Add hostkey to the ssh server

client/ssh/ssh.go

@@ -0,0 +1,52 @@
+package ssh
+
+import (
+	"crypto/rand"
+	"crypto/rsa"
+	"crypto/x509"
+	"encoding/pem"
+	gossh "golang.org/x/crypto/ssh"
+)
+
+// GeneratePrivateKey creates RSA Private Key of specified byte size
+func GeneratePrivateKey(bitSize int) (*rsa.PrivateKey, error) {
+	privateKey, err := rsa.GenerateKey(rand.Reader, bitSize)
+	if err != nil {
+		return nil, err
+	}
+
+	err = privateKey.Validate()
+	if err != nil {
+		return nil, err
+	}
+
+	return privateKey, nil
+}
+
+// GeneratePublicKey takes a rsa.PublicKey and return bytes suitable for writing to .pub file
+// returns the key in format format "ssh-rsa ..."
+func GeneratePublicKey(privateKey *rsa.PublicKey) ([]byte, error) {
+	publicRsaKey, err := gossh.NewPublicKey(privateKey)
+	if err != nil {
+		return nil, err
+	}
+	return gossh.MarshalAuthorizedKey(publicRsaKey), nil
+}
+
+// EncodePrivateKeyToPEM encodes Private Key from RSA to PEM format
+func 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
+}