From ff06b61508deb2ebaffcbb28ce86e8b73caff4c0 Mon Sep 17 00:00:00 2001
From: Camilo Viecco <cviecco@gmail.com>
Date: Mon, 3 Jun 2024 20:12:31 -0700
Subject: [PATCH] Allow self-signed ca certs with EcDSA and Ed25519

---
 lib/certgen/certgen.go      | 43 +++++++++++++++++++++-----------
 lib/certgen/certgen_test.go | 49 ++++++++++++++++++++-----------------
 2 files changed, 55 insertions(+), 37 deletions(-)

diff --git a/lib/certgen/certgen.go b/lib/certgen/certgen.go
index b75233e5..b18f2899 100644
--- a/lib/certgen/certgen.go
+++ b/lib/certgen/certgen.go
@@ -8,6 +8,7 @@ import (
 	"crypto"
 	"crypto/ecdsa"
 	"crypto/ed25519"
+	"crypto/elliptic"
 	"crypto/rand"
 	"crypto/rsa"
 	"crypto/sha256"
@@ -200,20 +201,30 @@ func GetSignerFromPEMBytes(privateKey []byte) (crypto.Signer, error) {
 	}
 }
 
-// copied from https://golang.org/src/crypto/tls/generate_cert.go
-func 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)
-	case *ed25519.PrivateKey:
-		return k.Public().(*ed25519.PublicKey)
+func getSignerHashFromPublic(pub interface{}) (crypto.Hash, error) {
+	// crypto.SHA256
+	switch pub := pub.(type) {
+	case *rsa.PublicKey:
+		return crypto.SHA256, nil
+	case *ecdsa.PublicKey:
+		switch pub.Curve {
+		case elliptic.P224(), elliptic.P256():
+			return crypto.SHA256, nil
+		case elliptic.P384():
+			return crypto.SHA384, nil
+		case elliptic.P521():
+			return crypto.SHA512, nil
+		default:
+			return 0, fmt.Errorf("x509: unknown elliptic curve")
+		}
+	//Ed25519 signatures (by default) dont have a prefered signer
+	case *ed25519.PublicKey, ed25519.PublicKey:
+		return 0, nil
+
 	default:
-		return nil
+		return 0, fmt.Errorf("unknown key type")
 	}
+
 }
 
 // ValidatePublicKeyStrenght checks if the "strength" of the key is good enough to be considered secure
@@ -268,7 +279,11 @@ func GenSelfSignedCACert(commonName string, organization string, caPriv crypto.S
 		return nil, err
 	}
 	sum := sha256.Sum256([]byte(commonName))
-	signedCN, err := caPriv.Sign(rand.Reader, sum[:], crypto.SHA256)
+	hashfunc, err := getSignerHashFromPublic(caPriv.Public())
+	if err != nil {
+		return nil, err
+	}
+	signedCN, err := caPriv.Sign(rand.Reader, sum[:], hashfunc)
 	if err != nil {
 		return nil, err
 	}
@@ -289,7 +304,7 @@ func GenSelfSignedCACert(commonName string, organization string, caPriv crypto.S
 		IsCA:                  true,
 	}
 
-	return x509.CreateCertificate(rand.Reader, &template, &template, publicKey(caPriv), caPriv)
+	return x509.CreateCertificate(rand.Reader, &template, &template, caPriv.Public(), caPriv)
 }
 
 // From RFC 4120 section 5.2.2 (https://tools.ietf.org/html/rfc4120)
diff --git a/lib/certgen/certgen_test.go b/lib/certgen/certgen_test.go
index 882b2d60..84d9ad03 100644
--- a/lib/certgen/certgen_test.go
+++ b/lib/certgen/certgen_test.go
@@ -540,32 +540,35 @@ func TestGenx509CertGoodWithRealm(t *testing.T) {
 
 // GenSelfSignedCACert
 func TestGenSelfSignedCACertGood(t *testing.T) {
-	caPriv, err := GetSignerFromPEMBytes([]byte(testSignerPrivateKey))
-	if err != nil {
-		t.Fatal(err)
-	}
-	derCACert, err := GenSelfSignedCACert("some hostname", "some organization", caPriv)
-	if err != nil {
-		t.Fatal(err)
-	}
+	validPemKeys := []string{testSignerPrivateKey, pkcs8ecPrivateKey, pkcs8Ed25519PrivateKey}
+	for _, signerPem := range validPemKeys {
+		caPriv, err := GetSignerFromPEMBytes([]byte(signerPem))
+		if err != nil {
+			t.Fatal(err)
+		}
+		derCACert, err := GenSelfSignedCACert("some hostname", "some organization", caPriv)
+		if err != nil {
+			t.Fatal(err)
+		}
 
-	cert, pemCert, err := derBytesCertToCertAndPem(derCACert)
-	if err != nil {
-		t.Fatal(err)
-	}
-	t.Logf("got '%s'", pemCert)
+		cert, pemCert, err := derBytesCertToCertAndPem(derCACert)
+		if err != nil {
+			t.Fatal(err)
+		}
+		t.Logf("got '%s'", pemCert)
 
-	// Now we use it to generate a user Cert
-	userPub, err := getPubKeyFromPem(testUserPEMPublicKey)
-	if err != nil {
-		t.Fatal(err)
-	}
-	_, err = GenUserX509Cert("username", userPub, cert, caPriv, nil,
-		testDuration, nil, nil, nil, testlogger.New(t))
-	if err != nil {
-		t.Fatal(err)
+		// Now we use it to generate a user Cert
+		userPub, err := getPubKeyFromPem(testUserPEMPublicKey)
+		if err != nil {
+			t.Fatal(err)
+		}
+		_, err = GenUserX509Cert("username", userPub, cert, caPriv, nil,
+			testDuration, nil, nil, nil, testlogger.New(t))
+		if err != nil {
+			t.Fatal(err)
+		}
+		//t.Logf("got '%s'", certString)
 	}
-	//t.Logf("got '%s'", certString)
 
 }