diff --git a/.github/workflows/dos-djgpp.yml b/.github/workflows/dos-djgpp.yml
index a1335d9..cae1021 100644
--- a/.github/workflows/dos-djgpp.yml
+++ b/.github/workflows/dos-djgpp.yml
@@ -42,7 +42,7 @@ jobs:
       - name: Setup build environment
         run: |
           sudo apt -y update
-          sudo apt -y install build-essential cmake wget 7zip git flex libfl-dev nasm libslang2-dev pkg-config libslang2-modules gcc-multilib
+          sudo apt -y install build-essential cmake wget 7zip git flex libfl-dev nasm libslang2-dev pkg-config libslang2-modules gcc-multilib dosbox
 
       - name: Download and Setup DJGPP Toolchain
         run: |
@@ -59,7 +59,16 @@ jobs:
           make -f djgpp.mak
           ln -s ${WATT_ROOT}/lib/libwatt.a ${{ github.workspace }}/djgpp/lib
 
+      - name: Cache OpenSSL 3.1.2
+        uses: actions/cache/restore@v4
+        id: cache-openssl
+        with:
+          path: |
+            ${{ github.workspace }}/djgpp
+          key: openssl-3.1.2-${{ hashFiles('**/CMakeLists.txt') }}
+
       - name: Checkout and Cross Compile OpenSSL 3.1.2
+        if: steps.cache-openssl.outputs.cache-hit != 'true'
         run: |
           git clone https://github.com/UMSKT/openssl.git openssl
           pushd openssl
@@ -68,6 +77,14 @@ jobs:
           make && make install_sw
           popd
 
+      - name: Save OpenSSL 3.1.2
+        if: steps.cache-openssl.outputs.cache-hit != 'true'
+        uses: actions/cache/save@v4
+        with:
+          path: |
+            ${{ github.workspace }}/djgpp
+          key: openssl-3.1.2-${{ hashFiles('**/CMakeLists.txt') }}
+
       - name: Build
         run: |
           source ${{ github.workspace }}/djgpp/setenv
@@ -75,6 +92,84 @@ jobs:
           cmake ../ -D DJGPP_WATT32=${WATT_ROOT}/lib/libwatt.a -D CMAKE_FIND_ROOT_PATH=${CMAKE_FIND_ROOT_PATH}
           make
 
+      - name: Setup DOSBox test environment
+        run: |
+          mkdir -p dosbox_test
+          cp build/umskt.exe dosbox_test/
+          # Download DPMI server directly
+          wget https://github.com/UMSKT/winactiontest/raw/refs/heads/main/CWSDPMI.EXE -O dosbox_test/CWSDPMI.EXE
+          # Create test batch file
+          cat > dosbox_test/test.bat << EOL
+          @echo off
+          echo Running test 1...
+          umskt.exe -b 2C -c 365 -s 069420 > TEST1.TXT
+          if errorlevel 1 goto error
+          echo Running test 2...
+          umskt.exe -i 253286028742154311079061239762245184619981623171292574 > TEST2.TXT
+          if errorlevel 1 goto error
+          echo Tests completed > DONE.TXT
+          goto end
+          :error
+          echo Test failed > ERROR.TXT
+          :end
+          exit
+          EOL
+          # Create DOSBox configuration
+          cat > dosbox_test/dosbox.conf << EOL
+          [sdl]
+          nosound=true
+          [cpu]
+          core=dynamic
+          cycles=max
+          [autoexec]
+          mount c .
+          c:
+          test.bat
+          exit
+          EOL
+
+      - name: Run tests in DOSBox
+        run: |
+          cd dosbox_test
+          timeout 30s dosbox -conf dosbox.conf -nogui -exit
+          # Check if the test completed successfully
+          if [ ! -f DONE.TXT ]; then
+            echo "Tests did not complete successfully"
+            if [ -f ERROR.TXT ]; then
+              echo "Test execution failed"
+            fi
+            if [ -f TEST1.TXT ]; then
+              echo "Test 1 output:"
+              cat TEST1.TXT
+            fi
+            if [ -f TEST2.TXT ]; then
+              echo "Test 2 output:"
+              cat TEST2.TXT
+            fi
+            exit 1
+          fi
+          # Verify test outputs
+          if [ ! -f TEST1.TXT ] || [ ! -f TEST2.TXT ]; then
+            echo "Test output files missing"
+            exit 1
+          fi
+          # Check test results - looking for key format patterns
+          if ! grep -qE '[A-Z0-9]{5}-[A-Z0-9]{5}-[A-Z0-9]{5}-[A-Z0-9]{5}-[A-Z0-9]{5}' TEST1.TXT || \
+             ! grep -qE '[0-9]{6}-[0-9]{6}-[0-9]{6}-[0-9]{6}-[0-9]{6}-[0-9]{6}-[0-9]{6}' TEST2.TXT; then
+            echo "Tests failed - unexpected output format"
+            echo "Test 1 output:"
+            cat TEST1.TXT
+            echo "Test 2 output:"
+            cat TEST2.TXT
+            exit 1
+          else
+            echo "All tests passed successfully"
+            echo "Test 1 output:"
+            cat TEST1.TXT
+            echo "Test 2 output:"
+            cat TEST2.TXT
+          fi
+
       - name: Move executable to upload directory
         run: |
           mkdir build/actions_upload
diff --git a/.github/workflows/freebsd.yml b/.github/workflows/freebsd.yml
index 406ac82..ef38927 100644
--- a/.github/workflows/freebsd.yml
+++ b/.github/workflows/freebsd.yml
@@ -51,7 +51,10 @@
            cd build 
            cmake .. 
            make 
-           ./umskt  # Execute the test here 
+           echo Test 1 - generating key
+           ./umskt -b 2C -c 365 -s 069420 -v
+           echo Test 2 - generating confid
+           ./umskt -i 253286028742154311079061239762245184619981623171292574
   
      - name: Move files to correct directory 
        run: | 
diff --git a/.github/workflows/linux.yml b/.github/workflows/linux.yml
index 4a8590f..85326da 100644
--- a/.github/workflows/linux.yml
+++ b/.github/workflows/linux.yml
@@ -28,18 +28,25 @@ on:
 
 jobs:
   build:
-    runs-on: ubuntu-latest
     strategy:
       matrix:
         include:
           - arch: x86
+            runner: ubuntu-latest
+            use_alpine: true
           - arch: x86_64
+            runner: ubuntu-latest
+            use_alpine: true
           - arch: aarch64
+            runner: ubuntu-24.04-arm
+            use_alpine: false
+    runs-on: ${{ matrix.runner }}
     steps:
     - name: Checkout Source Tree
       uses: actions/checkout@v4
 
-    - name: Setup latest Alpine Linux for ${{ matrix.arch }}
+    - name: Setup latest Alpine Linux
+      if: ${{ matrix.use_alpine }}
       uses: jirutka/setup-alpine@v1
       with:
         packages: >
@@ -54,13 +61,46 @@ jobs:
         arch: ${{ matrix.arch }}
         shell-name: alpine-target.sh
 
-    - name: Configure and build UMSKT
+    - name: Install Dependencies (Ubuntu ARM64)
+      if: ${{ !matrix.use_alpine }}
+      run: |
+        sudo apt-get update
+        sudo apt-get install -y build-essential cmake git libssl-dev zlib1g-dev
+
+    - name: Configure and build UMSKT (Alpine)
+      if: ${{ matrix.use_alpine }}
       uses: threeal/cmake-action@7ef2eb8da6e5ec0a6de6b1ddc96987080bed06e8
       with:
         options: MUSL_STATIC=ON
         run-build: true
         shell: alpine-target.sh {0}
 
+    - name: Configure and build UMSKT (Ubuntu)
+      if: ${{ !matrix.use_alpine }}
+      uses: threeal/cmake-action@7ef2eb8da6e5ec0a6de6b1ddc96987080bed06e8
+      with:
+        options: MUSL_STATIC=ON
+        run-build: true
+
+    - name: Test UMSKT (Alpine)
+      if: ${{ matrix.use_alpine }}
+      run: |
+        cd build
+        echo Test 1 - generating key
+        ./umskt -b 2C -c 365 -s 069420 -v
+        echo Test 2 - generating confid
+        ./umskt -i 253286028742154311079061239762245184619981623171292574
+      shell: alpine-target.sh {0}
+
+    - name: Test UMSKT (Ubuntu)
+      if: ${{ !matrix.use_alpine }}
+      run: |
+        cd build
+        echo Test 1 - generating key
+        ./umskt -b 2C -c 365 -s 069420 -v
+        echo Test 2 - generating confid
+        ./umskt -i 253286028742154311079061239762245184619981623171292574
+
     - name: Move files to correct directory
       run: |
           mkdir -p build/actions_upload
@@ -72,16 +112,70 @@ jobs:
         name: UMSKT-linux-${{ matrix.arch }}-static
         path: build/actions_upload
 
-    - name: Configure and build static internal deps UMSKT
+    - name: Configure and build static internal deps UMSKT (Alpine)
+      if: ${{ matrix.use_alpine }}
       uses: threeal/cmake-action@7ef2eb8da6e5ec0a6de6b1ddc96987080bed06e8
       with:
         options: MUSL_STATIC=OFF BUILD_SHARED_LIBS=OFF
         run-build: true
         shell: alpine-target.sh {0}
 
-    - name: Configure and build shared deps UMSKT
+    - name: Configure and build static internal deps UMSKT (Ubuntu)
+      if: ${{ !matrix.use_alpine }}
+      uses: threeal/cmake-action@7ef2eb8da6e5ec0a6de6b1ddc96987080bed06e8
+      with:
+        options: MUSL_STATIC=OFF BUILD_SHARED_LIBS=OFF
+        run-build: true
+
+    - name: Test static internal deps UMSKT (Alpine)
+      if: ${{ matrix.use_alpine }}
+      run: |
+        cd build
+        echo Test 1 - generating key
+        ./umskt -b 2C -c 365 -s 069420 -v
+        echo Test 2 - generating confid
+        ./umskt -i 253286028742154311079061239762245184619981623171292574
+      shell: alpine-target.sh {0}
+
+    - name: Test static internal deps UMSKT (Ubuntu)
+      if: ${{ !matrix.use_alpine }}
+      run: |
+        cd build
+        echo Test 1 - generating key
+        ./umskt -b 2C -c 365 -s 069420 -v
+        echo Test 2 - generating confid
+        ./umskt -i 253286028742154311079061239762245184619981623171292574
+
+    - name: Configure and build shared deps UMSKT (Alpine)
+      if: ${{ matrix.use_alpine }}
       uses: threeal/cmake-action@7ef2eb8da6e5ec0a6de6b1ddc96987080bed06e8
       with:
         options: MUSL_STATIC=OFF BUILD_SHARED_LIBS=ON
         run-build: true
         shell: alpine-target.sh {0}
+
+    - name: Configure and build shared deps UMSKT (Ubuntu)
+      if: ${{ !matrix.use_alpine }}
+      uses: threeal/cmake-action@7ef2eb8da6e5ec0a6de6b1ddc96987080bed06e8
+      with:
+        options: MUSL_STATIC=OFF BUILD_SHARED_LIBS=ON
+        run-build: true
+
+    - name: Test shared deps UMSKT (Alpine)
+      if: ${{ matrix.use_alpine }}
+      run: |
+        cd build
+        echo Test 1 - generating key
+        ./umskt -b 2C -c 365 -s 069420 -v
+        echo Test 2 - generating confid
+        ./umskt -i 253286028742154311079061239762245184619981623171292574
+      shell: alpine-target.sh {0}
+
+    - name: Test shared deps UMSKT (Ubuntu)
+      if: ${{ !matrix.use_alpine }}
+      run: |
+        cd build
+        echo Test 1 - generating key
+        ./umskt -b 2C -c 365 -s 069420 -v
+        echo Test 2 - generating confid
+        ./umskt -i 253286028742154311079061239762245184619981623171292574
diff --git a/.github/workflows/macos.yml b/.github/workflows/macos.yml
index 6b1108e..8d73d0e 100644
--- a/.github/workflows/macos.yml
+++ b/.github/workflows/macos.yml
@@ -85,7 +85,10 @@ jobs:
       - name: Run tests
         run: |
           cd build/actions_upload
-          ./umskt
+          echo Test 1 - generating key
+          ./umskt -b 2C -c 365 -s 069420 -v
+          echo Test 2 - generating confid
+          ./umskt -i 253286028742154311079061239762245184619981623171292574
 
       - name: Upload platform-specific build
         uses: actions/upload-artifact@v4.6.2
diff --git a/.github/workflows/windows.yml b/.github/workflows/windows.yml
index 29e33ca..612b29f 100644
--- a/.github/workflows/windows.yml
+++ b/.github/workflows/windows.yml
@@ -27,13 +27,14 @@ on:
   workflow_dispatch:
 
 jobs:
-  build-tdm:
+  build:
     runs-on: windows-latest
     strategy:
       matrix:
-        arch: [x64, x86]
+        arch: [x64, x86, arm64]
     steps:
       - name: Setup TDM-GCC
+        if: matrix.arch != 'arm64'
         run: |
           Write-Host Downloading TDM-GCC v10.3.0...
           Invoke-WebRequest -Uri 'https://github.com/jmeubank/tdm-gcc/releases/download/v10.3.0-tdm64-2/tdm64-gcc-10.3.0-2.exe' -OutFile 'C:\Windows\temp\TDM-GCC-64.exe'
@@ -49,10 +50,17 @@ jobs:
           $env:PATH = 'C:\TDM-GCC-64\bin;' + $env:PATH
           [Environment]::SetEnvironmentVariable('PATH', $env:PATH, [EnvironmentVariableTarget]::Machine)
 
+      - name: Setup MSVC for ARM64
+        if: matrix.arch == 'arm64'
+        uses: ilammy/msvc-dev-cmd@v1
+        with:
+          arch: arm64
+
       - name: Checkout Source Tree
         uses: actions/checkout@v4
 
       - name: Download OpenSSL-TDM release asset
+        if: matrix.arch != 'arm64'
         shell: pwsh
         run: |
           if ('${{ matrix.arch }}' -eq 'x64') {
@@ -74,7 +82,39 @@ jobs:
           echo "OPENSSL_LIBDIR=$libdir" | Out-File -FilePath $env:GITHUB_ENV -Append
           echo "CMAKE_FLAGS=$cmake_flags" | Out-File -FilePath $env:GITHUB_ENV -Append
 
+      - name: Setup vcpkg for ARM64
+        if: matrix.arch == 'arm64'
+        shell: pwsh
+        run: |
+          git clone https://github.com/Microsoft/vcpkg.git
+          cd vcpkg
+          .\bootstrap-vcpkg.bat
+          echo "VCPKG_ROOT=$env:GITHUB_WORKSPACE/vcpkg" | Out-File -FilePath $env:GITHUB_ENV -Append
+          echo "VCPKG_DEFAULT_BINARY_CACHE=$env:GITHUB_WORKSPACE/vcpkg/bincache" | Out-File -FilePath $env:GITHUB_ENV -Append
+          echo "VCPKG_BINARY_SOURCES=clear;default,readwrite" | Out-File -FilePath $env:GITHUB_ENV -Append
+
+      - name: Cache vcpkg packages
+        if: matrix.arch == 'arm64'
+        uses: actions/cache@v4
+        with:
+          path: |
+            ${{ github.workspace }}/vcpkg/bincache
+            ${{ github.workspace }}/vcpkg/installed
+            ${{ github.workspace }}/vcpkg/packages
+          key: vcpkg-arm64-${{ hashFiles('**/CMakeLists.txt') }}-${{ hashFiles('**/*.cmake') }}
+          restore-keys: |
+            vcpkg-arm64-${{ hashFiles('**/CMakeLists.txt') }}-
+            vcpkg-arm64-
+
+      - name: Install OpenSSL for ARM64
+        if: matrix.arch == 'arm64'
+        shell: pwsh
+        run: |
+          New-Item -ItemType Directory -Force -Path $env:VCPKG_DEFAULT_BINARY_CACHE
+          & "$env:VCPKG_ROOT\vcpkg.exe" install openssl:arm64-windows-static --clean-after-build
+
       - name: Configure UMSKT (TDM-GCC ${{ matrix.arch }})
+        if: matrix.arch != 'arm64'
         shell: pwsh
         run: |
           $env:PATH = 'C:\TDM-GCC-64\bin;' + $env:PATH
@@ -92,14 +132,60 @@ jobs:
             -DCMAKE_CXX_FLAGS="$env:CMAKE_FLAGS" `
             .
 
+      - name: Configure UMSKT (MSVC ARM64)
+        if: matrix.arch == 'arm64'
+        shell: pwsh
+        run: |
+          cmake -G "Visual Studio 17 2022" `
+            -A ARM64 `
+            -DWINDOWS_ARM=ON `
+            -DCMAKE_TOOLCHAIN_FILE="$env:VCPKG_ROOT/scripts/buildsystems/vcpkg.cmake" `
+            -DVCPKG_TARGET_TRIPLET=arm64-windows-static `
+            .
+
       - name: Build UMSKT (TDM-GCC ${{ matrix.arch }})
+        if: matrix.arch != 'arm64'
         shell: pwsh
         run: |
           $env:PATH = 'C:\TDM-GCC-64\bin;' + $env:PATH
           mingw32-make
 
+      - name: Build UMSKT (MSVC ARM64)
+        if: matrix.arch == 'arm64'
+        shell: pwsh
+        run: |
+          cmake --build . --config Release
+
+      - name: Run tests (x86/x64)
+        if: matrix.arch != 'arm64'
+        shell: pwsh
+        run: |
+          Write-Host Test 1 - generating key
+          .\umskt.exe -b 2C -c 365 -s 069420 -v
+          Write-Host Test 2 - generatng confid
+          .\umskt.exe -i 253286028742154311079061239762245184619981623171292574
+
       - name: Upload build artifact
         uses: actions/upload-artifact@v4.6.2
         with:
-          name: UMSKT-TDM${{ matrix.arch }}
-          path: umskt.exe
+          name: UMSKT-${{ matrix.arch }}
+          path: ${{ matrix.arch == 'arm64' && 'Release/umskt.exe' || 'umskt.exe' }}
+
+  test-arm64:
+    needs: build
+    if: success()
+    runs-on: windows-11-arm
+    steps:
+      - name: Download ARM64 artifact
+        uses: actions/download-artifact@v4
+        with:
+          name: UMSKT-arm64
+          path: .
+
+      - name: Run tests (ARM64)
+        shell: pwsh
+        run: |
+          Write-Host Test 1 - generating key
+          .\umskt.exe -b 2C -c 365 -s 069420 -v
+          Write-Host Test 2 - generatng confid
+          .\umskt.exe -i 253286028742154311079061239762245184619981623171292574
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 8b6d82d..10d6710 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -26,6 +26,24 @@ if (WIN32 AND NOT MSVC)
     set(CMAKE_C_COMPILER "C:/TDM-GCC-64/bin/gcc.exe" CACHE FILEPATH "C Compiler" FORCE)
     set(CMAKE_CXX_COMPILER "C:/TDM-GCC-64/bin/g++.exe" CACHE FILEPATH "C++ Compiler" FORCE)
     message(STATUS "[UMSKT] Forcing use of TDM-GCC in C:/TDM-GCC-64")
+    
+    # Configure windres for resource compilation
+    set(CMAKE_RC_COMPILER "C:/TDM-GCC-64/bin/windres.exe")
+    set(CMAKE_RC_COMPILER_INIT windres)
+    enable_language(RC)
+    set(CMAKE_RC_FLAGS "--use-temp-file -c65001")
+    
+    # Match resource architecture with target architecture
+    if(CMAKE_SIZEOF_VOID_P EQUAL 4)
+        set(CMAKE_RC_FLAGS "${CMAKE_RC_FLAGS} -F pe-i386")
+    else()
+        set(CMAKE_RC_FLAGS "${CMAKE_RC_FLAGS} -F pe-x86-64")
+    endif()
+    
+    set(CMAKE_RC_COMPILE_OBJECT "<CMAKE_RC_COMPILER> <FLAGS> -O coff -I${CMAKE_CURRENT_SOURCE_DIR}/src/windows <DEFINES> -i <SOURCE> -o <OBJECT>")
+    
+    # Set the Windows resource file for GCC builds
+    set(UMSKT_EXE_WINDOWS_EXTRA src/windows/umskt.rc)
 endif()
 
 SET(CMAKE_CXX_STANDARD 17)
@@ -36,6 +54,7 @@ OPTION(UMSKT_USE_SHARED_OPENSSL "Force linking against the system-wide OpenSSL l
 OPTION(MUSL_STATIC "Enable fully static builds in a muslc environment (i.e. Alpine Linux)" OFF)
 OPTION(DJGPP_WATT32 "Enable compilation and linking with DJGPP/WATT32/OpenSSL" OFF)
 OPTION(MSVC_MSDOS_STUB "Specify a custom MS-DOS stub for a 32-bit MSVC compilation" OFF)
+OPTION(WINDOWS_ARM "Enable compilation for Windows on ARM (requires appropriate toolchain)" OFF)
 
 SET(UMSKT_LINK_LIBS ${UMSKT_LINK_LIBS})
 SET(UMSKT_LINK_DIRS ${UMSKT_LINK_DIRS})
@@ -60,7 +79,22 @@ ELSE()
     MESSAGE(STATUS "[UMSKT] Requesting static version of OpenSSL")
 ENDIF()
 
-
+# Configure ARM-specific settings if enabled
+if (WINDOWS_ARM)
+    if (MSVC)
+        # MSVC ARM64 settings
+        set(CMAKE_SYSTEM_PROCESSOR ARM64)
+        set(CMAKE_VS_PLATFORM_TOOLSET_HOST_ARCHITECTURE ARM64)
+    else()
+        # MinGW/GCC ARM settings
+        set(CMAKE_SYSTEM_PROCESSOR arm)
+        if (CMAKE_CROSSCOMPILING)
+            set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -march=armv8-a")
+            set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -march=armv8-a")
+        endif()
+    endif()
+    message(STATUS "[UMSKT] Configuring for Windows on ARM")
+endif()
 
 IF(DJGPP_WATT32)
     SET(CMAKE_SYSTEM_NAME MSDOS)
diff --git a/src/libumskt/confid/confid.cpp b/src/libumskt/confid/confid.cpp
index 0b7a4d2..3949e0c 100644
--- a/src/libumskt/confid/confid.cpp
+++ b/src/libumskt/confid/confid.cpp
@@ -29,6 +29,10 @@
 
 #include "confid.h"
 
+#if defined(_MSC_VER)
+#include <intrin.h>
+#endif
+
 QWORD MOD = 0;
 QWORD NON_RESIDUE = 0;
 QWORD f[6] = { 0x0, 0x0, 0x0, 0x0, 0x0, 0x0 };
@@ -75,6 +79,12 @@ inline QWORD ConfirmationID::__umul128(QWORD a, QWORD b, QWORD* hi)
 #else
 #define __umul128 _umul128
 #endif
+#elif defined(_M_ARM64) // Microsoft implementation of ARM64
+inline QWORD ConfirmationID::__umul128(QWORD a, QWORD b, QWORD* hi)
+{
+    *hi = __umulh(a, b);
+    return a * b;
+}
 #elif defined(__i386__) || defined(_M_IX86) || defined(__arm__) || defined(__EMSCRIPTEN__)
 inline QWORD ConfirmationID::__umul128(QWORD multiplier, QWORD multiplicand, QWORD *product_hi) {
     // multiplier   = ab = a * 2^32 + b
diff --git a/src/windows/umskt.rc b/src/windows/umskt.rc
index df98e30..e4ef4e1 100644
Binary files a/src/windows/umskt.rc and b/src/windows/umskt.rc differ