Here's a simple cross-platform one, using only the DeviceId package, which is valid for both version 5 and version 6 of the library:

Here's a more complex device ID, making use of some of the advanced components from the DeviceId.Windows.Wmi (or DeviceId.Windows.Mmi) package:

Here's a complex cross-platform device ID, using DeviceId.Windows.Wmi, DeviceId.Linux, and DeviceId.Mac:

You can also generate a unique identifier for a database instance. Currently, only SQL Server is supported, but more may be added if there is demand and/or community support:

What can you include in a device identifier

The following extension methods are available out of the box to suit some common use cases:

From DeviceId:

• AddUserName adds the current user's username to the device identifer.
• AddMachineName adds the machine name to the device identifier.
• AddOsVersion adds the current OS version to the device identifier. Note: This uses Environment.OSVersion, so if you're targeting older .NET Framework versions, you'll get different values compared to when you target more modern versions of .NET (.NET Core, .NET 5, .NET 6, and anything later than that).
• AddMacAddress adds the MAC address to the device identifier.
• AddFileToken adds a unique token stored in a file to the device identifier. The file is created if it doesn't already exist. Fails silently if no permissions available to access the file.

From DeviceId.Windows:

• AddWindowsDeviceId adds the Windows Device ID (also known as Machine ID or Advertising ID) to the device identifier. This value is the one displayed as "Device ID" in the Windows Device Specifications UI.
• AddWindowsProductId adds the Windows Product ID to the device identifier. This value is the one displayed as "Product ID" in the Windows Device Specifications UI.
• AddRegistryValue adds a specified registry value to the device identifier.
• AddMachineGuid adds the machine GUID from HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Cryptography to the device identifier.

From DeviceId.Windows.Wmi and DeviceId.Windows.Mmi:

• AddMacAddressFromWmi / AddMacAddressFromMmi adds the MAC address to the device identifier. These use the improved query functionality from WMI/MMI to provide additional functionality over the basic AddMacAddress method (such as being able to exclude non-physical device).
• AddProcessorId adds the processor ID to the device identifier.
• AddSystemDriveSerialNumber adds the system drive's serial number to the device identifier.
• AddMotherboardSerialNumber adds the motherboard serial number to the device identifier.
• AddSystemUuid adds the system UUID to the device identifier.

From DeviceId.Linux:

• AddSystemDriveSerialNumber adds the system drive's serial number to the device identifier.
• AddMotherboardSerialNumber adds the motherboard serial number to the device identifier.
• AddMachineId adds the machine ID (from /var/lib/dbus/machine-id or /etc/machine-id) to the device identifier.
• AddProductUuid adds the product UUID (from /sys/class/dmi/id/product_uuid) to the device identifier.
• AddCpuInfo adds CPU info (from /proc/cpuinfo) to the device identifier.
• AddDockerContainerId adds the Docker container identifier (from /proc/1/cgroup) to the device identifier.

From DeviceId.Mac:

• AddSystemDriveSerialNumber adds the system drive's serial number to the device identifier.
• AddPlatformSerialNumber adds IOPlatformSerialNumber to the device identifier.

From DeviceId.SqlServer:

• AddServerName adds the server name to the device identifier.
• AddDatabaseName adds the server name to the device identifier.
• AddDatabaseId adds the database ID to the device identifier.
• AddServerProperty adds a specified server property to the device identifier.
• AddServerProperty adds a specified extended property to the device identifier.

Dealing with MAC Address randomization and virtual network adapters

Non physical network adapters like VPN connections tend not to have fixed MAC addresses. For wireless (802.11 based) adapters hardware (MAC) address randomization is frequently applied to avoid tracking with many modern operating systems support this out of the box. This makes wireless network adapters bad candidates for device identification.

Using the cross-platform AddMacAddress, you can exclude wireless network adapters like so:

If you're on Windows, you can also exclude non-physical adapters using the DeviceId.Windows.Wmi or DeviceId.Windows.Mmi packages like so:

Controlling how the device identifier is formatted

Use the UseFormatter method to set the formatter:

The "default" formatters are available in DeviceIdFormatters for quick reference. The default formatter changed between version 5 and version 6 of the library. If you're using version 6 but want to revert to the version 5 formatter, you can do so:

For more advanced usage scenarios, you can use one of the out-of-the-box implementations of IDeviceIdFormatter in the DeviceId.Formatters namespace, or you can create your own.

• StringDeviceIdFormatter - Formats the device ID as a string containing each component ID, using any desired component encoding.
• HashDeviceIdFormatter - Formats the device ID as a hash string, using any desired hash algorithm and byte array encoding.
• XmlDeviceIdFormatter - Formats the device ID as an XML document, using any desired component encoding.

There are a number of encoders that can be used customize the formatter. These implement IDeviceIdComponentEncoder and IByteArrayEncoder and are found in the DeviceId.Encoders namespace.

• PlainTextDeviceIdComponentEncoder - Encodes a device ID component as plain text.
• HashDeviceIdComponentEncoder - Encodes a device ID component as a hash string, using any desired hash algorithm.
• HexByteArrayEncoder - Encodes a byte array as a hex string.
• Base32UrlByteArrayEncoder - Encodes a byte array as a base 64 url-encoded string.
• Base64ByteArrayEncoder - Encodes a byte array as a base 64 string.
• Base64UrlByteArrayEncoder - Encodes a byte array as a base 64 url-encoded string.

Supporting/validating multiple device ID formats with backwards compatibility

Let's say you shipped an app, and were using DeviceId to perform license checks. You may have done something like:

Say you now want to release a new version of your app, and want to change how new device identifiers are generated (maybe just use MAC address and a file token), but you don't want to invalidate every single license file that currently exists. In other words, you want backwards compatible device ID validation.

In the latest version of DeviceId, you can use the DeviceIdManager to do so:

The device ID manager will work out which builder to use, and generate the current device ID in the correct format so that it can be sensibly compared to the device ID being validated.

Note that this functionality all works well but I'm not entirely happy with the naming or the API. I've currently built it so that there are no breaking changes for v6. In the future (v7 for example) I may rename some classes and break the API. In any case though I will keep the functionality, so it's safe to use this stuff.

Migration Guide 5.x -> 6.x

There were a few breaking changes going from v5 to v6.

• As mentioned above in the "What packages are needed" section, DeviceId was split into multiple packages, so you may need to add a reference to the packages for your platform (such as DeviceId.Windows, DeviceId.Windows.Wmi, DeviceId.Linux, etc.).

• As mentioned above in the "Controlling how the device identifier is formatted" section, the default formatter changed between version 5 and version 6. If you're using version 6 but want to revert to the version 5 formatter, you can do so via .UseFormatter(DeviceIdFormatters.DefaultV5)

• Some methods have been renamed or restricted to certain platforms. You can inspect the version 5.x methods and choose the corresponding new OS-specific methods. Note that these still may not be backwards compatible with a v5 device identifier due to the changes in the component names. Remember, if something is missing in v6 that you had in v5, you can always re-add it yourself via a custom component. Here are some examples of changes:

Strong naming

From version 5 onwards, the assemblies in this package are strong named for the convenience of those users who require strong naming. Please note, however, that the key files are checked in to this repository. This means that anyone can compile their own version and strong name it with the original keys. This is a common practice with open source projects, but it does mean that you shouldn't use the strong name as a guarantee of security or identity.

License and copyright

Copyright Matthew King 2015-2021. Distributed under the MIT License. Refer to license.txt for more information.

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