microsoft-authentication-library-for-dotnet: [Enhancement][L] ConfidentialClient does not support ECDsa client application certificates.

Which Version of MSAL are you using ? 4.30

Platform APSNETCORE 5.0

What authentication flow has the issue?

• Desktop / Mobile
  • Interactive
  • Integrated Windows Auth
  • Username Password
  • Device code flow (browserless)
• Web App
  • Authorization code
  • OBO
• Daemon App
  • Service to Service calls

Other? - please describe;

Is this a new or existing app? existing Repro

1. Register an AzureAD confidential client application with a certificate using ECDsa
2. Create an instance on the ConfidentialClient
3. Try and acquire an OBO token

var onBehalfOfClientApplication = await this.oauthTokenProvider.BindAsync(accountId, this.TenantId).ConfigureAwait(false);

var oboResult = await onBehalfOfClientApplication
    .AcquireTokenOnBehalfOf(oauthScopes, userAssertion)
    .ExecuteAsync().ConfigureAwait(false);

Expected behavior A token.

Actual behavior

      System.NotSupportedException: The certificate key algorithm is not supported.
         at System.Security.Cryptography.X509Certificates.PublicKey.get_Key()
         at Microsoft.Identity.Client.Platforms.netcore.NetCoreCryptographyManager.SignWithCertificate(String message, X509Certificate2 certificate)
         at Microsoft.Identity.Client.Internal.ClientCredentialWrapper.Sign(ICryptographyManager cryptographyManager, String message)
         at Microsoft.Identity.Client.Internal.JsonWebToken.Sign(ClientCredentialWrapper credential, Boolean sendCertificate)
         at Microsoft.Identity.Client.Internal.Requests.ClientCredentialHelper.CreateClientCredentialBodyParameters(ICoreLogger logger, ICryptographyManager cryptographyManager, ClientCredentialWrapper clientCredential, String clientId, AuthorityEndpoints endpoints, Boolean sendX5C)
         at Microsoft.Identity.Client.OAuth2.TokenClient.AddBodyParamsAndHeaders(IDictionary`2 additionalBodyParameters, String scopes)
         at Microsoft.Identity.Client.OAuth2.TokenClient.SendTokenRequestAsync(IDictionary`2 additionalBodyParameters, String scopeOverride, String tokenEndpointOverride, CancellationToken cancellationToken)
         at Microsoft.Identity.Client.Internal.Requests.RequestBase.SendTokenRequestAsync(String tokenEndpoint, IDictionary`2 additionalBodyParameters, CancellationToken cancellationToken)
         at Microsoft.Identity.Client.Internal.Requests.OnBehalfOfRequest.ExecuteAsync(CancellationToken cancellationToken)
         at Microsoft.Identity.Client.Internal.Requests.RequestBase.RunAsync(CancellationToken cancellationToken)
         at Microsoft.Identity.Client.ApiConfig.Executors.ConfidentialClientExecutor.ExecuteAsync(AcquireTokenCommonParameters commonParameters, AcquireTokenOnBehalfOfParameters onBehalfOfParameters, CancellationToken cancellationToken)
         at Chorus.Services.Application.ChorusServerApplication.AssignTenantOwnerAsync(TenantOptions tenantOptions, AuthenticationResult authenticationResult, TrackedTelemetry trackedTelemetry, CancellationToken cancellationToken) in C:\Ossiaco\chorus\src\Chorus.Services\src\Application\ChorusServerApplication.cs:line 94
         at Chorus.Services.Configure.Azure.ChorusResourceManager.<>c__DisplayClass12_1.<<ConfigureChorusApplicationAsync>b__2>d.MoveNext() in C:\Ossiaco\chorus\src\Chorus.Services.Configure\src\Azure\ChorusResourceManager.cs:line 374