How override ASP.NET Core Identity's password policy

Question

By default, ASP.NET Core Identity's password policy require at least one special character, one uppercase letter, one number, ...

How can I change this restrictions ?

There is nothing about that in the documentation (https://docs.asp.net/en/latest/security/authentication/identity.html)

I try to override the Identity's User Manager but I don't see which method manages the password policy.

public class ApplicationUserManager : UserManager<ApplicationUser> {     public ApplicationUserManager(         DbContextOptions<SecurityDbContext> options,         IServiceProvider services,         IHttpContextAccessor contextAccessor,         ILogger<UserManager<ApplicationUser>> logger)         : base(               new UserStore<ApplicationUser>(new SecurityDbContext(contextAccessor)),               new CustomOptions(),               new PasswordHasher<ApplicationUser>(),               new UserValidator<ApplicationUser>[] { new UserValidator<ApplicationUser>() },               new PasswordValidator[] { new PasswordValidator() },               new UpperInvariantLookupNormalizer(),               new IdentityErrorDescriber(),               services,               logger             // , contextAccessor               )     {     }      public class PasswordValidator : IPasswordValidator<ApplicationUser>     {         public Task<IdentityResult> ValidateAsync(UserManager<ApplicationUser> manager, ApplicationUser user, string password)         {             return Task.Run(() =>             {                 if (password.Length >= 4) return IdentityResult.Success;                 else { return IdentityResult.Failed(new IdentityError { Code = "SHORTPASSWORD", Description = "Password too short" }); }             });         }     }      public class CustomOptions : IOptions<IdentityOptions>     {         public IdentityOptions Value { get; private set; }         public CustomOptions()         {             Value = new IdentityOptions             {                 ClaimsIdentity = new ClaimsIdentityOptions(),                 Cookies = new IdentityCookieOptions(),                 Lockout = new LockoutOptions(),                 Password = null,                 User = new UserOptions(),                 SignIn = new SignInOptions(),                 Tokens = new TokenOptions()             };         }     } } 

I add this user manager dependency in startup's class :

services.AddScoped<ApplicationUserManager>(); 

But when I'm using ApplicationUserManager in controllers, I have the error : An unhandled exception occurred while processing the request.

InvalidOperationException: Unable to resolve service for type 'Microsoft.EntityFrameworkCore.DbContextOptions`1[SecurityDbContext]' while attempting to activate 'ApplicationUserManager'.

EDIT: User's management works when I use the ASP.NET Core Identity's default classes, so it's not a database problem, or something like this

EDIT 2 : I found the solution, you have just to configure Identity in the startup's class. My answer gives some details.

Answer 1

It's sooooo simple in the end ...

No need to override any class, you have just to configure the identity settings in your startup class, like this :

services.Configure<IdentityOptions>(options => {     options.Password.RequireDigit = false;     options.Password.RequiredLength = 5;     options.Password.RequireLowercase = true;     options.Password.RequireNonLetterOrDigit = true;     options.Password.RequireUppercase = false; }); 

Or you can configure identity when you add it :

services.AddIdentity<ApplicationUser, IdentityRole>(options=> {                 options.Password.RequireDigit = false;                 options.Password.RequiredLength = 4;                 options.Password.RequireNonAlphanumeric = false;                 options.Password.RequireUppercase = false;                 options.Password.RequireLowercase = false;             })                 .AddEntityFrameworkStores<SecurityDbContext>()                 .AddDefaultTokenProviders(); 

AS.NET Core is definitively good stuff ...