commit c60536eb4300270e36c06ca71c4b91d96d34fb9b
Author: Stefan Goppelt <stefan.goppelt@yoorie.de>
Date:   Thu Mar 17 10:14:40 2022 +0100

    Initial commit

diff --git a/Certificate.go b/Certificate.go
new file mode 100644
index 0000000..cb0a5ec
--- /dev/null
+++ b/Certificate.go
@@ -0,0 +1,137 @@
+package certs
+
+import (
+	"crypto/ecdsa"
+	"crypto/ed25519"
+	"crypto/elliptic"
+	"crypto/rand"
+	"crypto/rsa"
+	"crypto/tls"
+	"crypto/x509"
+	"crypto/x509/pkix"
+	"encoding/pem"
+	"log"
+	"math/big"
+	"net"
+	"strings"
+	"time"
+)
+
+// GenerateCertificate basic struct
+type GenerateCertificate struct {
+	Organization string
+	Host         string
+	ValidFrom    string
+	ValidFor     time.Duration
+	IsCA         bool
+	RSABits      int
+	EcdsaCurve   string
+	Ed25519Key   bool
+}
+
+func (gc *GenerateCertificate) publicKey(priv interface{}) interface{} {
+	switch k := priv.(type) {
+	case *rsa.PrivateKey:
+		return &k.PublicKey
+	case *ecdsa.PrivateKey:
+		return &k.PublicKey
+	case ed25519.PrivateKey:
+		return k.Public().(ed25519.PublicKey)
+	default:
+		return nil
+	}
+}
+
+// GenerateTLSConfig create a TLS Config
+func (gc *GenerateCertificate) GenerateTLSConfig() (*tls.Config, error) {
+	var priv interface{}
+	var err error
+	switch gc.EcdsaCurve {
+	case "":
+		if gc.Ed25519Key {
+			_, priv, err = ed25519.GenerateKey(rand.Reader)
+		} else {
+			priv, err = rsa.GenerateKey(rand.Reader, gc.RSABits)
+		}
+	case "P224":
+		priv, err = ecdsa.GenerateKey(elliptic.P224(), rand.Reader)
+	case "P256":
+		priv, err = ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+	case "P384":
+		priv, err = ecdsa.GenerateKey(elliptic.P384(), rand.Reader)
+	case "P521":
+		priv, err = ecdsa.GenerateKey(elliptic.P521(), rand.Reader)
+	default:
+		log.Fatalf("Unrecognized elliptic curve: %q", gc.EcdsaCurve)
+		return nil, err
+	}
+	if err != nil {
+		log.Fatalf("Failed to generate private key: %v", err)
+		return nil, err
+	}
+
+	var notBefore time.Time
+	if len(gc.ValidFrom) == 0 {
+		notBefore = time.Now()
+	} else {
+		notBefore, err = time.Parse("Jan 2 15:04:05 2006", gc.ValidFrom)
+		if err != nil {
+			log.Fatalf("Failed to parse creation date: %v", err)
+			return nil, err
+		}
+	}
+
+	notAfter := notBefore.Add(gc.ValidFor)
+
+	serialNumberLimit := new(big.Int).Lsh(big.NewInt(1), 128)
+	serialNumber, err := rand.Int(rand.Reader, serialNumberLimit)
+	if err != nil {
+		log.Fatalf("Failed to generate serial number: %v", err)
+		return nil, err
+	}
+
+	template := x509.Certificate{
+		SerialNumber: serialNumber,
+		Subject: pkix.Name{
+			Organization: []string{gc.Organization},
+		},
+		NotBefore: notBefore,
+		NotAfter:  notAfter,
+
+		KeyUsage:              x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature,
+		ExtKeyUsage:           []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
+		BasicConstraintsValid: true,
+	}
+
+	hosts := strings.Split(gc.Host, ",")
+	for _, h := range hosts {
+		if ip := net.ParseIP(h); ip != nil {
+			template.IPAddresses = append(template.IPAddresses, ip)
+		} else {
+			template.DNSNames = append(template.DNSNames, h)
+		}
+	}
+
+	if gc.IsCA {
+		template.IsCA = true
+		template.KeyUsage |= x509.KeyUsageCertSign
+	}
+
+	derBytes, err := x509.CreateCertificate(rand.Reader, &template, &template, gc.publicKey(priv), priv)
+	if err != nil {
+		log.Fatalf("Failed to create certificate: %v", err)
+		return nil, err
+	}
+
+	privBytes, err := x509.MarshalPKCS8PrivateKey(priv)
+	if err != nil {
+		log.Fatalf("Unable to marshal private key: %v", err)
+		return nil, err
+	}
+
+	keyPEM := pem.EncodeToMemory(&pem.Block{Type: "PRIVATE KEY", Bytes: privBytes})
+	certPEM := pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: derBytes})
+	tlsCert, err := tls.X509KeyPair(certPEM, keyPEM)
+
+	return &tls.Config{Certificates: []tls.Certificate{tlsCert}}, nil
+}
diff --git a/Certificate_test.go b/Certificate_test.go
new file mode 100644
index 0000000..3fcaaa4
--- /dev/null
+++ b/Certificate_test.go
@@ -0,0 +1,27 @@
+package certs
+
+import (
+	"testing"
+	"time"
+
+	"gotest.tools/assert"
+)
+
+func TestGenerateTLSConfig(t *testing.T) {
+	gc := &GenerateCertificate{
+		Organization: "yoorie.de",
+		Host:         "127.0.0.1",
+		ValidFor:     10 * 365 * 24 * time.Hour,
+		IsCA:         false,
+		EcdsaCurve:   "P256",
+		Ed25519Key:   true,
+	}
+	result, err := gc.GenerateTLSConfig()
+
+	assert.Assert(t, err == nil)
+	assert.Assert(t, result != nil)
+	assert.Equal(t, 1, len(result.Certificates))
+	cert := result.Certificates[0]
+	assert.Assert(t, len(cert.Certificate) > 0)
+	assert.Assert(t, len(cert.Certificate[0]) > 0)
+}
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..e788cdd
--- /dev/null
+++ b/README.md
@@ -0,0 +1 @@
+# TLS Library
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..2fe5879
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,10 @@
+module scm.yoorie.de/go-lib/certs
+
+go 1.18
+
+require gotest.tools v2.2.0+incompatible
+
+require (
+	github.com/google/go-cmp v0.5.7 // indirect
+	github.com/pkg/errors v0.9.1 // indirect
+)
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..bf21e2d
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,8 @@
+github.com/google/go-cmp v0.5.7 h1:81/ik6ipDQS2aGcBfIN5dHDB36BwrStyeAQquSYCV4o=
+github.com/google/go-cmp v0.5.7/go.mod h1:n+brtR0CgQNWTVd5ZUFpTBC8YFBDLK/h/bpaJ8/DtOE=
+github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
+github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+gotest.tools v2.2.0+incompatible h1:VsBPFP1AI068pPrMxtb/S8Zkgf9xEmTLJjfM+P5UIEo=
+gotest.tools v2.2.0+incompatible/go.mod h1:DsYFclhRJ6vuDpmuTbkuFWG+y2sxOXAzmJt81HFBacw=