Authentication

VEF authentication happens at the API operation layer. Every operation has an auth configuration, and the API middleware chain resolves a principal before the handler runs.

Default Behavior

If you do not configure anything special:

• operations are authenticated with the Bearer strategy
• Public operations are explicitly unauthenticated

That default comes from the API engine, not from your application config.

Built-In Strategies

The public api package exposes strategy helpers:

• api.Public()
• api.BearerAuth()
• api.SignatureAuth()
• api.IPAuth(...) (see Signature helpers below for how it resolves whitelists); the built-in strategy is fail-closed: a missing, empty, or unparseable whitelist denies every request with security.ErrIPNotAllowed (HTTP 401). That "empty means allow all" behavior belongs to the lower-level IPWhitelistValidator used by signature external apps, not to api.IPAuth(...)
• api.APIKeyAuth(...)
• api.HTTPBasicAuth()

In practice, you normally control this through operation settings:

api.OperationSpec{
	Action: "login",
	Public: true,
}

or resource-level auth defaults.

Bearer Authentication

Bearer auth reads tokens from:

• Authorization: Bearer <token>
• query parameter __accessToken

The API auth strategy delegates actual token validation to the security module's auth manager.

Signature Authentication

Signature auth is intended for external applications and request signing use cases.

It expects these headers:

• X-App-ID
• X-Timestamp
• X-Nonce
• X-Signature

The strategy delegates verification to the security module's signature authenticator.

API Key Authentication

api.APIKeyAuth() authenticates machine-to-machine callers by a static secret key, read from the X-API-Key header by default; pass one header name (api.APIKeyAuth("X-Custom-Key")) to read a custom header.

The presented key is resolved through the registered security.APIKeyLoader. The framework ships a configuration-backed loader over vef.security.api_keys (constant-time comparison across all configured keys):

[vef.security.api_keys.reporting]
key = "high-entropy-random-string"
roles = ["reporting"]

Applications may provide their own security.APIKeyLoader to load keys from a database or config center:

type APIKeyLoader interface {
    // LoadByKey resolves the presented key to its Principal, or nil when no
    // key matches. An error signals an infrastructure fault, not a rejection.
    LoadByKey(ctx context.Context, key string) (*security.Principal, error)
}

Implementations that scan candidate keys must compare in constant time; implementations that index by key should only serve high-entropy random keys, where lookup timing reveals nothing.

A missing or unmatched key is rejected uniformly with security.ErrAPIKeyInvalid (HTTP 401). The configuration-backed loader resolves matches to an external-app principal named after the entry (api_key:<name>) carrying the configured roles.

HTTP Basic Authentication

api.HTTPBasicAuth() authenticates RFC 7617 Authorization: Basic credentials. These are machine-to-machine service accounts — store high-entropy random secrets, not user passwords.

The framework ships a configuration-backed loader over vef.security.basic_accounts (the map key is the username):

[vef.security.basic_accounts.metrics-scraper]
password = "high-entropy-random-string"
roles = ["metrics"]

Applications may provide their own security.BasicAccountLoader; the loader returns the stored secret and the framework performs the constant-time comparison, so every implementation shares the same fail-closed semantics:

type BasicAccountLoader interface {
    // LoadByUsername retrieves a service account by username, returning the
    // Principal and its stored secret. A nil Principal or empty secret means
    // the account is unknown; an error signals an infrastructure fault.
    LoadByUsername(ctx context.Context, username string) (*security.Principal, string, error)
}

Malformed headers, unknown accounts, and wrong passwords are all rejected uniformly with security.ErrBasicCredentialsInvalid (HTTP 401), so callers cannot distinguish which part failed.

Reserved Identities

Certain identities attribute work the framework performs outside any request — they are audit authors, never callers. security.Principal.IsReserved() reports them:

• the system principal type (PrincipalTypeSystem);
• a principal whose ID equals orm.OperatorSystem ("system");
• a principal whose ID equals orm.OperatorCronJob ("cron_job").

PrincipalAnonymous is deliberately not reserved: it denotes the absence of an identity, which the public auth strategy produces legitimately.

The framework enforces this invariant fail-closed at every boundary:

• Authentication boundary: the API auth middleware rejects any strategy that returns a nil or reserved principal with security.ErrReservedPrincipal (code 1007, HTTP 401).
• Token issuance: both JWTTokenGenerator and OpaqueTokenGenerator refuse to mint tokens for reserved principals.
• Challenge flow: challenge-token parsing rejects reserved principal types and reserved IDs as ErrTokenInvalid; after a challenge provider resolves, resolve_challenge refuses a reserved result with ErrReservedPrincipal. Challenge tokens carry only the principal ID in their subject; user name, department, and other metadata live in separate claims.

The built-in password login additionally refuses the reserved identifiers (system, cron_job, and anonymous) as a login principal. Custom UserLoader, APIKeyLoader, and similar identity sources must never return principals whose ID collides with the reserved operator IDs.

Reserved-principal rejections are audited but not counted toward login lockout: the credential may have been correct, so the fault lies with the authenticator or challenge provider, not the caller. See Login Hardening for the lockout behavior.

Public Operations

Public operations are intentionally anonymous. The auth middleware injects an anonymous principal instead of rejecting the request.

Use Public for:

• login
• token refresh
• health-like anonymous endpoints
• public callbacks when appropriate

Built-In Auth Resource

The security module registers a built-in RPC resource at:

security/auth

Its main actions are:

• login
• refresh
• logout
• resolve_challenge
• get_user_info

The request fields, public flags, and rate-limit sources are part of the runtime contract:

Action	Public	Rate limit	Request fields
login	yes	vef.security.login_rate_limit	type, principal, credentials; all are validate:"required"
refresh	yes	vef.security.refresh_rate_limit	refreshToken; validate:"required". Only mounted under token_type = "jwt_token" — under opaque_token the operation does not exist (sessions renew themselves)
logout	no	default API rate limit	none
resolve_challenge	yes	vef.security.login_rate_limit	challengeToken, type, response; all are validate:"required"
get_user_info	no	default API rate limit	arbitrary params, forwarded to UserInfoLoader.LoadUserInfo(...)

The complete field-level wire contract — every action's request parameters and response fields, with JSON examples for both login response shapes — is tabulated in RPC Resource: security/auth.

This resource, every registered Authenticator, and the AuthManager aggregator are wired by the framework's security module — the same module that layers in brute-force lockout, password strength/history/expiry (see Login Hardening) and opaque-token session control (see Session Management).

The built-in authenticator type strings are password, jwt_token, opaque_token, refresh, and signature (the JWT authenticator is named jwt_token, not token). In normal client calls, security/auth.login uses type: "password" with username and password credentials. Bearer-protected operations dispatch the configured token mechanism internally (jwt_token or opaque_token per vef.security.token_type), security/auth.refresh uses refresh internally, and SignatureAuth maps the signature headers to the signature authenticator. Only the configured mechanism's authenticators are registered, and login refuses the framework-issued token types as login credentials (see Session Management).

logout always returns an ok result. Under jwt_token it is effectively a no-op — there is no server-side session to revoke, clients are expected to remove their stored tokens. Under opaque_token it revokes the session backing the presented bearer token, best-effort (a missing session or a store failure is only logged).

Login Flow

The auth resource supports a two-phase model:

1. authenticate credentials
2. optionally continue through challenge providers

If no challenge is required, login returns tokens directly.

If challenges are configured and applicable, login returns:

• a challenge token
• the next required challenge

Clients then call resolve_challenge until all required challenges are complete. At the Go API layer, this shape is represented by LoginResult; the active step is a LoginChallenge.

The login response DTOs use these exact fields:

DTO	Fields
AuthTokens	JSON accessToken, refreshToken
Authentication	JSON type, principal, credentials
LoginResult	JSON tokens, challengeToken, challenge
LoginChallenge	JSON type, data, required
ChallengeState	Go-only state: Principal, Username (original login identifier, preserved across steps for audit events), Pending, Resolved

Field-by-field tables for both response shapes — the token payload and the challenge envelope — with JSON examples live in RPC Resource: security/auth.

What Applications Usually Provide

The exact application-owned pieces depend on which auth paths you use:

• security.UserLoader is typically required for user login and refresh flows
• security.ExternalAppLoader is needed for signature-based external app auth
• challenge providers are optional and only matter if you use challenge-based login flows
• security.UserInfoLoader is only needed if you want security/auth.get_user_info to return application-defined user data

The framework ships the auth flow and middleware, but application identity sources remain application-owned.

Public API Surface

The complete public authentication surface — principals, JWT, the auth manager, challenge providers and token stores, signature auth, and login events — is indexed with contract notes in the Authentication Reference.

A Working Login Module

In real VEF apps, the auth module is often very small: one users table, one package that implements the loader interfaces, and a module declaration that provides them. The framework already ships the security/auth resource, the password and refresh authenticators, and a default bcrypt password.Encoder; the application only supplies its identity source. The auth package below is complete enough to log in against a real table.

The user model

internal/auth/user.go

package auth

import (
	"github.com/uptrace/bun"

	"github.com/coldsmirk/vef-framework-go/orm"
)

type User struct {
	bun.BaseModel `bun:"table:app_user,alias:au"`
	orm.FullAuditedModel

	Username     string `json:"username" validate:"required,alphanum,max=32" label:"Username"`
	Name         string `json:"name" validate:"required,max=32" label:"Name"`
	PasswordHash string `json:"-" bun:"password_hash,notnull"`
	Role         string `json:"role"`
	IsActive     bool   `json:"isActive"`
}

// UserDetails becomes Principal.Details and travels inside issued access tokens.
type UserDetails struct {
	Username string `json:"username"`
}

PasswordHash must hold output of the same password.Encoder the login flow uses — by default the security module provides bcrypt (password.NewBcryptEncoder). Wherever you create or seed users, inject password.Encoder and store encoder.Encode(plaintext); the built-in password authenticator later verifies the login credential with encoder.Matches(plaintext, storedHash).

UserLoader

security.UserLoader has exactly two methods: LoadByUsername powers type: "password" login and returns the principal plus the stored hash; LoadByID powers token refresh.

internal/auth/user_loader.go

package auth

import (
	"context"

	"github.com/coldsmirk/vef-framework-go/orm"
	"github.com/coldsmirk/vef-framework-go/security"
)

type userLoader struct {
	db orm.DB
}

func NewUserLoader(db orm.DB) security.UserLoader {
	return &userLoader{db: db}
}

func (l *userLoader) LoadByUsername(ctx context.Context, username string) (*security.Principal, string, error) {
	user, err := l.findActive(ctx, "username", username)
	if err != nil {
		return nil, "", err
	}

	return toPrincipal(user), user.PasswordHash, nil
}

func (l *userLoader) LoadByID(ctx context.Context, id string) (*security.Principal, error) {
	user, err := l.findActive(ctx, "id", id)
	if err != nil {
		return nil, err
	}

	return toPrincipal(user), nil
}

func (l *userLoader) findActive(ctx context.Context, column string, value any) (*User, error) {
	var user User

	err := l.db.NewSelect().Model(&user).
		Where(func(cb orm.ConditionBuilder) {
			cb.Equals(column, value).IsTrue("is_active")
		}).
		Scan(ctx)
	if err != nil {
		return nil, err
	}

	return &user, nil
}

func toPrincipal(user *User) *security.Principal {
	principal := security.NewUser(user.ID, user.Name, user.Role)
	principal.Details = &UserDetails{Username: user.Username}

	return principal
}

The error semantics match what the built-in authenticators expect:

• Scan already maps "no rows" to result.ErrRecordNotFound, so returning the error unchanged is correct. Filtering on is_active makes disabled users indistinguishable from missing ones.
• During login, any LoadByUsername error — and equally a nil principal or an empty hash — collapses into the generic invalid-credentials error (code 1008), so usernames cannot be enumerated. Record-not-found errors are logged at info level, everything else at warn level.
• During refresh, a LoadByID error is returned to the caller as-is; the refresh authenticator reloads the user precisely so deactivated accounts stop refreshing.

Permissions and user info

internal/auth/loaders.go

package auth

import (
	"context"

	"github.com/coldsmirk/vef-framework-go/security"
)

type rolePermissionsLoader struct{}

func NewRolePermissionsLoader() security.RolePermissionsLoader {
	return &rolePermissionsLoader{}
}

func (*rolePermissionsLoader) LoadPermissions(_ context.Context, role string) (map[string]security.DataScope, error) {
	if role == "admin" {
		return map[string]security.DataScope{
			"user:manage": security.NewAllDataScope(),
			"order:read":  security.NewAllDataScope(),
		}, nil
	}

	return map[string]security.DataScope{
		"order:read": security.NewSelfDataScope(""),
	}, nil
}

type userInfoLoader struct{}

func NewUserInfoLoader() security.UserInfoLoader {
	return &userInfoLoader{}
}

func (*userInfoLoader) LoadUserInfo(_ context.Context, principal *security.Principal, _ map[string]any) (*security.UserInfo, error) {
	return &security.UserInfo{
		ID:     principal.ID,
		Name:   principal.Name,
		Gender: security.GenderUnknown,
	}, nil
}

A production RolePermissionsLoader reads a role-permissions table instead of a switch; the security module automatically wraps whatever you provide in a cache invalidated by RolePermissionsChangedEvent. The permission tokens feed the RBAC checker described in Authorization.

Wiring

Constructors must return the interface types — the framework consumes security.UserLoader, security.UserInfoLoader, and security.RolePermissionsLoader from the DI graph as optional dependencies of exactly those types.

internal/auth/module.go

package auth

import (
	"github.com/coldsmirk/vef-framework-go"
	"github.com/coldsmirk/vef-framework-go/security"
)

func init() {
	security.SetUserDetailsType[*UserDetails]()
}

var Module = vef.Module(
	"app:auth",
	vef.Provide(
		NewUserLoader,
		NewUserInfoLoader,
		NewRolePermissionsLoader,
	),
)

Pass auth.Module to vef.Run(...) in main and the built-in security/auth resource picks the loaders up — no further registration is needed. This keeps authentication integration isolated from the rest of the application modules.

Logging in

With a seeded user (admin / ChangeMe_123, hash produced by the bcrypt encoder), call the built-in resource:

curl http://localhost:8080/api \
  -H 'Content-Type: application/json' \
  -d '{
    "resource": "security/auth",
    "action": "login",
    "version": "v1",
    "params": {
      "type": "password",
      "principal": "admin",
      "credentials": "ChangeMe_123"
    }
  }'

With no challenge providers registered, the response carries the token pair directly:

{
  "code": 0,
  "message": "成功",
  "data": {
    "tokens": {
      "accessToken": "eyJhbGciOiJIUzI1NiIs...",
      "refreshToken": "eyJhbGciOiJIUzI1NiIs..."
    }
  }
}

Access tokens expire after 30 minutes (a fixed framework constant); the refresh token lifetime comes from vef.security.token_expires (default 7 days). Exchange the refresh token for a new pair — note that refresh returns the token pair directly in data, without the tokens wrapper:

curl http://localhost:8080/api \
  -H 'Content-Type: application/json' \
  -d '{
    "resource": "security/auth",
    "action": "refresh",
    "version": "v1",
    "params": { "refreshToken": "eyJhbGciOiJIUzI1NiIs..." }
  }'

Request parameters for every security/auth action are tabulated in Built-in Resources; the response fields — including the challenge envelope and the get_user_info UserInfo shape — are covered in RPC Resource: security/auth.

Practical Advice

• use Public sparingly and intentionally
• keep browser/API user auth on Bearer unless you have a reason to change it
• use Signature auth for external system integration, not as a replacement for normal user sessions

Next Step

• Authentication Reference — the complete public API surface behind this guide
• Authorization — how authentication leads into permission checks