main.go

package main

import (
	"bufio"
	"context"
	"crypto/sha1"
	"encoding/hex"
	"fmt"
	"log"
	"net/http"
	"os"
	"os/signal"
	"strings"

	"golang.org/x/term"
)

func main() {
	ctx, cancel := signal.NotifyContext(context.Background(), os.Interrupt)
	defer cancel()

	log.SetFlags(0)
	fmt.Print("Password to check: ")

	password, err := term.ReadPassword(int(os.Stdin.Fd()))
	if err != nil {
		log.Fatalln(err)
	}

	h := sha1.New()
	h.Write(password)

	hash := h.Sum(nil)

	hashedPassword := strings.ToUpper(hex.EncodeToString(hash))

	fmt.Println("**********")

	prefix := hashedPassword[:5]
	suffix := hashedPassword[5:]

	baseURL := "https://api.pwnedpasswords.com/range"
	fullURL := fmt.Sprintf("%s/%s", baseURL, prefix)

	req, err := http.NewRequestWithContext(
		ctx,
		http.MethodGet,
		fullURL,
		http.NoBody,
	)
	if err != nil {
		log.Fatalln(err)
	}

	res, err := http.DefaultClient.Do(req)
	if err != nil {
		log.Fatalln(err)
	}

	defer res.Body.Close()

	scanner := bufio.NewScanner(res.Body)

	for scanner.Scan() {
		line := scanner.Text()

		if strings.HasPrefix(line, suffix) {
			fmt.Println("Uhoh, password is pwned")
			return
		}
	}

	fmt.Println("Password is safe!")
}