feat: implement Nostr NIP-01 WebSocket relay publishing (#129)

- BIP-340 Schnorr signatures over secp256k1 (pure PHP, requires ext-gmp)
- Kind-1 text note events with SHA-256 event ID and tagged hashes
- Raw WebSocket client via stream_socket_client (zero external deps)
- Multi-relay failover: tries each relay until one accepts
- Public key derivation from private key for account display
- Validates 64-char hex private key format and wss:// relay URLs

Authored-by: Moko Consulting

CHANGELOG.md

@@ -1,6 +1,12 @@
 # Changelog
 ## [Unreleased]
 
+### Added
+- **Nostr plugin**: Full NIP-01 WebSocket relay publishing with BIP-340 Schnorr signatures (pure PHP, requires ext-gmp)
+- **Nostr**: Publishes kind-1 text note events to multiple relays with automatic failover
+- **Nostr**: Raw WebSocket client using stream_socket_client (no external dependencies)
+- **Nostr**: Public key derivation and event signing via secp256k1 elliptic curve math
+
 ### Fixed
 - Webservices plugin Joomla 6 compatibility — `onBeforeApiRoute` receives `BeforeApiRouteEvent` object, extract router via `$event->getRouter()`
 

source/packages/plg_mokosuitecross_nostr/language/en-GB/plg_mokosuitecross_nostr.ini

@@ -1,2 +1,2 @@
 PLG_MOKOSUITECROSS_NOSTR="MokoSuiteCross - Nostr"
-PLG_MOKOSUITECROSS_NOSTR_DESCRIPTION="Cross-post Joomla articles to Nostr."
+PLG_MOKOSUITECROSS_NOSTR_DESCRIPTION="Cross-post Joomla articles to Nostr relays via NIP-01 WebSocket protocol. Requires PHP ext-gmp for secp256k1 Schnorr signing."

source/packages/plg_mokosuitecross_nostr/src/Extension/NostrService.php

@@ -20,12 +20,18 @@ use Joomla\Event\SubscriberInterface;
 /**
  * Nostr service plugin for MokoSuiteCross.
  *
- * Nostr uses NIP-01 WebSocket relays for event publishing.
- * This is a stub — full WebSocket implementation is deferred.
- * Events are signed with the private key and sent to configured relays.
+ * Publishes kind-1 text note events to NIP-01 WebSocket relays.
+ * Uses BIP-340 Schnorr signatures over secp256k1 (requires ext-gmp).
+ *
+ * Credentials: private_key (64-char hex nsec), relays (comma-separated wss:// URLs)
  */
 class NostrService extends CMSPlugin implements SubscriberInterface, MokoSuiteCrossServiceInterface
 {
+    private const SECP256K1_P  = 'FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEFFFFFC2F';
+    private const SECP256K1_N  = 'FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141';
+    private const SECP256K1_GX = '79BE667EF9DCBBAC55A06295CE870B07029BFCDB2DCE28D959F2815B16F81798';
+    private const SECP256K1_GY = '483ADA7726A3C4655DA4FBFC0E1108A8FD17B448A68554199C47D08FFB10D4B8';
+
     public static function getSubscribedEvents(): array
     {
         return ['onMokoSuiteCrossGetServices' => 'onMokoSuiteCrossGetServices'];
@@ -43,6 +49,10 @@ class NostrService extends CMSPlugin implements SubscriberInterface, MokoSuiteCr
 
     public function publish(string $message, array $media, array $credentials, array $params): array
     {
+        if (!extension_loaded('gmp')) {
+            return ['success' => false, 'platform_post_id' => '', 'response' => ['error' => 'PHP ext-gmp is required for Nostr signing.']];
+        }
+
         $privateKey = $credentials['private_key'] ?? '';
         $relays     = $credentials['relays'] ?? '';
 
@@ -50,48 +60,393 @@ class NostrService extends CMSPlugin implements SubscriberInterface, MokoSuiteCr
             return ['success' => false, 'platform_post_id' => '', 'response' => ['error' => 'Missing private key or relay URLs.']];
         }
 
-        // Nostr requires WebSocket connections to relays (wss://).
-        // Full NIP-01 event signing and relay publishing is not yet implemented.
+        $privateKey = strtolower(trim($privateKey));
+
+        if (!preg_match('/^[0-9a-f]{64}$/', $privateKey)) {
+            return ['success' => false, 'platform_post_id' => '', 'response' => ['error' => 'Private key must be 64 hex characters.']];
+        }
+
+        $pubkey = $this->getPublicKey($privateKey);
+
+        $event = $this->createEvent($pubkey, $message);
+        $event['sig'] = $this->schnorrSign($event['id'], $privateKey);
+
+        $relayList = array_filter(array_map('trim', explode(',', $relays)));
+        $lastError = '';
+        $published = false;
+
+        foreach ($relayList as $relayUrl) {
+            $result = $this->publishToRelay($relayUrl, $event);
+
+            if ($result['success']) {
+                $published = true;
+                break;
+            }
+
+            $lastError = $result['error'];
+        }
+
+        if (!$published) {
+            return ['success' => false, 'platform_post_id' => '', 'response' => ['error' => 'All relays failed. Last: ' . $lastError]];
+        }
+
         return [
-            'success'          => false,
-            'platform_post_id' => '',
-            'response'         => ['error' => 'Nostr WebSocket relay publishing is not yet implemented. This service will be available in a future release.'],
+            'success'          => true,
+            'platform_post_id' => $event['id'],
+            'response'         => ['event_id' => $event['id'], 'relay' => $relayUrl ?? ''],
         ];
     }
 
     public function validateCredentials(array $credentials): array
     {
-        $privateKey = $credentials['private_key'] ?? '';
+        if (!extension_loaded('gmp')) {
+            return ['valid' => false, 'message' => 'PHP ext-gmp is required for Nostr.', 'account_name' => ''];
+        }
+
+        $privateKey = strtolower(trim($credentials['private_key'] ?? ''));
         $relays     = $credentials['relays'] ?? '';
 
         if (empty($privateKey)) {
             return ['valid' => false, 'message' => 'Private key is required.', 'account_name' => ''];
         }
 
+        if (!preg_match('/^[0-9a-f]{64}$/', $privateKey)) {
+            return ['valid' => false, 'message' => 'Private key must be 64 hex characters.', 'account_name' => ''];
+        }
+
         if (empty($relays)) {
             return ['valid' => false, 'message' => 'At least one relay URL is required.', 'account_name' => ''];
         }
 
-        // Validate that relay URLs look like WebSocket URLs
         $relayList = array_filter(array_map('trim', explode(',', $relays)));
-        $valid     = true;
 
         foreach ($relayList as $relay) {
             if (!str_starts_with($relay, 'wss://') && !str_starts_with($relay, 'ws://')) {
-                $valid = false;
-                break;
+                return ['valid' => false, 'message' => 'Relay URLs must start with wss:// or ws://.', 'account_name' => ''];
             }
         }
 
-        if (!$valid) {
-            return ['valid' => false, 'message' => 'Relay URLs must start with wss:// or ws://.', 'account_name' => ''];
-        }
+        $pubkey = $this->getPublicKey($privateKey);
+        $npub   = substr($pubkey, 0, 16) . '...';
 
-        return ['valid' => true, 'message' => 'Credentials configured (' . count($relayList) . ' relay(s))', 'account_name' => 'Nostr'];
+        return ['valid' => true, 'message' => count($relayList) . ' relay(s) configured', 'account_name' => 'npub:' . $npub];
     }
 
     public function getSupportedMediaTypes(): array
     {
         return [];
     }
+
+    // -- NIP-01 event creation --
+
+    private function createEvent(string $pubkey, string $content, int $kind = 1, array $tags = []): array
+    {
+        $createdAt  = time();
+        $serialized = json_encode([0, $pubkey, $createdAt, $kind, $tags, $content], JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);
+        $id         = hash('sha256', $serialized);
+
+        return [
+            'id'         => $id,
+            'pubkey'     => $pubkey,
+            'created_at' => $createdAt,
+            'kind'       => $kind,
+            'tags'       => $tags,
+            'content'    => $content,
+            'sig'        => '',
+        ];
+    }
+
+    // -- WebSocket relay publishing --
+
+    private function publishToRelay(string $relayUrl, array $event): array
+    {
+        $parsed = parse_url($relayUrl);
+
+        if (!$parsed || !isset($parsed['host'])) {
+            return ['success' => false, 'error' => 'Invalid relay URL'];
+        }
+
+        $scheme = $parsed['scheme'] ?? 'wss';
+        $host   = $parsed['host'];
+        $port   = $parsed['port'] ?? ($scheme === 'wss' ? 443 : 80);
+        $path   = $parsed['path'] ?? '/';
+        $useTls = ($scheme === 'wss');
+
+        $address = ($useTls ? 'tls://' : 'tcp://') . $host . ':' . $port;
+        $context = stream_context_create(['ssl' => ['verify_peer' => true, 'verify_peer_name' => true]]);
+
+        $socket = @stream_socket_client($address, $errno, $errstr, 10, STREAM_CLIENT_CONNECT, $context);
+
+        if (!$socket) {
+            return ['success' => false, 'error' => "Connection failed: {$errstr} ({$errno})"];
+        }
+
+        stream_set_timeout($socket, 10);
+
+        // WebSocket upgrade handshake
+        $wsKey     = base64_encode(random_bytes(16));
+        $handshake = "GET {$path} HTTP/1.1\r\n"
+            . "Host: {$host}\r\n"
+            . "Upgrade: websocket\r\n"
+            . "Connection: Upgrade\r\n"
+            . "Sec-WebSocket-Key: {$wsKey}\r\n"
+            . "Sec-WebSocket-Version: 13\r\n"
+            . "\r\n";
+
+        fwrite($socket, $handshake);
+
+        $response = '';
+
+        while (($line = fgets($socket)) !== false) {
+            $response .= $line;
+
+            if (trim($line) === '') {
+                break;
+            }
+        }
+
+        if (strpos($response, '101') === false) {
+            fclose($socket);
+
+            return ['success' => false, 'error' => 'WebSocket upgrade failed'];
+        }
+
+        // Send EVENT message
+        $payload = json_encode(['EVENT', $event], JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);
+        $this->wsWrite($socket, $payload);
+
+        // Read OK response (with timeout)
+        $reply = $this->wsRead($socket);
+        fclose($socket);
+
+        if ($reply === null) {
+            return ['success' => false, 'error' => 'No response from relay'];
+        }
+
+        $decoded = json_decode($reply, true);
+
+        if (!is_array($decoded) || ($decoded[0] ?? '') !== 'OK') {
+            $msg = is_array($decoded) ? ($decoded[3] ?? $decoded[2] ?? 'Unknown error') : 'Invalid response';
+
+            return ['success' => false, 'error' => (string) $msg];
+        }
+
+        // ["OK", event_id, true/false, message]
+        $accepted = $decoded[2] ?? false;
+
+        if (!$accepted) {
+            return ['success' => false, 'error' => $decoded[3] ?? 'Relay rejected event'];
+        }
+
+        return ['success' => true, 'error' => ''];
+    }
+
+    private function wsWrite($socket, string $data): void
+    {
+        $len    = strlen($data);
+        $frame  = chr(0x81); // text frame, FIN bit set
+        $mask   = random_bytes(4);
+
+        if ($len < 126) {
+            $frame .= chr($len | 0x80); // mask bit set
+        } elseif ($len < 65536) {
+            $frame .= chr(126 | 0x80) . pack('n', $len);
+        } else {
+            $frame .= chr(127 | 0x80) . pack('J', $len);
+        }
+
+        $frame .= $mask;
+
+        for ($i = 0; $i < $len; $i++) {
+            $frame .= $data[$i] ^ $mask[$i % 4];
+        }
+
+        fwrite($socket, $frame);
+    }
+
+    private function wsRead($socket): ?string
+    {
+        $header = fread($socket, 2);
+
+        if ($header === false || strlen($header) < 2) {
+            return null;
+        }
+
+        $len = ord($header[1]) & 0x7F;
+
+        if ($len === 126) {
+            $ext = fread($socket, 2);
+            $len = unpack('n', $ext)[1];
+        } elseif ($len === 127) {
+            $ext = fread($socket, 8);
+            $len = unpack('J', $ext)[1];
+        }
+
+        $masked = (ord($header[1]) & 0x80) !== 0;
+        $mask   = $masked ? fread($socket, 4) : '';
+        $data   = '';
+
+        while (strlen($data) < $len) {
+            $chunk = fread($socket, $len - strlen($data));
+
+            if ($chunk === false) {
+                break;
+            }
+
+            $data .= $chunk;
+        }
+
+        if ($masked) {
+            for ($i = 0; $i < strlen($data); $i++) {
+                $data[$i] = $data[$i] ^ $mask[$i % 4];
+            }
+        }
+
+        return $data;
+    }
+
+    // -- BIP-340 Schnorr signature over secp256k1 --
+
+    private function getPublicKey(string $privateKeyHex): string
+    {
+        $d = gmp_init($privateKeyHex, 16);
+        $G = [gmp_init(self::SECP256K1_GX, 16), gmp_init(self::SECP256K1_GY, 16)];
+
+        $point = $this->ecMultiply($G, $d);
+
+        return str_pad(gmp_strval($point[0], 16), 64, '0', STR_PAD_LEFT);
+    }
+
+    private function schnorrSign(string $messageHex, string $privateKeyHex): string
+    {
+        $p = gmp_init(self::SECP256K1_P, 16);
+        $n = gmp_init(self::SECP256K1_N, 16);
+        $G = [gmp_init(self::SECP256K1_GX, 16), gmp_init(self::SECP256K1_GY, 16)];
+
+        $d  = gmp_init($privateKeyHex, 16);
+        $P  = $this->ecMultiply($G, $d);
+        $px = str_pad(gmp_strval($P[0], 16), 64, '0', STR_PAD_LEFT);
+
+        // BIP-340: if P.y is odd, negate d
+        if (gmp_testbit($P[1], 0)) {
+            $d = gmp_sub($n, $d);
+        }
+
+        $dBytes   = hex2bin(str_pad(gmp_strval($d, 16), 64, '0', STR_PAD_LEFT));
+        $auxRand  = random_bytes(32);
+        $t        = $dBytes ^ $this->taggedHash('BIP0340/aux', $auxRand);
+        $pxBytes  = hex2bin($px);
+        $msgBytes = hex2bin($messageHex);
+
+        $rand = $this->taggedHash('BIP0340/nonce', $t . $pxBytes . $msgBytes);
+        $k0   = gmp_mod(gmp_init(bin2hex($rand), 16), $n);
+
+        if (gmp_cmp($k0, 0) === 0) {
+            return str_repeat('00', 64);
+        }
+
+        $R = $this->ecMultiply($G, $k0);
+        $k = gmp_testbit($R[1], 0) ? gmp_sub($n, $k0) : $k0;
+
+        $rx      = str_pad(gmp_strval($R[0], 16), 64, '0', STR_PAD_LEFT);
+        $rxBytes = hex2bin($rx);
+
+        $eHash = $this->taggedHash('BIP0340/challenge', $rxBytes . $pxBytes . $msgBytes);
+        $e     = gmp_mod(gmp_init(bin2hex($eHash), 16), $n);
+
+        $s = gmp_mod(gmp_add($k, gmp_mul($e, $d)), $n);
+
+        return $rx . str_pad(gmp_strval($s, 16), 64, '0', STR_PAD_LEFT);
+    }
+
+    private function taggedHash(string $tag, string $data): string
+    {
+        $tagHash = hash('sha256', $tag, true);
+
+        return hash('sha256', $tagHash . $tagHash . $data, true);
+    }
+
+    // -- secp256k1 elliptic curve arithmetic --
+
+    private function ecMultiply(array $point, \GMP $scalar): array
+    {
+        $result = null;
+        $addend = $point;
+        $n      = gmp_init(self::SECP256K1_N, 16);
+
+        $scalar = gmp_mod($scalar, $n);
+
+        while (gmp_cmp($scalar, 0) > 0) {
+            if (gmp_testbit($scalar, 0)) {
+                $result = $result === null ? $addend : $this->ecAdd($result, $addend);
+            }
+
+            $addend = $this->ecDouble($addend);
+            $scalar = gmp_div_q($scalar, 2);
+        }
+
+        return $result;
+    }
+
+    private function ecAdd(array $p1, array $p2): array
+    {
+        $prime = gmp_init(self::SECP256K1_P, 16);
+
+        if (gmp_cmp($p1[0], $p2[0]) === 0 && gmp_cmp($p1[1], $p2[1]) === 0) {
+            return $this->ecDouble($p1);
+        }
+
+        $dx = gmp_mod(gmp_sub($p2[0], $p1[0]), $prime);
+
+        if (gmp_cmp($dx, 0) < 0) {
+            $dx = gmp_add($dx, $prime);
+        }
+
+        $dy = gmp_mod(gmp_sub($p2[1], $p1[1]), $prime);
+
+        if (gmp_cmp($dy, 0) < 0) {
+            $dy = gmp_add($dy, $prime);
+        }
+
+        $slope = gmp_mod(gmp_mul($dy, gmp_invert($dx, $prime)), $prime);
+        $x3    = gmp_mod(gmp_sub(gmp_sub(gmp_mul($slope, $slope), $p1[0]), $p2[0]), $prime);
+        $y3    = gmp_mod(gmp_sub(gmp_mul($slope, gmp_sub($p1[0], $x3)), $p1[1]), $prime);
+
+        if (gmp_cmp($x3, 0) < 0) {
+            $x3 = gmp_add($x3, $prime);
+        }
+
+        if (gmp_cmp($y3, 0) < 0) {
+            $y3 = gmp_add($y3, $prime);
+        }
+
+        return [$x3, $y3];
+    }
+
+    private function ecDouble(array $point): array
+    {
+        $prime = gmp_init(self::SECP256K1_P, 16);
+
+        // secp256k1 has a=0, so slope = 3*x^2 / (2*y)
+        $num   = gmp_mod(gmp_mul(3, gmp_mul($point[0], $point[0])), $prime);
+        $denom = gmp_mod(gmp_mul(2, $point[1]), $prime);
+
+        if (gmp_cmp($denom, 0) < 0) {
+            $denom = gmp_add($denom, $prime);
+        }
+
+        $slope = gmp_mod(gmp_mul($num, gmp_invert($denom, $prime)), $prime);
+        $x3    = gmp_mod(gmp_sub(gmp_mul($slope, $slope), gmp_mul(2, $point[0])), $prime);
+        $y3    = gmp_mod(gmp_sub(gmp_mul($slope, gmp_sub($point[0], $x3)), $point[1]), $prime);
+
+        if (gmp_cmp($x3, 0) < 0) {
+            $x3 = gmp_add($x3, $prime);
+        }
+
+        if (gmp_cmp($y3, 0) < 0) {
+            $y3 = gmp_add($y3, $prime);
+        }
+
+        return [$x3, $y3];
+    }
 }