diff --git a/.circleci/config.yml b/.circleci/config.yml
index eab76c4a6..9a65e928a 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -117,9 +117,11 @@ jobs:
       - run:
           name: Decrypt credentials.
           command: |
-            openssl aes-256-cbc -d -in .circleci/key.json.enc \
+            if ! [[ -z "${SYSTEM_TESTS_ENCRYPTION_KEY}" ]]; then
+              openssl aes-256-cbc -d -in .circleci/key.json.enc \
                 -out .circleci/key.json \
                 -k "${SYSTEM_TESTS_ENCRYPTION_KEY}"
+            fi
       - run: *npm_install_and_link
       - run: *samples_npm_install_and_link
       - run:
@@ -131,7 +133,10 @@ jobs:
             NPM_CONFIG_PREFIX: /home/node/.npm-global
       - run:
           name: Remove unencrypted key.
-          command: rm .circleci/key.json
+          command: |
+            if ! [[ -z "${SYSTEM_TESTS_ENCRYPTION_KEY}" ]]; then
+              rm .circleci/key.json
+            fi
           when: always
     working_directory: /home/node/samples/
   system_tests:
@@ -143,9 +148,11 @@ jobs:
       - run:
           name: Decrypt credentials.
           command: |
-            openssl aes-256-cbc -d -in .circleci/key.json.enc \
+            if ! [[ -z "${SYSTEM_TESTS_ENCRYPTION_KEY}" ]]; then
+              openssl aes-256-cbc -d -in .circleci/key.json.enc \
                 -out .circleci/key.json \
                 -k "${SYSTEM_TESTS_ENCRYPTION_KEY}"
+            fi
       - run: *npm_install_and_link
       - run:
           name: Run system tests.
@@ -154,7 +161,10 @@ jobs:
             GOOGLE_APPLICATION_CREDENTIALS: .circleci/key.json
       - run:
           name: Remove unencrypted key.
-          command: rm .circleci/key.json
+          command: |
+            if ! [[ -z "${SYSTEM_TESTS_ENCRYPTION_KEY}" ]]; then
+              rm .circleci/key.json
+            fi
           when: always
   publish_npm:
     docker:
@@ -162,6 +172,6 @@ jobs:
         user: node
     steps:
       - checkout
-      - npm install
+      - run: npm install
       - run: echo "//registry.npmjs.org/:_authToken=${NPM_TOKEN}" > ~/.npmrc
       - run: npm publish --access=public
diff --git a/.kokoro/docs.sh b/.kokoro/docs.sh
old mode 100644
new mode 100755
diff --git a/.kokoro/lint.sh b/.kokoro/lint.sh
old mode 100644
new mode 100755
diff --git a/.kokoro/samples-test.sh b/.kokoro/samples-test.sh
old mode 100644
new mode 100755
diff --git a/.kokoro/system-test.sh b/.kokoro/system-test.sh
old mode 100644
new mode 100755
diff --git a/.kokoro/test.sh b/.kokoro/test.sh
old mode 100644
new mode 100755
diff --git a/.kokoro/trampoline.sh b/.kokoro/trampoline.sh
old mode 100644
new mode 100755