Part 2: Pseudo code demonstrating how to isolate logging components through decoration.

LoggingAuthenticationProcedure.cs

public class LoggingAuthenticationProcedure : IAuthenticationProcedure
{
    private readonly ILogger logger;
    private readonly IAuthenticationProcedure innerProcedure;
    
    public LoggingAuthenticationProcedure(ILogger logger, IAuthenticationProcedure procedure)
    {
        this.logger = logger;
        this.innerProcedure = procedure;
    }
    
    public AuthenticationResult Authenticate(HttpRequest request)
    {
        AuthenticationResult result;
        
        try
        {
            this.logger.Trace("Beginning signature authentication procedure.")
            
            result = this.innerProcedure.Authenticate(request);    
            
            if(result == AuthenticationResult.Successful)
            {
                this.logger.Information("Authentication successful.")
            }
        }
        catch(Exception ex)
        {
            this.logger.Error(ex);
            throw;
        }
        finally
        {
            this.logger.Trace("Completed signature authentication procedure.");
        }
        
        return result;
    }
}

SignatureAuthenticationProcedure.cs

public class SignatureAuthenticationProcedure : IAuthenticationProcedure
{
    public AuthenticationResult Authenticate(HttpRequest request)
    {
        AuthenticationResult result = AuthenticationResult.Failed;
        
        if(IsTimestampValid(request) && IsSignatureValid(request))
        {
            result = AuthenticationResult.Success;
        }
        
        return result;
    }
    
    // ...
}