session

Femto.Modules.Auth/Models/Events/UserWasCreatedEvent.cs

@@ -0,0 +1,5 @@
+using Femto.Common.Domain;
+
+namespace Femto.Modules.Auth.Models.Events;
+
+internal record UserWasCreatedEvent(UserIdentity User) : DomainEvent;

Femto.Modules.Auth/Models/UserIdentity.cs

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+using System.Text;
+using System.Text.Unicode;
+using Femto.Common.Domain;
+using Femto.Modules.Auth.Models.Events;
+using Geralt;
+
+namespace Femto.Modules.Auth.Models;
+
+internal class UserIdentity : Entity
+{
+    public Guid Id { get; private set; }
+
+    public string Username { get; private set; }
+
+    public UserPassword Password { get; private set; }
+
+    public ICollection<UserSession> Sessions { get; private set; }
+
+    private UserIdentity() { }
+
+    public UserIdentity(string username)
+    {
+        this.Id = Guid.CreateVersion7();
+        this.Username = username;
+
+        this.AddDomainEvent(new UserWasCreatedEvent(this));
+    }
+
+    public UserIdentity WithPassword(string password)
+    {
+        this.SetPassword(password);
+        return this;
+    }
+
+    public void SetPassword(string password)
+    {
+        this.Password = new UserPassword(password);
+    }
+
+    public bool HasPassword(string requestPassword)
+    {
+        if (this.Password is null)
+        {
+            return false;
+        }
+        
+        return this.Password.Check(requestPassword);
+    }
+
+    public UserSession StartNewSession()
+    {
+        var session = UserSession.Create();
+        
+        this.Sessions.Add(session);
+
+        return session;
+    }
+}
+
+public class SetPasswordError(string message, Exception inner) : DomainException(message, inner);

Femto.Modules.Auth/Models/UserPassword.cs

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+using System.Text;
+using Geralt;
+using JetBrains.Annotations;
+
+namespace Femto.Modules.Auth.Models;
+
+internal class UserPassword
+{
+    private const int Iterations = 3;
+    private const int MemorySize = 67108864;
+    
+    public Guid Id { get; private set; }
+    
+    private byte[] Hash { get; set; }
+    
+    private byte[] Salt { get; set; }
+    
+    [UsedImplicitly]
+    private UserPassword() {}
+    
+    public UserPassword(string password)
+    {
+        this.Id = Guid.NewGuid();
+        this.Salt = ComputeSalt();
+        this.Hash = ComputePasswordHash(password, Salt);
+    }
+
+    public bool Check(string password)
+    {
+        var matches = Argon2id.VerifyHash(
+            Hash,
+            Combine(password, Salt)
+        );
+
+        if (!matches)
+            return false;
+
+        if (Argon2id.NeedsRehash(Hash, Iterations, MemorySize))
+        {
+            this.Salt = ComputeSalt();
+            this.Hash = ComputePasswordHash(password, Salt);
+        }
+
+        return true;
+    }
+    
+    private static byte[] ComputeSalt() => System.Security.Cryptography.RandomNumberGenerator.GetBytes(32);
+    
+    private static byte[] ComputePasswordHash(string password, byte[] salt)
+    {
+        var hash = new byte[128];
+        try
+        {
+            Argon2id.ComputeHash(hash, Combine(password, salt), Iterations, MemorySize);
+        }
+        catch (Exception e)
+        {
+            throw new SetPasswordError("Failed to hash password", e);
+        }
+
+        return hash;
+    }
+
+    private static byte[] Combine(string password, byte[] salt)
+    {
+        var passwordBytes = Encoding.UTF8.GetBytes(password);
+        var hashInput = new byte[passwordBytes.Length + salt.Length];
+        passwordBytes.CopyTo(hashInput, 0);
+        salt.CopyTo(hashInput, passwordBytes.Length);
+        
+        return hashInput;
+    }
+}

Femto.Modules.Auth/Models/UserSession.cs

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+namespace Femto.Modules.Auth.Models;
+
+public class UserSession
+{
+    private static TimeSpan SessionTimeout = TimeSpan.FromMinutes(30);
+    public string Id { get; private set; }
+    public DateTimeOffset Expires { get; private set; }
+    
+    private UserSession() {}
+
+    public static UserSession Create()
+    {
+        return new()
+        {
+            Id = Convert.ToBase64String(System.Security.Cryptography.RandomNumberGenerator.GetBytes(32)),
+            Expires = DateTimeOffset.Now + SessionTimeout
+        };
+    }
+}