mit-ocw

commit 94f085ab4564420e321b1fe2b0ac8a372660dcc5
parent 4f86d57e7ba1e18f2a2bb9191e431bbb6793a724
Author: Andrew Laack <andrew@laack.co>
Date:   Mon, 18 May 2026 14:54:46 -0500

Simple implementation of zero prefix matching pow

Diffstat:
A
mas.s62-cryptocurrency-engineering-and-design/simple-pow/go.mod
 | 
3
+++
A
mas.s62-cryptocurrency-engineering-and-design/simple-pow/main.go
 | 
76
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

2 files changed, 79 insertions(+), 0 deletions(-)
diff --git a/mas.s62-cryptocurrency-engineering-and-design/simple-pow/go.mod b/mas.s62-cryptocurrency-engineering-and-design/simple-pow/go.mod
@@ -0,0 +1,3 @@
+module pow
+
+go 1.26.3
diff --git a/mas.s62-cryptocurrency-engineering-and-design/simple-pow/main.go b/mas.s62-cryptocurrency-engineering-and-design/simple-pow/main.go
@@ -0,0 +1,76 @@
+package main
+
+import (
+	"crypto/rand"
+	"crypto/sha256"
+	"encoding/hex"
+	"flag"
+	"fmt"
+	"sync"
+)
+
+var done = false
+var final = ""
+
+func hashPrefixMatches(message string, prefix string) bool {
+
+	result := sha256.Sum256([]byte(message + "\n")) // echo adds this by default
+	resString := hex.EncodeToString(result[:])
+
+	for idx, _ := range prefix {
+		if prefix[idx] != resString[idx]{
+			return false
+		}
+	}
+
+	return true
+}
+
+func worker(message string, prefix string, wg *sync.WaitGroup) {
+
+	defer wg.Done()
+
+	for done == false {
+		text := message + rand.Text()
+
+		if hashPrefixMatches(text, prefix) {
+			fmt.Println("Good: " + text)
+			done = true
+			final = text
+			return
+		} else {
+			continue
+		}
+	}
+}
+
+
+func main() {
+
+	zeroesPtr := flag.Int("zeroes", 5, "Number of zeroes prefixed on sha256sum")
+
+	flag.Parse()
+
+	if len(flag.Args()) > 1 {
+		panic("Unexpected number of arguments")
+	}
+
+	message := flag.Args()[0] + " - "
+	zeroes := *zeroesPtr
+
+	prefix := ""
+
+	for i := 0 ; i < zeroes ; i++ {
+		prefix += "0"
+	}
+	
+	wg := sync.WaitGroup{}
+
+	for i := 0; i < 200; i++ {
+		wg.Add(1)
+		go worker(message, prefix, &wg)
+	}
+	wg.Wait()
+
+
+}