chain.rs

    /**
 Creates a SHA-256 hash of a Block
 
 - Parameter block: Block
 - returns: String
 
 */
    pub fn hash(block: &Block) -> String {
        let json = serde_json::to_string(block).unwrap();
        let readable_string = Cursor::new(&json);
        sha::calc_sha_sum(readable_string).hash_string()
    }

    /**
 Simple Proof of Work Algorithm:

 - Find a number p' such that hash(pp') contains leading 4 zeroes, where p is the previous p'
 - p is the previous proof, and p' is the new proof
 - Parameter: last_proof: u64
 - returns: u64
 */
    pub fn proof_of_work(last_proof: u64) -> u64 {
        let mut proof: u64 = 0;
        while !Chain::is_valid_proof(last_proof, proof) {
            proof += 1;
        }
        proof
    }

    /**
 Validates the Proof: Does hash(last_proof, proof) contain 4 leading zeroes?

 - Parameter last_proof: u64 Previous Proof
 - Parameter proof: u64 Current Proof
 - returns: True if correct, False if not.
 */
    pub fn is_valid_proof(last_proof: u64, proof: u64) -> bool {
        let guess = format!("{}{}", last_proof, proof);
        let readable_guess = Cursor::new(&guess);
        let guess_hash = sha::calc_sha_sum(readable_guess);
        guess_hash.hash_string().ends_with("0000")
    }