title: Is dotnet restore broken on macos?
body: <p>This has recently just started happening.</p>
  <pre><code>dotnet --version
  5.0.104
  </code></pre>
  <p>macOS Big Sur version 11.6</p>
  <p>when I run</p>
  <pre><code>dotnet restore
    Determining projects to restore...
  /Users/xxx/Work/mvc/mvc.csproj : warning NU3028: Package 'System.Security.Cryptography.ProtectedData 5.0.0' from source 'https://api.nuget.org/v3/index.json': The author primary signature's timestamp found a chain building issue: ExplicitDistrust: The trust setting for this policy was set to Deny.
  /Users/xxx/Work/mvc/mvc.csproj : warning NU3028: Package 'System.Windows.Extensions 5.0.0' from source 'https://api.nuget.org/v3/index.json': The author primary signature's timestamp found a chain building issue: ExplicitDistrust: The trust setting for this policy was set to Deny.
  /Users/xxx/Work/mvc/mvc.csproj : warning NU3028: Package 'System.Security.Principal.Windows 5.0.0' from source 'https://api.nuget.org/v3/index.json': The author primary signature's timestamp found a chain building issue: ExplicitDistrust: The trust setting for this policy was set to Deny.
  /Users/xxx/Work/mvc/mvc.csproj : warning NU3028: Package 'System.Security.Permissions 5.0.0' from source 'https://api.nuget.org/v3/index.json': The author primary signature's timestamp found a chain building issue: ExplicitDistrust: The trust setting for this policy was set to Deny.
  /Users/xxx/Work/mvc/mvc.csproj : warning NU3028: Package 'System.Configuration.ConfigurationManager 5.0.0' from source 'https://api.nuget.org/v3/index.json': The author primary signature's timestamp found a chain building issue: ExplicitDistrust: The trust setting for this policy was set to Deny.
  /Users/xxx/Work/mvc/mvc.csproj : error NU3037: Package 'System.Security.Principal.Windows 5.0.0' from source 'https://api.nuget.org/v3/index.json': The author primary signature validity period has expired.
  /Users/xxx/Work/mvc/mvc.csproj : error NU3037: Package 'System.Security.Permissions 5.0.0' from source 'https://api.nuget.org/v3/index.json': The author primary signature validity period has expired.
  /Users/xxx/Work/mvc/mvc.csproj : error NU3037: Package 'System.Windows.Extensions 5.0.0' from source 'https://api.nuget.org/v3/index.json': The author primary signature validity period has expired.
  /Users/xxx/Work/mvc/mvc.csproj : warning NU3028: Package 'System.Security.Principal.Windows 5.0.0' from source 'https://api.nuget.org/v3/index.json': The repository countersignature's timestamp found a chain building issue: ExplicitDistrust: The trust setting for this policy was set to Deny.
  /Users/xxx/Work/mvc/mvc.csproj : error NU3037: Package 'System.Security.Cryptography.ProtectedData 5.0.0' from source 'https://api.nuget.org/v3/index.json': The author primary signature validity period has expired.
  /Users/xxx/Work/mvc/mvc.csproj : error NU3037: Package 'System.Configuration.ConfigurationManager 5.0.0' from source 'https://api.nuget.org/v3/index.json': The author primary signature validity period has expired.
  /Users/xxx/Work/mvc/mvc.csproj : warning NU3028: Package 'System.Security.Permissions 5.0.0' from source 'https://api.nuget.org/v3/index.json': The repository countersignature's timestamp found a chain building issue: ExplicitDistrust: The trust setting for this policy was set to Deny.
  /Users/xxx/Work/mvc/mvc.csproj : error NU3037: Package 'System.Security.Principal.Windows 5.0.0' from source 'https://api.nuget.org/v3/index.json': The repository countersignature validity period has expired.
  /Users/xxx/Work/mvc/mvc.csproj : warning NU3028: Package 'System.Security.Cryptography.ProtectedData 5.0.0' from source 'https://api.nuget.org/v3/index.json': The repository countersignature's timestamp found a chain building issue: ExplicitDistrust: The trust setting for this policy was set to Deny.
  /Users/xxx/Work/mvc/mvc.csproj : warning NU3028: Package 'System.Configuration.ConfigurationManager 5.0.0' from source 'https://api.nuget.org/v3/index.json': The repository countersignature's timestamp found a chain building issue: ExplicitDistrust: The trust setting for this policy was set to Deny.
  /Users/xxx/Work/mvc/mvc.csproj : error NU3037: Package 'System.Security.Permissions 5.0.0' from source 'https://api.nuget.org/v3/index.json': The repository countersignature validity period has expired.
  /Users/xxx/Work/mvc/mvc.csproj : warning NU3028: Package 'System.Windows.Extensions 5.0.0' from source 'https://api.nuget.org/v3/index.json': The repository countersignature's timestamp found a chain building issue: ExplicitDistrust: The trust setting for this policy was set to Deny.
  /Users/xxx/Work/mvc/mvc.csproj : error NU3037: Package 'System.Configuration.ConfigurationManager 5.0.0' from source 'https://api.nuget.org/v3/index.json': The repository countersignature validity period has expired.
  /Users/xxx/Work/mvc/mvc.csproj : error NU3037: Package 'System.Windows.Extensions 5.0.0' from source 'https://api.nuget.org/v3/index.json': The repository countersignature validity period has expired.
  /Users/xxx/Work/mvc/mvc.csproj : error NU3037: Package 'System.Security.Cryptography.ProtectedData 5.0.0' from source 'https://api.nuget.org/v3/index.json': The repository countersignature validity period has expired.
  /Users/xxx/Work/mvc/mvc.csproj : warning NU3028: Package 'System.Drawing.Common 5.0.0' from source 'https://api.nuget.org/v3/index.json': The author primary signature's timestamp found a chain building issue: ExplicitDistrust: The trust setting for this policy was set to Deny.
  /Users/xxx/Work/mvc/mvc.csproj : error NU3037: Package 'System.Drawing.Common 5.0.0' from source 'https://api.nuget.org/v3/index.json': The author primary signature validity period has expired.
  /Users/xxx/Work/mvc/mvc.csproj : warning NU3028: Package 'System.Drawing.Common 5.0.0' from source 'https://api.nuget.org/v3/index.json': The repository countersignature's timestamp found a chain building issue: ExplicitDistrust: The trust setting for this policy was set to Deny.
  /Users/xxx/Work/mvc/mvc.csproj : error NU3037: Package 'System.Drawing.Common 5.0.0' from source 'https://api.nuget.org/v3/index.json': The repository countersignature validity period has expired.
  /Users/xxx/Work/mvc/mvc.csproj : warning NU3028: Package 'Microsoft.Win32.SystemEvents 5.0.0' from source 'https://api.nuget.org/v3/index.json': The author primary signature's timestamp found a chain building issue: ExplicitDistrust: The trust setting for this policy was set to Deny.
  /Users/xxx/Work/mvc/mvc.csproj : error NU3037: Package 'Microsoft.Win32.SystemEvents 5.0.0' from source 'https://api.nuget.org/v3/index.json': The author primary signature validity period has expired.
  /Users/xxx/Work/mvc/mvc.csproj : warning NU3028: Package 'Microsoft.Win32.SystemEvents 5.0.0' from source 'https://api.nuget.org/v3/index.json': The repository countersignature's timestamp found a chain building issue: ExplicitDistrust: The trust setting for this policy was set to Deny.
  /Users/xxx/Work/mvc/mvc.csproj : error NU3037: Package 'Microsoft.Win32.SystemEvents 5.0.0' from source 'https://api.nuget.org/v3/index.json': The repository countersignature validity period has expired.
  /Users/xxx/Work/mvc/mvc.csproj : warning NU3028: Package 'System.Security.AccessControl 5.0.0' from source 'https://api.nuget.org/v3/index.json': The author primary signature's timestamp found a chain building issue: ExplicitDistrust: The trust setting for this policy was set to Deny.
  /Users/xxx/Work/mvc/mvc.csproj : error NU3037: Package 'System.Security.AccessControl 5.0.0' from source 'https://api.nuget.org/v3/index.json': The author primary signature validity period has expired.
  /Users/xxx/Work/mvc/mvc.csproj : warning NU3028: Package 'System.Security.AccessControl 5.0.0' from source 'https://api.nuget.org/v3/index.json': The repository countersignature's timestamp found a chain building issue: ExplicitDistrust: The trust setting for this policy was set to Deny.
  /Users/xxx/Work/mvc/mvc.csproj : error NU3037: Package 'System.Security.AccessControl 5.0.0' from source 'https://api.nuget.org/v3/index.json': The repository countersignature validity period has expired.
  /Users/xxx/Work/mvc/mvc.csproj : warning NU3028: Package 'Microsoft.NETCore.Platforms 5.0.0' from source 'https://api.nuget.org/v3/index.json': The author primary signature's timestamp found a chain building issue: ExplicitDistrust: The trust setting for this policy was set to Deny.
  /Users/xxx/Work/mvc/mvc.csproj : error NU3037: Package 'Microsoft.NETCore.Platforms 5.0.0' from source 'https://api.nuget.org/v3/index.json': The author primary signature validity period has expired.
  /Users/xxx/Work/mvc/mvc.csproj : warning NU3028: Package 'Microsoft.NETCore.Platforms 5.0.0' from source 'https://api.nuget.org/v3/index.json': The repository countersignature's timestamp found a chain building issue: ExplicitDistrust: The trust setting for this policy was set to Deny.
  /Users/xxx/Work/mvc/mvc.csproj : error NU3037: Package 'Microsoft.NETCore.Platforms 5.0.0' from source 'https://api.nuget.org/v3/index.json': The repository countersignature validity period has expired.
    Failed to restore /Users/xxx/Work/mvc/mvc.csproj (in 753 ms).
    1 of 2 projects are up-to-date for restore.
  </code></pre>
  <p>Is this something broken in nuget?</p>
  <p>How do I fix &quot;The repository countersignature validity period has expired.&quot;?</p>