【Rust】getnewaddressのAPI機能を作る

### コマンドライン引数の書き方

fn main() {

   let command_name = std::env::args().nth(0).unwrap_or("CLI".to_string());
   let name = std::env::args().nth(1).unwrap_or("World".to_string());

   println!("Hello {} via {}!", name, command_name);
}

$ cargo run
Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.04s
Running `target/debug/ruscal`
Hello World via target/debug/ruscal!

### 上記を応用する

fn main() {
   let args = App::parse();
   match args.command {
    Command::Getnewaddress => getnewaddress(),
   }
}

fn getnewaddress() {
  address::get_address();
}

use p256::{
    ecdsa::{SigningKey},
    pkcs8::EncodePrivateKey, PublicKey,SecretKey};
use rand_core::{OsRng};
use std::{fs::File, io::Write, path::Path};
use ripemd::{Ripemd160};
use sha2::{Digest, Sha256};

pub fn get_address() {
    init_secret();
    let contents = std::fs::read_to_string("./config/tmp.pem")
        .expect("something went wrong reading the file");
    let secret_pem = contents.trim();

    let secret_key = secret_pem.parse::<SecretKey>().unwrap();
    let _private_key_serialized = hex::encode(&secret_key.to_bytes());

    let public_key = secret_key.public_key();
    let _public_key_serialized = hex::encode(&public_key.to_sec1_bytes());
    let address = create_address(&public_key);  
    println!("{}", address);
}

pub fn init_secret() {
    let path = Path::new("./config/tmp.pem");
    if path.is_file() {
        // println!("The private key, public key, and address have already been created.");
    } else {
        let secret_key = SigningKey::random(&mut OsRng);
        let secret_key_serialized = secret_key
            .to_pkcs8_pem(Default::default())
            .unwrap()
            .to_string();
        let mut file = File::create("./config/tmp.pem").expect("file not found.");
        writeln!(file, "{}", secret_key_serialized).expect("can not write.");
        println!("created a private key.");
    }
}

pub fn create_address(public_key: &PublicKey) -> String {

    let vk = public_key.to_sec1_bytes();
    let mut hasher = Sha256::new();
    hasher.update(vk);
    let hashed_sha256 = hasher.finalize();

    let mut hasher = Ripemd160::new();
    hasher.update(hashed_sha256);
    let account_id = hasher.finalize();

    let mut payload = account_id.to_vec();
    payload.insert(0, 0x00);

    let mut hasher = Sha256::new();
    hasher.update(&payload);
    let hash = hasher.finalize();

    let mut hasher = Sha256::new();
    hasher.update(hash);
    let checksum = hasher.finalize();

    payload.append(&mut checksum[0..4].to_vec());

    const ALPHABET: &str = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";
    let address = base_x::encode(ALPHABET, &payload);

    return address;
}

$ cargo run getnewaddress
Compiling ruscal v0.1.0 (/home/vagrant/dev/rust/api)
Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.92s
Running `target/debug/ruscal getnewaddress`
1BnpTXdSbSgMZwWYq7cdU3LPSw1g4YhyHZ