From 19ae62da453b9121275fb9369fd2fccef2087d11 Mon Sep 17 00:00:00 2001
From: cclohmar <claus.lohmar@lohmar.co.uk>
Date: Sun, 14 Jun 2026 17:24:28 +0000
Subject: [PATCH] feat(auth): use Authelia binary for password hashing instead
 of own argon2

---
 src/core/admin/admin_test.go |  9 ++++++-
 src/core/admin/users.go      | 46 +++++++++++++++++++-----------------
 2 files changed, 32 insertions(+), 23 deletions(-)

diff --git a/src/core/admin/admin_test.go b/src/core/admin/admin_test.go
index 6c4ac9a..c885b64 100644
--- a/src/core/admin/admin_test.go
+++ b/src/core/admin/admin_test.go
@@ -5,6 +5,7 @@ import (
 	"net/http"
 	"net/http/httptest"
 	"os"
+	"os/exec"
 	"path/filepath"
 	"testing"
 
@@ -547,7 +548,13 @@ func TestGeneratePassword(t *testing.T) {
 }
 
 func TestHashPassword(t *testing.T) {
-	hash := hashPassword("test-password")
+	if _, err := exec.LookPath("/opt/authelia/authelia"); err != nil {
+		t.Skip("Authelia binary not available for testing")
+	}
+	hash, err := hashWithAuthelia("test-password")
+	if err != nil {
+		t.Fatalf("hashWithAuthelia failed: %v", err)
+	}
 	if !contains(hash, "$argon2id$") {
 		t.Errorf("expected argon2id prefix, got %q", hash)
 	}
diff --git a/src/core/admin/users.go b/src/core/admin/users.go
index 2b0adb3..1ab1dc5 100644
--- a/src/core/admin/users.go
+++ b/src/core/admin/users.go
@@ -3,11 +3,10 @@ package admin
 import (
 	"crypto/rand"
 	"database/sql"
-	"encoding/base64"
 	"fmt"
 	"math/big"
-
-	"golang.org/x/crypto/argon2"
+	"os/exec"
+	"strings"
 )
 
 // User represents a managed user in the NextWks admin system.
@@ -125,8 +124,13 @@ func (s *UserStore) Create(req CreateUserRequest) []CreateUserResult {
 			continue
 		}
 
-		// Hash password with argon2id
-		hash := hashPassword(password)
+		// Hash password using Authelia's own crypto tool
+		hash, err := hashWithAuthelia(password)
+		if err != nil {
+			result.Error = fmt.Sprintf("password hashing failed: %v", err)
+			results = append(results, result)
+			continue
+		}
 
 		// Default role to "user" if not set
 		if input.Role == "" {
@@ -204,23 +208,21 @@ func generatePassword(length int) (string, error) {
 	return string(result), nil
 }
 
-// hashPassword hashes a password using argon2id (matching Authelia's format).
-func hashPassword(password string) string {
-	salt := make([]byte, 16)
-	rand.Read(salt)
-
-	hash := argon2.IDKey([]byte(password), salt, 3, 65536, 4, 32)
-
-	// Format: $argon2id$v=19$m=65536,t=3,p=4$<salt>$<hash>
-	saltB64 := encodeBase64Raw(salt)
-	hashB64 := encodeBase64Raw(hash)
-
-	return fmt.Sprintf("$argon2id$v=19$m=65536,t=3,p=4$%s$%s", saltB64, hashB64)
-}
-
-// encodeBase64Raw encodes to raw standard base64 (no padding), matching Authelia.
-func encodeBase64Raw(data []byte) string {
-	return base64.RawStdEncoding.EncodeToString(data)
+// hashWithAuthelia uses Authelia's own binary to hash a password.
+func hashWithAuthelia(password string) (string, error) {
+	cmd := exec.Command("/opt/authelia/authelia", "crypto", "hash", "generate", "--password", password)
+	out, err := cmd.Output()
+	if err != nil {
+		return "", fmt.Errorf("authelia hash: %w", err)
+	}
+	// Output format: "Digest: $argon2id$v=19$m=65536,t=3,p=4$salt$hash"
+	fields := strings.Fields(string(out))
+	for _, f := range fields {
+		if strings.HasPrefix(f, "$argon2") {
+			return f, nil
+		}
+	}
+	return "", fmt.Errorf("could not find hash in authelia output: %s", string(out))
 }
 
 // GetDB returns the underlying database connection for sync operations.