diff -rupN '-x*DS*' /home/a2k/tmp/boost_1_52_0_beta1/boost/asio/ssl/context.hpp asio/ssl/context.hpp
--- /home/a2k/tmp/boost_1_52_0_beta1/boost/asio/ssl/context.hpp	2012-01-15 15:46:25.000000000 +0200
+++ asio/ssl/context.hpp	2012-10-30 18:04:29.392985357 +0200
@@ -28,6 +28,7 @@
 # include <boost/asio/ssl/detail/openssl_init.hpp>
 # include <boost/asio/ssl/detail/password_callback.hpp>
 # include <boost/asio/ssl/detail/verify_callback.hpp>
+# include <boost/asio/ssl/detail/psk_callback.hpp>
 # include <boost/asio/ssl/verify_mode.hpp>
 #endif // defined(BOOST_ASIO_ENABLE_OLD_SSL)

@@ -167,6 +168,15 @@ public:
   BOOST_ASIO_DECL boost::system::error_code set_verify_mode(
       verify_mode v, boost::system::error_code& ec);

+  BOOST_ASIO_DECL void set_psk_identity(const char* psk);
+
+  template <typename PSKCallback>
+  void set_psk_server_callback(PSKCallback callback);
+
+  template <typename PSKCallback>
+  boost::system::error_code set_psk_server_callback(PSKCallback callback,
+      boost::system::error_code& ec);
+
   /// Set the callback used to verify peer certificates.
   /**
    * This function is used to specify a callback function that will be called
@@ -494,6 +504,14 @@ public:
       boost::system::error_code& ec);

 private:
+  // Helper function used to set a peer identity and PSK callback.
+  BOOST_ASIO_DECL boost::system::error_code do_set_psk_server_callback(
+      detail::psk_callback_base* callback, boost::system::error_code& ec);
+
+  // Callback used when the SSL implementation wants to verify a PSK.
+  BOOST_ASIO_DECL static unsigned int psk_server_callback_function(SSL *ssl,
+      const char* identity, unsigned char* psk, unsigned int max_psk_len);
+
   // Helper function used to set a peer certificate verification callback.
   BOOST_ASIO_DECL boost::system::error_code do_set_verify_callback(
       detail::verify_callback_base* callback, boost::system::error_code& ec);
diff -rupN '-x*DS*' /home/a2k/tmp/boost_1_52_0_beta1/boost/asio/ssl/detail/engine.hpp asio/ssl/detail/engine.hpp
--- /home/a2k/tmp/boost_1_52_0_beta1/boost/asio/ssl/detail/engine.hpp	2012-01-15 15:46:25.000000000 +0200
+++ asio/ssl/detail/engine.hpp	2012-10-30 18:04:29.388985026 +0200
@@ -77,6 +77,10 @@ public:
   BOOST_ASIO_DECL boost::system::error_code set_verify_callback(
       verify_callback_base* callback, boost::system::error_code& ec);

+  // Set a peer PSK verification callback
+  BOOST_ASIO_DECL boost::system::error_code set_psk_server_callback(
+      psk_callback_base* callback, boost::system::error_code& ec);
+
   // Perform an SSL handshake using either SSL_connect (client-side) or
   // SSL_accept (server-side).
   BOOST_ASIO_DECL want handshake(
@@ -116,6 +120,9 @@ private:
   BOOST_ASIO_DECL static int verify_callback_function(
       int preverified, X509_STORE_CTX* ctx);

+  BOOST_ASIO_DECL static unsigned int psk_server_callback_function(
+      SSL *ssl, const char* identity, unsigned char* psk, unsigned int max_psk_len);
+
   // The SSL_accept function may not be thread safe. This mutex is used to
   // protect all calls to the SSL_accept function.
   BOOST_ASIO_DECL static boost::asio::detail::static_mutex& accept_mutex();
diff -rupN '-x*DS*' /home/a2k/tmp/boost_1_52_0_beta1/boost/asio/ssl/detail/impl/engine.ipp asio/ssl/detail/impl/engine.ipp
--- /home/a2k/tmp/boost_1_52_0_beta1/boost/asio/ssl/detail/impl/engine.ipp	2012-07-16 09:26:30.000000000 +0300
+++ asio/ssl/detail/impl/engine.ipp	2012-10-30 18:03:44.032985793 +0200
@@ -98,6 +88,20 @@ boost::system::error_code engine::set_ve
   return ec;
 }

+boost::system::error_code engine::set_psk_server_callback(
+    psk_callback_base* callback, boost::system::error_code& ec)
+{
+  if (SSL_get_app_data(ssl_))
+    delete static_cast<psk_callback_base*>(SSL_get_app_data(ssl_));
+
+  SSL_set_app_data(ssl_, callback);
+
+  ::SSL_set_psk_server_callback(ssl_, &engine::psk_server_callback_function);
+
+  ec = boost::system::error_code();
+  return ec;
+}
+
 int engine::verify_callback_function(int preverified, X509_STORE_CTX* ctx)
 {
   if (ctx)
@@ -119,6 +123,22 @@ int engine::verify_callback_function(int
   }

   return 0;
+}
+
+unsigned int engine::psk_server_callback_function(SSL *ssl,
+    const char* identity, unsigned char* psk, unsigned int max_psk_len)
+{
+  if (SSL_get_app_data(ssl))
+  {
+    psk_callback_base* callback =
+      static_cast<psk_callback_base*>(
+          SSL_get_app_data(ssl));
+
+    psk_context psk_ctx(ssl, identity, psk, max_psk_len);
+    return callback->call(psk_ctx);
+  }
+
+  return 0;
 }

 engine::want engine::handshake(
diff -rupN '-x*DS*' /home/a2k/tmp/boost_1_52_0_beta1/boost/asio/ssl/detail/psk_callback.hpp asio/ssl/detail/psk_callback.hpp
--- /home/a2k/tmp/boost_1_52_0_beta1/boost/asio/ssl/detail/psk_callback.hpp	1970-01-01 03:00:00.000000000 +0300
+++ asio/ssl/detail/psk_callback.hpp	2012-10-30 18:18:49.192971249 +0200
@@ -0,0 +1,70 @@
+//
+// ssl/detail/psk_callback.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2012 Roman Bovsunovskiy (a2k0001 at gmail dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_SSL_DETAIL_PSK_CALLBACK_HPP
+#define BOOST_ASIO_SSL_DETAIL_PSK_CALLBACK_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+
+#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
+# include <boost/asio/ssl/psk_context.hpp>
+#endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace ssl {
+namespace detail {
+
+#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
+
+class psk_callback_base
+{
+public:
+  virtual ~psk_callback_base()
+  {
+  }
+
+  virtual unsigned int call(psk_context& ctx) = 0;
+};
+
+template <typename PSKCallback>
+class psk_callback : public psk_callback_base
+{
+public:
+  explicit psk_callback(PSKCallback callback)
+    : callback_(callback)
+  {
+  }
+
+  virtual unsigned int call(psk_context& ctx)
+  {
+    return callback_(ctx);
+  }
+
+private:
+  PSKCallback callback_;
+};
+
+#endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
+
+} // namespace detail
+} // namespace ssl
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_SSL_DETAIL_PSK_CALLBACK_HPP
diff -rupN '-x*DS*' /home/a2k/tmp/boost_1_52_0_beta1/boost/asio/ssl/impl/context.hpp asio/ssl/impl/context.hpp
--- /home/a2k/tmp/boost_1_52_0_beta1/boost/asio/ssl/impl/context.hpp	2012-01-15 15:46:25.000000000 +0200
+++ asio/ssl/impl/context.hpp	2012-10-30 18:04:29.392985357 +0200
@@ -30,6 +30,22 @@ namespace ssl {

 #if !defined(BOOST_ASIO_ENABLE_OLD_SSL)

+template <typename PSKCallback>
+void context::set_psk_server_callback(PSKCallback callback)
+{
+  boost::system::error_code ec;
+  this->set_psk_server_callback(callback, ec);
+  boost::asio::detail::throw_error(ec, "set_psk_callback");
+}
+
+template <typename PSKCallback>
+boost::system::error_code context::set_psk_server_callback(PSKCallback callback,
+    boost::system::error_code& ec)
+{
+  return do_set_psk_server_callback(
+      new detail::psk_callback<PSKCallback>(callback), ec);
+}
+
 template <typename VerifyCallback>
 void context::set_verify_callback(VerifyCallback callback)
 {
diff -rupN '-x*DS*' /home/a2k/tmp/boost_1_52_0_beta1/boost/asio/ssl/impl/context.ipp asio/ssl/impl/context.ipp
--- /home/a2k/tmp/boost_1_52_0_beta1/boost/asio/ssl/impl/context.ipp	2012-01-15 15:46:25.000000000 +0200
+++ asio/ssl/impl/context.ipp	2012-10-30 18:03:44.036986053 +0200
@@ -475,6 +487,36 @@ int context::verify_callback_function(in
   return 0;
 }

+BOOST_ASIO_DECL void context::set_psk_identity(const char* identity)
+{
+  SSL_CTX_use_psk_identity_hint(handle_, identity);
+}
+
+boost::system::error_code context::do_set_psk_server_callback(
+      detail::psk_callback_base* callback, boost::system::error_code& ec)
+{
+  SSL_CTX_set_app_data(handle_, callback);
+
+  ::SSL_CTX_set_psk_server_callback(handle_,
+      &context::psk_server_callback_function);
+
+  ec = boost::system::error_code();
+  return ec;
+}
+
+unsigned int context::psk_server_callback_function(SSL *ssl,
+      const char* identity, unsigned char* psk, unsigned int max_psk_len)
+{
+  SSL_CTX* handle = ::SSL_get_SSL_CTX(ssl);
+
+  detail::psk_callback_base* callback =
+    static_cast<detail::psk_callback_base*>(
+        SSL_CTX_get_app_data(handle));
+
+  psk_context psk_ctx(ssl, identity, psk, max_psk_len);
+  return callback->call(psk_ctx);
+}
+
 boost::system::error_code context::do_set_password_callback(
     detail::password_callback_base* callback, boost::system::error_code& ec)
 {
diff -rupN '-x*DS*' /home/a2k/tmp/boost_1_52_0_beta1/boost/asio/ssl/psk_context.hpp asio/ssl/psk_context.hpp
--- /home/a2k/tmp/boost_1_52_0_beta1/boost/asio/ssl/psk_context.hpp	1970-01-01 03:00:00.000000000 +0300
+++ asio/ssl/psk_context.hpp	2012-10-30 18:18:19.392969787 +0200
@@ -0,0 +1,99 @@
+//
+// ssl/psk_context.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2012 Roman Bovsunovskiy (a2k0001 at gmail dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_SSL_PSK_CONTEXT_HPP
+#define BOOST_ASIO_SSL_PSK_CONTEXT_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+
+#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
+# include <boost/asio/detail/noncopyable.hpp>
+# include <boost/asio/ssl/detail/openssl_types.hpp>
+#endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace ssl {
+
+#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
+
+/**
+ * @note The psk_context does not own the underlying PSK string.
+ */
+class psk_context
+  : private noncopyable
+{
+public:
+  /// The native handle type of the PSK context.
+  typedef SSL* native_handle_ssl_type;
+  typedef const char* native_handle_identity_type;
+  typedef unsigned char* native_handle_psk_type;
+  typedef unsigned int native_handle_psk_maxlen_type;
+
+  /// Constructor.
+  explicit psk_context(native_handle_ssl_type ssl_handle,
+                       native_handle_identity_type identity_handle,
+                       native_handle_psk_type psk_handle,
+                       native_handle_psk_maxlen_type psk_maxlen_handle)
+    : ssl_handle_(ssl_handle_),
+    identity_handle_(identity_handle),
+    psk_handle_(psk_handle),
+    psk_maxlen_handle_(psk_maxlen_handle)
+  {
+  }
+
+  /// Get the underlying implementation in the native type.
+  /**
+   * This function may be used to obtain the underlying implementation of the
+   * context. This is intended to allow access to context functionality that is
+   * not otherwise provided.
+   */
+  native_handle_ssl_type native_ssl_handle()
+  {
+    return ssl_handle_;
+  }
+
+  native_handle_identity_type native_identity_handle()
+  {
+    return identity_handle_;
+  }
+
+  native_handle_psk_type native_psk_handle()
+  {
+    return psk_handle_;
+  }
+  native_handle_psk_maxlen_type native_psk_maxlen_handle()
+  {
+    return psk_maxlen_handle_;
+  }
+
+private:
+  // The underlying native implementation.
+  native_handle_ssl_type ssl_handle_;
+  native_handle_identity_type identity_handle_;
+  native_handle_psk_type psk_handle_;
+  native_handle_psk_maxlen_type psk_maxlen_handle_;
+};
+
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SSL)
+
+} // namespace ssl
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_SSL_PSK_CONTEXT_HPP