refactored CA key generation into own function

edgelesssys · Jan 9, 2025 · fa57092 · fa57092
1 parent 62b0c66
commit fa57092
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Showing 6 changed files with 26 additions and 30 deletions.
diff --git a/bootstrapper/internal/initserver/initserver.go b/bootstrapper/internal/initserver/initserver.go
@@ -19,9 +19,7 @@ package initserver
 
 import (
 	"bufio"
-	"bytes"
 	"context"
-	"crypto/ed25519"
 	"errors"
 	"fmt"
 	"io"
@@ -234,16 +232,9 @@ func (s *Server) Init(req *initproto.InitRequest, stream initproto.API_InitServe
 		}
 		return err
 	}
-	_, priv, err := ed25519.GenerateKey(bytes.NewReader(key))
+	ca, err := crypto.GenerateEmergencySSHCAKey(key)
 	if err != nil {
-		if e := s.sendLogsWithMessage(stream, status.Errorf(codes.Internal, "generating signing key for emergency ssh CA: %s", err)); e != nil {
-			err = errors.Join(err, e)
-		}
-		return err
-	}
-	ca, err := ssh.NewSignerFromSigner(priv)
-	if err != nil {
-		if e := s.sendLogsWithMessage(stream, status.Errorf(codes.Internal, "signing emergency ssh CA key: %s", err)); e != nil {
+		if e := s.sendLogsWithMessage(stream, status.Errorf(codes.Internal, "generating emergency SSH CA key: %s", err)); e != nil {
 			err = errors.Join(err, e)
 		}
 		return err

diff --git a/bootstrapper/internal/joinclient/BUILD.bazel b/bootstrapper/internal/joinclient/BUILD.bazel
@@ -11,6 +11,7 @@ go_library(
         "//internal/attestation",
         "//internal/cloud/metadata",
         "//internal/constants",
+        "//internal/crypto",
         "//internal/file",
         "//internal/nodestate",
         "//internal/role",

diff --git a/bootstrapper/internal/joinclient/joinclient.go b/bootstrapper/internal/joinclient/joinclient.go
@@ -18,9 +18,7 @@ If the JoinClient finds an existing cluster, it will attempt to join it as eithe
 package joinclient
 
 import (
-	"bytes"
 	"context"
-	"crypto/ed25519"
 	"errors"
 	"fmt"
 	"log/slog"
@@ -33,6 +31,7 @@ import (
 	"github.com/edgelesssys/constellation/v2/internal/attestation"
 	"github.com/edgelesssys/constellation/v2/internal/cloud/metadata"
 	"github.com/edgelesssys/constellation/v2/internal/constants"
+	"github.com/edgelesssys/constellation/v2/internal/crypto"
 	"github.com/edgelesssys/constellation/v2/internal/file"
 	"github.com/edgelesssys/constellation/v2/internal/nodestate"
 	"github.com/edgelesssys/constellation/v2/internal/role"
@@ -274,14 +273,9 @@ func (c *JoinClient) startNodeAndJoin(ticket *joinproto.IssueJoinTicketResponse,
 		return fmt.Errorf("writing kubelet key: %w", err)
 	}
 
-	// derive CA key from emergency key
-	_, priv, err := ed25519.GenerateKey(bytes.NewReader(ticket.EmergencyCaKey))
+	ca, err := crypto.GenerateEmergencySSHCAKey(ticket.EmergencyCaKey)
 	if err != nil {
-		return fmt.Errorf("deriving ed25519 ssh emergency key: %w", err)
-	}
-	ca, err := ssh.NewSignerFromSigner(priv)
-	if err != nil {
-		return fmt.Errorf("creating emergency SSH CA key: %w", err)
+		return fmt.Errorf("generating emergency SSH CA key: %s", err)
 	}
 
 	if err := c.fileHandler.Write(constants.SSHCAKeyPath, ssh.MarshalAuthorizedKey(ca.PublicKey()), file.OptMkdirAll); err != nil {

diff --git a/cli/internal/cmd/ssh.go b/cli/internal/cmd/ssh.go
@@ -7,8 +7,6 @@ SPDX-License-Identifier: AGPL-3.0-only
 package cmd
 
 import (
-	"bytes"
-	"crypto/ed25519"
 	"crypto/rand"
 	"fmt"
 	"os"
@@ -77,14 +75,9 @@ func runSSH(cmd *cobra.Command, _ []string) error {
 		return fmt.Errorf("Failed to retrieve key from key management service: %s", err)
 	}
 
-	_, priv, err := ed25519.GenerateKey(bytes.NewReader(key))
+	ca, err := crypto.GenerateEmergencySSHCAKey(key)
 	if err != nil {
-		return fmt.Errorf("Failed to create signing key from master secret: %s", err)
-	}
-
-	ca, err := ssh.NewSignerFromSigner(priv)
-	if err != nil {
-		return fmt.Errorf("Failed to create ssh CA key from master secret: %s", err)
+		return fmt.Errorf("Failed to generate emergency SSH CA key: %s", err)
 	}
 
 	debugLogger.Debug("SSH CA KEY generated", "key", string(ssh.MarshalAuthorizedKey(ca.PublicKey())))

diff --git a/internal/crypto/BUILD.bazel b/internal/crypto/BUILD.bazel
@@ -6,7 +6,10 @@ go_library(
     srcs = ["crypto.go"],
     importpath = "github.com/edgelesssys/constellation/v2/internal/crypto",
     visibility = ["//:__subpackages__"],
-    deps = ["@org_golang_x_crypto//hkdf"],
+    deps = [
+        "@org_golang_x_crypto//hkdf",
+        "@org_golang_x_crypto//ssh",
+    ],
 )
 
 go_test(

diff --git a/internal/crypto/crypto.go b/internal/crypto/crypto.go
@@ -9,6 +9,7 @@ package crypto
 
 import (
 	"bytes"
+	"crypto/ed25519"
 	"crypto/rand"
 	"crypto/sha256"
 	"crypto/x509"
@@ -18,6 +19,7 @@ import (
 	"math/big"
 
 	"golang.org/x/crypto/hkdf"
+	"golang.org/x/crypto/ssh"
 )
 
 const (
@@ -62,6 +64,18 @@ func GenerateRandomBytes(length int) ([]byte, error) {
 	return nonce, nil
 }
 
+func GenerateEmergencySSHCAKey(key []byte) (ssh.Signer, error) {
+	_, priv, err := ed25519.GenerateKey(bytes.NewReader(key))
+	if err != nil {
+		return nil, err
+	}
+	ca, err := ssh.NewSignerFromSigner(priv)
+	if err != nil {
+		return nil, err
+	}
+	return ca, nil
+}
+
 // PemToX509Cert takes a list of PEM-encoded certificates, parses the first one and returns it
 // as an x.509 certificate.
 func PemToX509Cert(raw []byte) (*x509.Certificate, error) {