Golangによるsocket通信(2)

client.go

package main

import (
    "fmt"
    "net"
    "os"
    "time"

    "./utils"
    "./encryption"
    "math/big"
)

func main() {

    serverIP := "localhost"
    serverPort := "55555"
    myIP := "localhost"
    myPort := 55556

    base, myExp, modulus := encryption.FFDHE_key_gen("2048")
    myPub := encryption.FFDHE(base, myExp, modulus)

    tcpAddr, err := net.ResolveTCPAddr("tcp", serverIP + ":" + serverPort)
    checkError(err)
    myAddr := new(net.TCPAddr)
    myAddr.IP = net.ParseIP(myIP)
    myAddr.Port = myPort
    conn, err := net.DialTCP("tcp", myAddr, tcpAddr)
    checkError(err)
    defer conn.Close()

    conn.Write(myPub.Bytes())

    readBuf := make([]byte, 1024)
    conn.SetReadDeadline(time.Now().Add(10 * time.Second))
    readlen, err := conn.Read(readBuf)

    peerPub := new(big.Int).SetBytes(readBuf[:readlen])
    checkError(err)
    myPri := encryption.FFDHE(peerPub, myExp, modulus)
    fmt.Println("[+] DH Public Key :", myPub)
    fmt.Println("[+] DH Private Key :", myPri)

    conn.SetReadDeadline(time.Now().Add(10 * time.Second))
    readlen, err = conn.Read(readBuf)
    encrypted_message := readBuf[:readlen]
    checkError(err)
    fmt.Printf("[+] Received Message : % x\n", encrypted_message)


    bytesPriKey := myPri.Bytes() // 本来のHKDFを飛ばして, いきなりDH-Keyをつかう
    //secret := []byte("secret key")
    key, nonce := utils.Gen_key_and_iv(bytesPriKey, 32, 12, "sha256")
    message := encryption.Chacha20_encrypt(key, 1, nonce, encrypted_message)
    fmt.Printf("[+] Received Message : %s\n", message)

}

func checkError(err error) {
    if err != nil {
        fmt.Fprintf(os.Stderr, "fatal: error: %s", err.Error())
        os.Exit(1)
    }
}