diff --git a/.github/workflows/centos7.yml b/.github/workflows/centos7.yml
index 0da04465ed..dd3d6de286 100644
--- a/.github/workflows/centos7.yml
+++ b/.github/workflows/centos7.yml
@@ -9,6 +9,8 @@ on:
       - 'docs/**'
       - '**.adoc'
       - '**.md'
+      - '.github/workflows/*.yml'
+      - '!.github/workflows/centos7.yml'
   pull_request:
     paths-ignore:
       - 'docs/**'
@@ -36,19 +38,42 @@ jobs:
       matrix:
         env:
           - BUILD_MODE: normal
-            GPG_VERSION: stable
+            GPG_VERSION: stable          
+            CC: gcc
+            CXX: g++
+          - BUILD_MODE: normal
+            GPG_VERSION: beta
+            CC: gcc
+            CXX: g++
+          - BUILD_MODE: normal
+            GPG_VERSION: stable          
+            CC: clang
+            CXX: clang++
           - BUILD_MODE: normal
             GPG_VERSION: beta
+            CC: clang
+            CXX: clang++
+# Sanitize can only been tested with the clang compiler (why ???)
+# see env-common.inc.sh
           - BUILD_MODE: sanitize
             GPG_VERSION: stable
+            CC: clang
+            CXX: clang++
           - BUILD_MODE: sanitize
             GPG_VERSION: beta
+            CC: clang
+            CXX: clang++
+# Coverage can only been tested with the GNU compiler.
           - BUILD_MODE: coverage
             GPG_VERSION: beta
             RNP_TESTS: cli_tests
+            CC: gcc
+            CXX: g++
           - BUILD_MODE: coverage
             GPG_VERSION: beta
             RNP_TESTS: rnp_tests
+            CC: gcc
+            CXX: g++
     env: ${{ matrix.env }}
     steps:
       - run: |
@@ -72,7 +97,7 @@ jobs:
         uses: actions/cache@v2
         with:
           path: ${{ env.CACHE_DIR }}
-          key: ${{ github.workflow }}-${{ runner.os }}-${{ matrix.env.BUILD_MODE }}-gpg-${{ matrix.env.GPG_VERSION }}-${{ hashFiles('ci/**') }}-${{ hashFiles('.github/workflows/**') }}
+          key: ${{ github.workflow }}-${{ runner.os }}-${{ matrix.env.BUILD_MODE }}-${{ matrix.env.CC }}-gpg-${{ matrix.env.GPG_VERSION }}-${{ hashFiles('ci/**') }}-${{ hashFiles('.github/workflows/**') }}
       - name: Build cache
         if: steps.cache.outputs.cache-hit != 'true'
         run: |
@@ -95,14 +120,26 @@ jobs:
     if: "!contains(github.event.head_commit.message, 'skip ci')"
     container:
       image: centos:7
-    timeout-minutes: 10
+    timeout-minutes: 30
     strategy:
+      fail-fast: false
       matrix:
         env:
           - BUILD_SHARED_LIBS: yes
+            CC: gcc
+            CXX: g++
           - BUILD_SHARED_LIBS: no
+            CC: gcc
+            CXX: g++
+# We think do not need it but it is here if we start thinking that we need it
+#          - BUILD_SHARED_LIBS: yes
+#            CC: clang
+#            CXX: clang++
+#          - BUILD_SHARED_LIBS: no
+#            CC: clang
+#            CXX: clang++
     env: ${{ matrix.env }}
-    continue-on-error: true
+    name:  pkgconfig-cmake-target BUILD_SHARED_LIBS=${{ matrix.env.BUILD_SHARED_LIBS }}, ${{ matrix.env.CC }}, ${{ matrix.env.CXX }}
     steps:
       - run: |
           yum -y install http://opensource.wandisco.com/centos/7/git/x86_64/wandisco-git-release-7-2.noarch.rpm
@@ -116,12 +153,9 @@ jobs:
           export USE_STATIC_DEPENDENCIES=no
           ci/install_noncacheable_dependencies.sh
           ci/install_cacheable_dependencies.sh
-
           . ci/env.inc.sh
-
           # build+install
           build_and_install /usr
-
           # check for install issues
           check_build
           build_example_pkgconfig
diff --git a/.github/workflows/centos8-ossl.yml b/.github/workflows/centos8-ossl.yml
index 280f8a05e0..bbeb8ba9ff 100644
--- a/.github/workflows/centos8-ossl.yml
+++ b/.github/workflows/centos8-ossl.yml
@@ -1,11 +1,21 @@
 name: centos8-openssl
 
 on:
-  pull_request:
   push:
     branches:
       - master
       - 'release/**'
+    paths-ignore:
+      - 'docs/**'
+      - '**.adoc'
+      - '**.md'
+      - '.github/workflows/*.yml'
+      - '!.github/workflows/centos8-ossl.yml'
+  pull_request:
+    paths-ignore:
+      - 'docs/**'
+      - '**.adoc'
+      - '**.md'
 
 env:
   CORES: 2
@@ -23,17 +33,40 @@ jobs:
       image: centos:8
     timeout-minutes: 70
     strategy:
-      fail-fast: false
       matrix:
         env:
           - BUILD_MODE: normal
             RNP_TESTS: rnp_tests
+            CC: gcc
+            CXX: g++
           - BUILD_MODE: sanitize
             RNP_TESTS: rnp_tests
+            CC: gcc
+            CXX: g++
           - BUILD_MODE: normal
             RNP_TESTS: cli_tests
+            CC: gcc
+            CXX: g++
           - BUILD_MODE: sanitize
             RNP_TESTS: cli_tests          
+            CC: gcc
+            CXX: g++
+          - BUILD_MODE: normal
+            RNP_TESTS: rnp_tests
+            CC: clang
+            CXX: clang++
+          - BUILD_MODE: sanitize
+            RNP_TESTS: rnp_tests
+            CC: clang
+            CXX: clang++
+          - BUILD_MODE: normal
+            RNP_TESTS: cli_tests
+            CC: clang
+            CXX: clang++
+          - BUILD_MODE: sanitize
+            RNP_TESTS: cli_tests          
+            CC: clang
+            CXX: clang++
     env: ${{ matrix.env }}
     steps:
       - run: |
@@ -56,7 +89,7 @@ jobs:
         uses: actions/cache@v2
         with:
           path: ${{ env.CACHE_DIR }}
-          key: ${{ github.workflow }}-${{ runner.os }}-${{ matrix.env.BUILD_MODE }}-gpg-${{ matrix.env.GPG_VERSION }}-${{ hashFiles('ci/**') }}-${{ hashFiles('.github/workflows/**') }}
+          key: ${{ github.workflow }}-${{ runner.os }}-${{ matrix.env.BUILD_MODE }}-${{ matrix.env.CC }}-gpg-${{ matrix.env.GPG_VERSION }}-${{ hashFiles('ci/**') }}-${{ hashFiles('.github/workflows/**') }}
       - name: Build cache
         if: steps.cache.outputs.cache-hit != 'true'
         run: |
@@ -74,3 +107,4 @@ jobs:
           export CRYPTO_BACKEND=openssl
           chown -R rnpuser:rnpuser $PWD
           exec su rnpuser -c ci/run.sh
+
diff --git a/.github/workflows/centos8.yml b/.github/workflows/centos8.yml
index 0ddb2fb711..71830b4e9e 100644
--- a/.github/workflows/centos8.yml
+++ b/.github/workflows/centos8.yml
@@ -9,6 +9,8 @@ on:
       - 'docs/**'
       - '**.adoc'
       - '**.md'
+      - '.github/workflows/*.yml'
+      - '!.github/workflows/centos8.yml'
   pull_request:
     paths-ignore:
       - 'docs/**'
@@ -36,27 +38,49 @@ jobs:
         env:
           - BUILD_MODE: normal
             GPG_VERSION: stable
+            CC: gcc
+            CXX: g++
           - BUILD_MODE: normal
             GPG_VERSION: beta
+            CC: gcc
+            CXX: g++
           - BUILD_MODE: normal
             GPG_VERSION: 2.3.1
-          - BUILD_MODE: sanitize
+            CC: gcc
+            CXX: g++
+          - BUILD_MODE: normal
             GPG_VERSION: stable
-
-          # TODO: fix build error:
-          # libcommon.a(libcommon_a-iobuf.o):(.bss+0x8): multiple definition of `iobuf_debug_mode'
-          # t-iobuf.o:(.bss+0x0): first defined here
-          # clang-11: error: linker command failed with exit code 1 (use -v to see invocation)
-          #
-          # - BUILD_MODE: sanitize
-          #   GPG_VERSION: beta
-
+            CC: clang
+            CXX: clang++
+          - BUILD_MODE: normal
+            GPG_VERSION: beta
+            CC: clang
+            CXX: clang++
+          - BUILD_MODE: normal
+            GPG_VERSION: 2.3.1
+            CC: clang
+            CXX: clang++
+# Coverage can only been tested with the GNU compiler
           - BUILD_MODE: coverage
             GPG_VERSION: beta
             RNP_TESTS: cli_tests
+            CC: gcc
+            CXX: g++
           - BUILD_MODE: coverage
             GPG_VERSION: beta
             RNP_TESTS: rnp_tests
+            CC: gcc
+            CXX: g++
+# Sanitize is only tested with the clang compiler 
+# see env-common.inc.sh
+          - BUILD_MODE: sanitize
+            GPG_VERSION: stable
+            CC: clang
+            CXX: clang++
+          - BUILD_MODE: sanitize
+            GPG_VERSION: beta
+            CC: clang
+            CXX: clang++
     env: ${{ matrix.env }}
     steps:
       - run: |
@@ -79,7 +103,7 @@ jobs:
         uses: actions/cache@v2
         with:
           path: ${{ env.CACHE_DIR }}
-          key: ${{ github.workflow }}-${{ runner.os }}-${{ matrix.env.BUILD_MODE }}-gpg-${{ matrix.env.GPG_VERSION }}-${{ hashFiles('ci/**') }}-${{ hashFiles('.github/workflows/**') }}
+          key: ${{ github.workflow }}-${{ runner.os }}-${{ matrix.env.BUILD_MODE }}-${{ matrix.env.CC }}-gpg-${{ matrix.env.GPG_VERSION }}-${{ hashFiles('ci/**') }}-${{ hashFiles('.github/workflows/**') }}
       - name: Build cache
         if: steps.cache.outputs.cache-hit != 'true'
         run: |
@@ -99,18 +123,35 @@ jobs:
           grep -qw rnp_version_string exports
   pkgconfig-cmake-target:
     runs-on: ubuntu-latest
-    # TODO: re-enable when the following can pass
-    if: "${{ false && !contains(github.event.head_commit.message, 'skip ci') }}"
+    if: "${{ !contains(github.event.head_commit.message, 'skip ci') }}"
     container:
       image: centos:8
-    timeout-minutes: 10
+    timeout-minutes: 30
     strategy:
+      fail-fast: false
+# CXXFLAGS environment setting resolves dual ABI issues caused by BOTAN libraries
+# https://gcc.gnu.org/onlinedocs/gcc-5.2.0/libstdc++/manual/manual/using_dual_abi.html
       matrix:
         env:
           - BUILD_SHARED_LIBS: yes
+            CC: gcc
+            CXX: g++
+            CXXFLAGS: -D_GLIBCXX_USE_CXX11_ABI=0
           - BUILD_SHARED_LIBS: no
+            CC: gcc
+            CXX: g++
+            CXXFLAGS: -D_GLIBCXX_USE_CXX11_ABI=0
+# We think do not need it but it is here if we start thinking that we need it
+#          - BUILD_SHARED_LIBS: yes
+#            CC: clang
+#            CXX: clang++
+#            CXXFLAGS: -D_GLIBCXX_USE_CXX11_ABI=0
+#          - BUILD_SHARED_LIBS: no
+#            CC: clang
+#            CXX: clang++
+#            CXXFLAGS: -D_GLIBCXX_USE_CXX11_ABI=0
     env: ${{ matrix.env }}
-    continue-on-error: true
+    name:  pkgconfig-cmake-target BUILD_SHARED_LIBS=${{ matrix.env.BUILD_SHARED_LIBS }}, ${{ matrix.env.CC }}, ${{ matrix.env.CXX }}
     steps:
       - run: |
           yum -y install git
@@ -119,18 +160,14 @@ jobs:
           fetch-depth: 1
       - name: Test
         run: |
-
           # cmake
           set -euxo pipefail
           export USE_STATIC_DEPENDENCIES=no
           ci/install_noncacheable_dependencies.sh
           ci/install_cacheable_dependencies.sh
-
           . ci/env.inc.sh
-
           # build+install
           build_and_install /usr
-
           # check for install issues
           check_build
           build_example_pkgconfig
diff --git a/.github/workflows/debian9.yml b/.github/workflows/debian9.yml
index 84902dd1bf..5e142fa67d 100644
--- a/.github/workflows/debian9.yml
+++ b/.github/workflows/debian9.yml
@@ -9,6 +9,8 @@ on:
       - 'docs/**'
       - '**.adoc'
       - '**.md'
+      - '.github/workflows/*.yml'
+      - '!.github/workflows/debian9.yml'
   pull_request:
     paths-ignore:
       - 'docs/**'
@@ -37,44 +39,48 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-# I386: actions/checkout@V2,  actions/cache@V2 actions/cache@V2 
-#       give error about OCI container [https://github.com/actions/checkout/issues/334]
-#                                      [https://github.com/actions/runner/issues/1011]
         env:
-          - CPU: i386
+          - CC: gcc
+            CXX: g++
+            CPU: i386
+            IMAGE: "i386/debian:9"
+          - CC: clang
+            CXX: clang++
+            CPU: i386
             IMAGE: "i386/debian:9"
     env: ${{ matrix.env }}
+    name: ${{ matrix.env.IMAGE }}, ${{ matrix.env.CC }}, ${{ matrix.env.CXX }}
     steps:
       - name: Install prerequisites
         run: |
           apt update
           apt -y install git sudo
-      
+          apt -y install git sudo      
+# I386: actions/checkout@V2,  actions/cache@V2 actions/cache@V2 
+#       give error about OCI container [https://github.com/actions/checkout/issues/334]
+#                                      [https://github.com/actions/runner/issues/1011]
       - name: Check out repository
         uses: actions/checkout@v1
         with:
-          fetch-depth: 1
+          fetch-depth: 10
 
       - name: Setup noncacheable dependencies
         run: |
           . ci/gha/setup-env.inc.sh
           ci/install_noncacheable_dependencies.sh
         shell: bash
-
 #      - name: Cache 
 #        id: cache
 #        uses: actions/cache@v2
 #        with:
 #          path: ${{github.workspace}}/${{ env.CACHE_DIR }}
 #          key: ${{runner.os}}-${{ matrix.env.CPU }}-${{ matrix.env.IMAGE }}-v1
-
       - name: Setup cacheable dependencies
         if: steps.cache.outputs.cache-hit != 'true'
         run: |
           set -euxo pipefail
           ci/install_cacheable_dependencies.sh
         shell: bash
-
       - name: Add rnpuser
         # it's only needed for rnpkeys_generatekey_verifykeyHomeDirNoPermission test
         run: |
@@ -82,16 +88,15 @@ jobs:
            printf "\nrnpuser\tALL=(ALL)\tNOPASSWD:\tALL" > /etc/sudoers.d/rnpuser
            printf "\nrnpuser\tsoft\tnproc\tunlimited\n" > /etc/security/limits.d/30-rnpuser.conf
            echo "SUDO=sudo" >> $GITHUB_ENV
-
       - name: Build and Test
         run: |
           set -x
           chown -R rnpuser:rnpuser $PWD
           exec su rnpuser -c ci/run.sh
         shell: bash
-
       - name: Package
         run: |
           set -x
           cd ${LOCAL_BUILDS}/rnp-build
           cpack -G DEB -D CPACK_DEBIAN_PACKAGE_SHLIBDEPS_PRIVATE_DIRS="${BOTAN_INSTALL}/lib;${JSONC_INSTALL}/lib;${GPG_INSTALL}/lib"
+
diff --git a/.github/workflows/macos.yml b/.github/workflows/macos.yml
index 5d54b3e519..18d42aa243 100644
--- a/.github/workflows/macos.yml
+++ b/.github/workflows/macos.yml
@@ -9,6 +9,8 @@ on:
       - 'docs/**'
       - '**.adoc'
       - '**.md'
+      - '.github/workflows/*.yml'
+      - '!.github/workflows/macos.yml'
   pull_request:
     paths-ignore:
       - 'docs/**'
@@ -23,13 +25,19 @@ env:
 
 jobs:
   tests:
-    name: ${{ matrix.os }}
-    runs-on: ${{ matrix.os }}
     strategy:
       fail-fast: false
       matrix:
         os: [macos-10.15, macos-11.0]
+        env:
+          - CC: gcc
+            CXX: g++
+          - CC: clang
+            CXX: clang++
     if: "!contains(github.event.head_commit.message, 'skip ci')"
+    name: ${{ matrix.os }}, ${{ matrix.env.CC }}, ${{ matrix.env.CXX }}
+    runs-on: ${{ matrix.os }}
+    env: ${{ matrix.env }}    
     timeout-minutes: 250
     steps:
       - uses: actions/checkout@v2
@@ -44,7 +52,7 @@ jobs:
         uses: actions/cache@v2
         with:
           path: ${{ env.CACHE_DIR }}
-          key: ${{ github.workflow }}-${{ matrix.os }}-${{ env.BUILD_MODE }}-gpg-${{ env.GPG_VERSION }}-${{ hashFiles('ci/**') }}-${{ hashFiles('.github/workflows/**') }}
+          key: ${{ github.workflow }}-${{ matrix.os }}-${{ env.BUILD_MODE }}-${{ matrix.env.CC }}-gpg-${{ env.GPG_VERSION }}-${{ hashFiles('ci/**') }}-${{ hashFiles('.github/workflows/**') }}
       - name: Build cache
         if: steps.cache.outputs.cache-hit != 'true'
         run: |
diff --git a/.github/workflows/ubuntu.yml b/.github/workflows/ubuntu.yml
index 6bff64c01a..79461e526c 100644
--- a/.github/workflows/ubuntu.yml
+++ b/.github/workflows/ubuntu.yml
@@ -9,6 +9,8 @@ on:
       - 'docs/**'
       - '**.adoc'
       - '**.md'
+      - '.github/workflows/*.yml'
+      - '!.github/workflows/ubuntu.yml'
   pull_request:
     paths-ignore:
       - 'docs/**'
@@ -23,8 +25,17 @@ env:
 
 jobs:
   tests:
+    strategy:
+      matrix:
+        env:
+          - CC: gcc
+            CXX: g++
+          - CC: clang
+            CXX: clang++
     runs-on: ubuntu-latest
     if: "!contains(github.event.head_commit.message, 'skip ci')"
+    name: ubuntu ${{ matrix.env.CC }}, ${{ matrix.env.CXX }}
+    env: ${{ matrix.env }}    
     timeout-minutes: 50
     steps:
       - uses: actions/checkout@v2
@@ -39,7 +50,7 @@ jobs:
         uses: actions/cache@v2
         with:
           path: ${{ env.CACHE_DIR }}
-          key: ${{ github.workflow }}-${{ runner.os }}-${{ env.BUILD_MODE }}-gpg-${{ env.GPG_VERSION }}-${{ hashFiles('ci/**') }}-${{ hashFiles('.github/workflows/**') }}
+          key: ${{ github.workflow }}-${{ runner.os }}-${{ env.BUILD_MODE }}-${{ matrix.env.CC }}-gpg-${{ env.GPG_VERSION }}-${{ hashFiles('ci/**') }}-${{ hashFiles('.github/workflows/**') }}
       - name: Build cache
         if: steps.cache.outputs.cache-hit != 'true'
         run: |
@@ -55,12 +66,22 @@ jobs:
           cd ${LOCAL_BUILDS}/rnp-build
           cpack -G DEB -D CPACK_DEBIAN_PACKAGE_SHLIBDEPS_PRIVATE_DIRS="${BOTAN_INSTALL}/lib;${JSONC_INSTALL}/lib;${GPG_INSTALL}/lib"
   cmake-offline-googletest-src:
-    env:
-      GTEST_SOURCES: /usr/src/googletest
-      RNP_TESTS: rnp_tests
+    strategy:
+      matrix:
+        env:
+          - CC: gcc
+            CXX: g++
+            GTEST_SOURCES: /usr/src/googletest
+            RNP_TESTS: rnp_tests
+# We think do not need it but it is here if we start thinking that we need it
+#          - CC: clang
+#            CXX: clang++  
+#            GTEST_SOURCES: /usr/src/googletest
+#            RNP_TESTS: rnp_tests
     runs-on: ubuntu-latest
     if: "!contains(github.event.head_commit.message, 'skip ci')"
-    timeout-minutes: 30
+    env: ${{ matrix.env }}    
+    timeout-minutes: 50
     steps:
       - uses: actions/checkout@v2
         with:
@@ -89,11 +110,21 @@ jobs:
           [ -d "${LOCAL_BUILDS}/rnp-build/src/tests/googletest-build" ]
           [ ! -d "${LOCAL_BUILDS}/rnp-build/src/tests/googletest-src" ]
   cmake-offline-googletest:
-    env:
-      DOWNLOAD_GTEST: Off
-      RNP_TESTS: rnp_tests
+    strategy:
+      matrix:
+        env:
+          - CC: gcc
+            CXX: g++
+            DOWNLOAD_GTEST: Off
+            RNP_TESTS: rnp_tests
+# We think do not need it but it is here if we start thinking that we need it
+#          - CC: clang
+#            CXX: clang++  
+#            DOWNLOAD_GTEST: Off
+#            RNP_TESTS: rnp_tests
     runs-on: ubuntu-latest
     if: "!contains(github.event.head_commit.message, 'skip ci')"
+    env: ${{ matrix.env }}    
     timeout-minutes: 50
     steps:
       - uses: actions/checkout@v2
@@ -132,38 +163,48 @@ jobs:
           [ ! -d "${LOCAL_BUILDS}/rnp-build/src/tests/googletest-build" ]
           [ ! -d "${LOCAL_BUILDS}/rnp-build/src/tests/googletest-src" ]
   cmake-disable-rubyrnp:
-    env:
-      DOWNLOAD_RUBYRNP: Off
-      RNP_TESTS: rnp_tests.hash_test_success
+    strategy:
+      matrix:
+        env:
+          - CC: gcc
+            CXX: g++
+            DOWNLOAD_RUBYRNP: Off
+            RNP_TESTS: rnp_tests.hash_test_success
+# We think do not need it but it is here if we start thinking that we need it
+#          - CC: clang
+#            CXX: clang++  
+#            DOWNLOAD_RUBYRNP: Off
+#            RNP_TESTS: rnp_tests.hash_test_success
     runs-on: ubuntu-latest
     if: "!contains(github.event.head_commit.message, 'skip ci')"
+    env: ${{ matrix.env }}    
     timeout-minutes: 50
     steps:
-      - uses: actions/checkout@v2
-        with:
-          fetch-depth: 1
-      - name: Setup environment
-        run: |
-          . ci/gha/setup-env.inc.sh
-          ci/install_noncacheable_dependencies.sh
-      - name: Cache
-        id: cache
-        uses: actions/cache@v2
-        with:
-          path: ${{ env.CACHE_DIR }}
-          key: ${{ github.workflow }}-${{ github.job }}-${{ runner.os }}-${{ env.BUILD_MODE }}-gpg-${{ env.GPG_VERSION }}-${{ hashFiles('ci/**') }}-${{ hashFiles('.github/workflows/**') }}
-      - name: Build cache
-        if: steps.cache.outputs.cache-hit != 'true'
-        run: |
-          set -x
-          ci/install_cacheable_dependencies.sh
-      - name: tests
-        run: |
-          set -x
-          ci/run.sh
-          ls -la "${RNP_INSTALL}/lib/"librnp*.so
-          ! ctest -N | grep 'ruby' > /dev/null
-          ! ls -la src/tests/ | grep 'ruby' > /dev/null
+       - uses: actions/checkout@v2
+         with:
+           fetch-depth: 1
+       - name: Setup environment
+         run: |
+           . ci/gha/setup-env.inc.sh
+           ci/install_noncacheable_dependencies.sh
+       - name: Cache
+         id: cache
+         uses: actions/cache@v2
+         with:
+           path: ${{ env.CACHE_DIR }}
+           key: ${{ github.workflow }}-${{ github.job }}-${{ runner.os }}-${{ env.BUILD_MODE }}-gpg-${{ env.GPG_VERSION }}-${{ hashFiles('ci/**') }}-${{ hashFiles('.github/workflows/**') }}
+       - name: Build cache
+         if: steps.cache.outputs.cache-hit != 'true'
+         run: |
+           set -x
+           ci/install_cacheable_dependencies.sh
+       - name: tests
+         run: |
+           set -x
+           ci/run.sh
+           ls -la "${RNP_INSTALL}/lib/"librnp*.so
+           ! ctest -N | grep 'ruby' > /dev/null
+           ! ls -la src/tests/ | grep 'ruby' > /dev/null
   version-cmake-up-to-date:
     runs-on: ubuntu-latest
     if: "!contains(github.event.head_commit.message, 'skip ci')"
diff --git a/.github/workflows/windows-msvc.yml b/.github/workflows/windows-msvc.yml
index a8c3f32c5f..2b831032c1 100644
--- a/.github/workflows/windows-msvc.yml
+++ b/.github/workflows/windows-msvc.yml
@@ -8,6 +8,8 @@ on:
       - 'docs/**'
       - '**.adoc'
       - '**.md'
+      - '.github/workflows/*.yml'
+      - '!.github/workflows/windows-msvc.yml'
   pull_request:
     paths-ignore:
       - 'docs/**'
diff --git a/.github/workflows/windows.yml b/.github/workflows/windows.yml
index 7f1f66fe4b..13a290fb78 100644
--- a/.github/workflows/windows.yml
+++ b/.github/workflows/windows.yml
@@ -9,6 +9,8 @@ on:
       - 'docs/**'
       - '**.adoc'
       - '**.md'
+      - '.github/workflows/*.yml'
+      - '!.github/workflows/windows.yml'
   pull_request:
     paths-ignore:
       - 'docs/**'
@@ -22,11 +24,25 @@ env:
 
 jobs:
   tests:
+    strategy:
+      fail-fast: false
+      matrix:
+        env:
+          - CC: gcc
+            CXX: g++
+            GTEST_SOURCES: /home/runneradmin/googletest-download/googletest-src
+          - CC: clang
+            CXX: clang++
+            GTEST_SOURCES: /home/runneradmin/googletest-download/googletest-src
+ # Note re clang setup 
+ # https://github.com/randombit/botan/issues/1191:  "botan-2 is c++11 till the end of the times" 
+ # It may cause ABI problems with clang (but not with gcc) if extra library is required and it is not loaded from clang64 repo,  
+ # but comes from mingw64. If so try '-std=c++11'
     runs-on: windows-latest
+    name: msys2 ${{ matrix.env.CC }}, ${{ matrix.env.CXX }}
+    env:  ${{ matrix.env }}
     if: "!contains(github.event.head_commit.message, 'skip ci')"
     timeout-minutes: 70
-    env:
-      GTEST_SOURCES: /home/runneradmin/googletest-download/googletest-src
     steps:
       - uses: actions/checkout@v2
         with:
@@ -55,7 +71,8 @@ jobs:
       - name: tests
         shell: msys2 {0}
         run: bash ci/main.sh
-      - shell: msys2 {0}
+      - name: dependencies
+        shell: msys2 {0}
         run: |
           set -euxo pipefail
           wget https://github.com/lucasg/Dependencies/releases/download/v1.10/Dependencies_x64_Release.zip
@@ -63,3 +80,4 @@ jobs:
           ./Dependencies -exports $HOME/local-installs/rnp-install/bin/librnp*.dll > exports
           grep -qv dst_close exports
           grep -qw rnp_version_string exports
+
diff --git a/.gitignore b/.gitignore
index ef7ef66b7f..20c7cd1f7a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -443,6 +443,10 @@ $RECYCLE.BIN/
 *.msm
 *.msp
 
+# VS 
+CMakeSettings.json
+.vs/*
+
 # Windows shortcuts
 *.lnk
 
diff --git a/ci/env-freebsd.inc.sh b/ci/env-freebsd.inc.sh
index ba1f025eb2..d2a2fabad2 100644
--- a/ci/env-freebsd.inc.sh
+++ b/ci/env-freebsd.inc.sh
@@ -1,6 +1,6 @@
 #!/usr/bin/env sh
 
-export PATH=/usr/local/bin:$PATH
+export PATH="/usr/local/bin:$PATH"
 export MAKE=gmake
 export SUDO=sudo
 
diff --git a/ci/env-msys.inc.sh b/ci/env-msys.inc.sh
index 9ec404aca7..aafc258cee 100644
--- a/ci/env-msys.inc.sh
+++ b/ci/env-msys.inc.sh
@@ -6,8 +6,8 @@
 export CFLAGS="${CFLAGS}"
 export CXXFLAGS="${CXXFLAGS}"
 export LDFLAGS="${LDFLAGS}"
-export CC=gcc
-export CXX=g++
+export CC=${CC-gcc} 
+export CXX=${CXX-g++}
 : "${CORES:=$(nproc --all)}"
 export CORES
 export MAKE=make
diff --git a/ci/lib/cacheable_install_functions.inc.sh b/ci/lib/cacheable_install_functions.inc.sh
index f1cbd5bddf..76624b7472 100644
--- a/ci/lib/cacheable_install_functions.inc.sh
+++ b/ci/lib/cacheable_install_functions.inc.sh
@@ -158,7 +158,7 @@ _install_gpg() {
 
   local common_args=(
       --force-autogen
-#      --verbose		commnted out to speed up recurring CI builds
+#      --verbose		commented out to speed up recurring CI builds
 #      --trace                  uncomment if you are debugging CI
       --build-dir "${gpg_build}"
       --configure-opts "${configure_opts[*]}"
@@ -180,6 +180,11 @@ _install_gpg() {
   # Workaround to correctly build pinentry on the latest GHA on macOS. Most likely there is a better solution.
   export CFLAGS="-D_XOPEN_SOURCE_EXTENDED"
   export CXXFLAGS="-D_XOPEN_SOURCE_EXTENDED"
+  
+  # Always build gnugpg with gcc, even if we are testing clang
+  # ref https://github.com/rnpgp/rnp/issues/1669
+  export CC="gcc"
+  export CXX="g++"
 
   for component in libgpg-error:$LIBGPG_ERROR_VERSION \
                    libgcrypt:$LIBGCRYPT_VERSION \
diff --git a/ci/lib/install_functions.inc.sh b/ci/lib/install_functions.inc.sh
index 79e25bb882..83ef804a59 100644
--- a/ci/lib/install_functions.inc.sh
+++ b/ci/lib/install_functions.inc.sh
@@ -155,18 +155,19 @@ declare util_depedencies_yum=(
   git
 )
 
+
 declare basic_build_dependencies_yum=(
-  # cmake3 # XXX: Fedora 22+ only has cmake
-  clang
-  gcc
-  gcc-c++
-  make
-  autoconf
-  automake
-  libtool
-  bzip2
-  gzip
-)
+# cmake3 # XXX: Fedora 22+ only has cmake
+   clang
+   gcc
+   gcc-c++
+   make
+   autoconf
+   automake
+   libtool
+   bzip2
+   gzip
+ )
 
 declare build_dependencies_yum=(
   ncurses-devel
@@ -235,6 +236,7 @@ linux_install_centos7() {
   ensure_cmake
   ensure_ruby
   rubygem_install_build_dependencies
+
 }
 
 linux_install_centos8() {
@@ -248,6 +250,7 @@ linux_install_centos8() {
   ensure_cmake
   ensure_ruby
   rubygem_install_build_dependencies
+
 }
 
 is_use_static_dependencies() {
@@ -479,6 +482,7 @@ declare util_dependencies_deb=(
   sudo
   wget
   git
+  software-properties-common
 )
 
 declare basic_build_dependencies_deb=(
@@ -522,6 +526,17 @@ linux_install_debian() {
     "${build_dependencies_deb[@]}" \
     "$@"
 
+  if [ "${CC-gcc}" = "clang" ]; then
+# Add apt.llvm.org repository and install clang
+# We may use https://packages.debian.org/stretch/clang-3.8 as well but this package gets to
+# /usr/lib/clang... and requires update-alternatives which would be very ugly considering CC/CXX environment
+# coming from yaml already   
+    wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key|sudo apt-key add -
+    ${SUDO} apt-add-repository "deb http://apt.llvm.org/stretch/ llvm-toolchain-stretch main"
+    ${SUDO} apt-get install -y clang 
+  fi
+
+
   ensure_automake
   build_and_install_cmake
 }
@@ -535,8 +550,6 @@ linux_install() {
 msys_install() {
   local packages=(
     tar
-    zlib-devel
-    libbz2-devel
     git
     automake
     autoconf
@@ -544,21 +557,36 @@ msys_install() {
     automake-wrapper
     gnupg2
     make
-    pkg-config
+    pkg-config 
     mingw64/mingw-w64-x86_64-cmake
-    mingw64/mingw-w64-x86_64-gcc
-    mingw64/mingw-w64-x86_64-json-c
     mingw64/mingw-w64-x86_64-python3
   )
 
+  if [ "${CC-gcc}" = "gcc" ]; then
+    packages+=(mingw64/mingw-w64-x86_64-gcc 
+               mingw64/mingw-w64-x86_64-json-c
+    )
+  else
+   packages+=(clang64/mingw-w64-clang-x86_64-clang 
+              clang64/mingw-w64-clang-x86_64-openmp
+              clang64/mingw-w64-clang-x86_64-libc++
+              clang64/mingw-w64-clang-x86_64-libbotan
+              clang64/mingw-w64-clang-x86_64-libssp
+              clang64/mingw-w64-clang-x86_64-json-c
+              clang64/mingw-w64-clang-x86_64-libsystre
+   ) 
+  fi
+
   pacman --noconfirm -S --needed "${packages[@]}"
 
+  if [ "${CC-gcc}" = "gcc" ]; then
   # any version starting with 2.14 up to 2.17.3 caused the application to hang
   # as described in https://github.com/randombit/botan/issues/2582
   # fixed with https://github.com/msys2/MINGW-packages/pull/7640/files
-  botan_pkg="mingw-w64-x86_64-libbotan-2.17.3-2-any.pkg.tar.zst"
-  pacman --noconfirm -U https://repo.msys2.org/mingw/x86_64/${botan_pkg} || \
-  pacman --noconfirm -U https://sourceforge.net/projects/msys2/files/REPOS/MINGW/x86_64/${botan_pkg}
+    botan_pkg="mingw-w64-x86_64-libbotan-2.17.3-2-any.pkg.tar.zst"
+    pacman --noconfirm -U https://repo.msys2.org/mingw/x86_64/${botan_pkg} || \
+    pacman --noconfirm -U https://sourceforge.net/projects/msys2/files/REPOS/MINGW/x86_64/${botan_pkg}
+  fi
 
   # msys includes ruby 2.6.1 while we need lower version
   #wget http://repo.msys2.org/mingw/x86_64/mingw-w64-x86_64-ruby-2.5.3-1-any.pkg.tar.xz -O /tmp/ruby-2.5.3.pkg.tar.xz
@@ -699,7 +727,7 @@ is_version_at_least() {
   local installed_version installed_version_major installed_version_minor #version_patch
   installed_version="$("$@")"
 
-  # shellcheck disable=SC2181
+  # shellcheck disable=SC2181 
   if [[ $? -ne 0 ]]; then
     need_to_build=1
   else
@@ -707,7 +735,9 @@ is_version_at_least() {
     installed_version_minor="${installed_version#*.}"
     installed_version_minor="${installed_version_minor%%.*}"
     installed_version_minor="${installed_version_minor:-0}"
+  # shellcheck disable=SC2295  
     installed_version_patch="${installed_version#${installed_version_major}.}"
+  # shellcheck disable=SC2295  
     installed_version_patch="${installed_version_patch#${installed_version_minor}}"
     installed_version_patch="${installed_version_patch#.}"
     installed_version_patch="${installed_version_patch%%.*}"
@@ -719,7 +749,9 @@ is_version_at_least() {
     need_version_minor="${need_version_minor%%.*}"
     need_version_minor="${need_version_minor:-0}"
     need_version_patch="${version_constraint##*.}"
+  # shellcheck disable=SC2295  
     need_version_patch="${version_constraint#${need_version_major}.}"
+  # shellcheck disable=SC2295  
     need_version_patch="${need_version_patch#${need_version_minor}}"
     need_version_patch="${need_version_patch#.}"
     need_version_patch="${need_version_patch%%.*}"
@@ -780,7 +812,8 @@ build_and_install() {
   if [[ $# -gt 0 ]]; then
     shift
   fi
-
+  
+  post_build_tool_install_set_env              
   build_rnp "$@"
   make_install VERBOSE="${VERBOSE}"
 }
@@ -833,7 +866,7 @@ build_example_pkgconfig() {
   pushd "$(mktemp -d)" || return 1
 
   # shellcheck disable=SC2046
-  gcc "${rnpsrc}/src/examples/generate.c" -ogenerate $(pkg-config --cflags --libs $pkgflags librnp) $gccflags
+  ${CC-gcc} "${rnpsrc}/src/examples/generate.c" -ogenerate $(pkg-config --cflags --libs $pkgflags librnp) $gccflags
   ./generate
   readelf -d generate
   if is_true_cmake_bool "${BUILD_SHARED_LIBS}"; then
diff --git a/ci/main.sh b/ci/main.sh
index db1062b3fa..febab6c93f 100755
--- a/ci/main.sh
+++ b/ci/main.sh
@@ -32,11 +32,22 @@ prepare_build_prerequisites() {
 prepare_test_env() {
   prepare_build_tool_env
 
-  export LD_LIBRARY_PATH="${GPG_INSTALL}/lib:${BOTAN_INSTALL}/lib:${JSONC_INSTALL}/lib:${RNP_INSTALL}/lib:$LD_LIBRARY_PATH"
+  export LD_LIBRARY_PATH="${GPG_INSTALL}/lib:${BOTAN_INSTALL}/lib:${JSONC_INSTALL}/lib:${RNP_INSTALL}/lib:${LD_LIBRARY_PATH-}"
 
-  # update dll search path for windows
   if [[ "${OS}" = "msys" ]]; then
+  # update dll search path for windows
     export PATH="${LOCAL_BUILDS}/rnp-build/lib:${LOCAL_BUILDS}/rnp-build/bin:${LOCAL_BUILDS}/rnp-build/src/lib:$PATH"
+    if [[ "${CC-gcc}" = "clang" ]]; then
+  # clang paths shall have higher priority
+      export PATH="/clang64/bin:$PATH"
+      export LD_LIBRARY_PATH="/clang64/lib:$LD_LIBRARY_PATH"
+      export LIBRARY_PATH="/clang64/lib:${LIBRARY_PATH-}"
+      export C_INCLUDE_PATH="/clang64/include:${C_INCLUDE_PATH-}"
+      export CPP_INCLUDE_PATH="/clang64/include:${CPP_INCLUDE_PATH-}"
+
+  # clang 'wants' it explicit as opposed to gcc that links to glibc by default
+      export LDFLAGS="${LDFLAGS-} -lregex"
+    fi
   fi
 }