fix: use urlsafeB64Decode everywhere (#627)

Author: bshaffer

src/CachedKeySet.php

@@ -180,7 +180,8 @@ private function keyIdExists(string $keyId): bool
             $jwksResponse = $this->httpClient->sendRequest($request);
             if ($jwksResponse->getStatusCode() !== 200) {
                 throw new UnexpectedValueException(
-                    \sprintf('HTTP Error: %d %s for URI "%s"',
+                    \sprintf(
+                        'HTTP Error: %d %s for URI "%s"',
                         $jwksResponse->getStatusCode(),
                         $jwksResponse->getReasonPhrase(),
                         $this->jwksUri,

src/JWT.php

@@ -31,7 +31,7 @@ class JWT
     private const ASN1_SEQUENCE = 0x10;
     private const ASN1_BIT_STRING = 0x03;
 
-    private const RSA_KEY_MIN_LENGTH=2048;
+    private const RSA_KEY_MIN_LENGTH = 2048;
 
     /**
      * When checking nbf, iat or expiration times,
@@ -284,20 +284,8 @@ public static function sign(
                 }
                 return $signature;
             case 'sodium_crypto':
-                if (!\function_exists('sodium_crypto_sign_detached')) {
-                    throw new DomainException('libsodium is not available');
-                }
-                if (!\is_string($key)) {
-                    throw new InvalidArgumentException('key must be a string when using EdDSA');
-                }
                 try {
-                    // The last non-empty line is used as the key.
-                    $lines = array_filter(explode("\n", $key));
-                    $key = base64_decode((string) end($lines));
-                    if (\strlen($key) === 0) {
-                        throw new DomainException('Key cannot be empty string');
-                    }
-                    return sodium_crypto_sign_detached($msg, $key);
+                    return sodium_crypto_sign_detached($msg, self::validateEdDSAKey($key));
                 } catch (Exception $e) {
                     throw new DomainException($e->getMessage(), 0, $e);
                 }
@@ -352,19 +340,8 @@ private static function verify(
                     'OpenSSL error: ' . \openssl_error_string()
                 );
             case 'sodium_crypto':
-                if (!\function_exists('sodium_crypto_sign_verify_detached')) {
-                    throw new DomainException('libsodium is not available');
-                }
-                if (!\is_string($keyMaterial)) {
-                    throw new InvalidArgumentException('key must be a string when using EdDSA');
-                }
                 try {
-                    // The last non-empty line is used as the key.
-                    $lines = array_filter(explode("\n", $keyMaterial));
-                    $key = base64_decode((string) end($lines));
-                    if (\strlen($key) === 0) {
-                        throw new DomainException('Key cannot be empty string');
-                    }
+                    $key = self::validateEdDSAKey($keyMaterial);
                     if (\strlen($signature) === 0) {
                         throw new DomainException('Signature cannot be empty string');
                     }
@@ -473,7 +450,6 @@ public static function urlsafeB64Encode(string $input): string
         return \str_replace('=', '', \strtr(\base64_encode($input), '+/', '-_'));
     }
 
-
     /**
      * Determine if an algorithm has been provided for each Key
      *
@@ -745,4 +721,25 @@ private static function validateEcKeyLength(
             throw new DomainException('Provided key is too short');
         }
     }
+
+    /**
+     * @param string|OpenSSLAsymmetricKey|OpenSSLCertificate  $keyMaterial
+     * @return non-empty-string
+     */
+    private static function validateEdDSAKey(#[\SensitiveParameter] $keyMaterial): string
+    {
+        if (!\function_exists('sodium_crypto_sign_verify_detached')) {
+            throw new DomainException('libsodium is not available');
+        }
+        if (!\is_string($keyMaterial)) {
+            throw new InvalidArgumentException('key must be a string when using EdDSA');
+        }
+        // The last non-empty line is used as the key.
+        $lines = array_filter(explode("\n", $keyMaterial));
+        $key = self::urlsafeB64Decode((string) end($lines));
+        if (\strlen($key) === 0) {
+            throw new DomainException('Key cannot be empty string');
+        }
+        return $key;
+    }
 }

tests/JWTTest.php

@@ -678,6 +678,40 @@ public function provideHmac()
         ];
     }
 
+    public function testEdDsaHandlesBase64UrlKeys()
+    {
+        if (!\extension_loaded('sodium')) {
+            $this->markTestSkipped('libsodium is not available');
+        }
+
+        // Generate a deterministic Ed25519 keypair using a specific seed. The byte "\xfb"
+        // translates to '+' and '/' in standard base64, which become '-' and '_' in Base64URL.
+        // This guarantees our keys will contain the URL-safe characters that get incorrectly
+        // stripped by base64_decode().
+        $seed = str_repeat("\xfb", 32);
+        $keyPair = sodium_crypto_sign_seed_keypair($seed);
+
+        $secretKey = sodium_crypto_sign_secretkey($keyPair);
+        $publicKey = sodium_crypto_sign_publickey($keyPair);
+
+        // Convert the raw keys to Base64URL encoded strings
+        $secretKeyB64u = JWT::urlsafeB64Encode($secretKey);
+        $publicKeyB64u = JWT::urlsafeB64Encode($publicKey);
+
+        // Ensure our test keys actually contain the characters that get
+        // incorrectly stripped by a standard base64_decode().
+        $this->assertTrue(strpos($secretKeyB64u, '-') !== false || strpos($secretKeyB64u, '_') !== false);
+        $this->assertTrue(strpos($publicKeyB64u, '-') !== false || strpos($publicKeyB64u, '_') !== false);
+
+        // Test Encoding
+        $token = JWT::encode(['issue' => 596], $secretKeyB64u, 'EdDSA');
+        $this->assertIsString($token);
+
+        // Test Decoding
+        $decoded = JWT::decode($token, new Key($publicKeyB64u, 'EdDSA'));
+        $this->assertSame(596, $decoded->issue);
+    }
+
     /** @dataProvider provideEcKeyInvalidLength */
     public function testEcKeyLengthValidationThrowsExceptionEncode(string $keyFile, string $alg): void
     {