These exercises require a synced mainnet full node with the transaction index active (-txindex=1). Chaincode Labs can provide credentials to a hosted node with an authenticated proxy so students can complete the exercises using bitcoin-cli locally but without needing to sync a full node themselves. To use the proxy you must have bitcoin-cli installed. It is part of the package you can download from bitcoincore.org. These packages obviously include the Bitcoin Core daemon as well, but you do not need to run it or sync a mainnet node yourself for this exercise.

Students will be emailed unique username / password pairs.

Usage example:

$ bitcoin-cli -rpcconnect=35.209.148.157 -rpcuser=a_plus_student -rpcpassword=hunter2 getblockcount
823280

or you can add these lines to your bitcoin.conf file:

rpcconnect=35.209.148.157
rpcuser=a_plus_student
rpcpassword=hunter2

...and then execute bitcoin-cli getblockcount without extra options.

HINT: Use bitcoin-cli help and bitcoin-cli help <command name> to learn what commands are available and what they do.

Every question must be answered by providing a bash script that executes bitcoin-cli commands. No other commands should be necessary besides bash operators (for loops, if/else logic, etc) and jq, which is a JSON parsing command you may need to manually install on your system.

Each student will get a private fork of this repository when they join the GitHub Classroom assignment. You will commit and push your submissions to GitHub which will evaluate the answers automatically. You can commit and push as often as you like and GitHub will re-evaluate your code every time.

There are empty template files for each script in the submission directory in this repository. You MUST write your scripts into these files for the autograder to work properly. Do NOT rename the script files!

Answer as many as you can. Some are easy, some are very hard!

001.sh: What is the hash of block 654,321?

002.sh: (true / false) Verify the signature by this address over this message:

• address: 1E9YwDtYf9R29ekNAfbV7MvB4LNv7v3fGa
• message: 1E9YwDtYf9R29ekNAfbV7MvB4LNv7v3fGa
• signature: HCsBcgB+Wcm8kOGMH8IpNeg0H4gjCrlqwDf/GlSXphZGBYxm0QkKEPhh9DTJRp2IDNUhVr0FhP9qCqo2W0recNM=

003.sh: How many new outputs were created by block 123,456?

004.sh: Using descriptors, compute the taproot address at index 100 derived from this extended public key:

• xpub6Cx5tvq6nACSLJdra1A6WjqTo1SgeUZRFqsX5ysEtVBMwhCCRa4kfgFqaT2o1kwL3esB1PsYr3CUdfRZYfLHJunNWUABKftK2NjHUtzDms2

005.sh: Create a 1-of-4 P2SH multisig address from the public keys in the four inputs of this tx:

• 37d966a263350fe747f1c606b159987545844a493dd38d84b070027a895c4517

006.sh: Which tx in block 257,343 spends the coinbase output of block 256,128?

007.sh: Only one single output remains unspent from block 123,321. What address was it sent to?

008.sh: Which public key signed input 0 in this tx:

• e5969add849689854ac7f28e45628b89f7454b83e9699e551ce14b6f90c86163

How many transactions are confirmed in block 666,666?

Using local full node (or with proxy settings in bitcoin.conf):

hash=$(bitcoin-cli getblockhash 666666)
block=$(bitcoin-cli getblock $hash)
echo $block | jq .nTx

Answer: 2728