CSCI301 Assignment 2 Solution

General Instructions: Please read the following instructions carefully.

Implementing Pay-to-Multi-Signature (P2MS)

In this assignment, your task is to implement programs creating/executing P2MS script using the Pycryptodome package.

The requirements for the programs are as follows:
1. Use Python 3.5 or above and Pycryptodome package.
2. To simulate 2-of-4 P2MS script, the program (randomly) is needed to generate 4 pairs of DSA 2048 bits public keys/private keys under the same public parameters (g, p, q). a) The public keys are written in the scriptPubKey (i.e., scriptPubKey.txt) in the following format:

OP_2 [PubKey1] [PubKey2] … [PubKey4] OP_4 OP_CHECKMULTISIG

b) The program generates 2 DSA signatures using the private keys generated. The text – “Contemporary topic in security” is signed in each signature and they must be signed by the different private keys. The signature is stored in the scriptSig (i.e., scriptSig.txt) in the following format:

OP_1 [Sig1] [Sig2]

3. You need to implement a separate program to execute a P2MS script by taking scriptPubKey and scriptSig from the above task. In particular, the program 1) takes scriptPubKey and scriptSig from files 2) constructs a script and 3) executes the script. You must implement this in a separate program if you want. Show how the script is executed in your program by printing out the stack information for each processing step.

Additional information:
1) The scriptPubKey and scriptSig must be properly formatted and all values written in them must be represented as hexadecimal numbers.
2) It should be noted that the program is using DSA 2048 bits as a signature algorithm.
3) It should be noted that the message signed in the signatures is fixed as “Contemporary topic in security”.
4) scriptPubKey and scriptSig must be properly formatted as described above.
5) For the detail on how P2MS script is processed, please check the following websites:
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CSCI301 Contemporary Topics in Security
This material is copyrighted. It must not be distributed without permission from Jongkil Kim

- https://learnmeabitcoin.com/technical/p2ms
- https://wiki.bitcoinsv.io/index.php/Bitcoin_Transactions


Submission
Write a program (or programs) that satisfies the above requirements. Make a folder named
Assignment2 and include
• A creating/executing program for a P2MS script, which satisfies the above
requirements. [80 marks]
• Three different pairs of scriptSig and scriptPubKey which are generated by your program. [10 marks]
• A report that explains 1) all necessary information to run your programs (e.g., additional python packages for your code) expected outcomes (with screenshots) for
the program(s). [10 marks]


Use the Subject Moodle site to upload your assignment. Compress the Assignment2 folder using a zip program to create yourStudentID_Assignment2.zip.
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