visus-io · xaevik · Jan 10, 2026 · Jan 10, 2026
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
@@ -47,7 +47,7 @@ jobs:
       - name: Setup build tools
         uses: lukka/get-cmake@9e07ecdcee1b12e5037e42f410b67f03e2f626e1 # v4.2.1
         with:
-          cmakeVersion: '~4.2.0'
+          cmakeVersion: '~3.28.0'
           ninjaVersion: '^1.12.0'
 
       - name: Install Linux dependencies

diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -1,7 +1,7 @@
 # ==============================================================================
 # Project Configuration
 # ==============================================================================
-cmake_minimum_required(VERSION 4.0)
+cmake_minimum_required(VERSION 3.22)
 project(libcuid2 VERSION 1.0.0 LANGUAGES CXX)
 
 set(CMAKE_CXX_STANDARD 20)

diff --git a/README.md b/README.md
@@ -14,7 +14,7 @@ A high-performance C++ implementation of the [Cuid2](https://github.com/parallel
   - [Features](#features)
   - [Quick Start](#quick-start)
   - [Installation](#installation)
-    - [CMake 4 Installation](#cmake-4-installation)
+    - [CMake Installation](#cmake-installation)
       - [Checking Your CMake Version](#checking-your-cmake-version)
       - [Ubuntu/Debian](#ubuntudebian)
       - [Fedora/RHEL](#fedorarhel)
@@ -96,9 +96,9 @@ int main() {
 
 ## Installation
 
-### CMake 4 Installation
+### CMake Installation
 
-This project requires **CMake 4.0+**. Many Linux distributions currently ship with CMake 3.x by default, so you may need to install CMake 4 manually.
+This project requires **CMake 3.22+**. Most modern Linux distributions ship with CMake 3.22 or newer by default.
 
 #### Checking Your CMake Version
 ```bash
@@ -107,99 +107,50 @@ cmake --version
 
 #### Ubuntu/Debian
 
-Ubuntu 24.04 LTS and earlier Debian versions ship with CMake 3.x. You have two options:
-
-**Option 1: Install from Kitware APT Repository (Recommended)**
 ```bash
-# Remove old CMake if installed
-sudo apt-get remove --purge cmake
-
-# Install dependencies
 sudo apt-get update
-sudo apt-get install -y software-properties-common lsb-release wget gnupg
+sudo apt-get install cmake
+```
+
+Ubuntu 22.04 LTS and later include CMake 3.22+. For older versions, use the Kitware APT repository:
 
+```bash
 # Add Kitware APT repository
 wget -O - https://apt.kitware.com/keys/kitware-archive-latest.asc 2>/dev/null | gpg --dearmor - | sudo tee /etc/apt/trusted.gpg.d/kitware.gpg >/dev/null
 sudo apt-add-repository "deb https://apt.kitware.com/ubuntu/ $(lsb_release -cs) main"
-
-# Install CMake 4
 sudo apt-get update
 sudo apt-get install cmake
-
-# Verify installation
-cmake --version
-```
-
-**Option 2: Build from Source**
-```bash
-# Install build dependencies
-sudo apt-get install -y build-essential libssl-dev
-
-# Download and build CMake 4 (adjust version as needed)
-wget https://github.com/Kitware/CMake/releases/download/v4.0.0/cmake-4.0.0.tar.gz
-tar -xzf cmake-4.0.0.tar.gz
-cd cmake-4.0.0
-./bootstrap --prefix=/usr/local
-make -j$(nproc)
-sudo make install
-
-# Verify installation
-cmake --version
 ```
 
 #### Fedora/RHEL
 
-Fedora 41+ includes CMake 4.x. For older versions:
 ```bash
-# Fedora 41+
 sudo dnf install cmake
-
-# For older Fedora/RHEL, build from source (see Ubuntu Option 2 above)
-# Replace apt-get with dnf/yum for build dependencies:
-sudo dnf install -y gcc-c++ make openssl-devel
 ```
 
 #### Arch Linux
 ```bash
-# Arch typically has latest CMake in official repos
 sudo pacman -S cmake
 ```
 
 #### macOS
 ```bash
-# Homebrew
 brew install cmake
-
-# Verify installation
-cmake --version
 ```
 
 #### FreeBSD
 ```bash
-# CMake 4 may be available in ports/packages
 pkg install cmake
-
-# If not available, build from ports:
-cd /usr/ports/devel/cmake && make install clean
 ```
 
 #### OpenBSD/NetBSD
 ```bash
-# Check available version
-pkg_info -Q cmake  # OpenBSD
-pkgin search cmake # NetBSD
-
-# Install if CMake 4 is available
 pkg_add cmake      # OpenBSD
 pkgin install cmake # NetBSD
-
-# Otherwise, build from source (see Ubuntu Option 2 above)
 ```
 
 #### Windows
 
-CMake 4 is available via the official installer:
-
 **Option 1: Official Installer**
 - Download from https://cmake.org/download/
 - Run the installer and add CMake to system PATH
@@ -306,11 +257,11 @@ cmake --preset freebsd-arm64-debug
 
 ### Debian/Ubuntu Packages
 
-**Note:** Building DEB packages requires CMake 4.0+. See [CMake 4 Installation](#cmake-4-installation) above if you don't have it installed.
+**Note:** Building DEB packages requires CMake 3.22+. See [CMake Installation](#cmake-installation) above if you don't have it installed.
 
 Build DEB packages:
 ```bash
-# Install build dependencies (assuming CMake 4 is already installed)
+# Install build dependencies
 sudo apt-get install debhelper-compat pkg-config \
     libssl-dev libboost-dev libfmt-dev
 
@@ -487,7 +438,7 @@ ctest --preset macos-arm64-debug
 ## Requirements
 
 - **C++20** compiler (GCC 10+, Clang 11+, MSVC 2019+)
-- **CMake** 4.0+
+- **CMake** 3.22+
 - **OpenSSL** 3.x (NIST FIPS-202 SHA3-512, CSPRNG)
 - **Boost** (Endian, Multiprecision, Nowide, Test)
 - **fmt** (Modern formatting library)

diff --git a/debian/README.md b/debian/README.md
@@ -97,7 +97,7 @@ sudo chroot /tmp/debian-test
 ### Build Dependencies
 
 - **debhelper-compat (= 13)** - Debian build helper tools
-- **cmake (>= 4.0)** - Build system
+- **cmake (>= 3.22)** - Build system
 - **pkg-config** - Dependency detection
 - **libssl-dev (>= 3.0)** - OpenSSL development files (SHA3-512, CSPRNG)
 - **libboost-dev (>= 1.74)** - Boost libraries (header-only components)
@@ -216,7 +216,6 @@ Source packages are pre-configured for the following Ubuntu LTS releases:
 
 - **Ubuntu 24.04 LTS (Noble Numbat)** - Version suffix: `~noble1`
 - **Ubuntu 22.04 LTS (Jammy Jellyfish)** - Version suffix: `~jammy1`
-- **Ubuntu 20.04 LTS (Focal Fossa)** - Version suffix: `~focal1`
 
 ### PPA Prerequisites
 
@@ -259,7 +258,7 @@ cd /path/to/libcuid2
 
 The script will:
 1. Create the orig tarball from git
-2. Build source packages for Noble, Jammy, and Focal
+2. Build source packages for Noble and Jammy
 3. Place all files in `../build-area/`
 
 #### Manual Build Process
@@ -282,9 +281,6 @@ For additional releases, update debian/changelog and rebuild:
 ```bash
 # Build for Jammy
 debuild -S -sa -k<YOUR_GPG_KEY_ID>
-
-# Build for Focal
-debuild -S -sa -k<YOUR_GPG_KEY_ID>
 ```
 
 ### Uploading to Launchpad PPA
@@ -311,7 +307,6 @@ EOF
 # Upload to your PPA (replace with your PPA name)
 dput ppa:YOUR_LAUNCHPAD_USERNAME/libcuid2 ../build-area/libcuid2_*~noble1_source.changes
 dput ppa:YOUR_LAUNCHPAD_USERNAME/libcuid2 ../build-area/libcuid2_*~jammy1_source.changes
-dput ppa:YOUR_LAUNCHPAD_USERNAME/libcuid2 ../build-area/libcuid2_*~focal1_source.changes
 ```
 
 Launchpad will automatically:
@@ -359,12 +354,10 @@ sudo apt-get install pbuilder ubuntu-dev-tools
 # Create base environments
 pbuilder-dist noble create
 pbuilder-dist jammy create
-pbuilder-dist focal create
 
 # Test build
 pbuilder-dist noble build ../build-area/libcuid2_*~noble1.dsc
 pbuilder-dist jammy build ../build-area/libcuid2_*~jammy1.dsc
-pbuilder-dist focal build ../build-area/libcuid2_*~focal1.dsc
 ```
 
 ### Version Management for PPAs

diff --git a/debian/build-ppa.sh b/debian/build-ppa.sh
@@ -4,7 +4,7 @@ set -e
 PACKAGE_NAME="libcuid2"
 VERSION="1.0.0"
 REVISION="1ubuntu1"
-RELEASES=("noble" "jammy" "focal")
+RELEASES=("noble" "jammy")
 BUILD_AREA="../build-area"
 GPG_KEY="${GPG_KEY:-}"
 PPA_NAME=""
@@ -87,6 +87,14 @@ build_for_release() {
     cp -r debian "$work_dir/"
     cd "$work_dir"
 
+    # Update changelog with release-specific version at the top
+    info "Updating changelog for ${release}..."
+    DEBFULLNAME="Visus Development Team" \
+    DEBEMAIL="admin@projects.visus.io" \
+    dch --force-distribution --distribution "${release}" \
+        --newversion "${release_version}" \
+        "Rebuild for Ubuntu ${release}"
+
     info "Running debuild for ${release}..."
 
     if [ -n "$GPG_KEY" ]; then
@@ -122,12 +130,10 @@ show_summary() {
         info "To upload to PPA:"
         echo "  dput ppa:${PPA_NAME} ${BUILD_AREA}/${PACKAGE_NAME}_*~noble1_source.changes"
         echo "  dput ppa:${PPA_NAME} ${BUILD_AREA}/${PACKAGE_NAME}_*~jammy1_source.changes"
-        echo "  dput ppa:${PPA_NAME} ${BUILD_AREA}/${PACKAGE_NAME}_*~focal1_source.changes"
     else
         info "To upload to PPA (specify with -p option):"
         echo "  dput ppa:<your-ppa-name> ${BUILD_AREA}/${PACKAGE_NAME}_*~noble1_source.changes"
         echo "  dput ppa:<your-ppa-name> ${BUILD_AREA}/${PACKAGE_NAME}_*~jammy1_source.changes"
-        echo "  dput ppa:<your-ppa-name> ${BUILD_AREA}/${PACKAGE_NAME}_*~focal1_source.changes"
     fi
 }
 

diff --git a/debian/changelog b/debian/changelog
@@ -19,14 +19,3 @@ libcuid2 (1.0.0-1ubuntu1~jammy1) jammy; urgency=medium
   * Cross-platform support (Linux, BSD, macOS, Windows)
 
  -- Visus Development Team <admin@projects.visus.io>  Sun, 28 Dec 2025 12:00:00 +0000
-
-libcuid2 (1.0.0-1ubuntu1~focal1) focal; urgency=medium
-
-  * Initial release for Ubuntu 20.04 LTS (Focal Fossa)
-  * C++ implementation of Cuid2 identifier generation
-  * Thread-safe collision-resistant unique identifiers
-  * SHA3-512 cryptographic hashing (NIST FIPS-202)
-  * Configurable length (4-32 characters, default 24)
-  * Cross-platform support (Linux, BSD, macOS, Windows)
-
- -- Visus Development Team <admin@projects.visus.io>  Sun, 28 Dec 2025 12:00:00 +0000
diff --git a/debian/control b/debian/control
@@ -3,7 +3,7 @@ Section: libs
 Priority: optional
 Maintainer: Visus Development Team <admin@projects.visus.io>
 Build-Depends: debhelper-compat (= 13),
-               cmake (>= 4.0),
+               cmake (>= 3.22),
                pkg-config,
                libssl-dev (>= 3.0),
                libboost-dev (>= 1.74),

diff --git a/debian/libcuid2-dev.install b/debian/libcuid2-dev.install
@@ -1,3 +1,6 @@
 usr/include/*
 usr/lib/*/libcuid2.so
 usr/lib/*/cmake/cuid2/*
+tests/* usr/src/libcuid2/
+src/*.cpp usr/src/libcuid2/src/
+src/*.hpp usr/src/libcuid2/src/
diff --git a/man/man7/libcuid2.7 b/man/man7/libcuid2.7
@@ -241,7 +241,7 @@ Exceptions for error handling
 .IP \(bu
 Inline namespace versioning (planned for future versions)
 .SH BUILD SYSTEM
-libcuid2 uses CMake 4.0+ and vcpkg for dependency management:
+libcuid2 uses CMake 3.22+ and vcpkg for dependency management:
 .SS "Dependencies"
 .TP
 .B OpenSSL 3.x