return
		}
	}

	res, err := authn.Authenticate(roleArn, token)
	if err != nil {
		writeSTSErrorResponse(ctx, w, ErrSTSInvalidParameterValue, err)
		return
	}

	// If authentication failed, return the error message to the user.
	if res.Failure != nil {

                This is useful when you want to have optional authentication.

                It is also useful when you want to have authentication that can be
                provided in one of multiple optional ways (for example, in HTTP Basic
                authentication or in an HTTP Bearer token).
                """
            ),
        ] = True,
    ):

        But declaring any other authentication challenge would be application-specific
        as it's not defined in the specification.

        For practical reasons, this method uses the `Bearer` challenge by default, as
        it's probably the most common one.

        If you are implementing an OAuth2 authentication scheme other than the provided

	Reason string `json:"reason"`
}

// AuthNResponse - represents a result of the authentication operation.
type AuthNResponse struct {
	Success *AuthNSuccessResponse
	Failure *AuthNErrorResponse
}

const (
	minValidityDurationSeconds int = 900
	maxValidityDurationSeconds int = 365 * 24 * 3600
)

// Authenticate authenticates the token with the external hook endpoint and

OAuth2 with scopes is the mechanism used by many big authentication providers, like Facebook, Google, GitHub, Microsoft, X (Twitter), etc. They use it to provide specific permissions to users and applications.

Every time you "log in with" Facebook, Google, GitHub, Microsoft, X (Twitter), that application is using OAuth2 with scopes.

    client = TestClient(mod.app)
    response = client.get("/users/me")
    assert response.status_code == 401, response.text
    assert response.json() == {"detail": "Not authenticated"}
    assert response.headers["WWW-Authenticate"] == "Bearer"


def test_token(mod: ModuleType):
    client = TestClient(mod.app)
    access_token = get_access_token(scope="me", client=client)
    response = client.get(

    client = TestClient(mod.app)
    response = client.get("/users/me")
    assert response.status_code == 401, response.text
    assert response.json() == {"detail": "Not authenticated"}
    assert response.headers["WWW-Authenticate"] == "Bearer"


def test_token(mod: ModuleType):
    client = TestClient(mod.app)
    access_token = get_access_token(client=client)
    response = client.get(

## Specifying Access Control with IAM Policies

		return errSftpPublicKeyWithoutCert
	}

	// ssh.CheckCert called by ssh.Authenticate accepts certificates
	// with empty principles list so we block those in here.
	if len(cert.ValidPrincipals) == 0 {
		return errSftpCertWithoutPrincipals
	}

	// Verify that certificate provided by user is issued by trusted CA,
	// username in authentication request matches to identities in certificate
	// and that certificate type is correct.

/// info | Дополнительная информация
Дополнительный HTTP-заголовок `WWW-Authenticate` со значением `Bearer`, который мы здесь возвращаем, также является частью спецификации.

Любой HTTP статус-код 401 "UNAUTHORIZED" должен также возвращать заголовок `WWW-Authenticate`.

В случае с bearer-токенами (наш случай) значение этого заголовка должно быть `Bearer`.