Remotely/Server/Services/ExpiringTokenService.cs

using Remotely.Shared.Helpers;
using Microsoft.Extensions.Caching.Memory;
using Remotely.Shared.Utilities;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace Remotely.Server.Services;

public interface IExpiringTokenService
{
    string GetToken(DateTimeOffset expiration);
    bool TryGetExpiration(string secret, out DateTimeOffset tokenExpiration);
}

public class ExpiringTokenService : IExpiringTokenService
{
    private static readonly MemoryCache _tokenCache = new(new MemoryCacheOptions());

    public string GetToken(DateTimeOffset expiration)
    {
        var secret = RandomGenerator.GenerateString(36);
        _tokenCache.Set(secret, expiration, expiration);
        return secret;
    }

    public bool TryGetExpiration(string secret, out DateTimeOffset tokenExpiration)
    {
        return _tokenCache.TryGetValue(secret, out tokenExpiration);
    }
}