Generates RSA KeyPair and writes to file in PEM format.

keypair_gen.go

package main

import (
        "crypto/rsa"
	"crypto/rand"
	"crypto/x509"
	"encoding/pem"
	"os"
	"fmt"
)

type KeyPair struct {
	PublicKeyPEM string
	PrivateKeyPEM string
}

func (this *KeyPair) Generate() {
	priv, err := rsa.GenerateKey(rand.Reader, 2048)
	if err != nil {
		fmt.Println(err)
		return
	}

	err = priv.Validate()
	if err != nil {
		fmt.Println("Validation failed:", err)
		return
	}

	privDer := x509.MarshalPKCS1PrivateKey(priv)
	privBlock := pem.Block {
		Type: "RSA PRIVATE KEY",
		Headers: nil,
		Bytes: privDer,
	}

	pub := priv.PublicKey
	pubDer, err := x509.MarshalPKIXPublicKey(&pub)
	if err != nil {
		fmt.Println("Failed to get der format of PublicKey: ", err)
		return
	}

	pubBlock := pem.Block {
		Type: "RSA PUBLIC KEY",
		Headers: nil,
		Bytes: pubDer,
	}

	this.PrivateKeyPEM = string(pem.EncodeToMemory(&privBlock))
	this.PublicKeyPEM = string(pem.EncodeToMemory(&pubBlock))
}

func (this *KeyPair) WriteToFile(filepath string) error {
	file, err := os.Create(filepath)
	if err != nil {
		return err
	}
	defer file.Close()

	file.WriteString(this.PublicKeyPEM)
	file.WriteString(this.PrivateKeyPEM)

	return nil
}

func main() {
	keyPair := new(KeyPair)
	keyPair.Generate()

	fmt.Printf(keyPair.PublicKeyPEM)
	fmt.Printf(keyPair.PrivateKeyPEM)

	filepath := "testfile.pem"

	err := keyPair.WriteToFile(filepath)
	if err != nil {
		fmt.Println("Unable to write", filepath)
	} else {
		fmt.Println("Successfull wrote", filepath)
	}
}