diff --git a/src/__phutil_library_map__.php b/src/__phutil_library_map__.php
--- a/src/__phutil_library_map__.php
+++ b/src/__phutil_library_map__.php
@@ -212,6 +212,7 @@
     'PhutilLunarPhaseTestCase' => 'utils/__tests__/PhutilLunarPhaseTestCase.php',
     'PhutilMarkupEngine' => 'markup/PhutilMarkupEngine.php',
     'PhutilMarkupTestCase' => 'markup/__tests__/PhutilMarkupTestCase.php',
+    'PhutilMediaWikiAuthAdapter' => 'auth/PhutilMediaWikiAuthAdapter.php',
     'PhutilMemcacheKeyValueCache' => 'cache/PhutilMemcacheKeyValueCache.php',
     'PhutilMethodNotImplementedException' => 'error/PhutilMethodNotImplementedException.php',
     'PhutilMetricsChannel' => 'channel/PhutilMetricsChannel.php',
@@ -620,6 +621,7 @@
     'PhutilLogfileChannel' => 'PhutilChannelChannel',
     'PhutilLunarPhaseTestCase' => 'PhutilTestCase',
     'PhutilMarkupTestCase' => 'PhutilTestCase',
+    'PhutilMediaWikiAuthAdapter' => 'PhutilOAuth1AuthAdapter',
     'PhutilMemcacheKeyValueCache' => 'PhutilKeyValueCache',
     'PhutilMethodNotImplementedException' => 'Exception',
     'PhutilMetricsChannel' => 'PhutilChannelChannel',
diff --git a/src/auth/PhutilMediaWikiAuthAdapter.php b/src/auth/PhutilMediaWikiAuthAdapter.php
new file mode 100644
--- /dev/null
+++ b/src/auth/PhutilMediaWikiAuthAdapter.php
@@ -0,0 +1,206 @@
+<?php
+
+/**
+ * Authentication adapter for MediaWiki OAuth1.
+ */
+final class PhutilMediaWikiAuthAdapter
+    extends PhutilOAuth1AuthAdapter {
+
+  private $userinfo;
+  private $domain = '';
+  private $mediaWikiBaseURI = '';
+
+  public function getWikiPageURI($title, $query_params = null) {
+    $uri = $this->mediaWikiBaseURI;
+    if (substr($uri, -1) != '/') {
+      $uri .= '/';
+    }
+    if (!is_array($query_params)) {
+      $query_params = array();
+    }
+    $query_params['title'] = $title;
+    return $uri.'index.php?'.
+        http_build_query(
+          $query_params,
+          '',
+          '&');
+  }
+
+  public function getAccountID() {
+    $this->getHandshakeData();
+    return idx($this->getUserInfo(), 'userid');
+  }
+
+  public function getAccountName() {
+    return idx($this->getUserInfo(), 'username');
+  }
+
+  public function getAccountURI() {
+    $name = $this->getAccountName();
+    if (strlen($name)) {
+      return $this->getWikiPageURI('User:'.urlencode($name));
+    }
+    return null;
+  }
+
+  public function getAccountImageURI() {
+    $info = $this->getUserInfo();
+    return idx($info, 'profile_image_url');
+  }
+
+  public function getAccountRealName() {
+    $info = $this->getUserInfo();
+    return idx($info, 'name');
+  }
+
+  public function getAdapterType() {
+    return 'mediawiki';
+  }
+
+  public function getAdapterDomain() {
+    return $this->domain;
+  }
+
+  /* mediawiki oauth needs the callback uri to be "oob"
+   (out of band callback) */
+  public function getCallbackURI() {
+    return 'oob';
+  }
+
+  public function shouldAddCSRFTokenToCallbackURI() {
+    return false;
+  }
+
+  protected function getRequestTokenURI() {
+    return $this->getWikiPageURI('Special:OAuth/initiate',
+                  array('oauth_callback' => 'oob'));
+  }
+
+  protected function getAuthorizeTokenURI() {
+    return $this->getWikiPageURI('Special:OAuth/authorize');
+  }
+
+  public function setAdapterDomain($domain) {
+    $this->domain = $domain;
+    return $this;
+  }
+
+  public function setMediaWikiBaseURI($uri) {
+    $this->mediaWikiBaseURI = $uri;
+    return $this;
+  }
+
+  public function getClientRedirectURI() {
+    $p = parent::getClientRedirectURI();
+    return $p."&oauth_consumer_key={$this->getConsumerKey()}";
+  }
+
+  protected function getValidateTokenURI() {
+    return $this->getWikiPageURI('Special:OAuth/token');
+  }
+
+  private function getUserInfo() {
+    if ($this->userinfo === null) {
+      $uri = new PhutilURI(
+        $this->getWikiPageURI('Special:OAuth/identify',
+                        array('format' => 'json')));
+
+      // We gen this so we can check for replay below:
+      $nonce = Filesystem::readRandomCharacters(32);
+      list($body) = $this->newOAuth1Future($uri)
+        ->setMethod('GET')
+        ->setNonce($nonce)
+        ->resolvex();
+      $this->userinfo = $this->decodeAndVerifyJWT($body, $nonce);
+    }
+    return $this->userinfo;
+  }
+
+  protected function willProcessTokenRequestResponse($body) {
+    if (substr_count($body, 'Error:') > 0) {
+      phlog('OAuth provider returned error in response body: '.$body);
+      throw new Exception(
+        pht('OAuth provider returned an error response.'));
+    }
+  }
+
+  /**
+   * MediaWiki uses a signed JWT to assert the user's identity
+   * here we verify the identity, not just the jwt signature.
+   */
+  private function decodeAndVerifyJWT($jwt, $nonce) {
+    $userinfo = array();
+    $identity = $this->decodeJWT($jwt);
+    $iss_uri = new PhutilURI($identity->iss);
+    $expected_uri = new PhutilURI($this->mediaWikiBaseURI);
+
+    $now = time();
+
+    if ($iss_uri->getDomain() !== $expected_uri->getDomain()) {
+      throw new Exception(
+        pht('OAuth JWT iss didn\'t match expected server name'));
+    }
+    if ($identity->aud !== $this->getConsumerKey()) {
+      throw new Exception(
+        pht('OAuth JWT aud didn\'t match expected consumer key'));
+    }
+    if ($identity->iat > $now || $identity->exp < $now) {
+      throw new Exception(
+        pht('OAuth JWT wasn\'t valid at this time'));
+    }
+    if ($identity->nonce !== $nonce) {
+      throw new Exception(
+        pht('OAuth JWT nonce didn\'t match what we sent.'));
+    }
+    $userinfo['userid'] = $identity->sub;
+    $userinfo['username'] = $identity->username;
+    $userinfo['groups'] = $identity->groups;
+    $userinfo['blocked'] = $identity->blocked;
+    $userinfo['editcount'] = $identity->editcount;
+    return $userinfo;
+  }
+
+  /** decode a JWT and verify the signature is valid */
+  private function decodeJWT($jwt) {
+    list($headb64, $bodyb64, $sigb64) = explode('.', $jwt);
+
+    $header = json_decode($this->urlsafeB64Decode($headb64));
+    $body = json_decode($this->urlsafeB64Decode($bodyb64));
+    $sig = $this->urlsafeB64Decode($sigb64);
+
+    $expect_sig = hash_hmac(
+        'sha256',
+        "$headb64.$bodyb64",
+        $this->getConsumerSecret()->openEnvelope(),
+        true);
+
+    // MediaWiki will only use sha256 hmac (HS256) for now.
+    // This checks that an attacker doesn't return invalid JWT signature type.
+    if ($header->alg !== 'HS256' ||
+        !$this->compareHash($sig, $expect_sig)) {
+      throw new Exception('Invalid JWT signature from /identify.');
+    }
+
+    return $body;
+  }
+
+  private function urlsafeB64Decode($input) {
+    $remainder = strlen($input) % 4;
+    if ($remainder) {
+      $padlen = 4 - $remainder;
+      $input .= str_repeat('=', $padlen);
+    }
+    return base64_decode(strtr($input, '-_', '+/'));
+  }
+
+  /** return true if hash1 has the same value as hash2 */
+  private function compareHash($hash1, $hash2) {
+    $result = strlen($hash1) ^ strlen($hash2);
+    $len = min(strlen($hash1), strlen($hash2));
+    for ($i = 0; $i < $len; $i++) {
+        $result |= ord($hash1{$i}) ^ ord($hash2{$i});
+    }
+    // this is just a constant time compare of the two hash strings
+    return $result == 0;
+  }
+}
diff --git a/src/auth/PhutilOAuth1AuthAdapter.php b/src/auth/PhutilOAuth1AuthAdapter.php
--- a/src/auth/PhutilOAuth1AuthAdapter.php
+++ b/src/auth/PhutilOAuth1AuthAdapter.php
@@ -88,6 +88,8 @@
   abstract protected function getAuthorizeTokenURI();
   abstract protected function getValidateTokenURI();
 
+
+
   protected function getSignatureMethod() {
     return 'HMAC-SHA1';
   }
@@ -133,6 +135,9 @@
     }
 
     list($body) = $future->resolvex();
+
+    $this->willProcessTokenRequestResponse($body);
+
     $data = id(new PhutilQueryStringParser())->parseQueryString($body);
 
     // NOTE: Per the spec, this value MUST be the string 'true'.
@@ -198,4 +203,21 @@
     return;
   }
 
+  /**
+   * Hook that allows subclasses to parse errors from the response body
+   * returned by the oauth provider during the token request call
+   */
+  protected function willProcessTokenRequestResponse($body) {
+    return;
+  }
+
+  /**
+   * This tells the authentication provider whether CSRF token should be
+   * added to callback uri and verified after the callback completes.
+   * A subclass can return false to disable the extra CSRF check.
+   */
+  public function shouldAddCSRFTokenToCallbackURI() {
+    return true;
+  }
+
 }