Release v0.7.1 - Bug Fixes & Client Compatibility

## Fixed - CRITICAL: Fixed API Verification Secret not displayed in PHP fallback template - Response signing now includes /update-check endpoint ## Changed - Updated magdev/wc-licensed-product-client to v0.2.2 - Updated symfony/http-client to v7.4.5 Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Update translations for v0.7.1
2026-01-28 12:07:23 +01:00 · 2026-01-28 12:06:45 +01:00 · 2026-01-28 11:38:59 +01:00 · 2026-01-28 11:35:56 +01:00 · 2026-01-28 11:31:56 +01:00 · 2026-01-28 11:28:02 +01:00
22 changed files with 4222 additions and 3629 deletions
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,49 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0

 ## [Unreleased]

+## [0.7.1] - 2026-01-28
+
+### Fixed
+
+- **CRITICAL:** Fixed API Verification Secret not displayed in PHP fallback template on customer account licenses page
+- Response signing now includes `/update-check` endpoint (was missing from signed routes)
+
+### Changed
+
+- Updated `magdev/wc-licensed-product-client` dependency to v0.2.2
+- Updated `symfony/http-client` dependency to v7.4.5
+
+### Technical Details
+
+- Added customer secret display to `displayLicensesFallback()` method in `AccountController`
+- Added `/update-check` route to `ResponseSigner::shouldSign()` method for consistent signature headers
+- Verified server implementation aligns with updated client library documentation
+
+## [0.7.0] - 2026-01-28
+
+### Security
+
+- Fixed XSS vulnerability in checkout blocks DOM fallback injection
+- Unified IP detection for rate limiting across all REST API endpoints
+- Added rate limiting to license transfers (5 per hour) and downloads (30 per hour)
+- Added file size (2MB), row count (1000), and rate limiting to CSV import
+- Added JSON decode error handling in Store API extension
+- Added jQuery selector sanitization for license ID validation
+
+### Added
+
+- New `IpDetectionTrait` for shared IP detection logic with proxy support
+- New `RateLimitTrait` for reusable frontend rate limiting
+- New `src/Common/` directory for shared traits
+
+### Changed
+
+- RestApiController now uses IpDetectionTrait instead of inline methods
+- UpdateController now uses IpDetectionTrait for consistent rate limiting behind proxies
+- AccountController now uses RateLimitTrait for transfer rate limiting
+- DownloadController now uses RateLimitTrait for download rate limiting
+- Checkout blocks fallback uses safe DOM construction instead of innerHTML
+
 ## [0.6.1] - 2026-01-27

 ### Added
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -32,9 +32,9 @@ This project is proudly **"vibe-coded"** using Claude.AI - the entire codebase w

 **Note for AI Assistants:** Clean this section after the specific features are done or new releases are made. Effective changes are tracked in `CHANGELOG.md`. Do not add completed versions here - document them in the Session History section at the end of this file.

-### Version 0.7.0
+### Version 0.7.2

-No changes planned at the moment
+No pending features.

 ## Technical Stack

@@ -55,6 +55,13 @@ No changes planned at the moment
 - Nonce verification on form submissions
 - Output escaping in templates (`esc_attr`, `esc_html`, `esc_js`)
 - Direct file access prevention via `ABSPATH` check
+- XSS-safe DOM construction in JavaScript (no `innerHTML` with user data)
+- Rate limiting on API endpoints (configurable via `WC_LICENSE_RATE_LIMIT`)
+- Rate limiting on frontend operations (transfers: 5/hour, downloads: 30/hour)
+- CSV import limits (2MB max, 1000 rows max, 5-minute cooldown)
+- IP detection with proxy support via `IpDetectionTrait` (supports `WC_LICENSE_TRUSTED_PROXIES`)
+- SQL injection prevention using `$wpdb->prepare()` throughout
+- Secure download URLs with hash verification using `hash_equals()`

 ### Translation Ready

@@ -1782,3 +1789,86 @@ Bug fix and improvement release addressing admin license testing, auto-update se
 **Dependency Updates:**

 - Updated `magdev/wc-licensed-product-client` from v0.2.0 to v0.2.1
+
+### 2026-01-28 - Version 0.7.0 - Security Hardening
+
+**Overview:**
+
+Security-focused release with comprehensive audit and hardening. Performed OWASP Top 10 testing against live shop (shop.magdev.cc) and fixed identified vulnerabilities.
+
+**Security Audit Results:**
+
+- SQL injection: Protected (prepared statements throughout)
+- CSRF: Protected (nonce verification on all forms/AJAX)
+- Rate limiting: Working (429 responses after ~28 requests)
+- Access control: Working (403 for unauthorized access)
+- HTTPS: Enforced with proper redirect
+- Missing security headers noted: X-Frame-Options, HSTS, CSP (server-level configuration)
+
+**Critical Fixes:**
+
+- **XSS in checkout-blocks.js**: Replaced `innerHTML` template literals with safe DOM construction using `document.createElement()` and `textContent`
+- **IP Detection**: UpdateController was using raw `$_SERVER['REMOTE_ADDR']` without proxy support - now uses shared `IpDetectionTrait`
+
+**New Files:**
+
+- `src/Api/IpDetectionTrait.php` - Shared IP detection with proxy header support (Cloudflare, X-Forwarded-For, X-Real-IP)
+- `src/Common/RateLimitTrait.php` - Reusable rate limiting for frontend operations
+
+**Security Enhancements:**
+
+- Added rate limiting to license transfers (5/hour per user)
+- Added rate limiting to file downloads (30/hour per user)
+- Added CSV import limits: 2MB max file size, 1000 max rows, 5-minute cooldown
+- Added JSON error handling in StoreApiExtension
+- Added license ID validation in frontend.js to prevent selector injection
+
+**Modified Files:**
+
+- `assets/js/checkout-blocks.js` - XSS-safe DOM construction
+- `assets/js/frontend.js` - Added `sanitizeForSelector()` helper
+- `src/Api/RestApiController.php` - Use IpDetectionTrait, remove duplicate methods
+- `src/Api/UpdateController.php` - Use IpDetectionTrait for rate limiting
+- `src/Admin/AdminController.php` - CSV import security limits
+- `src/Frontend/AccountController.php` - Transfer rate limiting
+- `src/Frontend/DownloadController.php` - Download rate limiting
+- `src/Checkout/StoreApiExtension.php` - JSON error handling
+
+**Technical Notes:**
+
+- IpDetectionTrait supports `WC_LICENSE_TRUSTED_PROXIES` constant for proxy configuration
+- RateLimitTrait uses WordPress transients with user ID-based keys
+- CSV import constants: `MAX_IMPORT_FILE_SIZE = 2097152`, `MAX_IMPORT_ROWS = 1000`, `IMPORT_RATE_LIMIT_WINDOW = 300`
+
+**Release v0.7.0:**
+
+- Created release package: `releases/wc-licensed-product-0.7.0.zip` (883 KB)
+- SHA256: `12f8452316e350273003f36bf6d7b7121a7bedc9a6964c3d0732d26318d94c18`
+- Tagged as `v0.7.0` and pushed to `main` branch
+
+### 2026-01-28 - Version 0.7.1 - Bug Fixes & Client Compatibility
+
+**Overview:**
+
+Bug fix release ensuring compatibility with updated `magdev/wc-licensed-product-client` v0.2.2 and fixing API Verification Secret display.
+
+**Bug Fixes:**
+
+- **CRITICAL:** Fixed API Verification Secret not displaying on customer account licenses page when using PHP fallback (Twig unavailable)
+- Fixed `/update-check` endpoint responses not being signed (missing from `ResponseSigner::shouldSign()`)
+
+**Dependency Updates:**
+
+- Updated `magdev/wc-licensed-product-client` from `760e1e7` to `56abe8a` (v0.2.2)
+- Updated `symfony/http-client` from v7.4.4 to v7.4.5
+
+**Modified files:**
+
+- `src/Frontend/AccountController.php` - Added customer secret display to PHP fallback method `displayLicensesFallback()`
+- `src/Api/ResponseSigner.php` - Added `/update-check` to `shouldSign()` method
+
+**Technical notes:**
+
+- PHP fallback template now includes the collapsible API Verification Secret section matching the Twig template
+- All four API endpoints (`/validate`, `/status`, `/activate`, `/update-check`) now include signature headers when `WC_LICENSE_SERVER_SECRET` is configured
+- Client library v0.2.2 verified compatible with server implementation
--- a/README.md
+++ b/README.md
@@ -21,6 +21,7 @@ WC Licensed Product adds a new product type "Licensed Product" to WooCommerce, e
 - **Version Binding**: Optional binding to major software versions
 - **Expiration Support**: Set license validity periods or lifetime licenses
 - **Rate Limiting**: API endpoints protected with configurable rate limiting (default: 30 requests/minute)
+- **Frontend Rate Limiting**: Transfer requests (5/hour) and downloads (30/hour) protected against abuse
 - **Trusted Proxy Support**: Configurable trusted proxies for accurate rate limiting behind CDNs
 - **Checkout Blocks**: Full support for WooCommerce Checkout Blocks (default since WC 8.3+)
 - **Self-Licensing**: The plugin can validate its own license (for commercial distribution)
@@ -132,17 +133,26 @@ When a customer purchases a licensed product, they must enter the domain where t
 3. Upload a CSV file (supports exported format or simplified format)
 4. Choose options: skip header row, update existing licenses

+**Import Limits (Security):**
+
+- Maximum file size: 2MB
+- Maximum rows per import: 1000
+- Cooldown between imports: 5 minutes
+
 ## Security

 The plugin implements several security best practices:

 - **Input Sanitization**: All user inputs are sanitized using WordPress functions
 - **Output Escaping**: All output is escaped to prevent XSS attacks
+- **XSS-Safe DOM Construction**: JavaScript uses `createElement()` and `textContent` instead of `innerHTML`
 - **CSRF Protection**: Nonce verification on all forms and AJAX requests
 - **SQL Injection Prevention**: All database queries use prepared statements
 - **Capability Checks**: Admin functions require `manage_woocommerce` capability
 - **Secure Downloads**: File downloads use hash-verified URLs with user authentication
 - **Response Signing**: Optional HMAC-SHA256 signatures for API tamper protection
+- **Rate Limiting**: API and frontend operations protected against abuse
+- **Import Limits**: CSV imports limited by file size, row count, and cooldown period

 ### Trusted Proxy Configuration

--- a/assets/js/checkout-blocks.js
+++ b/assets/js/checkout-blocks.js
@@ -367,64 +367,90 @@
        container.className = 'wc-block-components-licensed-product-wrapper';
        container.style.cssText = 'margin: 20px 0; padding: 16px; background: #f0f0f0; border-radius: 4px;';

+        // Helper function to create elements with text content (XSS-safe)
+        function createEl(tag, textContent, styles) {
+            var el = document.createElement(tag);
+            if (textContent) el.textContent = textContent;
+            if (styles) el.style.cssText = styles;
+            return el;
+        }
+
        if (settings.isMultiDomainEnabled && settings.licensedProducts) {
-            container.innerHTML = `
-                <h4 style="margin: 0 0 8px 0;">${settings.sectionTitle || 'License Domains'}</h4>
-                <p style="margin-bottom: 12px; color: #666; font-size: 0.9em;">
-                    ${settings.fieldDescription || 'Enter a unique domain for each license.'}
-                </p>
-                ${settings.licensedProducts.map(product => {
-                    const productKey = product.variation_id && product.variation_id > 0
-                        ? `${product.product_id}_${product.variation_id}`
-                        : product.product_id;
-                    const durationLabel = product.duration_label || '';
-                    const displayName = durationLabel
-                        ? `${product.name} (${durationLabel})`
+            // Build header safely using DOM methods
+            var header = createEl('h4', settings.sectionTitle || 'License Domains', 'margin: 0 0 8px 0;');
+            container.appendChild(header);
+
+            var desc = createEl('p', settings.fieldDescription || 'Enter a unique domain for each license.',
+                'margin-bottom: 12px; color: #666; font-size: 0.9em;');
+            container.appendChild(desc);
+
+            // Build product sections
+            settings.licensedProducts.forEach(function(product) {
+                var productKey = product.variation_id && product.variation_id > 0
+                    ? product.product_id + '_' + product.variation_id
+                    : String(product.product_id);
+                var durationLabel = product.duration_label || '';
+                var displayName = durationLabel
+                    ? product.name + ' (' + durationLabel + ')'
                    : product.name;

-                    return `
-                    <div style="margin-bottom: 16px; padding: 12px; background: #fff; border-radius: 4px;">
-                        <strong style="display: block; margin-bottom: 8px;">
-                            ${displayName}${product.quantity > 1 ? ` ×${product.quantity}` : ''}
-                        </strong>
-                        ${Array.from({ length: product.quantity }, (_, i) => `
-                            <div style="margin-bottom: 8px;">
-                                <label style="display: block; margin-bottom: 4px;">
-                                    ${(settings.licenseLabel || 'License %d:').replace('%d', i + 1)}
-                                </label>
-                                <input type="text"
-                                    name="licensed_domains[${productKey}][${i}]"
-                                    placeholder="${settings.fieldPlaceholder || 'example.com'}"
-                                    style="width: 100%; padding: 8px; border: 1px solid #ccc; border-radius: 4px;"
-                                />
-                                ${product.variation_id && product.variation_id > 0 ? `
-                                    <input type="hidden"
-                                        name="licensed_variation_ids[${productKey}]"
-                                        value="${product.variation_id}"
-                                    />
-                                ` : ''}
-                            </div>
-                        `).join('')}
-                    </div>
-                `}).join('')}
-            `;
+                var productDiv = createEl('div', null, 'margin-bottom: 16px; padding: 12px; background: #fff; border-radius: 4px;');
+
+                var nameEl = createEl('strong', displayName + (product.quantity > 1 ? ' ×' + product.quantity : ''),
+                    'display: block; margin-bottom: 8px;');
+                productDiv.appendChild(nameEl);
+
+                // Create input fields for each quantity
+                for (var i = 0; i < product.quantity; i++) {
+                    var fieldDiv = createEl('div', null, 'margin-bottom: 8px;');
+
+                    var label = createEl('label', (settings.licenseLabel || 'License %d:').replace('%d', i + 1),
+                        'display: block; margin-bottom: 4px;');
+                    fieldDiv.appendChild(label);
+
+                    var input = document.createElement('input');
+                    input.type = 'text';
+                    input.name = 'licensed_domains[' + productKey + '][' + i + ']';
+                    input.placeholder = settings.fieldPlaceholder || 'example.com';
+                    input.style.cssText = 'width: 100%; padding: 8px; border: 1px solid #ccc; border-radius: 4px;';
+                    fieldDiv.appendChild(input);
+
+                    // Hidden variation ID if applicable
+                    if (product.variation_id && product.variation_id > 0) {
+                        var hiddenInput = document.createElement('input');
+                        hiddenInput.type = 'hidden';
+                        hiddenInput.name = 'licensed_variation_ids[' + productKey + ']';
+                        hiddenInput.value = String(product.variation_id);
+                        fieldDiv.appendChild(hiddenInput);
+                    }
+
+                    productDiv.appendChild(fieldDiv);
+                }
+
+                container.appendChild(productDiv);
+            });
        } else {
-            container.innerHTML = `
-                <h4 style="margin: 0 0 8px 0;">${settings.sectionTitle || 'License Domain'}</h4>
-                <p style="margin-bottom: 12px; color: #666; font-size: 0.9em;">
-                    ${settings.fieldDescription || 'Enter the domain where you will use the license.'}
-                </p>
-                <div style="margin-bottom: 8px;">
-                    <label style="display: block; margin-bottom: 4px;">
-                        ${settings.singleDomainLabel || 'Domain'}
-                    </label>
-                    <input type="text"
-                        name="licensed_product_domain"
-                        placeholder="${settings.fieldPlaceholder || 'example.com'}"
-                        style="width: 100%; padding: 8px; border: 1px solid #ccc; border-radius: 4px;"
-                    />
-                </div>
-            `;
+            // Single domain mode - build safely using DOM methods
+            var header = createEl('h4', settings.sectionTitle || 'License Domain', 'margin: 0 0 8px 0;');
+            container.appendChild(header);
+
+            var desc = createEl('p', settings.fieldDescription || 'Enter the domain where you will use the license.',
+                'margin-bottom: 12px; color: #666; font-size: 0.9em;');
+            container.appendChild(desc);
+
+            var fieldDiv = createEl('div', null, 'margin-bottom: 8px;');
+
+            var label = createEl('label', settings.singleDomainLabel || 'Domain', 'display: block; margin-bottom: 4px;');
+            fieldDiv.appendChild(label);
+
+            var input = document.createElement('input');
+            input.type = 'text';
+            input.name = 'licensed_product_domain';
+            input.placeholder = settings.fieldPlaceholder || 'example.com';
+            input.style.cssText = 'width: 100%; padding: 8px; border: 1px solid #ccc; border-radius: 4px;';
+            fieldDiv.appendChild(input);
+
+            container.appendChild(fieldDiv);
        }

        if (contactInfo) {
--- a/assets/js/frontend.js
+++ b/assets/js/frontend.js
@@ -11,6 +11,14 @@
        $modal: null,
        $form: null,

+        /**
+         * Sanitize a value for safe use in jQuery selectors
+         * License IDs should be numeric only
+         */
+        sanitizeForSelector: function(value) {
+            return String(value).replace(/[^\d]/g, '');
+        },
+
        init: function() {
            this.$modal = $('#wclp-transfer-modal');
            this.$form = $('#wclp-transfer-form');
@@ -171,6 +179,11 @@
            var licenseId = $btn.data('license-id');
            var currentDomain = $btn.data('current-domain');

+            // Validate license ID is numeric
+            if (!licenseId || !/^\d+$/.test(String(licenseId))) {
+                return;
+            }
+
            $('#transfer-license-id').val(licenseId);
            $('#transfer-current-domain').text(currentDomain);
            $('#transfer-new-domain').val('');
@@ -235,9 +248,12 @@
                            .removeClass('error').addClass('success').show();

                        // Update the domain display in the license card
-                        var $domainDisplay = $('.license-domain-display[data-license-id="' + licenseId + '"]');
+                        var safeLicenseId = self.sanitizeForSelector(licenseId);
+                        if (safeLicenseId) {
+                            var $domainDisplay = $('.license-domain-display[data-license-id="' + safeLicenseId + '"]');
                            $domainDisplay.find('.domain-value').text(response.data.new_domain);
                            $domainDisplay.find('.wclp-transfer-btn').data('current-domain', response.data.new_domain);
+                        }

                        // Close modal after a short delay
                        setTimeout(function() {
--- a/composer.lock
+++ b/composer.lock
@@ -12,7 +12,7 @@
            "source": {
                "type": "git",
                "url": "https://src.bundespruefstelle.ch/magdev/wc-licensed-product-client.git",
-                "reference": "760e1e752a0c088fa634cf7ff678e0735ed525a4"
+                "reference": "56abe8a97c72419c07a6daf263ba6f4a9b5fe4b1"
            },
            "require": {
                "php": "^8.3",
@@ -52,7 +52,7 @@
                "issues": "https://src.bundespruefstelle.ch/magdev/wc-licensed-product-client/issues",
                "source": "https://src.bundespruefstelle.ch/magdev/wc-licensed-product-client"
            },
-            "time": "2026-01-27T19:52:12+00:00"
+            "time": "2026-01-28T10:56:47+00:00"
        },
        {
            "name": "psr/cache",
@@ -380,16 +380,16 @@
        },
        {
            "name": "symfony/http-client",
-            "version": "v7.4.4",
+            "version": "v7.4.5",
            "source": {
                "type": "git",
                "url": "https://github.com/symfony/http-client.git",
-                "reference": "d63c23357d74715a589454c141c843f0172bec6c"
+                "reference": "84bb634857a893cc146cceb467e31b3f02c5fe9f"
            },
            "dist": {
                "type": "zip",
-                "url": "https://api.github.com/repos/symfony/http-client/zipball/d63c23357d74715a589454c141c843f0172bec6c",
-                "reference": "d63c23357d74715a589454c141c843f0172bec6c",
+                "url": "https://api.github.com/repos/symfony/http-client/zipball/84bb634857a893cc146cceb467e31b3f02c5fe9f",
+                "reference": "84bb634857a893cc146cceb467e31b3f02c5fe9f",
                "shasum": ""
            },
            "require": {
@@ -457,7 +457,7 @@
                "http"
            ],
            "support": {
-                "source": "https://github.com/symfony/http-client/tree/v7.4.4"
+                "source": "https://github.com/symfony/http-client/tree/v7.4.5"
            },
            "funding": [
                {
@@ -477,7 +477,7 @@
                    "type": "tidelift"
                }
            ],
-            "time": "2026-01-23T16:34:22+00:00"
+            "time": "2026-01-27T16:16:02+00:00"
        },
        {
            "name": "symfony/http-client-contracts",
--- a/docs/server-implementation.md
+++ b/docs/server-implementation.md
@@ -21,7 +21,7 @@ This prevents attackers from:

 ## Requirements

- PHP 7.4+ (8.0+ recommended)
+- PHP 8.3+
 - A server secret stored securely (not in version control)

 ## Server Configuration
@@ -51,25 +51,33 @@ php -r "echo bin2hex(random_bytes(32));"

 ### Key Derivation

-Each license key gets a unique signing key derived from the server secret:
+Each license key gets a unique signing key derived from the server secret using RFC 5869 HKDF:

 ```php
 /**
 * Derive a unique signing key for a license.
 *
- * @param string $licenseKey The license key
- * @param string $serverSecret The server's master secret
- * @return string The derived key (hex encoded)
+ * Uses PHP's native hash_hkdf() function per RFC 5869.
+ *
+ * @param string $licenseKey The license key (used as "info" context)
+ * @param string $serverSecret The server's master secret (used as IKM)
+ * @return string The derived key (hex encoded, 64 characters)
 */
 function derive_signing_key(string $licenseKey, string $serverSecret): string
 {
-    // HKDF-like key derivation
-    $prk = hash_hmac('sha256', $licenseKey, $serverSecret, true);
-
-    return hash_hmac('sha256', $prk . "\x01", $serverSecret);
+    // HKDF key derivation per RFC 5869
+    // IKM: server_secret, Length: 32 bytes, Info: license_key
+    return bin2hex(hash_hkdf('sha256', $serverSecret, 32, $licenseKey));
 }
 ```

+**Important:** This uses PHP's native `hash_hkdf()` function (available since PHP 7.1.2). The parameters are:
+
+- **Algorithm:** sha256
+- **IKM (Input Keying Material):** server_secret
+- **Length:** 32 bytes (256 bits)
+- **Info:** license_key (context-specific information)
+
 ### Response Signing

 Sign every API response before sending:
@@ -88,8 +96,8 @@ function sign_response(array $responseData, string $licenseKey, string $serverSe
    $timestamp = time();
    $signingKey = derive_signing_key($licenseKey, $serverSecret);

-    // Sort keys for consistent ordering
-    ksort($responseData);
+    // Recursively sort keys for consistent ordering (important for nested arrays!)
+    $responseData = recursive_key_sort($responseData);

    // Build signature payload
    $jsonBody = json_encode($responseData, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE);
@@ -103,6 +111,20 @@ function sign_response(array $responseData, string $licenseKey, string $serverSe
        'X-License-Timestamp' => (string) $timestamp,
    ];
 }
+
+/**
+ * Recursively sort array keys alphabetically.
+ */
+function recursive_key_sort(array $data): array
+{
+    ksort($data);
+    foreach ($data as $key => $value) {
+        if (is_array($value)) {
+            $data[$key] = recursive_key_sort($value);
+        }
+    }
+    return $data;
+}
 ```

 ### WordPress REST API Integration
@@ -214,7 +236,7 @@ class ResponseSigner
        $timestamp = time();
        $signingKey = $this->deriveKey($licenseKey);

-        ksort($data);
+        $data = $this->recursiveKeySort($data);
        $payload = $timestamp . ':' . json_encode(
            $data,
            JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE
@@ -226,11 +248,21 @@ class ResponseSigner
        ];
    }

+    private function recursiveKeySort(array $data): array
+    {
+        ksort($data);
+        foreach ($data as $key => $value) {
+            if (is_array($value)) {
+                $data[$key] = $this->recursiveKeySort($value);
+            }
+        }
+        return $data;
+    }
+
    private function deriveKey(string $licenseKey): string
    {
-        $prk = hash_hmac('sha256', $licenseKey, $this->serverSecret, true);
-
-        return hash_hmac('sha256', $prk . "\x01", $this->serverSecret);
+        // HKDF key derivation per RFC 5869
+        return bin2hex(hash_hkdf('sha256', $this->serverSecret, 32, $licenseKey));
    }
 }

@@ -262,8 +294,8 @@ signature = HMAC-SHA256(

 Where:

- `derive_signing_key` uses HKDF-like derivation (see above)
- `canonical_json` sorts keys alphabetically, no escaping of slashes/unicode
+- `derive_signing_key` uses RFC 5869 HKDF: `hash_hkdf('sha256', server_secret, 32, license_key)`
+- `canonical_json` recursively sorts keys alphabetically, no escaping of slashes/unicode
 - Result is hex-encoded (64 characters)

 ## Testing
--- a/languages/wc-licensed-product-de_CH.mo
+++ b/languages/wc-licensed-product-de_CH.mo
--- a/languages/wc-licensed-product-de_CH.po
+++ b/languages/wc-licensed-product-de_CH.po
--- a/languages/wc-licensed-product.pot
+++ b/languages/wc-licensed-product.pot
--- a/releases/wc-licensed-product-0.7.0.zip
+++ b/releases/wc-licensed-product-0.7.0.zip
--- a/releases/wc-licensed-product-0.7.0.zip.sha256
+++ b/releases/wc-licensed-product-0.7.0.zip.sha256
@@ -0,0 +1 @@
+12f8452316e350273003f36bf6d7b7121a7bedc9a6964c3d0732d26318d94c18  wc-licensed-product-0.7.0.zip
--- a/src/Admin/AdminController.php
+++ b/src/Admin/AdminController.php
@@ -18,6 +18,21 @@ use Twig\Environment;
 */
 final class AdminController
 {
+    /**
+     * Maximum CSV file size in bytes (2MB)
+     */
+    private const MAX_IMPORT_FILE_SIZE = 2 * 1024 * 1024;
+
+    /**
+     * Maximum rows to import per file
+     */
+    private const MAX_IMPORT_ROWS = 1000;
+
+    /**
+     * Minimum time between imports in seconds (5 minutes)
+     */
+    private const IMPORT_RATE_LIMIT_WINDOW = 300;
+
    private Environment $twig;
    private LicenseManager $licenseManager;

@@ -653,6 +668,23 @@ final class AdminController
            exit;
        }

+        // Check file size limit
+        if ($file['size'] > self::MAX_IMPORT_FILE_SIZE) {
+            wp_redirect(admin_url('admin.php?page=wc-licenses&action=import_csv&import_error=size'));
+            exit;
+        }
+
+        // Check rate limit for imports
+        $lastImport = get_transient('wclp_last_csv_import_' . get_current_user_id());
+        if ($lastImport !== false && (time() - $lastImport) < self::IMPORT_RATE_LIMIT_WINDOW) {
+            $retryAfter = self::IMPORT_RATE_LIMIT_WINDOW - (time() - $lastImport);
+            wp_redirect(admin_url('admin.php?page=wc-licenses&action=import_csv&import_error=rate_limit&retry_after=' . $retryAfter));
+            exit;
+        }
+
+        // Set rate limit marker
+        set_transient('wclp_last_csv_import_' . get_current_user_id(), time(), self::IMPORT_RATE_LIMIT_WINDOW);
+
        // Read the CSV file
        $handle = fopen($file['tmp_name'], 'r');
        if (!$handle) {
@@ -679,6 +711,7 @@ final class AdminController
        $updated = 0;
        $skipped = 0;
        $errors = [];
+        $rowCount = 0;

        while (($row = fgetcsv($handle)) !== false) {
            // Skip empty rows
@@ -686,6 +719,24 @@ final class AdminController
                continue;
            }

+            // Check row limit
+            $rowCount++;
+            if ($rowCount > self::MAX_IMPORT_ROWS) {
+                fclose($handle);
+                $this->addNotice(
+                    sprintf(
+                        /* translators: %1$d: max rows, %2$d: imported count, %3$d: updated count */
+                        __('Import stopped: Maximum of %1$d rows allowed. %2$d imported, %3$d updated.', 'wc-licensed-product'),
+                        self::MAX_IMPORT_ROWS,
+                        $imported,
+                        $updated
+                    ),
+                    'warning'
+                );
+                wp_redirect(admin_url('admin.php?page=wc-licenses&import_success=partial'));
+                exit;
+            }
+
            // Map CSV columns (expected format from export):
            // ID, License Key, Product, Product ID, Order ID, Order Number, Customer, Customer Email, Customer ID, Domain, Status, Activations, Max Activations, Expires At, Created At, Updated At
            // For import we need: License Key (or generate), Product ID, Customer ID, Domain, Status, Max Activations, Expires At
@@ -1700,6 +1751,21 @@ final class AdminController
                            case 'read':
                                esc_html_e('Error reading file. Please check the file format.', 'wc-licensed-product');
                                break;
+                            case 'size':
+                                printf(
+                                    /* translators: %s: max file size */
+                                    esc_html__('File too large. Maximum size is %s.', 'wc-licensed-product'),
+                                    esc_html(size_format(self::MAX_IMPORT_FILE_SIZE))
+                                );
+                                break;
+                            case 'rate_limit':
+                                $retryAfter = isset($_GET['retry_after']) ? absint($_GET['retry_after']) : self::IMPORT_RATE_LIMIT_WINDOW;
+                                printf(
+                                    /* translators: %d: seconds to wait */
+                                    esc_html__('Please wait %d seconds before importing again.', 'wc-licensed-product'),
+                                    $retryAfter
+                                );
+                                break;
                            default:
                                esc_html_e('An error occurred during import.', 'wc-licensed-product');
                        }
@@ -1708,6 +1774,20 @@ final class AdminController
                </div>
            <?php endif; ?>

+            <div class="notice notice-info" style="max-width: 800px;">
+                <p>
+                    <?php
+                    printf(
+                        /* translators: %1$s: max file size, %2$d: max rows, %3$d: rate limit minutes */
+                        esc_html__('Import limits: Maximum file size %1$s, maximum %2$d rows per import. You can import again after %3$d minutes.', 'wc-licensed-product'),
+                        esc_html(size_format(self::MAX_IMPORT_FILE_SIZE)),
+                        self::MAX_IMPORT_ROWS,
+                        (int) (self::IMPORT_RATE_LIMIT_WINDOW / 60)
+                    );
+                    ?>
+                </p>
+            </div>
+
            <div class="card" style="max-width: 800px; padding: 20px;">
                <h2><?php esc_html_e('Import Licenses from CSV', 'wc-licensed-product'); ?></h2>

--- a/src/Api/IpDetectionTrait.php
+++ b/src/Api/IpDetectionTrait.php
@@ -0,0 +1,168 @@
+<?php
+/**
+ * IP Detection Trait
+ *
+ * Provides shared IP detection logic for API controllers with proxy support.
+ *
+ * @package Jeremias\WcLicensedProduct\Api
+ */
+
+declare(strict_types=1);
+
+namespace Jeremias\WcLicensedProduct\Api;
+
+/**
+ * Trait for detecting client IP addresses with proxy support
+ *
+ * Security note: Only trust proxy headers when explicitly configured.
+ * Set WC_LICENSE_TRUSTED_PROXIES constant in wp-config.php to enable proxy header support.
+ *
+ * Examples:
+ *   define('WC_LICENSE_TRUSTED_PROXIES', 'CLOUDFLARE');
+ *   define('WC_LICENSE_TRUSTED_PROXIES', '10.0.0.1,192.168.1.0/24');
+ */
+trait IpDetectionTrait
+{
+    /**
+     * Get client IP address with proxy support
+     *
+     * @return string Client IP address
+     */
+    protected function getClientIp(): string
+    {
+        // Get the direct connection IP first
+        $remoteAddr = $_SERVER['REMOTE_ADDR'] ?? '0.0.0.0';
+
+        // Only check proxy headers if we're behind a trusted proxy
+        if ($this->isTrustedProxy($remoteAddr)) {
+            // Check headers in order of trust preference
+            $headers = [
+                'HTTP_CF_CONNECTING_IP', // Cloudflare
+                'HTTP_X_FORWARDED_FOR',
+                'HTTP_X_REAL_IP',
+            ];
+
+            foreach ($headers as $header) {
+                if (!empty($_SERVER[$header])) {
+                    $ips = explode(',', $_SERVER[$header]);
+                    $ip = trim($ips[0]);
+                    if (filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE)) {
+                        return $ip;
+                    }
+                }
+            }
+        }
+
+        // Validate and return direct connection IP
+        if (filter_var($remoteAddr, FILTER_VALIDATE_IP)) {
+            return $remoteAddr;
+        }
+
+        return '0.0.0.0';
+    }
+
+    /**
+     * Check if the given IP is a trusted proxy
+     *
+     * @param string $ip The IP address to check
+     * @return bool Whether the IP is a trusted proxy
+     */
+    protected function isTrustedProxy(string $ip): bool
+    {
+        // Check if trusted proxies are configured
+        if (!defined('WC_LICENSE_TRUSTED_PROXIES')) {
+            return false;
+        }
+
+        $trustedProxies = WC_LICENSE_TRUSTED_PROXIES;
+
+        // Handle string constant (comma-separated list)
+        if (is_string($trustedProxies)) {
+            $trustedProxies = array_map('trim', explode(',', $trustedProxies));
+        }
+
+        if (!is_array($trustedProxies)) {
+            return false;
+        }
+
+        // Check for special keywords
+        if (in_array('CLOUDFLARE', $trustedProxies, true)) {
+            if ($this->isCloudflareIp($ip)) {
+                return true;
+            }
+        }
+
+        // Check direct IP match or CIDR notation
+        foreach ($trustedProxies as $proxy) {
+            if ($proxy === $ip) {
+                return true;
+            }
+
+            // Support CIDR notation
+            if (str_contains($proxy, '/') && $this->ipMatchesCidr($ip, $proxy)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    /**
+     * Check if IP is in Cloudflare range
+     *
+     * @param string $ip The IP to check
+     * @return bool Whether IP belongs to Cloudflare
+     */
+    protected function isCloudflareIp(string $ip): bool
+    {
+        // Cloudflare IPv4 ranges (as of 2024)
+        $cloudflareRanges = [
+            '173.245.48.0/20',
+            '103.21.244.0/22',
+            '103.22.200.0/22',
+            '103.31.4.0/22',
+            '141.101.64.0/18',
+            '108.162.192.0/18',
+            '190.93.240.0/20',
+            '188.114.96.0/20',
+            '197.234.240.0/22',
+            '198.41.128.0/17',
+            '162.158.0.0/15',
+            '104.16.0.0/13',
+            '104.24.0.0/14',
+            '172.64.0.0/13',
+            '131.0.72.0/22',
+        ];
+
+        foreach ($cloudflareRanges as $range) {
+            if ($this->ipMatchesCidr($ip, $range)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    /**
+     * Check if an IP matches a CIDR range
+     *
+     * @param string $ip The IP to check
+     * @param string $cidr The CIDR range (e.g., "192.168.1.0/24")
+     * @return bool Whether the IP matches the CIDR range
+     */
+    protected function ipMatchesCidr(string $ip, string $cidr): bool
+    {
+        [$subnet, $bits] = explode('/', $cidr);
+
+        if (!filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4) ||
+            !filter_var($subnet, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4)) {
+            return false;
+        }
+
+        $ipLong = ip2long($ip);
+        $subnetLong = ip2long($subnet);
+        $mask = -1 << (32 - (int) $bits);
+
+        return ($ipLong & $mask) === ($subnetLong & $mask);
+    }
+}
--- a/src/Api/ResponseSigner.php
+++ b/src/Api/ResponseSigner.php
@@ -79,7 +79,8 @@ final class ResponseSigner

        return str_starts_with($route, '/wc-licensed-product/v1/validate')
            || str_starts_with($route, '/wc-licensed-product/v1/status')
-            || str_starts_with($route, '/wc-licensed-product/v1/activate');
+            || str_starts_with($route, '/wc-licensed-product/v1/activate')
+            || str_starts_with($route, '/wc-licensed-product/v1/update-check');
    }

    /**
--- a/src/Api/RestApiController.php
+++ b/src/Api/RestApiController.php
@@ -19,6 +19,7 @@ use WP_REST_Server;
 */
 final class RestApiController
 {
+    use IpDetectionTrait;
    private const NAMESPACE = 'wc-licensed-product/v1';

    /**
@@ -115,154 +116,6 @@ final class RestApiController
        return null;
    }

-    /**
-     * Get client IP address
-     *
-     * Security note: Only trust proxy headers when explicitly configured.
-     * Set WC_LICENSE_TRUSTED_PROXIES constant or configure trusted_proxies
-     * in wp-config.php to enable proxy header support.
-     *
-     * @return string Client IP address
-     */
-    private function getClientIp(): string
-    {
-        // Get the direct connection IP first
-        $remoteAddr = $_SERVER['REMOTE_ADDR'] ?? '0.0.0.0';
-
-        // Only check proxy headers if we're behind a trusted proxy
-        if ($this->isTrustedProxy($remoteAddr)) {
-            // Check headers in order of trust preference
-            $headers = [
-                'HTTP_CF_CONNECTING_IP', // Cloudflare
-                'HTTP_X_FORWARDED_FOR',
-                'HTTP_X_REAL_IP',
-            ];
-
-            foreach ($headers as $header) {
-                if (!empty($_SERVER[$header])) {
-                    $ips = explode(',', $_SERVER[$header]);
-                    $ip = trim($ips[0]);
-                    if (filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE)) {
-                        return $ip;
-                    }
-                }
-            }
-        }
-
-        // Validate and return direct connection IP
-        if (filter_var($remoteAddr, FILTER_VALIDATE_IP)) {
-            return $remoteAddr;
-        }
-
-        return '0.0.0.0';
-    }
-
-    /**
-     * Check if the given IP is a trusted proxy
-     *
-     * @param string $ip The IP address to check
-     * @return bool Whether the IP is a trusted proxy
-     */
-    private function isTrustedProxy(string $ip): bool
-    {
-        // Check if trusted proxies are configured
-        if (!defined('WC_LICENSE_TRUSTED_PROXIES')) {
-            return false;
-        }
-
-        $trustedProxies = WC_LICENSE_TRUSTED_PROXIES;
-
-        // Handle string constant (comma-separated list)
-        if (is_string($trustedProxies)) {
-            $trustedProxies = array_map('trim', explode(',', $trustedProxies));
-        }
-
-        if (!is_array($trustedProxies)) {
-            return false;
-        }
-
-        // Check for special keywords
-        if (in_array('CLOUDFLARE', $trustedProxies, true)) {
-            // Cloudflare IP ranges (simplified - in production, fetch from Cloudflare API)
-            if ($this->isCloudflareIp($ip)) {
-                return true;
-            }
-        }
-
-        // Check direct IP match or CIDR notation
-        foreach ($trustedProxies as $proxy) {
-            if ($proxy === $ip) {
-                return true;
-            }
-
-            // Support CIDR notation
-            if (str_contains($proxy, '/') && $this->ipMatchesCidr($ip, $proxy)) {
-                return true;
-            }
-        }
-
-        return false;
-    }
-
-    /**
-     * Check if IP is in Cloudflare range
-     *
-     * @param string $ip The IP to check
-     * @return bool Whether IP belongs to Cloudflare
-     */
-    private function isCloudflareIp(string $ip): bool
-    {
-        // Cloudflare IPv4 ranges (as of 2024)
-        $cloudflareRanges = [
-            '173.245.48.0/20',
-            '103.21.244.0/22',
-            '103.22.200.0/22',
-            '103.31.4.0/22',
-            '141.101.64.0/18',
-            '108.162.192.0/18',
-            '190.93.240.0/20',
-            '188.114.96.0/20',
-            '197.234.240.0/22',
-            '198.41.128.0/17',
-            '162.158.0.0/15',
-            '104.16.0.0/13',
-            '104.24.0.0/14',
-            '172.64.0.0/13',
-            '131.0.72.0/22',
-        ];
-
-        foreach ($cloudflareRanges as $range) {
-            if ($this->ipMatchesCidr($ip, $range)) {
-                return true;
-            }
-        }
-
-        return false;
-    }
-
-    /**
-     * Check if an IP matches a CIDR range
-     *
-     * @param string $ip The IP to check
-     * @param string $cidr The CIDR range (e.g., "192.168.1.0/24")
-     * @return bool Whether the IP matches the CIDR range
-     */
-    private function ipMatchesCidr(string $ip, string $cidr): bool
-    {
-        [$subnet, $bits] = explode('/', $cidr);
-
-        if (!filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4) ||
-            !filter_var($subnet, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4)) {
-            return false;
-        }
-
-        $ipLong = ip2long($ip);
-        $subnetLong = ip2long($subnet);
-        $mask = -1 << (32 - (int) $bits);
-
-        return ($ipLong & $mask) === ($subnetLong & $mask);
-    }
-
    /**
     * Register REST API routes
     */
--- a/src/Api/UpdateController.php
+++ b/src/Api/UpdateController.php
@@ -26,6 +26,7 @@ use WP_REST_Server;
 */
 final class UpdateController
 {
+    use IpDetectionTrait;
    private const NAMESPACE = 'wc-licensed-product/v1';

    /**
@@ -83,7 +84,7 @@ final class UpdateController
     */
    private function checkRateLimit(): ?WP_REST_Response
    {
-        $ip = $_SERVER['REMOTE_ADDR'] ?? '0.0.0.0';
+        $ip = $this->getClientIp();
        $transientKey = 'wclp_update_rate_' . md5($ip);
        $rateLimit = $this->getRateLimit();
        $rateWindow = $this->getRateWindow();
--- a/src/Checkout/StoreApiExtension.php
+++ b/src/Checkout/StoreApiExtension.php
@@ -200,6 +200,11 @@ final class StoreApiExtension
    {
        $requestData = json_decode(file_get_contents('php://input'), true);

+        // Handle JSON decode errors gracefully
+        if (json_last_error() !== JSON_ERROR_NONE) {
+            $requestData = null;
+        }
+
        if (SettingsController::isMultiDomainEnabled()) {
            $this->processMultiDomainOrder($order, $requestData);
        } else {
@@ -270,7 +275,7 @@ final class StoreApiExtension
        // Check for wclp_license_domains (from our hidden input - JSON string)
        if (empty($domainData) && isset($requestData['wclp_license_domains'])) {
            $parsed = json_decode($requestData['wclp_license_domains'], true);
-            if (is_array($parsed)) {
+            if (json_last_error() === JSON_ERROR_NONE && is_array($parsed)) {
                $domainData = $this->normalizeDomainsData($parsed);
            }
        }
--- a/src/Common/RateLimitTrait.php
+++ b/src/Common/RateLimitTrait.php
@@ -0,0 +1,91 @@
+<?php
+/**
+ * Rate Limit Trait
+ *
+ * Provides rate limiting functionality for frontend operations.
+ *
+ * @package Jeremias\WcLicensedProduct\Common
+ */
+
+declare(strict_types=1);
+
+namespace Jeremias\WcLicensedProduct\Common;
+
+/**
+ * Trait for implementing rate limiting on user actions
+ *
+ * Uses WordPress transients for storage. Rate limits are per-user when logged in,
+ * or per-IP when not logged in.
+ */
+trait RateLimitTrait
+{
+    /**
+     * Check rate limit for a user action
+     *
+     * @param string $action Action identifier (e.g., 'transfer', 'download')
+     * @param int $limit Maximum attempts per window
+     * @param int $window Time window in seconds
+     * @return bool True if within limit, false if exceeded
+     */
+    protected function checkUserRateLimit(string $action, int $limit, int $window): bool
+    {
+        $userId = get_current_user_id();
+        $key = $userId > 0
+            ? (string) $userId
+            : 'ip_' . md5($_SERVER['REMOTE_ADDR'] ?? '0.0.0.0');
+
+        $transientKey = 'wclp_rate_' . $action . '_' . $key;
+        $data = get_transient($transientKey);
+
+        if ($data === false) {
+            // First request, start counting
+            set_transient($transientKey, ['count' => 1, 'start' => time()], $window);
+            return true;
+        }
+
+        $count = (int) ($data['count'] ?? 0);
+        $start = (int) ($data['start'] ?? time());
+
+        // Check if window has expired
+        if (time() - $start >= $window) {
+            // Reset counter
+            set_transient($transientKey, ['count' => 1, 'start' => time()], $window);
+            return true;
+        }
+
+        // Check if limit exceeded
+        if ($count >= $limit) {
+            return false;
+        }
+
+        // Increment counter
+        set_transient($transientKey, ['count' => $count + 1, 'start' => $start], $window);
+        return true;
+    }
+
+    /**
+     * Get remaining time until rate limit resets
+     *
+     * @param string $action Action identifier
+     * @param int $window Time window in seconds (must match the one used in checkUserRateLimit)
+     * @return int Seconds until rate limit resets, or 0 if not rate limited
+     */
+    protected function getRateLimitRetryAfter(string $action, int $window): int
+    {
+        $userId = get_current_user_id();
+        $key = $userId > 0
+            ? (string) $userId
+            : 'ip_' . md5($_SERVER['REMOTE_ADDR'] ?? '0.0.0.0');
+
+        $transientKey = 'wclp_rate_' . $action . '_' . $key;
+        $data = get_transient($transientKey);
+
+        if ($data === false) {
+            return 0;
+        }
+
+        $start = (int) ($data['start'] ?? time());
+
+        return max(0, $window - (time() - $start));
+    }
+}
--- a/src/Frontend/AccountController.php
+++ b/src/Frontend/AccountController.php
@@ -10,6 +10,7 @@ declare(strict_types=1);
 namespace Jeremias\WcLicensedProduct\Frontend;

 use Jeremias\WcLicensedProduct\Api\ResponseSigner;
+use Jeremias\WcLicensedProduct\Common\RateLimitTrait;
 use Jeremias\WcLicensedProduct\License\LicenseManager;
 use Jeremias\WcLicensedProduct\Product\VersionManager;
 use Twig\Environment;
@@ -19,6 +20,8 @@ use Twig\Environment;
 */
 final class AccountController
 {
+    use RateLimitTrait;
+
    private Environment $twig;
    private LicenseManager $licenseManager;
    private VersionManager $versionManager;
@@ -425,6 +428,26 @@ final class AccountController
                                        ?>
                                    </span>
                                </div>
+                                <?php if (ResponseSigner::isSigningEnabled() && !empty($license['customer_secret'])): ?>
+                                    <div class="license-row-secret">
+                                        <button type="button" class="secret-toggle" aria-expanded="false">
+                                            <span class="dashicons dashicons-lock"></span>
+                                            <?php esc_html_e('API Verification Secret', 'wc-licensed-product'); ?>
+                                            <span class="dashicons dashicons-arrow-down-alt2 toggle-arrow"></span>
+                                        </button>
+                                        <div class="secret-content" style="display: none;">
+                                            <p class="secret-description">
+                                                <?php esc_html_e('Use this secret to verify signed API responses. Keep it secure.', 'wc-licensed-product'); ?>
+                                            </p>
+                                            <div class="secret-value-wrapper">
+                                                <code class="secret-value"><?php echo esc_html($license['customer_secret']); ?></code>
+                                                <button type="button" class="copy-secret-btn" data-secret="<?php echo esc_attr($license['customer_secret']); ?>" title="<?php esc_attr_e('Copy to clipboard', 'wc-licensed-product'); ?>">
+                                                    <span class="dashicons dashicons-clipboard"></span>
+                                                </button>
+                                            </div>
+                                        </div>
+                                    </div>
+                                <?php endif; ?>
                            </div>
                        <?php endforeach; ?>
                    </div>
@@ -575,6 +598,15 @@ final class AccountController
     */
    public function handleTransferRequest(): void
    {
+        // Rate limit: 5 transfer attempts per hour per user
+        if (!$this->checkUserRateLimit('transfer', 5, 3600)) {
+            $retryAfter = $this->getRateLimitRetryAfter('transfer', 3600);
+            wp_send_json_error([
+                'message' => __('Too many transfer attempts. Please try again later.', 'wc-licensed-product'),
+                'retry_after' => $retryAfter,
+            ], 429);
+        }
+
        // Verify nonce
        if (!check_ajax_referer('wclp_customer_transfer', 'nonce', false)) {
            wp_send_json_error(['message' => __('Security check failed.', 'wc-licensed-product')], 403);
--- a/src/Frontend/DownloadController.php
+++ b/src/Frontend/DownloadController.php
@@ -9,6 +9,7 @@ declare(strict_types=1);

 namespace Jeremias\WcLicensedProduct\Frontend;

+use Jeremias\WcLicensedProduct\Common\RateLimitTrait;
 use Jeremias\WcLicensedProduct\License\LicenseManager;
 use Jeremias\WcLicensedProduct\Product\VersionManager;

@@ -17,6 +18,8 @@ use Jeremias\WcLicensedProduct\Product\VersionManager;
 */
 final class DownloadController
 {
+    use RateLimitTrait;
+
    private LicenseManager $licenseManager;
    private VersionManager $versionManager;

@@ -110,6 +113,15 @@ final class DownloadController
            exit;
        }

+        // Rate limit: 30 downloads per hour per user
+        if (!$this->checkUserRateLimit('download', 30, 3600)) {
+            wp_die(
+                __('Too many download attempts. Please try again later.', 'wc-licensed-product'),
+                __('Download Error', 'wc-licensed-product'),
+                ['response' => 429]
+            );
+        }
+
        // Get license
        $license = $this->licenseManager->getLicenseById($licenseId);
        if (!$license) {
--- a/wc-licensed-product.php
+++ b/wc-licensed-product.php
@@ -3,7 +3,7 @@
 * Plugin Name: WooCommerce Licensed Product
 * Plugin URI: https://src.bundespruefstelle.ch/magdev/wc-licensed-product
 * Description: WooCommerce plugin to sell software products using license keys with domain-based validation.
- * Version: 0.6.1
+ * Version: 0.7.1
 * Author: Marco Graetsch
 * Author URI: https://src.bundespruefstelle.ch/magdev
 * License: GPL-2.0-or-later
@@ -28,7 +28,7 @@ if (!defined('ABSPATH')) {
 }

 // Plugin constants
-define('WC_LICENSED_PRODUCT_VERSION', '0.6.1');
+define('WC_LICENSED_PRODUCT_VERSION', '0.7.1');
 define('WC_LICENSED_PRODUCT_PLUGIN_FILE', __FILE__);
 define('WC_LICENSED_PRODUCT_PLUGIN_DIR', plugin_dir_path(__FILE__));
 define('WC_LICENSED_PRODUCT_PLUGIN_URL', plugin_dir_url(__FILE__));
Author	SHA1	Message	Date
magdev	2d6bfa219a	Release v0.7.1 - Bug Fixes & Client Compatibility ## Fixed - CRITICAL: Fixed API Verification Secret not displayed in PHP fallback template - Response signing now includes /update-check endpoint ## Changed - Updated magdev/wc-licensed-product-client to v0.2.2 - Updated symfony/http-client to v7.4.5 Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>	2026-01-28 12:07:23 +01:00
magdev	302f2e76ca	Update translations for v0.7.1 - Regenerated .pot template with 388 strings - All German (de_CH) translations up to date - Compiled .mo file for production Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>	2026-01-28 12:06:45 +01:00
magdev	5938aaed1b	Update documentation for v0.7.0 security features README.md: - Added frontend rate limiting info (transfers: 5/hour, downloads: 30/hour) - Added CSV import limits section (2MB, 1000 rows, 5-min cooldown) - Added XSS-safe DOM construction to security section - Added rate limiting and import limits to security best practices docs/server-implementation.md: - Updated PHP requirement to 8.3+ - Fixed key derivation to use RFC 5869 hash_hkdf() (v0.5.5 fix) - Added recursive key sorting for signature generation - Updated signature algorithm documentation Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>	2026-01-28 11:38:59 +01:00
magdev	630a5859d3	Update CLAUDE.md with v0.7.0 security documentation - Updated Security Best Practices section with v0.7.0 security measures - Cleared Temporary Roadmap (v0.7.0 completed) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>	2026-01-28 11:35:56 +01:00
magdev	36e1fdc20a	Add release package for v0.7.0 - Release package: wc-licensed-product-0.7.0.zip (883 KB) - SHA256: 12f8452316e350273003f36bf6d7b7121a7bedc9a6964c3d0732d26318d94c18 Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>	2026-01-28 11:31:56 +01:00
magdev	cbece2f279	Update CLAUDE.md with v0.7.0 session history Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>	2026-01-28 11:28:02 +01:00
magdev	b50969f701	Release v0.7.0 - Security Hardening Security Fixes: - Fixed XSS vulnerability in checkout blocks DOM injection (replaced innerHTML with safe DOM methods) - Unified IP detection for rate limiting across all API endpoints (new IpDetectionTrait) - Added rate limiting to license transfers (5/hour) and downloads (30/hour) (new RateLimitTrait) - Added file size limit (2MB), row limit (1000), and rate limiting to CSV import - Added JSON decode error handling in StoreApiExtension - Added license ID validation in frontend.js to prevent selector injection New Files: - src/Api/IpDetectionTrait.php - Shared IP detection with proxy support - src/Common/RateLimitTrait.php - Reusable rate limiting for frontend operations Breaking Changes: - None Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>	2026-01-28 11:27:08 +01:00
magdev	d0af939f5e	Update translations for v0.7.0 Added new translatable strings for security features: - Rate limiting messages for transfers and downloads - CSV import security limits (file size, row count, rate limit) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>	2026-01-28 11:25:49 +01:00
magdev	c1a337aabe	Update CLAUDE.md with v0.6.1 session history Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>	2026-01-27 21:25:34 +01:00
				`@@ -0,0 +1 @@`
				`12f8452316e350273003f36bf6d7b7121a7bedc9a6964c3d0732d26318d94c18 wc-licensed-product-0.7.0.zip`