diff --git a/src/Auth/NativeAuthServer.php b/src/Auth/NativeAuthServer.php
index caad3f8..ff9d220 100644
--- a/src/Auth/NativeAuthServer.php
+++ b/src/Auth/NativeAuthServer.php
@@ -9,6 +9,10 @@
 use Peerme\Mx\UserVerifier;
 use Peerme\MxLaravel\Auth\NativeAuthDecoded;
 use Peerme\MxLaravel\Auth\NativeAuthValidateResult;
+use Peerme\MxLaravel\Exceptions\NativeAuthInvalidSignatureException;
+use Peerme\MxLaravel\Exceptions\NativeAuthInvalidTokenTtlException;
+use Peerme\MxLaravel\Exceptions\NativeAuthOriginNotAcceptedException;
+use Peerme\MxLaravel\Exceptions\NativeAuthTokenExpiredException;
 
 class NativeAuthServer
 {
@@ -32,7 +36,7 @@ public function decode(string $accessToken): NativeAuthDecoded {
 
         [$origin, $blockHash, $ttl, $extraInfo] = $bodyComponents;
 
-        $parsedExtraInfo = $extraInfo === '{}' ? '' : json_decode(base64_decode($this->unescape($extraInfo)));
+        $parsedExtraInfo = $extraInfo === '{}' ? null : json_decode(base64_decode($this->unescape($extraInfo)), true);
         $parsedOrigin = base64_decode($this->unescape($origin));
 
         return new NativeAuthDecoded(
@@ -49,14 +53,13 @@ public function decode(string $accessToken): NativeAuthDecoded {
       public function validate(string $accessToken): NativeAuthValidateResult {
         $decoded = $this->decode($accessToken);
 
-        throw_unless($decoded->ttl <= $this->maxExpirySeconds, InvalidArgumentException::class, 'token expired');
+        throw_unless($decoded->ttl <= $this->maxExpirySeconds, NativeAuthInvalidTokenTtlException::class, $decoded->ttl, $this->maxExpirySeconds);
 
         $hasAcceptedOrigins = count($this->acceptedOrigins) > 0;
         $isInvalidOrigin = !in_array($decoded->origin, $this->acceptedOrigins) && !in_array('https://' . $decoded->origin, $this->acceptedOrigins);
-        throw_if($hasAcceptedOrigins && $isInvalidOrigin, InvalidArgumentException::class, "invalid origin: {$decoded->origin}");
+        throw_if($hasAcceptedOrigins && $isInvalidOrigin, NativeAuthOriginNotAcceptedException::class, $decoded->origin);
 
-        // TODO: implement block timestamp & ttl verification:
-        // https://github.com/multiversx/mx-sdk-js-native-auth-server/blob/5707b04c3d1e40088a1cbe12c3b51fdd6a8ada90/src/native.auth.server.ts#L98
+        $this->ensureNotExpired($decoded);
 
         $verifiable = new SignableMessage(
             message: "{$decoded->address}{$decoded->body}",
@@ -78,7 +81,7 @@ public function validate(string $accessToken): NativeAuthValidateResult {
                 ->verify($verifiable);
         }
 
-        throw_unless($valid, InvalidArgumentException::class, 'invalid signature');
+        throw_unless($valid, NativeAuthInvalidSignatureException::class);
 
         return new NativeAuthValidateResult(
             issued: 1, // TODO implement as part of block timestamp & ttl verification
@@ -89,7 +92,19 @@ public function validate(string $accessToken): NativeAuthValidateResult {
         );
       }
 
-      private function unescape(string $str): string {
+    private function unescape(string $str): string
+    {
         return str_replace(['-', '_'], ['+', '/'], $str);
     }
+
+    private function ensureNotExpired(NativeAuthDecoded $decoded): void
+    {
+        if (isset($decoded->extraInfo['timestamp'])) {
+            $timestamp = $decoded->extraInfo['timestamp'];
+            $expiry = $timestamp + $decoded->ttl;
+            $now = time();
+
+            throw_if($expiry < $now, NativeAuthTokenExpiredException::class);
+        }
+    }
 }
diff --git a/src/Exceptions/NativeAuthInvalidSignatureException.php b/src/Exceptions/NativeAuthInvalidSignatureException.php
new file mode 100644
index 0000000..5b9e48d
--- /dev/null
+++ b/src/Exceptions/NativeAuthInvalidSignatureException.php
@@ -0,0 +1,13 @@
+<?php
+
+namespace Peerme\MxLaravel\Exceptions;
+
+use Exception;
+
+class NativeAuthInvalidSignatureException extends Exception
+{
+    public function __construct()
+    {
+        parent::__construct('Invalid signature');
+    }
+}
diff --git a/src/Exceptions/NativeAuthInvalidTokenTtlException.php b/src/Exceptions/NativeAuthInvalidTokenTtlException.php
new file mode 100644
index 0000000..ccf7dcb
--- /dev/null
+++ b/src/Exceptions/NativeAuthInvalidTokenTtlException.php
@@ -0,0 +1,15 @@
+<?php
+
+namespace Peerme\MxLaravel\Exceptions;
+
+use Exception;
+
+class NativeAuthInvalidTokenTtlException extends Exception
+{
+    public function __construct(int $currentTtl, int $maxTtl)
+    {
+        parent::__construct(
+            "The provided TTL in the token ({$currentTtl}) is larger than the maximum allowed TTL ({$maxTtl})"
+        );
+    }
+}
diff --git a/src/Exceptions/NativeAuthOriginNotAcceptedException.php b/src/Exceptions/NativeAuthOriginNotAcceptedException.php
new file mode 100644
index 0000000..c1c2d53
--- /dev/null
+++ b/src/Exceptions/NativeAuthOriginNotAcceptedException.php
@@ -0,0 +1,13 @@
+<?php
+
+namespace Peerme\MxLaravel\Exceptions;
+
+use Exception;
+
+class NativeAuthOriginNotAcceptedException extends Exception
+{
+    public function __construct(string $origin)
+    {
+        parent::__construct("Origin ({$origin}) not accepted");
+    }
+}
diff --git a/src/Exceptions/NativeAuthTokenExpiredException.php b/src/Exceptions/NativeAuthTokenExpiredException.php
new file mode 100644
index 0000000..08ec831
--- /dev/null
+++ b/src/Exceptions/NativeAuthTokenExpiredException.php
@@ -0,0 +1,13 @@
+<?php
+
+namespace Peerme\MxLaravel\Exceptions;
+
+use Exception;
+
+class NativeAuthTokenExpiredException extends Exception
+{
+    public function __construct()
+    {
+        parent::__construct('Token expired');
+    }
+}
diff --git a/tests/Auth/NativeAuthServerTest.php b/tests/Auth/NativeAuthServerTest.php
index 4d3af5c..5bc7f1f 100644
--- a/tests/Auth/NativeAuthServerTest.php
+++ b/tests/Auth/NativeAuthServerTest.php
@@ -1,18 +1,44 @@
 <?php
 
+use Peerme\Mx\Address;
+use Peerme\Mx\SignableMessage;
+use Peerme\Mx\Signature;
+use Peerme\Mx\UserSigner;
 use Peerme\MxLaravel\Auth\NativeAuthDecoded;
 use Peerme\MxLaravel\Auth\NativeAuthServer;
+use Peerme\MxLaravel\Exceptions\NativeAuthInvalidSignatureException;
+use Peerme\MxLaravel\Exceptions\NativeAuthOriginNotAcceptedException;
+use Peerme\MxLaravel\Exceptions\NativeAuthTokenExpiredException;
 
 beforeEach(function () {
-    $this->address = 'erd1kc7v0lhqu0sclywkgeg4um8ea5nvch9psf2lf8t96j3w622qss8sav2zl8';
-    $this->signature = '1f384391dd1d17dfb75307fff47bcce05aa1a2a2034089d4ea0c54757895c63520169cc5d6eb4414a1b77abfd185655c13bb5a4233eecf258b64ed05dde36c0d';
-    $this->blockHash = '591a3cf6fc0d083179f18640e7c63e2b6a0711f95b9d67910bc525139fce106d';
-    $this->ttl = 86_400;
-    $this->accessToken = 'ZXJkMWtjN3YwbGhxdTBzY2x5d2tnZWc0dW04ZWE1bnZjaDlwc2YybGY4dDk2ajN3NjIycXNzOHNhdjJ6bDg.ZUdWNFkyaGhibWRsTG1OdmJRLjU5MWEzY2Y2ZmMwZDA4MzE3OWYxODY0MGU3YzYzZTJiNmEwNzExZjk1YjlkNjc5MTBiYzUyNTEzOWZjZTEwNmQuODY0MDAuZXlKMGFXMWxjM1JoYlhBaU9qRTJOemN5T0RBeU16Wjk.1f384391dd1d17dfb75307fff47bcce05aa1a2a2034089d4ea0c54757895c63520169cc5d6eb4414a1b77abfd185655c13bb5a4233eecf258b64ed05dde36c0d';
+    $alicePem = "-----BEGIN PRIVATE KEY for erd1qyu5wthldzr8wx5c9ucg8kjagg0jfs53s8nr3zpz3hypefsdd8ssycr6th-----
+    NDEzZjQyNTc1ZjdmMjZmYWQzMzE3YTc3ODc3MTIxMmZkYjgwMjQ1ODUwOTgxZTQ4
+    YjU4YTRmMjVlMzQ0ZThmOTAxMzk0NzJlZmY2ODg2NzcxYTk4MmYzMDgzZGE1ZDQy
+    MWYyNGMyOTE4MWU2Mzg4ODIyOGRjODFjYTYwZDY5ZTE=
+    -----END PRIVATE KEY for erd1qyu5wthldzr8wx5c9ucg8kjagg0jfs53s8nr3zpz3hypefsdd8ssycr6th-----";
+
+    $signer = UserSigner::fromPem($alicePem);
+    $address = 'erd1qyu5wthldzr8wx5c9ucg8kjagg0jfs53s8nr3zpz3hypefsdd8ssycr6th';
+    $blockHash = '591a3cf6fc0d083179f18640e7c63e2b6a0711f95b9d67910bc525139fce106d';
+    $ttl = 86_400;
+    $origin = 'api.multiversx.com';
+    $init = rtrim(base64_encode($origin), '=') . '.' . $blockHash . '.' . $ttl . '.' . 'e30';
+
+    $signature = $signer->sign((new SignableMessage(
+        message: $address.$init,
+        signature: new Signature(''),
+        address: Address::zero(),
+    ))->serializeForSigning())->hex();
+
+    $this->address = $address;
+    $this->signature = $signature;
+    $this->blockHash = $blockHash;
+    $this->ttl = $ttl;
+    $this->accessToken = rtrim(base64_encode($this->address), '=') . '.' . rtrim(base64_encode($init), '=') . '.' . $signature;
     $this->blockTimestamp = 1671009408;
-    $this->origin = 'xexchange.com';
+    $this->origin = $origin;
     $this->nativeServerConfig = [
-        'acceptedOrigins' => ['https://xexchange.com'],
+        'acceptedOrigins' => [$origin],
         'maxExpirySeconds' => 86_400,
         'apiUrl' => 'https://api.multiversx.com',
     ];
@@ -39,14 +65,14 @@
     expect($actual->address)->toBe($this->address);
 });
 
-it('throws if invalid signature in access token', function () {
+it('throws when invalid signature in access token', function () {
     $subject = new NativeAuthServer(...$this->nativeServerConfig);
 
     $subject->validate($this->accessToken.'abcdef');
 })
-    ->expectExceptionMessage('invalid signature');
+    ->expectException(NativeAuthInvalidSignatureException::class);
 
-it('throws if invalid origin', function () {
+it('throws when invalid origin', function () {
     $subject = new NativeAuthServer(...[
         ...$this->nativeServerConfig,
         'acceptedOrigins' => ['other-origin'],
@@ -54,4 +80,14 @@
 
     $subject->validate($this->accessToken);
 })
-    ->expectExceptionMessage('invalid origin');
+    ->expectException(NativeAuthOriginNotAcceptedException::class);
+
+it('throws when extra info timestamp exceeds ttl', function () {
+    $subject = new NativeAuthServer(...[
+        ...$this->nativeServerConfig,
+        'acceptedOrigins' => ['localhost'],
+    ]);
+
+    $subject->validate('ZXJkMXdqeXRmbjZ6aHFmY3NlanZod3Y3cTR1c2F6czVyeWMzajhoYzc4ZmxkZ2pueWN0OHdlanFrYXN1bmM.Ykc5allXeG9iM04wLjE4YmM5ODI0NjFkMWI1M2M4MzdhMjRkZTRiNDYyM2MyYmI4MzU4NjdlYTJlOGRmMTQzNjVjZjQzNmRlZTFiMjMuNjAwLmV5SjBhVzFsYzNSaGJYQWlPakUyTnpNNU56SXpOalI5.f8d651eda06e82a894ff1dc9480a33aa1030b076dfd5983346eec6793381587b88c2daf770a10ac39f9911968c2f1d1304c0c7dd86a82bc79f07e89f873f7e02');
+})
+    ->expectException(NativeAuthTokenExpiredException::class);