Python script to create and spend a time-locked bitcoin script address.

Assignment for COMP-541 February 2019.

send_to_p2sh_timelock.py creates a P2SH address containing a timelock script. All funds sent to the address will be locked for 200 blocks. Run it with: python3 send_to_p2sh_timelock.py [private key] where [private key] is the private key for the P2PKH part of the redeem script. It should be in quotes.

spend_p2sh_timelock.py spends funds from the time-locked address. Run it with: python3 spend_p2sh_timelock.py [private key] [receiver address] where [private key] is the same private key as was used in the first script, and [receiver address] is a P2PKH address to send the funds to. Both should be in quotes.

Peter Todd's bitcoin library is used extensively, make sure it's installed. (https://github.com/petertodd/python-bitcoinlib)

Assignment description:

Using the programming language of your choice implement two programs/scripts. The first one will create an address where all funds sent to it should be locked for N time after its creation; other than the time locking the redeem script should be equivalent to P2PKH. The second program will allow someone to spent funds from this address. Both programs should:

• use testnet
• assume a local Bitcoin testnet node is running The first program should:
• accept a public (or optionally a private) key for the P2PKH part of the redeem script
• accept a future time period expressed either in block height or in UNIX Epoch time
• display the P2SH address The second program should:
• accept a future time period and a private key (to recreate the redeem script as above and also use to unlock the P2PKH part)
• accept a P2SH address to get the funds from
• accept a P2PKH address to sent the funds to
• calculate the appropriate fees
• sent all funds of the local wallet from the P2SH address to the P2PKH address provided
• display the transaction id Notes:
• there is some repetition between the 2 programs; this is fine
• you will submit a single compressed file (ZIP or TGZ) that contains the source code and the executables, if any (e.g. for static languages). It should include a text file with detailed instructions on how to run your programs.
• If an executable is submitted it should be compiled for x86_64 on linux. Unfortunately, I cannot check executables on Windows or Mac so make sure you use an interpreted language if you work on any of these.
• the source code is your main submission and it should contain everything you want to share with me. It should include detailed comments and everything else you think I should be aware of.
• you are expected to manually construct the Bitcoin locking/unlocking script for the timelock transactions. If the programming libraries you are using have functionality to automatically create timelock transactions do not use them (it will be penalized).
• do not use CHECKLOCKTIMEVERIFY