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SYSLIB0027: PublicKey.Key is obsolete

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The PublicKey.Key property is marked as obsolete, starting in .NET 6. Using this API in code generates warning SYSLIB0027 at compile time.

Workarounds

Use the appropriate method to get the public key, such as GetRSAPublicKey().

Suppress a warning

If you must use the obsolete APIs, you can suppress the warning in code or in your project file.

To suppress only a single violation, add preprocessor directives to your source file to disable and then re-enable the warning.

// Disable the warning.
#pragma warning disable SYSLIB0027

// Code that uses obsolete API.
// ...

// Re-enable the warning.
#pragma warning restore SYSLIB0027

To suppress all the SYSLIB0027 warnings in your project, add a <NoWarn> property to your project file.

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
   ...
   <NoWarn>$(NoWarn);SYSLIB0027</NoWarn>
  </PropertyGroup>
</Project>

For more information, see Suppress warnings.