add vendoring

vendor/gitlab.com/etke.cc/go/secgen/keypair.go

@@ -0,0 +1,68 @@
+package secgen
+
+import (
+	"crypto/ed25519"
+	"crypto/rand"
+	"crypto/rsa"
+	"crypto/x509"
+	"encoding/base64"
+	"encoding/pem"
+	"strings"
+
+	"github.com/mikesmitty/edkey"
+	"golang.org/x/crypto/ssh"
+)
+
+// RSABits used for DKIM keypair
+const RSABits = 3072
+
+// Keypair generates ed25519 keypair for ssh (public key, private key)
+func Keypair() (string, string, error) {
+	publicBytes, privateBytes, err := ed25519.GenerateKey(nil)
+	if err != nil {
+		return "", "", err
+	}
+	publicStruct, err := ssh.NewPublicKey(publicBytes)
+	if err != nil {
+		return "", "", err
+	}
+
+	pemblock := &pem.Block{
+		Type:  "OPENSSH PRIVATE KEY",
+		Bytes: edkey.MarshalED25519PrivateKey(privateBytes),
+	}
+	private := pem.EncodeToMemory(pemblock)
+	public := ssh.MarshalAuthorizedKey(publicStruct)
+
+	return string(public), string(private), nil
+}
+
+// DKIM generates DKIM signature and private key (TXT record, private key)
+func DKIM() (string, string, error) {
+	privateBytes, err := rsa.GenerateKey(rand.Reader, RSABits)
+	if err != nil {
+		return "", "", err
+	}
+	publicBytes, err := x509.MarshalPKIXPublicKey(privateBytes.Public())
+	if err != nil {
+		return "", "", err
+	}
+
+	pkcs8, err := x509.MarshalPKCS8PrivateKey(privateBytes)
+	if err != nil {
+		return "", "", err
+	}
+
+	pemblock := &pem.Block{
+		Type:  "PRIVATE KEY",
+		Bytes: pkcs8,
+	}
+	private := pem.EncodeToMemory(pemblock)
+	dkim := []string{
+		"v=DKIM1",
+		"k=rsa",
+		"p=" + base64.StdEncoding.EncodeToString(publicBytes),
+	}
+
+	return strings.Join(dkim, "; "), string(private), nil
+}