Helper to generate ssh keys

SSH_gen.go

package main

import (
	"crypto/rand"
	"crypto/rsa"
	"crypto/x509"
	"encoding/pem"
	"flag"
	"io/ioutil"
	"log"
	"path/filepath"

	"golang.org/x/crypto/ssh"
)

func main() {
	strength := flag.Int("bits", 2048, "key bit size to generate")
	name := flag.String("name", "id_rsa", "file name for generated keys")
	dir := flag.String("dir", ".", "destination directory for generated keys")

	// Generate keys
	pub, priv, err := GenerateSSHKeyPair(*strength)
	if err != nil {
		log.Fatal(err)
	}

	// Write keys to destination
	keyFile := filepath.Join(*dir, *name)
	err = ioutil.WriteFile(keyFile, priv, 0600)
	if err != nil {
		log.Fatal(err)
	}
	err = ioutil.WriteFile(keyFile+".pub", pub, 0644)
	if err != nil {
		log.Fatal(err)
	}
	log.Println(keyFile, "created.")
}

// GenerateSSHKeyPair creates a pair of keys (public + private) for SSH auth.
func GenerateSSHKeyPair(strength int) (pub, priv []byte, err error) {
	privKey, err := rsa.GenerateKey(rand.Reader, strength)
	if err != nil {
		return nil, nil, err
	}
	privKeyPEM := &pem.Block{Type: "RSA PRIVATE KEY", Bytes: x509.MarshalPKCS1PrivateKey(privKey)}
	pubKey, err := ssh.NewPublicKey(&privKey.PublicKey)
	if err != nil {
		return nil, nil, err
	}
	return ssh.MarshalAuthorizedKey(pubKey), pem.EncodeToMemory(privKeyPEM), nil
}