/
generator.go
100 lines (78 loc) · 2.24 KB
/
generator.go
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package sshhelper
import (
"crypto/rand"
"crypto/rsa"
"crypto/x509"
"encoding/pem"
"time"
"golang.org/x/crypto/ssh"
"github.com/konstellation-io/kdl-server/app/api/entity"
"github.com/konstellation-io/kdl-server/app/api/pkg/logging"
)
type generator struct {
logger logging.Logger
}
// NewGenerator is a constructor function.
func NewGenerator(logger logging.Logger) SSHKeyGenerator {
return &generator{
logger: logger,
}
}
// NewKeys returns a new private and public SSH keys.
func (g *generator) NewKeys() (entity.SSHKey, error) {
bitSize := 4096
privateKey, err := g.generatePrivateKey(bitSize)
if err != nil {
return entity.SSHKey{}, err
}
publicKeyBytes, err := g.generatePublicKey(&privateKey.PublicKey)
if err != nil {
return entity.SSHKey{}, err
}
privateKeyBytes := g.encodePrivateKeyToPEM(privateKey)
return entity.SSHKey{
Public: string(publicKeyBytes),
Private: string(privateKeyBytes),
CreationDate: time.Now().UTC(),
}, nil
}
// generatePrivateKey creates a RSA Private Key of specified byte size.
func (g *generator) generatePrivateKey(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
}
g.logger.Info("Private Key generated")
return privateKey, nil
}
// encodePrivateKeyToPEM encodes Private Key from RSA to PEM format.
func (g *generator) encodePrivateKeyToPEM(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
}
// generatePublicKey take a rsa.PublicKey and return bytes suitable for writing to .pub file
// returns in the format "ssh-rsa ...".
func (g *generator) generatePublicKey(privatekey *rsa.PublicKey) ([]byte, error) {
publicRsaKey, err := ssh.NewPublicKey(privatekey)
if err != nil {
return nil, err
}
pubKeyBytes := ssh.MarshalAuthorizedKey(publicRsaKey)
g.logger.Info("Public key generated")
return pubKeyBytes, nil
}