Description

▪ Follow the instructions very carefully. Answers that do not conform to the instructions will not be given credit.
▪ Submit your solutions through Blackboard as individual separate files, and not as zip archive.
▪ Understand thoroughly all the code given to you in this lab. Search for documentation online if there is a primitive or API you have not encountered before.
▪ Use Java 8.
▪ Only use the external Java libraries provided to you in the lab, if any.
▪ The term “mainnet” refers to the actual Bitcoin blockchain network. The term “testnet” is an alternative to mainnet to be used for testing. Testnet coins are separate and distinct from actual bitcoins, and are never supposed to have any value. This allows application developers or bitcoin testers to experiment, without having to use real bitcoins or worrying about breaking the main bitcoin chain. You can obtain testnet coins for free from the faucet at https://testnet.coinfaucet.eu/en/. It is courteous to send the testnet coins back to the faucet after you are done experimenting with them.

1. Read:
a. Bitcoin addresses:
i. https://en.bitcoin.it/wiki/Address
ii. https://en.bitcoin.it/wiki/Technical_background_of_version_1_Bitcoin_addresses
iii. https://en.bitcoin.it/wiki/List_of_address_prefixes
b. Base58 encoding: https://en.bitcoin.it/wiki/Base58Check_encoding
c. Bitcoin address reuse and privacy: https://en.bitcoin.it/wiki/Address_reuse
d. Testnet: https://en.bitcoin.it/wiki/Testnet
e. BitcoinJ
i. https://bitcoinj.github.io/#getting-started
ii. https://bitcoinj.github.io/working-with-transactions iii. https://bitcoinj.github.io/working-with-the-wallet
2. Set the hw5.WalletInit.WALLETS_DIR constant to a directory that stores all the wallets.
3. Read and thoroughly understand hw5.WalletInit.
6. Run the hw5.WalletInitTest class again to update your wallet’s blockchain and confirm that it contains the amount given to you in question 3.
7. Use BitcoinJ to write a custom Bitcoin address generator for mainnet. Place your implementation in the method CustomAddressGenerator.get(String). This method has one parameter which is a string called prefix encoded in base58. The method returns a bitcoin address on mainnet that begins with 1 followed by prefix. Submit your CustomAddressGenerator class.
8. Use the CustomAddressGenerator.get(String) method to generate a mainnet address that begins with 1 followed by the first four letters of your last name in uppercase. If your last name is shorter than four letters, append as many “X” characters as necessary. If the first four letters of your last name in uppercase includes a letter not allowed in a Bitcoin address, then use “X” instead of the letter. Submit your custom bitcoin address as your solution to question 8 in a text file called homework5solutions.txt.