feat: support octet typed JWK (#587)

Author: apiwat-chantawibul

Diff for: src/JWK.php

@@ -172,6 +172,12 @@ public static function parseKey(array $jwk, ?string $defaultAlg = null): ?Key
                 // This library works internally with EdDSA keys (Ed25519) encoded in standard base64.
                 $publicKey = JWT::convertBase64urlToBase64($jwk['x']);
                 return new Key($publicKey, $jwk['alg']);
+            case 'oct':
+                if (!isset($jwk['k'])) {
+                    throw new UnexpectedValueException('k not set');
+                }
+
+                return new Key(JWT::urlsafeB64Decode($jwk['k']), $jwk['alg']);
             default:
                 break;
         }

Diff for: tests/JWKTest.php

@@ -170,6 +170,31 @@ public function testDecodeByMultiJwkKeySet()
         $this->assertSame('bar', $result->sub);
     }
 
+    public function testDecodeByOctetJwkKeySet()
+    {
+        $jwkSet = json_decode(
+            file_get_contents(__DIR__ . '/data/octet-jwkset.json'),
+            true
+        );
+        $keys = JWK::parseKeySet($jwkSet);
+        $payload = ['sub' => 'foo', 'exp' => strtotime('+10 seconds')];
+        foreach ($keys as $keyId => $key) {
+            $msg = JWT::encode($payload, $key->getKeyMaterial(), $key->getAlgorithm(), $keyId);
+            $result = JWT::decode($msg, $keys);
+
+            $this->assertSame('foo', $result->sub);
+        }
+    }
+
+    public function testOctetJwkMissingK()
+    {
+        $this->expectException(UnexpectedValueException::class);
+        $this->expectExceptionMessage('k not set');
+
+        $badJwk = ['kty' => 'oct', 'alg' => 'HS256'];
+        $keys = JWK::parseKeySet(['keys' => [$badJwk]]);
+    }
+
     public function testParseKey()
     {
         // Use a known module and exponent, and ensure it parses as expected

Diff for: tests/data/octet-jwkset.json

@@ -0,0 +1,22 @@
+{
+    "keys": [
+        {
+            "kty": "oct",
+            "alg": "HS256",
+            "kid": "jwk1",
+            "k": "xUNfVvQ-WdmXB9qp6qK0SrG-yKW4AJqmcSP66Gm2TrE"
+        },
+        {
+            "kty": "oct",
+            "alg": "HS384",
+            "kid": "jwk2",
+            "k": "z7990HoD72QDX9JKqeQc3l7EtXutco72j2YulZMjeakFVDbFGXGDFG4awOF7eu9l"
+        },
+        {
+            "kty": "oct",
+            "alg": "HS512",
+            "kid": "jwk3",
+            "k": "EmYGSDG5W1UjkPIL7LelG-QMVtsXn7bz5lUxBrkqq3kdFEzkLWVGrXKpZxRe7YcApCe0d4s9lXRQtn5Nzaf49w"
+        }
+    ]
+}