implement keygen cmd

cmd/hppktool/cmd/keygen.go

@@ -4,25 +4,91 @@ Copyright © 2024 NAME HERE <EMAIL ADDRESS>
 package cmd
 
 import (
+	"bufio"
+	"encoding/json"
+	"errors"
 	"fmt"
+	"os"
 
 	"github.com/spf13/cobra"
+	"github.com/xtaci/hppk"
 )
 
 // keygenCmd represents the keygen command
 var keygenCmd = &cobra.Command{
-	Use:   "keygen",
-	Short: "A brief description of your command",
-	Long: `A longer description that spans multiple lines and likely contains examples
-and usage of using your command. For example:
-
-Cobra is a CLI library for Go that empowers applications.
-This application is a tool to generate the needed files
-to quickly create a Cobra application.`,
+	Use:   "keygen [directory]",
+	Short: "generate a hppk private/public key pair",
+	Args: func(cmd *cobra.Command, args []string) error {
+		if err := cobra.ExactArgs(1)(cmd, args); err != nil {
+			return errors.New("Missing directory, Use `hppktool keygen -h` to see how the usage.\n")
+		}
+		return nil
+	},
 	Run: func(cmd *cobra.Command, args []string) {
-		if dir, err := cmd.Flags().GetString("dir"); err == nil {
-			fmt.Println(dir)
+		dir := args[0]
+		order, err := cmd.Flags().GetInt("order")
+		if err != nil {
+			panic("cannot get param -> order")
+		}
+
+		priv, err := hppk.GenerateKey(order)
+		if err != nil {
+			panic(err)
+		}
+
+		// let user confirm
+		prefix := "id_hppk"
+		privFile := fmt.Sprintf("%v/%v", dir, prefix)
+		pubFile := fmt.Sprintf("%v/%v.pub", dir, prefix)
+
+		fmt.Print("Do you want to save the key pair to the following files?\n\n")
+		fmt.Printf("Polynomial order:%d\n", order)
+		fmt.Printf("[1/2] Private key: %v\n", privFile)
+		fmt.Printf("[2/2] Public key: %v\n", pubFile)
+		fmt.Print("Proceed with key generation? [y/N]: ")
+		reader := bufio.NewReader(os.Stdin)
+		char, _, err := reader.ReadRune()
+
+		switch char {
+		case 'Y', 'y':
+		default:
+			return
+		}
+
+		// write private key
+		bts, err := json.Marshal(priv)
+		if err != nil {
+			panic(err)
 		}
+
+		fPriv, err := os.OpenFile(privFile, os.O_CREATE|os.O_WRONLY, 0600)
+		if err != nil {
+			panic(err)
+		}
+		defer fPriv.Close()
+		_, err = fPriv.Write(bts)
+		if err != nil {
+			panic(err)
+		}
+
+		// write public key
+		fPub, err := os.OpenFile(pubFile, os.O_CREATE|os.O_WRONLY, 0644)
+		if err != nil {
+			panic(err)
+		}
+		defer fPub.Close()
+
+		bts, err = json.Marshal(&priv.PublicKey)
+		if err != nil {
+			panic(err)
+		}
+
+		_, err = fPub.Write(bts)
+		if err != nil {
+			panic(err)
+		}
+
+		fmt.Println("Done.")
 	},
 }
 
@@ -37,5 +103,5 @@ func init() {
 
 	// Cobra supports local flags which will only run when this command
 	// is called directly, e.g.:
-	keygenCmd.Flags().StringP("dir", "d", ".", "the key pair output path")
+	keygenCmd.Flags().IntP("order", "o", 5, "the order of the polynomial")
 }