Remove extra \0 byte if present (#478)

Author: Spomky

src/Component/Core/Util/ECKey.php

@@ -317,9 +317,12 @@ private static function getKey(JWK $jwk): string
         if (! is_string($y)) {
             throw new InvalidArgumentException('Unable to get the public key');
         }
+        $binX = ltrim(Base64UrlSafe::decode($x), "\0");
+        $binY = ltrim(Base64UrlSafe::decode($y), "\0");
 
         return "\04"
-            . str_pad(Base64UrlSafe::decode($x), $length, "\0", STR_PAD_LEFT)
-            . str_pad(Base64UrlSafe::decode($y), $length, "\0", STR_PAD_LEFT);
+            . str_pad($binX, $length, "\0", STR_PAD_LEFT)
+            . str_pad($binY, $length, "\0", STR_PAD_LEFT)
+        ;
     }
 }

tests/Component/Core/JWKTest.php

@@ -6,6 +6,7 @@
 
 use InvalidArgumentException;
 use Jose\Component\Core\JWK;
+use Jose\Component\Core\Util\ECKey;
 use const JSON_THROW_ON_ERROR;
 use PHPUnit\Framework\TestCase;
 
@@ -136,4 +137,28 @@ public function iCanConvertAPrivateKeyIntoPublicKey(): void
             'kid' => '9876543210',
         ]), json_encode($public, JSON_THROW_ON_ERROR));
     }
+
+    /**
+     * @test
+     * @see https://github.com/web-token/jwt-framework/issues/475
+     */
+    public static function convertToPEM(): void
+    {
+        // Given
+        $key = '{"kty":"EC","crv":"P-256","x":"GDDdmNtwNvlXN04SEUp20BZJ9im6SQqkP8u4d8G6RAk","y":"AIAxkBwTTqbCcNbqbpk8l_Eh-4KtpgyyHkNJ6K4jnvOv","use":"sig","alg":"ES256","kid":"ayRrlw","key_ops":["verify"]}';
+        $jwk = JWK::createFromJson($key);
+        $expectedPEM = <<<'PEM'
+-----BEGIN PUBLIC KEY-----
+MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEGDDdmNtwNvlXN04SEUp20BZJ9im6
+SQqkP8u4d8G6RAmAMZAcE06mwnDW6m6ZPJfxIfuCraYMsh5DSeiuI57zrw==
+-----END PUBLIC KEY-----
+
+PEM;
+
+        //When
+        $pem = ECKey::convertToPEM($jwk);
+
+        //Then
+        static::assertSame($expectedPEM, $pem);
+    }
 }