/
ssh.go
105 lines (84 loc) · 2.43 KB
/
ssh.go
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// This shows an example of how to generate a SSH RSA Private/Public key pair and save it locally
package helper
import (
"crypto/rand"
"crypto/rsa"
"crypto/x509"
"encoding/pem"
"io/ioutil"
"log"
"github.com/sirupsen/logrus"
"golang.org/x/crypto/ssh"
)
// GenerateSSHKeys create SSH keys (private and public) into a given directory
func GenerateSSHKeys(dir string) {
savePrivateFileTo := dir + "/id_rsa"
savePublicFileTo := dir + "/id_rsa.pub"
bitSize := 4096
privateKey, err := GeneratePrivateSSHKey(bitSize)
if err != nil {
log.Fatal(err.Error())
}
publicKeyBytes, err := GeneratePublicSSHKey(&privateKey.PublicKey)
if err != nil {
log.Fatal(err.Error())
}
privateKeyBytes := EncodePrivateSSHKeyToPEM(privateKey)
err = WriteSSHKeyToFile(privateKeyBytes, savePrivateFileTo)
if err != nil {
log.Fatal(err.Error())
}
err = WriteSSHKeyToFile([]byte(publicKeyBytes), savePublicFileTo)
if err != nil {
log.Fatal(err.Error())
}
}
// GeneratePrivateSSHKey creates a RSA Private Key of specified byte size
func GeneratePrivateSSHKey(bitSize int) (*rsa.PrivateKey, error) {
// Private Key generation
privateKey, err := rsa.GenerateKey(rand.Reader, bitSize)
if err != nil {
return nil, err
}
// Validate Private Key
err = privateKey.Validate()
if err != nil {
return nil, err
}
logrus.Traceln("Private Key generated")
return privateKey, nil
}
// EncodePrivateSSHKeyToPEM encodes Private Key from RSA to PEM format
func EncodePrivateSSHKeyToPEM(privateKey *rsa.PrivateKey) []byte {
// Get ASN.1 DER format
privDER := x509.MarshalPKCS1PrivateKey(privateKey)
// pem.Block
privBlock := pem.Block{
Type: "RSA PRIVATE KEY",
Headers: nil,
Bytes: privDER,
}
// Private key in PEM format
privatePEM := pem.EncodeToMemory(&privBlock)
return privatePEM
}
// GeneratePublicSSHKey take a rsa.PublicKey and return bytes suitable for writing to .pub file
// returns in the format "ssh-rsa ..."
func GeneratePublicSSHKey(privatekey *rsa.PublicKey) ([]byte, error) {
publicRsaKey, err := ssh.NewPublicKey(privatekey)
if err != nil {
return nil, err
}
pubKeyBytes := ssh.MarshalAuthorizedKey(publicRsaKey)
logrus.Traceln("Public key generated")
return pubKeyBytes, nil
}
// WriteSSHKeyToFile writes keys to a file
func WriteSSHKeyToFile(keyBytes []byte, saveFileTo string) error {
err := ioutil.WriteFile(saveFileTo, keyBytes, 0600)
if err != nil {
return err
}
log.Printf("Key saved to: %s", saveFileTo)
return nil
}