diff --git a/lib/gssapi/Makefile.am b/lib/gssapi/Makefile.am
index ab6e7c553..464dd9b7e 100644
--- a/lib/gssapi/Makefile.am
+++ b/lib/gssapi/Makefile.am
@@ -202,6 +202,7 @@ ntlmsrc = \
 	ntlm/process_context_token.c \
 	ntlm/release_cred.c \
 	ntlm/release_name.c \
+	ntlm/set_sec_context_option.c \
 	ntlm/kdc.c
 
 $(srcdir)/ntlm/ntlm-private.h: $(ntlmsrc)
diff --git a/lib/gssapi/NTMakefile b/lib/gssapi/NTMakefile
index 501345825..54a6dffe3 100644
--- a/lib/gssapi/NTMakefile
+++ b/lib/gssapi/NTMakefile
@@ -218,6 +218,7 @@ ntlmsrc = \
 	ntlm/process_context_token.c \
 	ntlm/release_cred.c \
 	ntlm/release_name.c \
+	ntlm/set_sec_context_option.c \
 	ntlm/kdc.c
 
 $(OBJ)\ntlm\ntlm-private.h: $(ntlmsrc)
@@ -442,6 +443,7 @@ libgssapi_OBJs = \
 	$(OBJ)\ntlm/process_context_token.obj \
 	$(OBJ)\ntlm/release_cred.obj \
 	$(OBJ)\ntlm/release_name.obj \
+	$(OBJ)\ntlm/set_sec_context_option.obj \
 	$(OBJ)\ntlm/kdc.obj \
 	$(OBJ)\gkrb5_err.obj \
 	$(spnego_files:.x=.obj) \
diff --git a/lib/gssapi/gssapi/gssapi_oid.h b/lib/gssapi/gssapi/gssapi_oid.h
index a61466144..30ffbe4ad 100644
--- a/lib/gssapi/gssapi/gssapi_oid.h
+++ b/lib/gssapi/gssapi/gssapi_oid.h
@@ -148,6 +148,9 @@ extern GSSAPI_LIB_VARIABLE gss_OID_desc __gss_spnego_mechanism_oid_desc;
 extern GSSAPI_LIB_VARIABLE gss_OID_desc __gss_c_peer_has_updated_spnego_oid_desc;
 #define GSS_C_PEER_HAS_UPDATED_SPNEGO (&__gss_c_peer_has_updated_spnego_oid_desc)
 
+extern GSSAPI_LIB_VARIABLE gss_OID_desc __gss_c_ntlm_reset_crypto_oid_desc;
+#define GSS_C_NTLM_RESET_CRYPTO (&__gss_c_ntlm_reset_crypto_oid_desc)
+
 /*
  * OID mappings with name and short description and and slightly longer description
  */
diff --git a/lib/gssapi/mech/gss_oid.c b/lib/gssapi/mech/gss_oid.c
index f2e1562e4..5b9bd3623 100644
--- a/lib/gssapi/mech/gss_oid.c
+++ b/lib/gssapi/mech/gss_oid.c
@@ -136,6 +136,9 @@ gss_OID_desc GSSAPI_LIB_VARIABLE __gss_spnego_mechanism_oid_desc = { 6, rk_UNCON
 /* GSS_C_PEER_HAS_UPDATED_SPNEGO - 1.3.6.1.4.1.5322.19.5 */
 gss_OID_desc GSSAPI_LIB_VARIABLE __gss_c_peer_has_updated_spnego_oid_desc = { 9, rk_UNCONST("\x2b\x06\x01\x04\x01\xa9\x4a\x13\x05") };
 
+/* GSS_C_NTLM_RESET_CRYPTO - 1.3.6.1.4.1.7165.655.1.3 */
+gss_OID_desc GSSAPI_LIB_VARIABLE __gss_c_ntlm_reset_crypto_oid_desc = { 11, rk_UNCONST("\x2b\x06\x01\x04\x01\xb7\x7d\x85\x0f\x01\x03") };
+
 /* GSS_C_MA_MECH_CONCRETE - 1.3.6.1.5.5.13.1 */
 gss_OID_desc GSSAPI_LIB_VARIABLE __gss_c_ma_mech_concrete_oid_desc = { 7, rk_UNCONST("\x2b\x06\x01\x05\x05\x0d\x01") };
 
@@ -304,6 +307,7 @@ gss_OID _gss_ot_internal[] = {
   &__gss_ntlm_mechanism_oid_desc,
   &__gss_spnego_mechanism_oid_desc,
   &__gss_c_peer_has_updated_spnego_oid_desc,
+  &__gss_c_ntlm_reset_crypto_oid_desc,
   &__gss_c_ma_mech_concrete_oid_desc,
   &__gss_c_ma_mech_pseudo_oid_desc,
   &__gss_c_ma_mech_composite_oid_desc,
diff --git a/lib/gssapi/ntlm/accept_sec_context.c b/lib/gssapi/ntlm/accept_sec_context.c
index 1dbfb9d97..b169f788d 100644
--- a/lib/gssapi/ntlm/accept_sec_context.c
+++ b/lib/gssapi/ntlm/accept_sec_context.c
@@ -237,28 +237,7 @@ _gss_ntlm_accept_sec_context
 	    return GSS_S_FAILURE;
 	}
 
-	if (session.length != 0) {
-
-	    ctx->status |= STATUS_SESSIONKEY;
-
-	    if (ctx->flags & NTLM_NEG_NTLM2_SESSION) {
-		_gss_ntlm_set_key(&ctx->u.v2.send, 1,
-				  (ctx->flags & NTLM_NEG_KEYEX),
-				  ctx->sessionkey.data,
-				  ctx->sessionkey.length);
-		_gss_ntlm_set_key(&ctx->u.v2.recv, 0,
-				  (ctx->flags & NTLM_NEG_KEYEX),
-				  ctx->sessionkey.data,
-				  ctx->sessionkey.length);
-	    } else {
-		RC4_set_key(&ctx->u.v1.crypto_send.key,
-			    ctx->sessionkey.length,
-			    ctx->sessionkey.data);
-		RC4_set_key(&ctx->u.v1.crypto_recv.key,
-			    ctx->sessionkey.length,
-			    ctx->sessionkey.data);
-	    }
-	}
+	_gss_ntlm_set_keys(ctx);
 
 	if (mech_type)
 	    *mech_type = GSS_NTLM_MECHANISM;
diff --git a/lib/gssapi/ntlm/crypto.c b/lib/gssapi/ntlm/crypto.c
index 40469a7a7..20f7377b7 100644
--- a/lib/gssapi/ntlm/crypto.c
+++ b/lib/gssapi/ntlm/crypto.c
@@ -115,6 +115,37 @@ _gss_ntlm_set_key(struct ntlmv2_key *key, int acceptor, int sealsign,
 	key->signsealkey = &key->sealkey;
 }
 
+/*
+ * Set (or reset) keys
+ */
+
+void
+_gss_ntlm_set_keys(ntlm_ctx ctx)
+{
+    if (ctx->sessionkey.length == 0)
+	return;
+
+    ctx->status |= STATUS_SESSIONKEY;
+
+    if (ctx->flags & NTLM_NEG_NTLM2_SESSION) {
+	_gss_ntlm_set_key(&ctx->u.v2.send, 1,
+			  (ctx->flags & NTLM_NEG_KEYEX),
+			  ctx->sessionkey.data,
+			  ctx->sessionkey.length);
+	_gss_ntlm_set_key(&ctx->u.v2.recv, 0,
+			  (ctx->flags & NTLM_NEG_KEYEX),
+			  ctx->sessionkey.data,
+			  ctx->sessionkey.length);
+    } else {
+	RC4_set_key(&ctx->u.v1.crypto_send.key,
+		    ctx->sessionkey.length,
+		    ctx->sessionkey.data);
+	RC4_set_key(&ctx->u.v1.crypto_recv.key,
+		    ctx->sessionkey.length,
+		    ctx->sessionkey.data);
+    }
+}
+
 /*
  *
  */
diff --git a/lib/gssapi/ntlm/external.c b/lib/gssapi/ntlm/external.c
index 986f9f3df..3c0fba86c 100644
--- a/lib/gssapi/ntlm/external.c
+++ b/lib/gssapi/ntlm/external.c
@@ -96,7 +96,7 @@ static gssapi_mech_interface_desc ntlm_mech = {
     _gss_ntlm_duplicate_name,
     _gss_ntlm_inquire_sec_context_by_oid,
     NULL,
-    NULL,
+    _gss_ntlm_set_sec_context_option,
     NULL,
     NULL,
     NULL,
diff --git a/lib/gssapi/ntlm/set_sec_context_option.c b/lib/gssapi/ntlm/set_sec_context_option.c
new file mode 100644
index 000000000..372ad9ffa
--- /dev/null
+++ b/lib/gssapi/ntlm/set_sec_context_option.c
@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2006 Kungliga Tekniska Högskolan
+ * (Royal Institute of Technology, Stockholm, Sweden).
+ * All rights reserved.
+ *
+ * Portions Copyright (c) 2009 Apple Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * 3. Neither the name of the Institute nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include "ntlm.h"
+
+OM_uint32 GSSAPI_CALLCONV
+_gss_ntlm_set_sec_context_option(OM_uint32 *minor_status,
+				 gss_ctx_id_t *context_handle,
+				 const gss_OID object,
+				 const gss_buffer_t value)
+{
+    ntlm_ctx ctx;
+
+    if (context_handle == NULL)
+	return GSS_S_UNAVAILABLE;
+
+    *minor_status = 0;
+
+    ctx = (ntlm_ctx)*context_handle;
+    if (ctx == NULL)
+	return GSS_S_NO_CONTEXT;
+
+    if (gss_oid_equal(object, GSS_C_NTLM_RESET_CRYPTO)) {
+	/* OM_uint32 verify = *((OM_uint32 *)value->value); */
+	_gss_ntlm_set_keys(ctx);
+	return GSS_S_COMPLETE;
+    } else
+	return GSS_S_UNAVAILABLE;
+}
diff --git a/lib/gssapi/oid.txt b/lib/gssapi/oid.txt
index 263202759..5eaa4f585 100644
--- a/lib/gssapi/oid.txt
+++ b/lib/gssapi/oid.txt
@@ -64,6 +64,8 @@ oid	base	GSS_SPNEGO_MECHANISM			1.3.6.1.5.5.2
 # /* From Luke Howard */
 
 oid	base	GSS_C_PEER_HAS_UPDATED_SPNEGO		1.3.6.1.4.1.5322.19.5
+oid	base	GSS_C_NTLM_RESET_CRYPTO			1.3.6.1.4.1.7165.655.1.3
+
 
 #/*
 # * OID mappings with name and short description and and slightly longer description
diff --git a/lib/gssapi/spnego/accept_sec_context.c b/lib/gssapi/spnego/accept_sec_context.c
index 4f9bc4f1e..ce73cd8b1 100644
--- a/lib/gssapi/spnego/accept_sec_context.c
+++ b/lib/gssapi/spnego/accept_sec_context.c
@@ -236,6 +236,10 @@ send_accept (OM_uint32 *minor_status,
 			  0,
 			  mech_buf,
 			  &mech_mic_buf);
+	if (ret == GSS_S_COMPLETE &&
+	    gss_oid_equal(context_handle->negotiated_mech_type,
+			  GSS_NTLM_MECHANISM))
+	    _gss_spnego_ntlm_reset_crypto(minor_status, context_handle, 0);
 	if (ret == GSS_S_COMPLETE) {
 	    ALLOC(nt.u.negTokenResp.mechListMIC, 1);
 	    if (nt.u.negTokenResp.mechListMIC == NULL) {
diff --git a/lib/gssapi/spnego/compat.c b/lib/gssapi/spnego/compat.c
index b902e0469..0dc6425c8 100644
--- a/lib/gssapi/spnego/compat.c
+++ b/lib/gssapi/spnego/compat.c
@@ -315,3 +315,19 @@ _gss_spnego_indicate_mechtypelist (OM_uint32 *minor_status,
 
     return ret;
 }
+
+OM_uint32
+_gss_spnego_ntlm_reset_crypto(OM_uint32 *minor_status,
+			      gssspnego_ctx ctx,
+			      OM_uint32 verify)
+{
+    gss_buffer_desc value;
+
+    value.length = sizeof(verify);
+    value.value = &verify;
+
+    return gss_set_sec_context_option(minor_status,
+				      &ctx->negotiated_ctx_id,
+				      GSS_C_NTLM_RESET_CRYPTO,
+				      &value);
+}
diff --git a/lib/gssapi/spnego/init_sec_context.c b/lib/gssapi/spnego/init_sec_context.c
index 4f7ff7fd8..1428f88fb 100644
--- a/lib/gssapi/spnego/init_sec_context.c
+++ b/lib/gssapi/spnego/init_sec_context.c
@@ -136,6 +136,9 @@ spnego_reply_internal(OM_uint32 *minor_status,
 			  0,
 			  mech_buf,
 			  &mic_buf);
+	if (ret == GSS_S_COMPLETE &&
+	    gss_oid_equal(context_handle->negotiated_mech_type, GSS_NTLM_MECHANISM))
+	    _gss_spnego_ntlm_reset_crypto(minor_status, context_handle, 0);
 	if (ret == GSS_S_COMPLETE) {
 	    ALLOC(nt.u.negTokenResp.mechListMIC, 1);
 	    if (nt.u.negTokenResp.mechListMIC == NULL) {
@@ -580,6 +583,9 @@ spnego_reply
 				 &mech_buf,
 				 &mic_buf,
 				 NULL);
+	   if (ret == GSS_S_COMPLETE &&
+	       gss_oid_equal(ctx->negotiated_mech_type, GSS_NTLM_MECHANISM))
+		_gss_spnego_ntlm_reset_crypto(minor_status, ctx, 1);
 	   if (ret) {
 		HEIMDAL_MUTEX_unlock(&ctx->ctx_id_mutex);
 		free(mech_buf.value);