Week3

hash-puzzle/hashing-puzzle.go

@@ -0,0 +1,102 @@
+package main
+
+import (
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+	"math/rand"
+	"sort"
+	"time"
+)
+
+func main() {
+
+	trialset := []int{}
+	numtrials := 100
+	for i := 0; i < numtrials; i++ {
+		trialset = append(trialset, hashTrial())
+	}
+
+	fmt.Println("Mean Trials: " + fmt.Sprint(mean(trialset)))
+	fmt.Println()
+	fmt.Println("Median Trials: " + fmt.Sprint(median(trialset)))
+	fmt.Println()
+
+}
+
+func median(numbers []int) float64 {
+	sort.Ints(numbers)
+	n := len(numbers)
+	if n%2 == 0 {
+		return float64(numbers[n/2-1]+numbers[n/2]) / 2
+	}
+	return float64(numbers[n/2])
+}
+
+func mean(numbers []int) float64 {
+	var sum int
+	for _, n := range numbers {
+		sum += n
+	}
+	return float64(sum) / float64(len(numbers))
+}
+
+func hashTrial() int {
+
+	// puzzle difficulty
+	difficulty := 5
+
+	// string to match leading zeros
+	m := ""
+	for i := 0; i < difficulty; i++ {
+		m += "0"
+	}
+
+	// counter for number of trials
+	trials := 1
+
+	// original message to hash
+	s := "Hello"
+
+	// random seed using time and generation of a nonce
+	rand.Seed(time.Now().UnixNano())
+	nonce := rand.Intn(1000000)
+
+	// compute first sha256
+	h := sha256.New()
+	p := string(s) + " " + fmt.Sprint(nonce)
+
+	h.Write([]byte(p))
+
+	fmt.Println()
+	fmt.Println(s)
+	fmt.Println()
+	fmt.Println(p)
+	fmt.Println()
+	fmt.Println(hex.EncodeToString(h.Sum(nil)))
+	fmt.Println()
+
+	// compute sha256 until leading zeros are found
+	for string(hex.EncodeToString(h.Sum(nil))[:difficulty]) != m {
+
+		h.Reset()
+
+		nonce++
+		p = string(s) + " " + fmt.Sprint(nonce)
+		h.Write([]byte(p))
+
+		fmt.Println(p)
+		fmt.Println()
+		fmt.Println(hex.EncodeToString(h.Sum(nil)))
+		fmt.Println()
+
+		trials++
+
+	}
+
+	fmt.Println("Trials: " + fmt.Sprint(trials))
+	fmt.Println()
+
+	return trials
+
+}

hashing/hashing-examples.go

@@ -7,8 +7,8 @@ import (
 )
 
 func main() {
-	s := "Hello World"
-	//s := "In the heart of a bustling city, a small, unassuming cafe stood tucked between towering skyscrapers. Its walls, a mosaic of colorful tiles, held stories of a thousand meetings, whispered secrets, and shared laughter. Inside, the aroma of freshly ground coffee mingled with the scent of old books, creating an ambiance of warmth and nostalgia. Each table bore the marks of countless cups and conversations, and the worn-out sofa in the corner was a silent testament to many a weary traveler finding solace in its embrace. Outside, the city rushed by in a blur of lights and sounds, but within the cafe's walls, time seemed to slow down, inviting passersby to pause and savor the small joys of life. ~ChatGPT"
+	//s := "Hello World"
+	s := "In the heart of a bustling city, a small, unassuming cafe stood tucked between towering skyscrapers. Its walls, a mosaic of colorful tiles, held stories of a thousand meetings, whispered secrets, and shared laughter. Inside, the aroma of freshly ground coffee mingled with the scent of old books, creating an ambiance of warmth and nostalgia. Each table bore the marks of countless cups and conversations, and the worn-out sofa in the corner was a silent testament to many a weary traveler finding solace in its embrace. Outside, the city rushed by in a blur of lights and sounds, but within the cafe's walls, time seemed to slow down, inviting passersby to pause and savor the small joys of life ~ChatGPT"
 
 	sha256 := sha256.Sum256([]byte(s))
 	md5 := md5.Sum([]byte(s))

rsa/rsa-encrypt-sign.go

@@ -20,11 +20,11 @@ func main() {
 	}
 	alicePublicKey := &alicePrivateKey.PublicKey
 
-	trudyPrivateKey, err := rsa.GenerateKey(rand.Reader, 2048)
-	if err != nil {
-		fmt.Println(err)
-		os.Exit(1)
-	}
+	//trudyPrivateKey, err := rsa.GenerateKey(rand.Reader, 2048)
+	//if err != nil {
+	//	fmt.Println(err)
+	//	os.Exit(1)
+	//}
 	//trudyPublicKey := &trudyPrivateKey.PublicKey
 
 	bobPrivateKey, err := rsa.GenerateKey(rand.Reader, 2048)
@@ -92,7 +92,7 @@ func main() {
 	hashed := pssh.Sum(nil)
 	signature, err := rsa.SignPSS(
 		rand.Reader,
-		trudyPrivateKey,
+		alicePrivateKey,
 		newhash,
 		hashed,
 		&opts)