE580

The only weird package required is a python3 specific fork of a package called primefac

$ pip3 install git+git://github.com/elliptic-shiho/primefac-fork@master

Then you simply need to run the program

$ python3 submission_autograder_encryption_reversed.py 
-------------------------------------------------------------------------------

CS 188 Local Submission Autograder Tool
-------------------------------------------------------------------------------

usage: submission_autograder_encryption_reversed.py [-h] [--encrypt]
                                                    [--decrypt] [--modify]
                                                    [--genkeys] [--size SIZE]
                                                    [--crackkey]
                                                    [--printcsce580key] [-n N]
                                                    [-p P] [-q Q] [-e E]
                                                    [-d D]

optional arguments:
  -h, --help         show this help message and exit
  --encrypt          Encrypts a reinforcement.plaintext.token
  --decrypt          Decrypts a reinforcement.token
  --modify           Modifies a reinforcement.plaintext.token
  --genkeys          Generates private and public keys for encryption
  --size SIZE        The size of the keys to generate
  --crackkey         Attempts to factor and then recover a private key from a
                     public key
  --printcsce580key  Prints the public key that was found in the csce580
                     reinforcement assignment
  -n N               n component of public and private key
  -p P               p component of the private key
  -q Q               q component of the private key
  -e E               e component of public key
  -d D               d component of private key

Notes on Key Strength

The key found within the obfuscated CSCE 580 submission_autograder.py was found to be very short and weak. It can be retrieved as shown below:

$ python3 submission_autograder_encryption_reversed.py --printcsce580key
-------------------------------------------------------------------------------

CS 188 Local Submission Autograder Tool
-------------------------------------------------------------------------------

Key found in obfuscated file: -e 33751518165820762234153612797743228623 -n 56285023496349038954935919614579038707

If you want to crack it you can easily do this with --crackkey as shown:

$ python3 submission_autograder_encryption_reversed.py --crackkey -e 33751518165820762234153612797743228623 -n 56285023496349038954935919614579038707
-------------------------------------------------------------------------------

CS 188 Local Submission Autograder Tool
-------------------------------------------------------------------------------

 Crack key: -e 33751518165820762234153612797743228623 -n 56285023496349038954935919614579038707

Cracking Public_Key....................................................... DONE

 Private Key found: -d 36786304852261144029274009415324198959 -p 6480256949166153253 -q 8685616008419467319

If you are a professor or TA for another class based on these tools then you should use a much stronger key! I provide a function for generating a significantly better key that can be included in the program without much problem. Run it with --genkeys. By default it will create a 2048 bit key which is much better for this task.

DO NOT USE THESE KEYS THIS IS JUST AN EXAMPLE

$ python3 submission_autograder_encryption_reversed.py --genkeys
-------------------------------------------------------------------------------

CS 188 Local Submission Autograder Tool
-------------------------------------------------------------------------------

Generating keys of size: 2048............................................. DONE

 Generated Keys:

 Private_Key: -d 11777646818189557037170692783343828249185976674860675697981225511684329356541181199734717744444158582229447050353437374461486405115990871123706633377607282799600489937709780267821366570195552502876432588302917697820261235869984154331218196971163331837044162399831352588399476621874040511577017871194591135882133762248033463060845129267539669890432067788799031660590676376111495066817152857080418934368933974868772556474304272392320365130025697444044249989973643491791152570647551618869351701686993496375750734693129150978979342893401076699043783896599665846313187026230222236896009991980598883235022974683723366542337 -p 175568442352164289159475769601710579547542445668006085101325859263705909706392432173679228993696911871934104929504878632055288858414838527527941536861378543309713980904708144472504215711537616476808097424517030055062388514580781400424390811787581727576542317775399277199999068910735531181535059361691647254017 -q 151815133976452480267888387325105576320262952289485352490626775123627553504622670359910575663563522373683986190495179598765911916863026972367882125815118028984210128370352250692598452496982012468190610162516068370348683275524651244847111028850246311808303339614120068575187227169182139662026219308306547917623
 Public_Key: -e 65537 -n 26653946597730895388136872576470336405500927288246973418232521024871573363708670613177740834201347456872518779619918685385629149213947087980743866558522341684361245521174276370461994575465517606996538642204783216341947602307094565503126730028631212355549683041463702288958061375315411202293691778876339627484266759122769069430728073325294071434338968997340140629212214302995332779278412001407149516723865838816727143009101170139916810759272275990255574054364837796836096353569704217321969358130840592099029437224921325495039484207827949431943433372508828438909253894485070806096806754121718458528692004587577471841591

License

This project is licensed under the MIT License - see the LICENSE file for details