一个基于 web 服务器的 PoW 案例（一）

go get github.com/davecgh/go-spew/spew

go get github.com/gorilla/mux

go get github.com/joho/godotenv

const difficulty = 4​type Block struct {    Index int    Timestamp string    BMP int    HashCode string    PreHash string    Diff int    Nonce int}​var Blockchain []Blocktype Message struct {    BlockPostMessage int}var mutex = &sync.Mutex{}

func generateBlock(oldBlock Block, BlockPostMessage int) Block {    var newBlock Block    newBlock.PreHash = oldBlock.HashCode        newBlock.Index = oldBlock.Index + 1        t := time.Now()    newBlock.Timestamp = t.String()        newBlock.BlockPostMessage = BlockPostMessage        newBlock.Diff = difficulty​    for i := 0; ; i++ {        newBlock.Nonce++        hash := calculateHash(newBlock)        fmt.Println(hash)                if isHashValid(hash, newBlock.Diff) {            fmt.Println("挖矿成功")            newBlock.HashCode = hash            return newBlock        }    }}

func calculateHash(block Block) string {    hashed := strconv.Itoa(block.Index) + block.Timestamp +        strconv.Itoa(block.Nonce) + strconv.Itoa(block.BlockPostMessage) +        block.PreHash    sha := sha256.New()    sha.Write([]byte(hashed))    hash := sha.Sum(nil)    return hex.EncodeToString(hash)}