Add command to create client certificate

cmd/pki/create/create.go

@@ -32,8 +32,11 @@ package create
 
 import (
 	"context"
+	"crypto/x509"
+	"encoding/pem"
 	"fmt"
 	"io"
+	"os"
 
 	aeCMD "github.com/aurae-runtime/ae/cmd"
 	"github.com/aurae-runtime/ae/pkg/cli"
@@ -48,6 +51,11 @@ type option struct {
 	directory    string
 	domain       string
 	user         string
+	caPath       string
+	caKeyPath    string
+	csrPath      string
+	csr          *pki.CertificateRequest
+	ca           *pki.Certificate
 	silent       bool
 	writer       io.Writer
 }
@@ -60,17 +68,97 @@ func (o *option) Complete(args []string) error {
 		return fmt.Errorf("too many arguments for command 'create', expect %d, got %d", 1, len(args))
 	}
 
+	if o.caPath != "" {
+		b, err := os.ReadFile(o.caPath)
+		if err != nil {
+			return fmt.Errorf("failed to read ca certificate: %w", err)
+		}
+
+		o.ca = &pki.Certificate{}
+		o.ca.Certificate = string(b)
+
+		if o.caKeyPath != "" {
+			b, err := os.ReadFile(o.caKeyPath)
+			if err != nil {
+				return fmt.Errorf("failed to read ca private key: %w", err)
+			}
+
+			o.ca.PrivateKey = string(b)
+		} else {
+			return fmt.Errorf("must provide --caKey and --csr when using --ca")
+		}
+
+		if o.csrPath != "" {
+			b, err := os.ReadFile(o.csrPath)
+			if err != nil {
+				return fmt.Errorf("failed to read csr: %w", err)
+			}
+
+			o.csr = &pki.CertificateRequest{}
+			o.csr.CSR = string(b)
+		} else {
+			return fmt.Errorf("must provide --caKey and --csr when using --ca")
+		}
+	}
+
+	if o.csrPath != "" {
+		b, err := os.ReadFile(o.csrPath)
+		if err != nil {
+			return fmt.Errorf("failed to read csr: %w", err)
+		}
+
+		o.csr = &pki.CertificateRequest{}
+		o.csr.CSR = string(b)
+	}
+
 	o.domain = args[0]
 
 	return nil
 }
 
 func (o *option) Validate() error {
+	if o.caPath != "" {
+		caPem, _ := pem.Decode([]byte(o.ca.Certificate))
+		_, err := x509.ParseCertificate(caPem.Bytes)
+		if err != nil {
+			return fmt.Errorf("could not parse ca file")
+		}
+	}
+
+	if o.caKeyPath != "" {
+		caKeyPem, _ := pem.Decode([]byte(o.ca.PrivateKey))
+		_, err := x509.ParsePKCS1PrivateKey(caKeyPem.Bytes)
+		if err != nil {
+			return fmt.Errorf("could not parse key file")
+		}
+	}
+
+	if o.csrPath != "" {
+		csrPem, _ := pem.Decode([]byte(o.csr.CSR))
+		_, err := x509.ParseCertificateRequest(csrPem.Bytes)
+		if err != nil {
+			return fmt.Errorf("could not parse csr file")
+		}
+	}
+
 	return nil
 }
 
 func (o *option) Execute(_ context.Context) error {
 	if o.user != "" {
+
+		if o.caPath != "" {
+			clientCrt, err := pki.CreateClientCertificate(o.directory, o.csr.CSR, o.ca, o.user)
+			if err != nil {
+				return fmt.Errorf("failed to create client certificate: %w", err)
+			}
+			if !o.silent {
+				o.outputFormat.ToPrinter().Print(o.writer, &clientCrt)
+			}
+
+			return nil
+		}
+
 		clientCSR, err := pki.CreateClientCSR(o.directory, o.domain, o.user)
 		if err != nil {
 			return fmt.Errorf("failed to create client csr: %w", err)
@@ -118,6 +206,9 @@ ae pki create --dir ./pki/ my.domain.com`,
 	o.outputFormat.AddFlags(cmd)
 	cmd.Flags().StringVarP(&o.directory, "dir", "d", o.directory, "Output directory to store CA files.")
 	cmd.Flags().StringVarP(&o.user, "user", "u", o.user, "Creates client certificate for a given user.")
+	cmd.Flags().StringVar(&o.caPath, "ca", o.caPath, "Use the given CA certificate.")
+	cmd.Flags().StringVar(&o.caKeyPath, "caKey", o.caKeyPath, "The corresponding CA key.")
+	cmd.Flags().StringVar(&o.csrPath, "csr", o.csrPath, "CSR input file.")
 	cmd.Flags().BoolVarP(&o.silent, "silent", "s", o.silent, "Silent mode, omits output")
 
 	return cmd

pkg/pki/pki.go

@@ -31,6 +31,7 @@
 package pki
 
 import (
+	"bytes"
 	"crypto/rand"
 	"crypto/rsa"
 	"crypto/sha1"
@@ -55,10 +56,10 @@ type CertificateRequest struct {
 	User       string `json:"user" yaml:"user"`
 }
 
-func CreateAuraeRootCA(path string, domainName string) (*Certificate, error) {
+func createCA(domainName string) ([]byte, *rsa.PrivateKey, error) {
 	priv, err := rsa.GenerateKey(rand.Reader, 2048)
 	if err != nil {
-		return &Certificate{}, fmt.Errorf("failed to generate private key: %w", err)
+		return nil, nil, fmt.Errorf("failed to generate private key: %w", err)
 	}
 
 	subj := pkix.Name{
@@ -75,7 +76,7 @@ func CreateAuraeRootCA(path string, domainName string) (*Certificate, error) {
 	serialNumberLimit := new(big.Int).Lsh(big.NewInt(1), 128)
 	serialNumber, err := rand.Int(rand.Reader, serialNumberLimit)
 	if err != nil {
-		return &Certificate{}, fmt.Errorf("failed to generate serial number: %w", err)
+		return nil, nil, fmt.Errorf("failed to generate serial number: %w", err)
 	}
 
 	template := x509.Certificate{
@@ -107,22 +108,31 @@ func CreateAuraeRootCA(path string, domainName string) (*Certificate, error) {
 
 	crtBytes, err := x509.CreateCertificate(rand.Reader, &template, &template, &priv.PublicKey, priv)
 	if err != nil {
-		return &Certificate{}, fmt.Errorf("failed to create certificate: %w", err)
+		return nil, nil, fmt.Errorf("failed to create certificate: %w", err)
 	}
 
-	crtPem := pem.EncodeToMemory(&pem.Block{
-		Type:  "CERTIFICATE",
-		Bytes: crtBytes,
-	})
+	return crtBytes, priv, nil
+}
 
-	keyPem := pem.EncodeToMemory(&pem.Block{
-		Type:  "RSA PRIVATE KEY",
-		Bytes: x509.MarshalPKCS1PrivateKey(priv),
-	})
+func CreateAuraeRootCA(path string, domainName string) (*Certificate, error) {
+	crtBytes, priv, err := createCA(domainName)
+	if err != nil {
+		return nil, err
+	}
+
+	crtPem, err := getPemBuffer(crtBytes, "CERTIFICATE")
+	if err != nil {
+		return nil, err
+	}
+
+	keyPem, err := getPemBuffer(x509.MarshalPKCS1PrivateKey(priv), "RSA PRIVATE KEY")
+	if err != nil {
+		return nil, err
+	}
 
 	ca := &Certificate{
-		Certificate: string(crtPem),
-		PrivateKey:  string(keyPem),
+		Certificate: crtPem.String(),
+		PrivateKey:  keyPem.String(),
 	}
 
 	if path != "" {
@@ -187,6 +197,108 @@ func CreateClientCSR(path, domain, user string) (*CertificateRequest, error) {
 	return csr, nil
 }
 
+func CreateClientCertificate(path, csrStr string, ca *Certificate, user string) (*Certificate, error) {
+	csrPem, _ := pem.Decode([]byte(csrStr))
+	if csrPem == nil || csrPem.Type != "CERTIFICATE REQUEST" {
+		return &Certificate{}, fmt.Errorf("failed to decode certificate request")
+	}
+
+	csr, err := x509.ParseCertificateRequest(csrPem.Bytes)
+	if err != nil {
+		return &Certificate{}, fmt.Errorf("failed to parse certificate request: %w", err)
+	}
+
+	caCrtPem, _ := pem.Decode([]byte(ca.Certificate))
+	if caCrtPem == nil || caCrtPem.Type != "CERTIFICATE" {
+		return &Certificate{}, fmt.Errorf("failed to decode certificate")
+	}
+
+	caCrt, err := x509.ParseCertificate(caCrtPem.Bytes)
+	if err != nil {
+		return &Certificate{}, fmt.Errorf("failed to parse certificate: %w", err)
+	}
+
+	caPrivPem, _ := pem.Decode([]byte(ca.PrivateKey))
+	if caPrivPem == nil || caPrivPem.Type != "RSA PRIVATE KEY" {
+		return &Certificate{}, fmt.Errorf("failed to decode private key")
+	}
+
+	caPriv, err := x509.ParsePKCS1PrivateKey(caPrivPem.Bytes)
+	if err != nil {
+		return &Certificate{}, fmt.Errorf("failed to parse private key: %w", err)
+	}
+
+	now := time.Now()
+
+	serialNumberLimit := new(big.Int).Lsh(big.NewInt(1), 128)
+	serialNumber, err := rand.Int(rand.Reader, serialNumberLimit)
+	if err != nil {
+		return &Certificate{}, fmt.Errorf("failed to generate serial number: %w", err)
+	}
+
+	template := x509.Certificate{
+		Subject:               csr.Subject,
+		NotBefore:             now,
+		NotAfter:              now.Add(24 * time.Hour * 9999),
+		SerialNumber:          serialNumber,
+		IsCA:                  false,
+		BasicConstraintsValid: true,
+		KeyUsage:              x509.KeyUsageDigitalSignature | x509.KeyUsageContentCommitment | x509.KeyUsageKeyEncipherment | x509.KeyUsageDataEncipherment,
+	}
+
+	crtPrivKey, err := rsa.GenerateKey(rand.Reader, 4096)
+	if err != nil {
+		return &Certificate{}, fmt.Errorf("failed to generate private key: %w", err)
+	}
+
+	// TODO: is this the correct Subject Key Identifier?
+	pubHash := sha1.Sum(crtPrivKey.PublicKey.N.Bytes())
+	template.SubjectKeyId = pubHash[:]
+
+	crtPrivPem := pem.EncodeToMemory(&pem.Block{
+		Type:  "RSA PRIVATE KEY",
+		Bytes: x509.MarshalPKCS1PrivateKey(crtPrivKey),
+	})
+
+	clientCrtBytes, err := x509.CreateCertificate(rand.Reader, &template, caCrt, &crtPrivKey.PublicKey, caPriv)
+	if err != nil {
+		return &Certificate{}, fmt.Errorf("failed to create certificate: %w", err)
+	}
+
+	clientCrtPem := pem.EncodeToMemory(&pem.Block{
+		Type:  "CERTIFICATE",
+		Bytes: clientCrtBytes,
+	})
+
+	clientCert := &Certificate{
+		Certificate: string(clientCrtPem),
+		PrivateKey:  string(crtPrivPem),
+	}
+
+	// if path != "" {
+	// 	err = createCsrFiles(path, csr)
+	// 	if err != nil {
+	// 		return csr, err
+	// 	}
+	// }
+
+	return clientCert, nil
+}
+
+func getPemBuffer(b []byte, t string) (*bytes.Buffer, error) {
+	// var certBytes []byte
+	pemBuffer := bytes.NewBuffer([]byte{})
+	err := pem.Encode(pemBuffer, &pem.Block{
+		Type:  t,
+		Bytes: b,
+	})
+	if err != nil {
+		return &bytes.Buffer{}, fmt.Errorf("failed to write \"%s\" pem buffer of type: %w", t, err)
+	}
+
+	return pemBuffer, nil
+}
+
 func createCAFiles(path string, ca *Certificate) error {
 	path = filepath.Clean(path)
 	err := os.MkdirAll(path, os.ModePerm)