diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 8b8b4d3..1ad2e99 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -15,12 +15,24 @@
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [windows-2019]
+        os: [ubuntu-18.04, windows-2019]
         USE_MBEDTLS: ["ON", "OFF"]
         USE_CONTEXT: ["ON", "OFF"]
         CMAKE_OPTIONS:
           [
             "-DCOSE_C_INCLUDE_ENCRYPT=ON -DCOSE_C_INCLUDE_ENCRYPT0=OFF -DCOSE_C_INCLUDE_MAC0=OFF -DCOSE_C_INCLUDE_MAC=OFF -DCOSE_C_INCLUDE_SIGN=OFF -DCOSE_C_INCLUDE_SIGN1=OFF -DCOSE_C_INCLUDE_COUNTERSIGN=OFF",
+            "-DCOSE_C_INCLUDE_ENCRYPT=OFF -DCOSE_C_INCLUDE_ENCRYPT0=ON -DCOSE_C_INCLUDE_MAC0=OFF -DCOSE_C_INCLUDE_MAC=OFF -DCOSE_C_INCLUDE_SIGN=OFF -DCOSE_C_INCLUDE_SIGN1=OFF -DCOSE_C_INCLUDE_COUNTERSIGN=OFF",
+            "-DCOSE_C_INCLUDE_ENCRYPT=OFF -DCOSE_C_INCLUDE_ENCRYPT0=OFF -DCOSE_C_INCLUDE_MAC0=ON -DCOSE_C_INCLUDE_MAC=OFF -DCOSE_C_INCLUDE_SIGN=OFF -DCOSE_C_INCLUDE_SIGN1=OFF -DCOSE_C_INCLUDE_COUNTERSIGN=OFF",
+            "-DCOSE_C_INCLUDE_ENCRYPT=OFF -DCOSE_C_INCLUDE_ENCRYPT0=OFF -DCOSE_C_INCLUDE_MAC0=OFF -DCOSE_C_INCLUDE_MAC=ON -DCOSE_C_INCLUDE_SIGN=OFF -DCOSE_C_INCLUDE_SIGN1=OFF -DCOSE_C_INCLUDE_COUNTERSIGN=OFF",
+            "-DCOSE_C_INCLUDE_ENCRYPT=OFF -DCOSE_C_INCLUDE_ENCRYPT0=OFF -DCOSE_C_INCLUDE_MAC0=OFF -DCOSE_C_INCLUDE_MAC=OFF -DCOSE_C_INCLUDE_SIGN=ON -DCOSE_C_INCLUDE_SIGN1=OFF -DCOSE_C_INCLUDE_COUNTERSIGN=OFF",
+            "-DCOSE_C_INCLUDE_ENCRYPT=OFF -DCOSE_C_INCLUDE_ENCRYPT0=OFF -DCOSE_C_INCLUDE_MAC0=OFF -DCOSE_C_INCLUDE_MAC=OFF -DCOSE_C_INCLUDE_SIGN=OFF -DCOSE_C_INCLUDE_SIGN1=ON -DCOSE_C_INCLUDE_COUNTERSIGN=OFF",
+            "-DCOSE_C_INCLUDE_ENCRYPT=ON -DCOSE_C_INCLUDE_ENCRYPT0=OFF -DCOSE_C_INCLUDE_MAC0=OFF -DCOSE_C_INCLUDE_MAC=OFF -DCOSE_C_INCLUDE_SIGN=OFF -DCOSE_C_INCLUDE_SIGN1=OFF -DCOSE_C_INCLUDE_COUNTERSIGN=ON",
+            "-DCOSE_C_INCLUDE_ENCRYPT=OFF -DCOSE_C_INCLUDE_ENCRYPT0=ON -DCOSE_C_INCLUDE_MAC0=OFF -DCOSE_C_INCLUDE_MAC=OFF -DCOSE_C_INCLUDE_SIGN=OFF -DCOSE_C_INCLUDE_SIGN1=OFF -DCOSE_C_INCLUDE_COUNTERSIGN=ON",
+            "-DCOSE_C_INCLUDE_ENCRYPT=OFF -DCOSE_C_INCLUDE_ENCRYPT0=OFF -DCOSE_C_INCLUDE_MAC0=ON -DCOSE_C_INCLUDE_MAC=OFF -DCOSE_C_INCLUDE_SIGN=OFF -DCOSE_C_INCLUDE_SIGN1=OFF -DCOSE_C_INCLUDE_COUNTERSIGN=ON",
+            "-DCOSE_C_INCLUDE_ENCRYPT=OFF -DCOSE_C_INCLUDE_ENCRYPT0=OFF -DCOSE_C_INCLUDE_MAC0=OFF -DCOSE_C_INCLUDE_MAC=ON -DCOSE_C_INCLUDE_SIGN=OFF -DCOSE_C_INCLUDE_SIGN1=OFF -DCOSE_C_INCLUDE_COUNTERSIGN=ON",
+            "-DCOSE_C_INCLUDE_ENCRYPT=OFF -DCOSE_C_INCLUDE_ENCRYPT0=OFF -DCOSE_C_INCLUDE_MAC0=OFF -DCOSE_C_INCLUDE_MAC=OFF -DCOSE_C_INCLUDE_SIGN=ON -DCOSE_C_INCLUDE_SIGN1=OFF -DCOSE_C_INCLUDE_COUNTERSIGN=ON",
+            "-DCOSE_C_INCLUDE_ENCRYPT=OFF -DCOSE_C_INCLUDE_ENCRYPT0=OFF -DCOSE_C_INCLUDE_MAC0=OFF -DCOSE_C_INCLUDE_MAC=OFF -DCOSE_C_INCLUDE_SIGN=OFF -DCOSE_C_INCLUDE_SIGN1=ON -DCOSE_C_INCLUDE_COUNTERSIGN=ON",
+            "-DCOSE_C_OPTIMIZE=ON -DCOSE_C_INCLUDE_COUNTERSIGN=ON"
           ]
 
     steps:
@@ -30,6 +42,11 @@
         if: startsWith(matrix.os, 'windows')
         run: |
           choco install openssl cmake
+      
+      - name: setup (linux)
+        if: startsWith(matrix.os, 'ubuntu')
+        run: |
+          sudo apt install cmake-data
 
       - name: Create Build directory
         shell: bash
@@ -41,7 +58,6 @@
 
       - name: Configure CMake
         shell: bash
-        # working-directory: ${{runner.workspace}}/build
         run: |
           cd $GITHUB_WORKSPACE/build
           cmake $GITHUB_WORKSPACE \
@@ -55,14 +71,12 @@
           -DCOSE_C_USE_MBEDTLS=${{matrix.USE_MBEDTLS}}
 
       - name: Build
-        # working-directory: ${{runner.workspace}}/build
         shell: bash
         run: |
           cd $GITHUB_WORKSPACE/build
           cmake --build .
 
       - name: get test data
-        # working-directory: ${{runner.workspace}}
         shell: bash
         run: |
           echo $GITHUB_WORKSPACE
@@ -73,7 +87,6 @@
           ls -al
 
       - name: Test
-        # working-directory: ${{runner.workspace}}/build
         shell: bash
         run: |
           pwd
@@ -85,3 +98,53 @@
           ls -al
           ctest -C Debug --verbose
 
+  clang-tidy:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest]
+        USE_MBEDTLS: ["ON", "OFF"]
+        USE_CONTEXT: ["ON", "OFF"]
+        CMAKE_OPTIONS:
+          [
+            "-DCOSE_C_INCLUDE_ENCRYPT=ON -DCOSE_C_INCLUDE_ENCRYPT0=OFF -DCOSE_C_INCLUDE_MAC0=OFF -DCOSE_C_INCLUDE_MAC=OFF -DCOSE_C_INCLUDE_SIGN=OFF -DCOSE_C_INCLUDE_SIGN1=OFF -DCOSE_C_INCLUDE_COUNTERSIGN=OFF",
+            "-DCOSE_C_INCLUDE_ENCRYPT=OFF -DCOSE_C_INCLUDE_ENCRYPT0=ON -DCOSE_C_INCLUDE_MAC0=OFF -DCOSE_C_INCLUDE_MAC=OFF -DCOSE_C_INCLUDE_SIGN=OFF -DCOSE_C_INCLUDE_SIGN1=OFF -DCOSE_C_INCLUDE_COUNTERSIGN=OFF",
+            "-DCOSE_C_INCLUDE_ENCRYPT=OFF -DCOSE_C_INCLUDE_ENCRYPT0=OFF -DCOSE_C_INCLUDE_MAC0=ON -DCOSE_C_INCLUDE_MAC=OFF -DCOSE_C_INCLUDE_SIGN=OFF -DCOSE_C_INCLUDE_SIGN1=OFF -DCOSE_C_INCLUDE_COUNTERSIGN=OFF",
+            "-DCOSE_C_INCLUDE_ENCRYPT=OFF -DCOSE_C_INCLUDE_ENCRYPT0=OFF -DCOSE_C_INCLUDE_MAC0=OFF -DCOSE_C_INCLUDE_MAC=ON -DCOSE_C_INCLUDE_SIGN=OFF -DCOSE_C_INCLUDE_SIGN1=OFF -DCOSE_C_INCLUDE_COUNTERSIGN=OFF",
+            "-DCOSE_C_INCLUDE_ENCRYPT=OFF -DCOSE_C_INCLUDE_ENCRYPT0=OFF -DCOSE_C_INCLUDE_MAC0=OFF -DCOSE_C_INCLUDE_MAC=OFF -DCOSE_C_INCLUDE_SIGN=ON -DCOSE_C_INCLUDE_SIGN1=OFF -DCOSE_C_INCLUDE_COUNTERSIGN=OFF",
+            "-DCOSE_C_INCLUDE_ENCRYPT=OFF -DCOSE_C_INCLUDE_ENCRYPT0=OFF -DCOSE_C_INCLUDE_MAC0=OFF -DCOSE_C_INCLUDE_MAC=OFF -DCOSE_C_INCLUDE_SIGN=OFF -DCOSE_C_INCLUDE_SIGN1=ON -DCOSE_C_INCLUDE_COUNTERSIGN=OFF",
+            "-DCOSE_C_INCLUDE_ENCRYPT=ON -DCOSE_C_INCLUDE_ENCRYPT0=OFF -DCOSE_C_INCLUDE_MAC0=OFF -DCOSE_C_INCLUDE_MAC=OFF -DCOSE_C_INCLUDE_SIGN=OFF -DCOSE_C_INCLUDE_SIGN1=OFF -DCOSE_C_INCLUDE_COUNTERSIGN=ON",
+            "-DCOSE_C_INCLUDE_ENCRYPT=OFF -DCOSE_C_INCLUDE_ENCRYPT0=ON -DCOSE_C_INCLUDE_MAC0=OFF -DCOSE_C_INCLUDE_MAC=OFF -DCOSE_C_INCLUDE_SIGN=OFF -DCOSE_C_INCLUDE_SIGN1=OFF -DCOSE_C_INCLUDE_COUNTERSIGN=ON",
+            "-DCOSE_C_INCLUDE_ENCRYPT=OFF -DCOSE_C_INCLUDE_ENCRYPT0=OFF -DCOSE_C_INCLUDE_MAC0=ON -DCOSE_C_INCLUDE_MAC=OFF -DCOSE_C_INCLUDE_SIGN=OFF -DCOSE_C_INCLUDE_SIGN1=OFF -DCOSE_C_INCLUDE_COUNTERSIGN=ON",
+            "-DCOSE_C_INCLUDE_ENCRYPT=OFF -DCOSE_C_INCLUDE_ENCRYPT0=OFF -DCOSE_C_INCLUDE_MAC0=OFF -DCOSE_C_INCLUDE_MAC=ON -DCOSE_C_INCLUDE_SIGN=OFF -DCOSE_C_INCLUDE_SIGN1=OFF -DCOSE_C_INCLUDE_COUNTERSIGN=ON",
+            "-DCOSE_C_INCLUDE_ENCRYPT=OFF -DCOSE_C_INCLUDE_ENCRYPT0=OFF -DCOSE_C_INCLUDE_MAC0=OFF -DCOSE_C_INCLUDE_MAC=OFF -DCOSE_C_INCLUDE_SIGN=ON -DCOSE_C_INCLUDE_SIGN1=OFF -DCOSE_C_INCLUDE_COUNTERSIGN=ON",
+            "-DCOSE_C_INCLUDE_ENCRYPT=OFF -DCOSE_C_INCLUDE_ENCRYPT0=OFF -DCOSE_C_INCLUDE_MAC0=OFF -DCOSE_C_INCLUDE_MAC=OFF -DCOSE_C_INCLUDE_SIGN=OFF -DCOSE_C_INCLUDE_SIGN1=ON -DCOSE_C_INCLUDE_COUNTERSIGN=ON",
+          ]
+
+    steps:
+      - uses: actions/checkout@v1
+      - name: setup (linux)
+        if: startsWith(matrix.os, 'ubuntu')
+        run: |
+          sudo apt install cmake-data clang clang-tidy
+      - name: Create Build directory
+        run: cmake -E make_directory ${{runner.workspace}}/build
+
+      - name: Configure CMake
+        shell: bash
+        working-directory: ${{runner.workspace}}/build
+        run: |
+          export CC=clang && \
+          export CXX=clang++ && \
+          cmake $GITHUB_WORKSPACE \
+          -DCOSE_C_USE_CONTEXT=${{matrix.USE_CONTEXT}} \
+          -DCOSE_C_BUILD_DOCS=OFF \
+          -DCOSE_C_BUILD_TESTS=ON \
+          -DCOSE_C_RUN_CLANG_TIDY=ON \
+          ${{matrix.CMAKE_OPTIONS}} \
+          -DCOSE_C_USE_MBEDTLS=${{matrix.USE_MBEDTLS}}
+
+      - name: Build
+        working-directory: ${{runner.workspace}}/build
+        shell: bash
+        run: cmake --build .
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