correctly pack JOSE signatures for ECDSA

vicephp/Virtue-JWT/src/Encoding/ASN1.php

@@ -4,24 +4,27 @@
 
 class ASN1
 {
-    private const INTEGER = 2;
-    private const BIT_STRING = 3;
-    private const OCTET_STRING = 4;
-    private const OBJECT_IDENTIFIER = 6;
-    private const NULL = 5;
-    private const SEQUENCE = 48;
-
+    public const INTEGER = 2;
+    public const BIT_STRING = 3;
+    public const OCTET_STRING = 4;
+    public const OBJECT_IDENTIFIER = 6;
+    public const NULL = 5;
+    public const SEQUENCE = 48;
 
     /** @var int */
     private $type;
 
     /** @var string */
     private $bytes;
 
-    private function __construct(int $type, string $bytes)
+    /** @var string */
+    private $rest;
+
+    private function __construct(int $type, string $bytes, string $rest = "")
     {
         $this->type = $type;
         $this->bytes = $bytes;
+        $this->rest = $rest;
     }
 
     public function encode(): string
@@ -100,4 +103,47 @@ public static function null(): self
     {
         return new self(self::NULL, "");
     }
+
+    public static function decode(string $string): self
+    {
+        $offset = 0;
+        assert(strlen($string) > 1);
+        $type = ord($string[$offset++]);
+
+        $length = ord($string[$offset++]);
+        if ($length & 0x80) {
+            $temp = $length & ~0x80;
+            $result = \unpack("N", str_pad(substr($string, $offset, $temp), 4, "\00", STR_PAD_LEFT));
+            assert($result !== false);
+            assert(count($result) == 1);
+            $length = array_shift($result);
+            assert(is_int($length));
+            $offset += $temp;
+        }
+
+        $bytes = substr($string, $offset, $length);
+        $rest = substr($string, $offset + $length);
+
+        return new self($type, $bytes, $rest);
+    }
+
+    public function bytes(): string
+    {
+        return $this->bytes;
+    }
+
+    public function type(): int
+    {
+        return $this->type;
+    }
+
+    public function rest(): string
+    {
+        return $this->rest;
+    }
+
+    public function length(): int
+    {
+        return strlen($this->bytes);
+    }
 }

vicephp/Virtue-JWT/src/JWT/Algorithms/OpenSSLSign.php

@@ -2,6 +2,7 @@
 
 namespace Virtue\JWT\Algorithms;
 
+use Virtue\Encoding\ASN1;
 use Virtue\JWK\AsymmetricKey;
 use Virtue\JWK\Key\OpenSSL\Exportable;
 use Virtue\JWT\Algorithm;
@@ -58,14 +59,34 @@ public function sign(string $msg): string
 
         $signature = '';
         $success = \openssl_sign($msg, $signature, $private, $this->supported[$this->name]);
+
+        Assert::string($signature);
+        $ecPadding = [
+            'ES256' => 32,
+            'ES384' => 48,
+            'ES512' => 66,
+        ];
+        if (array_key_exists($this->private->alg(), $ecPadding)) {
+            $block = ASN1::decode($signature);
+            assert($block->type() == ASN1::SEQUENCE);
+
+            $block = ASN1::decode($block->bytes());
+            assert($block->type() == ASN1::INTEGER);
+            $x = str_pad(ltrim($block->bytes(), "\00"), $ecPadding[$this->private->alg()], "\00", STR_PAD_LEFT);
+
+            $block = ASN1::decode($block->rest());
+            assert($block->type() == ASN1::INTEGER);
+            $y = str_pad(ltrim($block->bytes(), "\00"), $ecPadding[$this->private->alg()], "\00", STR_PAD_LEFT);
+            $signature = $x . $y;
+        }
+
         //TODO remove together with the support of PHP versions < 8.0
         if (version_compare(PHP_VERSION, '8.0.0') < 0) {
             \openssl_pkey_free($private);
         }
         if (!$success) {
             throw new SignFailed('OpenSSL error: ' . \openssl_error_string());
         } else {
-            Assert::string($signature);
             return $signature;
         }
     }

vicephp/Virtue-JWT/src/JWT/Algorithms/OpenSSLVerify.php

@@ -2,6 +2,7 @@
 
 namespace Virtue\JWT\Algorithms;
 
+use Virtue\Encoding\ASN1;
 use Virtue\JWK\AsymmetricKey;
 use Virtue\JWK\Key\EdDSA;
 use Virtue\JWT\Algorithm;
@@ -63,6 +64,17 @@ public function verify(Token $token): void
         if (!$public = \openssl_pkey_get_public($this->public->asPem())) {
             throw new VerificationFailed('Key is invalid.', VerificationFailed::ON_SIGNATURE);
         }
+        $ecPadding = [
+            'ES256' => 32,
+            'ES384' => 48,
+            'ES512' => 66,
+        ];
+        if (array_key_exists($alg, $ecPadding)) {
+            $x = substr($sig, 0, $ecPadding[$alg]);
+            $y = substr($sig, $ecPadding[$alg]);
+            $sig = ASN1::seq(ASN1::uint(ltrim($x, "\00")), ASN1::uint(ltrim($y, "\00")));
+            $sig = $sig->encode();
+        }
 
         // returns 1 on success, 0 on failure, -1 on error.
         $success = \openssl_verify($msg, $sig, $public, $this->supported[$alg]);

vicephp/Virtue-JWT/tests/Encoding/ASN1Test.php

@@ -48,4 +48,39 @@ public function testOctetString(): void
         $asn1 = ASN1::octstr("Hello World");
         $this->assertEquals("BAtIZWxsbyBXb3JsZA==", $asn1->__toString());
     }
+
+    public function testDecode(): void
+    {
+        $longString = "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA" .
+                      "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA" .
+                      "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA" .
+                      "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA" .
+                      "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA" .
+                      "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA" .
+                      "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA" .
+                      "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA";
+        $asn1 = ASN1::seq(
+            ASN1::int(\strrev(\pack('s', 1337))),
+            ASN1::bitstr($longString),
+        );
+
+        $block = ASN1::decode($asn1->encode());
+        $this->assertEquals(ASN1::SEQUENCE, $block->type());
+        $this->assertEquals(521, $block->length());
+        $this->assertEmpty($block->rest());
+
+        $block = ASN1::decode($block->bytes());
+        $this->assertEquals(ASN1::INTEGER, $block->type());
+        $this->assertEquals(2, $block->length());
+        $this->assertEquals(\strrev(\pack('s', 1337)), $block->bytes());
+        $this->assertNotEmpty($block->rest());
+
+        $block = ASN1::decode($block->rest());
+        $this->assertEquals(ASN1::BIT_STRING, $block->type());
+        $this->assertEquals(strlen($longString) + 1, $block->length());
+        $this->assertEquals("\00" . $longString, $block->bytes());
+        $this->assertEmpty($block->rest());
+
+    }
+
 }

vicephp/Virtue-JWT/tests/JWT/Algorithms/OpenSSLTest.php

@@ -34,7 +34,6 @@ public function testSignRSA(string $alg): void
         $private = new OpenSSL\PrivateKey($alg, $private);
 
         $details = \openssl_pkey_get_details($key);
-        /* var_dump($details['key']); */
         $this->assertNotFalse($details);
         Assert::isMap($details['rsa']);
         Assert::string($details['rsa']['n']);