diff --git a/citadel/citadeld/NOTICE b/citadel/citadeld/NOTICE
new file mode 100644
index 0000000..f433b1a
--- /dev/null
+++ b/citadel/citadeld/NOTICE
@@ -0,0 +1,177 @@
+
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
+      or by an individual or Legal Entity authorized to submit on behalf of
+      the copyright owner. For the purposes of this definition, "submitted"
+      means any form of electronic, verbal, or written communication sent
+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
+      and issue tracking systems that are managed by, or on behalf of, the
+      Licensor for the purpose of discussing and improving the Work, but
+      excluding communication that is conspicuously marked or otherwise
+      designated in writing by the copyright owner as "Not a Contribution."
+
+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
+
+   2. Grant of Copyright License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
+      publicly display, publicly perform, sublicense, and distribute the
+      Work and such Derivative Works in Source or Object form.
+
+   3. Grant of Patent License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      (except as stated in this section) patent license to make, have made,
+      use, offer to sell, sell, import, and otherwise transfer the Work,
+      where such license applies only to those patent claims licensable
+      by such Contributor that are necessarily infringed by their
+      Contribution(s) alone or by combination of their Contribution(s)
+      with the Work to which such Contribution(s) was submitted. If You
+      institute patent litigation against any entity (including a
+      cross-claim or counterclaim in a lawsuit) alleging that the Work
+      or a Contribution incorporated within the Work constitutes direct
+      or contributory patent infringement, then any patent licenses
+      granted to You under this License for that Work shall terminate
+      as of the date such litigation is filed.
+
+   4. Redistribution. You may reproduce and distribute copies of the
+      Work or Derivative Works thereof in any medium, with or without
+      modifications, and in Source or Object form, provided that You
+      meet the following conditions:
+
+      (a) You must give any other recipients of the Work or
+          Derivative Works a copy of this License; and
+
+      (b) You must cause any modified files to carry prominent notices
+          stating that You changed the files; and
+
+      (c) You must retain, in the Source form of any Derivative Works
+          that You distribute, all copyright, patent, trademark, and
+          attribution notices from the Source form of the Work,
+          excluding those notices that do not pertain to any part of
+          the Derivative Works; and
+
+      (d) If the Work includes a "NOTICE" text file as part of its
+          distribution, then any Derivative Works that You distribute must
+          include a readable copy of the attribution notices contained
+          within such NOTICE file, excluding those notices that do not
+          pertain to any part of the Derivative Works, in at least one
+          of the following places: within a NOTICE text file distributed
+          as part of the Derivative Works; within the Source form or
+          documentation, if provided along with the Derivative Works; or,
+          within a display generated by the Derivative Works, if and
+          wherever such third-party notices normally appear. The contents
+          of the NOTICE file are for informational purposes only and
+          do not modify the License. You may add Your own attribution
+          notices within Derivative Works that You distribute, alongside
+          or as an addendum to the NOTICE text from the Work, provided
+          that such additional attribution notices cannot be construed
+          as modifying the License.
+
+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
+      for any such Derivative Works as a whole, provided Your use,
+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
+      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
diff --git a/hals/NOTICE b/hals/NOTICE
new file mode 100644
index 0000000..f433b1a
--- /dev/null
+++ b/hals/NOTICE
@@ -0,0 +1,177 @@
+
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
+      or by an individual or Legal Entity authorized to submit on behalf of
+      the copyright owner. For the purposes of this definition, "submitted"
+      means any form of electronic, verbal, or written communication sent
+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
+      and issue tracking systems that are managed by, or on behalf of, the
+      Licensor for the purpose of discussing and improving the Work, but
+      excluding communication that is conspicuously marked or otherwise
+      designated in writing by the copyright owner as "Not a Contribution."
+
+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
+
+   2. Grant of Copyright License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
+      publicly display, publicly perform, sublicense, and distribute the
+      Work and such Derivative Works in Source or Object form.
+
+   3. Grant of Patent License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      (except as stated in this section) patent license to make, have made,
+      use, offer to sell, sell, import, and otherwise transfer the Work,
+      where such license applies only to those patent claims licensable
+      by such Contributor that are necessarily infringed by their
+      Contribution(s) alone or by combination of their Contribution(s)
+      with the Work to which such Contribution(s) was submitted. If You
+      institute patent litigation against any entity (including a
+      cross-claim or counterclaim in a lawsuit) alleging that the Work
+      or a Contribution incorporated within the Work constitutes direct
+      or contributory patent infringement, then any patent licenses
+      granted to You under this License for that Work shall terminate
+      as of the date such litigation is filed.
+
+   4. Redistribution. You may reproduce and distribute copies of the
+      Work or Derivative Works thereof in any medium, with or without
+      modifications, and in Source or Object form, provided that You
+      meet the following conditions:
+
+      (a) You must give any other recipients of the Work or
+          Derivative Works a copy of this License; and
+
+      (b) You must cause any modified files to carry prominent notices
+          stating that You changed the files; and
+
+      (c) You must retain, in the Source form of any Derivative Works
+          that You distribute, all copyright, patent, trademark, and
+          attribution notices from the Source form of the Work,
+          excluding those notices that do not pertain to any part of
+          the Derivative Works; and
+
+      (d) If the Work includes a "NOTICE" text file as part of its
+          distribution, then any Derivative Works that You distribute must
+          include a readable copy of the attribution notices contained
+          within such NOTICE file, excluding those notices that do not
+          pertain to any part of the Derivative Works, in at least one
+          of the following places: within a NOTICE text file distributed
+          as part of the Derivative Works; within the Source form or
+          documentation, if provided along with the Derivative Works; or,
+          within a display generated by the Derivative Works, if and
+          wherever such third-party notices normally appear. The contents
+          of the NOTICE file are for informational purposes only and
+          do not modify the License. You may add Your own attribution
+          notices within Derivative Works that You distribute, alongside
+          or as an addendum to the NOTICE text from the Work, provided
+          that such additional attribution notices cannot be construed
+          as modifying the License.
+
+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
+      for any such Derivative Works as a whole, provided Your use,
+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
+      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
diff --git a/hals/authsecret/AuthSecret.cpp b/hals/authsecret/AuthSecret.cpp
index 01ea99d..0f4bb66 100644
--- a/hals/authsecret/AuthSecret.cpp
+++ b/hals/authsecret/AuthSecret.cpp
@@ -128,7 +128,7 @@
     msg->which_headers = NUGGET_ENABLE_HEADER_RW | NUGGET_ENABLE_HEADER_RO;
     const uint32_t appStatus = client.CallApp(APP_ID_NUGGET,
                                               NUGGET_PARAM_ENABLE_UPDATE,
-                                              buffer, nullptr);
+                                              buffer, &buffer);
     if (appStatus == APP_ERROR_BOGUS_ARGS) {
         LOG(ERROR) << "Incorrect Citadel update password";
         return;
@@ -139,8 +139,12 @@
         return;
     }
 
-    // Reboot for the update to take effect
-    RebootCitadel(client);
+    // If the header[s] changed, reboot for the update to take effect
+    // Old firmware doesn't have a reply but still needs to be updated
+    if (buffer.empty() || buffer[0]) {
+      LOG(INFO) << "Update password enabled a new image; rebooting Citadel";
+      RebootCitadel(client);
+    }
 }
 
 } // namespace
diff --git a/hals/keymaster/Android.bp b/hals/keymaster/Android.bp
index d730504..865fdeb 100644
--- a/hals/keymaster/Android.bp
+++ b/hals/keymaster/Android.bp
@@ -17,6 +17,7 @@
 cc_library {
     name: "android.hardware.keymaster@4.0-impl.nos",
     srcs: [
+        "buffer.cpp",
         "export_key.cpp",
         "import_key.cpp",
         "import_wrapped_key.cpp",
diff --git a/hals/keymaster/KeymasterDevice.cpp b/hals/keymaster/KeymasterDevice.cpp
index ee5c7d4..e56590d 100644
--- a/hals/keymaster/KeymasterDevice.cpp
+++ b/hals/keymaster/KeymasterDevice.cpp
@@ -15,6 +15,7 @@
  */
 
 #include "KeymasterDevice.h"
+#include "buffer.h"
 #include "export_key.h"
 #include "import_key.h"
 #include "import_wrapped_key.h"
@@ -49,6 +50,48 @@
     return filtered_code;
 }
 
+/** Get one version number from a string and move loc to the point after the
+ * next version delimiter.
+ */
+uint32_t ExtractVersion(const std::string& version, size_t* loc) {
+    if (*loc == std::string::npos || *loc >= version.size()) {
+        return 0;
+    }
+
+    uint32_t value = 0;
+    size_t new_loc = version.find('.', *loc);
+    if (new_loc == std::string::npos) {
+        auto sanitized = DigitsOnly(version.substr(*loc));
+        if (!sanitized.empty()) {
+            if (sanitized.size() < version.size() - *loc) {
+                LOG(ERROR) << "Unexpected version format: \"" << version
+                           << "\"";
+            }
+            value = std::stoi(sanitized);
+        }
+        *loc = new_loc;
+    } else {
+        auto sanitized = DigitsOnly(version.substr(*loc, new_loc - *loc));
+        if (!sanitized.empty()) {
+            if (sanitized.size() < new_loc - *loc) {
+                LOG(ERROR) << "Unexpected version format: \"" << version
+                           << "\"";
+            }
+            value = std::stoi(sanitized);
+        }
+        *loc = new_loc + 1;
+    }
+    return value;
+}
+
+uint32_t VersionToUint32(const std::string& version) {
+    size_t loc = 0;
+    uint32_t major = ExtractVersion(version, &loc);
+    uint32_t minor = ExtractVersion(version, &loc);
+    uint32_t subminor = ExtractVersion(version, &loc);
+    return major * 10000 + minor * 100 + subminor;
+}
+
 uint32_t DateCodeToUint32(const std::string& code, bool include_day) {
     // Keep digits only.
     std::string filtered_code = DigitsOnly(code);
@@ -65,6 +108,8 @@
         if (include_day) {
             return_value *= 100;
         }
+    } else {
+        LOG(ERROR) << "Unexpected patchset format: \"" << code << "\"";
     }
     return return_value;
 }
@@ -104,8 +149,12 @@
 using ::nugget::app::keymaster::ImportKeyResponse;
 using ::nugget::app::keymaster::ExportKeyRequest;
 using ::nugget::app::keymaster::ExportKeyResponse;
-using ::nugget::app::keymaster::AttestKeyRequest;
-using ::nugget::app::keymaster::AttestKeyResponse;
+using ::nugget::app::keymaster::StartAttestKeyRequest;
+using ::nugget::app::keymaster::StartAttestKeyResponse;
+using ::nugget::app::keymaster::ContinueAttestKeyRequest;
+using ::nugget::app::keymaster::ContinueAttestKeyResponse;
+using ::nugget::app::keymaster::FinishAttestKeyRequest;
+using ::nugget::app::keymaster::FinishAttestKeyResponse;
 using ::nugget::app::keymaster::UpgradeKeyRequest;
 using ::nugget::app::keymaster::UpgradeKeyResponse;
 using ::nugget::app::keymaster::DeleteKeyRequest;
@@ -160,7 +209,7 @@
     }
 }
 
-#define KM_CALL(meth) {                                                       \
+#define KM_CALL(meth, request, response) {                                    \
     const uint32_t status = _keymaster. meth (request, &response);            \
     const ErrorCode error_code = translate_error_code(response.error_code()); \
     if (status != APP_SUCCESS) {                                              \
@@ -175,7 +224,7 @@
     }                                                                         \
 }
 
-#define KM_CALLV(meth, ...) {                                                 \
+#define KM_CALLV(meth, request, response, ...) {                              \
     const uint32_t status = _keymaster. meth (request, &response);            \
     const ErrorCode error_code = translate_error_code(response.error_code()); \
     if (status != APP_SUCCESS) {                                              \
@@ -196,7 +245,7 @@
 
 KeymasterDevice::KeymasterDevice(KeymasterClient& keymaster) :
         _keymaster{keymaster} {
-    _os_version = std::stoi(DigitsOnly(GetProperty(PROPERTY_OS_VERSION, "")));
+    _os_version = VersionToUint32(GetProperty(PROPERTY_OS_VERSION, ""));
     _os_patchlevel = DateCodeToUint32(GetProperty(PROPERTY_OS_PATCHLEVEL, ""),
                                      false /* include_day */);
     _vendor_patchlevel = DateCodeToUint32(
@@ -228,7 +277,7 @@
     GetHmacSharingParametersResponse response;
     HmacSharingParameters result;
 
-    KM_CALLV(GetHmacSharingParameters, result);
+    KM_CALLV(GetHmacSharingParameters, request, response, result);
 
     ErrorCode ec = translate_error_code(response.error_code());
 
@@ -286,7 +335,7 @@
                 param.seed.size());
     }
 
-    KM_CALLV(ComputeSharedHmac, result);
+    KM_CALLV(ComputeSharedHmac, request, response, result);
 
     ErrorCode ec = translate_error_code(response.error_code());
 
@@ -334,7 +383,7 @@
         request.set_data(&data[i], std::min(chunk_size, data.size() - i));
 
         // Call device.
-        KM_CALL(AddRngEntropy);
+        KM_CALL(AddRngEntropy, request, response);
     }
 
     return ErrorCode::OK;
@@ -358,7 +407,8 @@
     }
 
     // Call device.
-    KM_CALLV(GenerateKey, hidl_vec<uint8_t>{}, KeyCharacteristics());
+    KM_CALLV(GenerateKey, request, response,
+             hidl_vec<uint8_t>{}, KeyCharacteristics());
 
     blob.setToExternal(
         reinterpret_cast<uint8_t*>(
@@ -390,7 +440,7 @@
     request.set_app_data(&appData[0], appData.size());
 
     // Call device.
-    KM_CALLV(GetKeyCharacteristics, KeyCharacteristics());
+    KM_CALLV(GetKeyCharacteristics, request, response, KeyCharacteristics());
 
     KeyCharacteristics characteristics;
     pb_to_hidl_params(response.characteristics().software_enforced(),
@@ -420,7 +470,8 @@
         return Void();
     }
 
-    KM_CALLV(ImportKey, hidl_vec<uint8_t>{}, KeyCharacteristics{});
+    KM_CALLV(ImportKey, request, response,
+             hidl_vec<uint8_t>{}, KeyCharacteristics{});
 
     hidl_vec<uint8_t> blob;
     blob.setToExternal(
@@ -459,7 +510,7 @@
     request.set_client_id(&clientId[0], clientId.size());
     request.set_app_data(&appData[0], appData.size());
 
-    KM_CALLV(ExportKey, hidl_vec<uint8_t>{});
+    KM_CALLV(ExportKey, request, response, hidl_vec<uint8_t>{});
 
     ErrorCode error_code = translate_error_code(response.error_code());
     if (error_code != ErrorCode::OK) {
@@ -480,32 +531,63 @@
 {
     LOG(VERBOSE) << "Running KeymasterDevice::attestKey";
 
-    AttestKeyRequest request;
-    AttestKeyResponse response;
+    StartAttestKeyRequest startRequest;
+    StartAttestKeyResponse startResponse;
 
-    request.mutable_blob()->set_blob(&keyToAttest[0], keyToAttest.size());
+    startRequest.mutable_blob()->set_blob(&keyToAttest[0], keyToAttest.size());
 
     vector<hidl_vec<uint8_t> > chain;
     if (hidl_params_to_pb(
-            attestParams, request.mutable_params()) != ErrorCode::OK) {
+            attestParams, startRequest.mutable_params()) != ErrorCode::OK) {
       _hidl_cb(ErrorCode::INVALID_ARGUMENT, chain);
       return Void();
     }
 
-    KM_CALLV(AttestKey, hidl_vec<hidl_vec<uint8_t> >{});
+    // TODO:
+    // startRequest.set_attestation_app_id_len(
+    //     attestation_app_id_len(attestParams));
 
-    for (int i = 0; i < response.chain().certificates_size(); i++) {
-        hidl_vec<uint8_t> blob;
-        blob.setToExternal(
-            reinterpret_cast<uint8_t*>(
-                const_cast<char*>(
-                    response.chain().certificates(i).data().data())),
-            response.chain().certificates(i).data().size(), false);
-        chain.push_back(blob);
-    }
+    KM_CALLV(StartAttestKey, startRequest, startResponse,
+             hidl_vec<hidl_vec<uint8_t> >{});
 
-    _hidl_cb(translate_error_code(response.error_code()),
-             hidl_vec<hidl_vec<uint8_t> >(chain));
+    uint64_t operationHandle = startResponse.handle().handle();
+    ContinueAttestKeyRequest continueRequest;
+    ContinueAttestKeyResponse continueResponse;
+
+    continueRequest.mutable_handle()->set_handle(operationHandle);
+    // TODO
+    // continueRequest.set_attestation_app_id(
+    //     attestation_app_id(attestParams));
+
+    KM_CALLV(ContinueAttestKey, continueRequest, continueResponse,
+             hidl_vec<hidl_vec<uint8_t> >{});
+
+    FinishAttestKeyRequest finishRequest;
+    FinishAttestKeyResponse finishResponse;
+
+    finishRequest.mutable_handle()->set_handle(operationHandle);
+
+    KM_CALLV(FinishAttestKey, finishRequest, finishResponse,
+             hidl_vec<hidl_vec<uint8_t> >{});
+
+    std::stringstream ss;
+    ss << startResponse.certificate_prologue();
+    ss << continueResponse.certificate_body();
+    ss << finishResponse.certificate_epilogue();
+
+    hidl_vec<uint8_t> attestation_certificate;
+    attestation_certificate.setToExternal(
+        reinterpret_cast<uint8_t*>(
+            const_cast<char*>(ss.str().data())),
+        ss.str().size(), false);
+
+    chain.push_back(attestation_certificate);
+    // TODO:
+    // chain.push_back(intermediate_certificate());
+    // chain.push_back(root_certificate());
+    // verify cert chain
+
+    _hidl_cb(ErrorCode::OK, hidl_vec<hidl_vec<uint8_t> >(chain));
     return Void();
 }
 
@@ -529,7 +611,7 @@
       return Void();
     }
 
-    KM_CALLV(UpgradeKey, hidl_vec<uint8_t>{});
+    KM_CALLV(UpgradeKey, request, response, hidl_vec<uint8_t>{});
 
     blob.setToExternal(
         reinterpret_cast<uint8_t*>(
@@ -549,7 +631,7 @@
 
     request.mutable_blob()->set_blob(&keyBlob[0], keyBlob.size());
 
-    KM_CALL(DeleteKey);
+    KM_CALL(DeleteKey, request, response);
 
     return translate_error_code(response.error_code());
 }
@@ -561,7 +643,7 @@
     DeleteAllKeysRequest request;
     DeleteAllKeysResponse response;
 
-    KM_CALL(DeleteAllKeys);
+    KM_CALL(DeleteAllKeys, request, response);
 
     return translate_error_code(response.error_code());
 }
@@ -573,7 +655,7 @@
     DestroyAttestationIdsRequest request;
     DestroyAttestationIdsResponse response;
 
-    KM_CALL(DestroyAttestationIds);
+    KM_CALL(DestroyAttestationIds, request, response);
 
     return translate_error_code(response.error_code());
 }
@@ -593,6 +675,7 @@
     request.mutable_blob()->set_blob(&key[0], key.size());
 
     hidl_vec<KeyParameter> params;
+    tag_map_t tag_map;
     if (translate_auth_token(
             authToken, request.mutable_auth_token()) != ErrorCode::OK) {
         _hidl_cb(ErrorCode::INVALID_ARGUMENT, params,
@@ -605,8 +688,36 @@
                response.handle().handle());
       return Void();
     }
+    if (hidl_params_to_map(inParams, &tag_map) != ErrorCode::OK) {
+        _hidl_cb(ErrorCode::INVALID_ARGUMENT, params,
+                 response.handle().handle());
+      return Void();
+    }
 
-    KM_CALLV(BeginOperation, hidl_vec<KeyParameter>{}, 0);
+    KM_CALLV(BeginOperation, request, response, hidl_vec<KeyParameter>{}, 0);
+
+    // Setup HAL buffering for this operation's data.
+    Algorithm algorithm;
+    if (translate_algorithm(response.algorithm(), &algorithm) !=
+        ErrorCode::OK) {
+        if (this->abort(response.handle().handle()) != ErrorCode::OK) {
+            LOG(ERROR) << "abort( " << response.handle().handle()
+                       << ") failed";
+        }
+        _hidl_cb(ErrorCode::INVALID_ARGUMENT, params,
+                 response.handle().handle());
+        return Void();
+    }
+    ErrorCode error_code = buffer_begin(response.handle().handle(), algorithm);
+    if (error_code != ErrorCode::OK) {
+        if (this->abort(response.handle().handle()) != ErrorCode::OK) {
+            LOG(ERROR) << "abort( " << response.handle().handle()
+                       << ") failed";
+        }
+        _hidl_cb(ErrorCode::UNKNOWN_ERROR, params,
+                 response.handle().handle());
+        return Void();
+    }
 
     pb_to_hidl_params(response.params(), &params);
 
@@ -628,6 +739,7 @@
     UpdateOperationRequest request;
     UpdateOperationResponse response;
 
+    // TODO: does keystore chunk stream data?  To what quantum?
     if (input.size() > KM_MAX_PROTO_FIELD_SIZE) {
         LOG(ERROR) << "Excess input length: " << input.size()
                    << "max allowed: " << KM_MAX_PROTO_FIELD_SIZE;
@@ -640,17 +752,38 @@
         return Void();
     }
 
+    uint32_t consumed;
+    hidl_vec<uint8_t> output;
+    hidl_vec<KeyParameter> params;
+    ErrorCode error_code;
+    error_code = buffer_append(operationHandle, input, &consumed);
+    if (error_code != ErrorCode::OK) {
+        _hidl_cb(error_code, 0, params, output);
+        return Void();
+    }
+
+    hidl_vec<uint8_t> blocks;
+    error_code = buffer_peek(operationHandle, &blocks);
+    if (error_code != ErrorCode::OK) {
+        _hidl_cb(error_code, 0, params, output);
+        return Void();
+    }
+
+    if (blocks.size() == 0) {
+        // Insufficient data available to proceed.
+        _hidl_cb(ErrorCode::OK, consumed, params, output);
+        return Void();
+    }
+
     request.mutable_handle()->set_handle(operationHandle);
 
-    hidl_vec<KeyParameter> params;
-    hidl_vec<uint8_t> output;
     if (hidl_params_to_pb(
             inParams, request.mutable_params()) != ErrorCode::OK) {
       _hidl_cb(ErrorCode::INVALID_ARGUMENT, 0, params, output);
       return Void();
     }
 
-    request.set_input(&input[0], input.size());
+    request.set_input(&blocks[0], blocks.size());
     if (translate_auth_token(
             authToken, request.mutable_auth_token()) != ErrorCode::OK) {
         _hidl_cb(ErrorCode::INVALID_ARGUMENT, 0, params, output);
@@ -659,14 +792,20 @@
     translate_verification_token(verificationToken,
                                  request.mutable_verification_token());
 
-    KM_CALLV(UpdateOperation, 0, hidl_vec<KeyParameter>{}, hidl_vec<uint8_t>{});
+    KM_CALLV(UpdateOperation, request, response,
+             0, hidl_vec<KeyParameter>{}, hidl_vec<uint8_t>{});
+
+    if (buffer_advance(operationHandle, response.consumed()) != ErrorCode::OK) {
+        _hidl_cb(ErrorCode::UNKNOWN_ERROR, 0, params, output);
+        return Void();
+    }
 
     pb_to_hidl_params(response.params(), &params);
     output.setToExternal(
         reinterpret_cast<uint8_t*>(const_cast<char*>(response.output().data())),
         response.output().size(), false);
 
-    _hidl_cb(ErrorCode::OK, response.consumed(), params, output);
+    _hidl_cb(ErrorCode::OK, consumed, params, output);
     return Void();
 }
 
@@ -696,6 +835,23 @@
         return Void();
     }
 
+    uint32_t consumed;
+    ErrorCode error_code;
+    error_code = buffer_append(operationHandle, input, &consumed);
+    if (error_code != ErrorCode::OK) {
+        _hidl_cb(error_code,
+                 hidl_vec<KeyParameter>{}, hidl_vec<uint8_t>{});
+        return Void();
+    }
+
+    hidl_vec<uint8_t> data;
+    error_code = buffer_final(operationHandle, &data);
+    if (error_code != ErrorCode::OK) {
+        _hidl_cb(error_code,
+                 hidl_vec<KeyParameter>{}, hidl_vec<uint8_t>{});
+        return Void();
+    }
+
     request.mutable_handle()->set_handle(operationHandle);
 
     hidl_vec<KeyParameter> params;
@@ -706,7 +862,7 @@
       return Void();
     }
 
-    request.set_input(&input[0], input.size());
+    request.set_input(&data[0], data.size());
     request.set_signature(&signature[0], signature.size());
 
     if (translate_auth_token(
@@ -717,7 +873,8 @@
     translate_verification_token(verificationToken,
                                  request.mutable_verification_token());
 
-    KM_CALLV(FinishOperation, hidl_vec<KeyParameter>{}, hidl_vec<uint8_t>{});
+    KM_CALLV(FinishOperation, request, response,
+             hidl_vec<KeyParameter>{}, hidl_vec<uint8_t>{});
 
     pb_to_hidl_params(response.params(), &params);
     output.setToExternal(
@@ -737,7 +894,7 @@
 
     request.mutable_handle()->set_handle(operationHandle);
 
-    KM_CALL(AbortOperation);
+    KM_CALL(AbortOperation, request, response);
 
     return ErrorCode::OK;
 }
@@ -772,7 +929,8 @@
         return Void();
     }
 
-    KM_CALLV(ImportWrappedKey, hidl_vec<uint8_t>{}, KeyCharacteristics{});
+    KM_CALLV(ImportWrappedKey, request, response,
+             hidl_vec<uint8_t>{}, KeyCharacteristics{});
 
     hidl_vec<uint8_t> blob;
     blob.setToExternal(
@@ -807,7 +965,7 @@
     request.set_system_security_level(_os_patchlevel);
     request.set_vendor_security_level(_vendor_patchlevel);
 
-    KM_CALL(SetSystemVersionInfo);
+    KM_CALL(SetSystemVersionInfo, request, response);
     return ErrorCode::OK;
 }
 
@@ -815,7 +973,7 @@
     GetBootInfoRequest request;
     GetBootInfoResponse response;
 
-    KM_CALL(GetBootInfo);
+    KM_CALL(GetBootInfo, request, response);
 
     _is_unlocked = response.is_unlocked();
     _boot_color = response.boot_color();
diff --git a/hals/keymaster/buffer.cpp b/hals/keymaster/buffer.cpp
new file mode 100644
index 0000000..05e9c3e
--- /dev/null
+++ b/hals/keymaster/buffer.cpp
@@ -0,0 +1,195 @@
+/*
+ * Copyright 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "buffer.h"
+#include "proto_utils.h"
+
+#include <keymasterV4_0/key_param_output.h>
+
+#include <android-base/logging.h>
+
+#include <openssl/rsa.h>
+
+#include <map>
+#include <vector>
+
+namespace android {
+namespace hardware {
+namespace keymaster {
+
+// HAL
+using ::android::hardware::keymaster::V4_0::Algorithm;
+using ::android::hardware::keymaster::V4_0::ErrorCode;
+
+// std
+using std::map;
+using std::pair;
+using std::vector;
+
+static const size_t kMaxChunkSize = 256;
+
+class Operation {
+public:
+    Operation(Algorithm algorithm) : _algorithm(algorithm), _buffer{} {
+        switch (_algorithm) {
+        case Algorithm::AES:
+            _blockSize = 16;
+            break;
+        case Algorithm::TRIPLE_DES:
+            _blockSize = 8;
+            break;
+        case Algorithm::RSA:
+        case Algorithm::EC:
+        case Algorithm::HMAC:
+            _blockSize = 0;
+        default:
+            break;
+        }
+    }
+
+    size_t remaining() const {
+        return _buffer.size();
+    }
+
+    void append(const hidl_vec<uint8_t>& input, uint32_t *consumed) {
+        _buffer.insert(_buffer.end(), input.begin(), input.end());
+        *consumed = input.size();
+    }
+
+    void peek(hidl_vec<uint8_t> *data) {
+        // Retain at least one full block; this is done so that when
+        // either GCM mode or PKCS7 padding are in use, the last block
+        // will be available to be consumed by final().
+        if (_buffer.size() <= _blockSize) {
+            *data = vector<uint8_t>();
+            return;
+        }
+
+        size_t retain;
+        if (_blockSize == 0) {
+            retain = 0;
+        } else {
+            retain = (_buffer.size() % _blockSize) + _blockSize;
+        }
+        const size_t count = std::min(_buffer.size() - retain, kMaxChunkSize);
+        *data = vector<uint8_t>(_buffer.begin(), _buffer.begin() + count);
+    }
+
+    ErrorCode advance(size_t count) {
+        if (count > _buffer.size()) {
+            LOG(ERROR) << "Attempt to advance " << count
+                       << " bytes, where occupancy is " << _buffer.size();
+            return ErrorCode::UNKNOWN_ERROR;
+        }
+        _buffer.erase(_buffer.begin(), _buffer.begin() + count);
+        return ErrorCode::OK;
+    }
+
+    void final(hidl_vec<uint8_t> *data) {
+        if (data != NULL) {
+            *data = _buffer;
+        }
+        _buffer.clear();
+    }
+
+private:
+    Algorithm _algorithm;
+    size_t _blockSize;
+    vector<uint8_t> _buffer;
+};
+
+static map<uint64_t, Operation>  buffer_map;
+typedef map<uint64_t, Operation>::iterator  buffer_item;
+
+ErrorCode buffer_begin(uint64_t handle, Algorithm algorithm)
+{
+    if (buffer_map.find(handle) != buffer_map.end()) {
+        LOG(ERROR) << "Duplicate operation handle " << handle
+                   << "returned by begin()";
+        // Final the existing op to potential mishandling of data.
+        buffer_final(handle, NULL);
+        return ErrorCode::UNKNOWN_ERROR;
+    }
+
+    buffer_map.insert(
+        pair<uint64_t, Operation>(handle, Operation(algorithm)));
+    return ErrorCode::OK;
+}
+
+size_t buffer_remaining(uint64_t handle) {
+    if (buffer_map.find(handle) == buffer_map.end()) {
+        LOG(ERROR) << "Remaining requested on absent operation: " << handle;
+        return 0;
+    }
+
+    const Operation &op = buffer_map.find(handle)->second;
+    return op.remaining();
+}
+
+ErrorCode buffer_append(uint64_t handle,
+                        const hidl_vec<uint8_t>& input,
+                        uint32_t *consumed)
+{
+    if (buffer_map.find(handle) == buffer_map.end()) {
+        LOG(ERROR) << "Append requested on absent operation: " << handle;
+        return ErrorCode::UNKNOWN_ERROR;
+    }
+
+    Operation *op = &buffer_map.find(handle)->second;
+    op->append(input, consumed);
+    return ErrorCode::OK;
+}
+
+ErrorCode buffer_peek(uint64_t handle,
+                      hidl_vec<uint8_t> *data)
+{
+    if (buffer_map.find(handle) == buffer_map.end()) {
+        LOG(ERROR) << "Read requested on absent operation: " << handle;
+        return ErrorCode::UNKNOWN_ERROR;
+    }
+
+    Operation *op = &buffer_map.find(handle)->second;
+    op->peek(data);
+    return ErrorCode::OK;
+}
+
+ErrorCode buffer_advance(uint64_t handle, size_t count)
+{
+    if (buffer_map.find(handle) == buffer_map.end()) {
+        LOG(ERROR) << "Read requested on absent operation: " << handle;
+        return ErrorCode::UNKNOWN_ERROR;
+    }
+
+    Operation *op = &buffer_map.find(handle)->second;
+    return op->advance(count);
+}
+
+ErrorCode buffer_final(uint64_t handle,
+                   hidl_vec<uint8_t> *data)
+{
+    if (buffer_map.find(handle) == buffer_map.end()) {
+        LOG(ERROR) << "Final requested on absent operation: " << handle;
+        return ErrorCode::UNKNOWN_ERROR;
+    }
+    Operation *op = &buffer_map.find(handle)->second;
+    op->final(data);
+    buffer_map.erase(handle);
+    return ErrorCode::OK;
+}
+
+}  // namespace keymaster
+}  // hardware
+}  // android
diff --git a/hals/keymaster/buffer.h b/hals/keymaster/buffer.h
new file mode 100644
index 0000000..a4a23e3
--- /dev/null
+++ b/hals/keymaster/buffer.h
@@ -0,0 +1,49 @@
+/*
+ * Copyright 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ANDROID_HARDWARE_KEYMASTER_BUFFER_H
+#define ANDROID_HARDWARE_KEYMASTER_BUFFER_H
+
+#include <android/hardware/keymaster/4.0/IKeymasterDevice.h>
+
+#include <Keymaster.client.h>
+
+using ::nugget::app::keymaster::BeginOperationResponse;
+
+namespace android {
+namespace hardware {
+namespace keymaster {
+
+// HAL
+using ::android::hardware::keymaster::V4_0::Algorithm;
+using ::android::hardware::keymaster::V4_0::ErrorCode;
+
+size_t buffer_remaining(uint64_t handle);
+ErrorCode buffer_begin(uint64_t handle, Algorithm algorithm);
+ErrorCode buffer_append(uint64_t handle,
+                        const hidl_vec<uint8_t>& input,
+                        uint32_t *consumed);
+ErrorCode buffer_peek(uint64_t handle,
+                      hidl_vec<uint8_t> *data);
+ErrorCode buffer_advance(uint64_t handle, size_t count);
+ErrorCode buffer_final(uint64_t handle,
+                       hidl_vec<uint8_t> *data);
+
+}  // namespace keymaster
+}  // hardware
+}  // android
+
+#endif  // ANDROID_HARDWARE_KEYMASTER_IMPORT_KEY_H
diff --git a/hals/keymaster/proto_utils.cpp b/hals/keymaster/proto_utils.cpp
index d3cb753..c27b76b 100644
--- a/hals/keymaster/proto_utils.cpp
+++ b/hals/keymaster/proto_utils.cpp
@@ -127,8 +127,8 @@
     }
 }
 
-static ErrorCode translate_algorithm(nosapp::Algorithm algorithm,
-                                     Algorithm *out)
+ErrorCode translate_algorithm(nosapp::Algorithm algorithm,
+                              Algorithm *out)
 {
     switch (algorithm) {
     case nosapp::Algorithm::RSA:
diff --git a/hals/keymaster/proto_utils.h b/hals/keymaster/proto_utils.h
index b1d0f41..a59eab3 100644
--- a/hals/keymaster/proto_utils.h
+++ b/hals/keymaster/proto_utils.h
@@ -29,6 +29,7 @@
 namespace keymaster {
 
 // HAL
+using ::android::hardware::keymaster::V4_0::Algorithm;
 using ::android::hardware::keymaster::V4_0::EcCurve;
 using ::android::hardware::keymaster::V4_0::ErrorCode;
 using ::android::hardware::keymaster::V4_0::HardwareAuthToken;
@@ -57,6 +58,8 @@
                            nosapp::KeyParameters *pbParams);
 ErrorCode pb_to_hidl_params(const nosapp::KeyParameters& pbParams,
                             hidl_vec<KeyParameter> *params);
+ErrorCode translate_algorithm(nosapp::Algorithm algorithm,
+                              Algorithm *out);
 ErrorCode translate_error_code(nosapp::ErrorCode error_code);
 ErrorCode translate_ec_curve(nosapp::EcCurve ec_curve, EcCurve *out);
 ErrorCode translate_auth_token(const HardwareAuthToken& auth_token,