CAC middleware options have gotten complicated with all the different platforms and vendor solutions flying around. As someone who evaluated and deployed CAC middleware across multiple DoD organizations, I learned everything there is to know about middleware selection and configuration. Today, I will share it all with you.
What Is CAC Middleware?
Probably should have led with this section, honestly. Middleware is software that creates the bridge between your smart card reader hardware and the applications that need to read your CAC certificates. It handles certificate retrieval, PIN validation, and cryptographic operations on your behalf—basically all the behind-the-scenes work that makes CAC authentication actually function.
ActivClient
ActivClient is the most widely deployed CAC middleware in government environments, and for good reason:
- Full PKCS#11 support for all browsers—it just works across the board
- Certificate management tools that let you see what’s on your CAC
- PIN caching and management so you’re not typing your PIN fifty times a day
- Available through enterprise licensing (your organization pays for it)
ActivClient is typically provided by your organization’s IT department rather than purchased individually. Don’t try to buy this yourself—your IT department either provides it or they don’t use it. That’s what makes ActivClient endearing to us IT professionals—when everyone in your organization uses the same middleware, troubleshooting becomes way easier.
OpenSC (Open Source)
OpenSC is a free, open-source middleware option that’s surprisingly capable:
- Works on Windows, Mac, and Linux—true cross-platform support
- PKCS#11 module for Firefox and other applications that support it
- Command-line tools for certificate management if you’re into that
- Community-supported with active development and regular updates
Download OpenSC from github.com/OpenSC/OpenSC. It’s a solid option if you’re using a personal computer and don’t have access to enterprise middleware. The learning curve is a bit steeper than ActivClient, but it gets the job done.
90Meter (Mac)
90Meter is designed specifically for macOS users who need a lightweight solution:
- Lightweight installation that doesn’t bloat your system
- Integrates seamlessly with macOS Keychain
- Supports older Mac hardware that sometimes has issues with native support
- Available from militarycac.com (the go-to resource for CAC help)
Windows Native Support
Windows 10 and 11 include built-in smart card support through the Microsoft Base Smart Card Crypto Provider. For basic CAC authentication to websites and email, you may not need additional middleware at all. However, some organizations require ActivClient for additional security features and centralized management. Try the native support first—if it works for what you need, you’re done.
Choosing the Right Option
- Enterprise users: Use whatever your IT department provides (usually ActivClient). Don’t fight this—they have their reasons and trying to use something else will just create problems.
- Personal Mac: Try native macOS support first, add 90Meter if you run into issues with PIN prompts or older hardware.
- Linux users: OpenSC is your primary option. The Linux community has done great work making this reliable.
- Windows home users: Native support often works perfectly fine for basic CAC use. Keep OpenSC in mind as a backup if you run into compatibility issues.
