Release v0.2.0 - Security and integrity features

- Add REST API response signing using HMAC-SHA256
- Add SHA256 hash validation for version file uploads
- Add ResponseSigner class for automatic API response signing
- Add file_hash column to database schema
- Remove external URL support from version uploads
- Update translations with all fuzzy strings resolved

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/Product/ProductVersion.php

@@ -23,6 +23,7 @@ class ProductVersion
     private ?string $releaseNotes;
     private ?string $downloadUrl;
     private ?int $attachmentId;
+    private ?string $fileHash;
     private bool $isActive;
     private \DateTimeInterface $releasedAt;
     private \DateTimeInterface $createdAt;
@@ -42,6 +43,7 @@ class ProductVersion
         $version->releaseNotes = $data['release_notes'] ?: null;
         $version->downloadUrl = $data['download_url'] ?: null;
         $version->attachmentId = !empty($data['attachment_id']) ? (int) $data['attachment_id'] : null;
+        $version->fileHash = $data['file_hash'] ?? null;
         $version->isActive = (bool) $data['is_active'];
         $version->releasedAt = new \DateTimeImmutable($data['released_at']);
         $version->createdAt = new \DateTimeImmutable($data['created_at']);
@@ -137,15 +139,20 @@ class ProductVersion
         return $this->attachmentId;
     }
 
+    public function getFileHash(): ?string
+    {
+        return $this->fileHash;
+    }
+
     /**
-     * Get the effective download URL (from attachment or direct URL)
+     * Get the download URL from attachment
      */
     public function getEffectiveDownloadUrl(): ?string
     {
         if ($this->attachmentId) {
             return wp_get_attachment_url($this->attachmentId) ?: null;
         }
-        return $this->downloadUrl;
+        return null;
     }
 
     /**
@@ -156,9 +163,6 @@ class ProductVersion
         if ($this->attachmentId) {
             return wp_basename(get_attached_file($this->attachmentId) ?: '');
         }
-        if ($this->downloadUrl) {
-            return wp_basename($this->downloadUrl);
-        }
         return null;
     }
 
@@ -192,6 +196,7 @@ class ProductVersion
             'release_notes' => $this->releaseNotes,
             'download_url' => $this->downloadUrl,
             'attachment_id' => $this->attachmentId,
+            'file_hash' => $this->fileHash,
             'is_active' => $this->isActive,
             'released_at' => $this->releasedAt->format('Y-m-d H:i:s'),
             'created_at' => $this->createdAt->format('Y-m-d H:i:s'),

src/Product/VersionManager.php

@@ -92,16 +92,27 @@ class VersionManager
 
     /**
      * Create a new version
+     *
+     * @throws \InvalidArgumentException If file hash validation fails
      */
     public function createVersion(
         int $productId,
         string $version,
         ?string $releaseNotes = null,
-        ?string $downloadUrl = null,
-        ?int $attachmentId = null
+        ?int $attachmentId = null,
+        ?string $fileHash = null
     ): ?ProductVersion {
         global $wpdb;
 
+        // Validate file hash if both attachment and hash are provided
+        if ($attachmentId !== null && $attachmentId > 0 && $fileHash !== null && $fileHash !== '') {
+            $validatedHash = $this->validateFileHash($attachmentId, $fileHash);
+            if ($validatedHash === false) {
+                return null;
+            }
+            $fileHash = $validatedHash;
+        }
+
         $parsed = ProductVersion::parseVersion($version);
 
         $tableName = Installer::getVersionsTable();
@@ -114,10 +125,9 @@ class VersionManager
             'minor_version' => $parsed['minor'],
             'patch_version' => $parsed['patch'],
             'release_notes' => $releaseNotes,
-            'download_url' => $downloadUrl,
             'is_active' => 1,
         ];
-        $formats = ['%d', '%s', '%d', '%d', '%d', '%s', '%s', '%d'];
+        $formats = ['%d', '%s', '%d', '%d', '%d', '%s', '%d'];
 
         // Only include attachment_id if it's set
         if ($attachmentId !== null && $attachmentId > 0) {
@@ -125,6 +135,12 @@ class VersionManager
             $formats[] = '%d';
         }
 
+        // Only include file_hash if it's set
+        if ($fileHash !== null && $fileHash !== '') {
+            $data['file_hash'] = $fileHash;
+            $formats[] = '%s';
+        }
+
         $result = $wpdb->insert($tableName, $data, $formats);
 
         if ($result === false) {
@@ -136,13 +152,44 @@ class VersionManager
         return $this->getVersionById((int) $wpdb->insert_id);
     }
 
+    /**
+     * Validate file hash against attachment
+     *
+     * @return string|false The validated hash (lowercase) or false on mismatch
+     * @throws \InvalidArgumentException If hash doesn't match
+     */
+    private function validateFileHash(int $attachmentId, string $providedHash): string|false
+    {
+        $filePath = get_attached_file($attachmentId);
+        if (!$filePath || !file_exists($filePath)) {
+            throw new \InvalidArgumentException(
+                __('Attachment file not found.', 'wc-licensed-product')
+            );
+        }
+
+        $calculatedHash = hash_file('sha256', $filePath);
+        $providedHash = strtolower(trim($providedHash));
+
+        if (!hash_equals($calculatedHash, $providedHash)) {
+            throw new \InvalidArgumentException(
+                sprintf(
+                    /* translators: 1: provided hash, 2: calculated hash */
+                    __('File checksum does not match. Expected: %1$s, Got: %2$s', 'wc-licensed-product'),
+                    $providedHash,
+                    $calculatedHash
+                )
+            );
+        }
+
+        return $calculatedHash;
+    }
+
     /**
      * Update a version
      */
     public function updateVersion(
         int $versionId,
         ?string $releaseNotes = null,
-        ?string $downloadUrl = null,
         ?bool $isActive = null,
         ?int $attachmentId = null
     ): bool {
@@ -156,11 +203,6 @@ class VersionManager
             $formats[] = '%s';
         }
 
-        if ($downloadUrl !== null) {
-            $data['download_url'] = $downloadUrl;
-            $formats[] = '%s';
-        }
-
         if ($isActive !== null) {
             $data['is_active'] = $isActive ? 1 : 0;
             $formats[] = '%d';