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Verify user's ID token generated via firebase client. Bump version 0.2.1 #8

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3aedc85
Verify user's ID token generated via firebase client. Bump version 0.2.1
Dec 23, 2019
8d1cce0
Update user data on firebase
Jan 13, 2020
b65680e
Guard cond to handle non-firebase jwt token: Bump version 0.2.3
Feb 12, 2020
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38 changes: 38 additions & 0 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -210,6 +210,44 @@ iex(4)> FirebaseAdminEx.Auth.generate_sign_in_with_email_link(action_code_settin
"{\n \"kind\": \"identitytoolkit#GetOobConfirmationCodeResponse\",\n \"email\": \"[email protected]\",\n \"oobLink\": \"https://YOUR-FIREBASE-CLIENT.firebaseapp.com/__/auth/action?mode=signIn&oobCode=xcdwelFRvfbtghHjswvw2f3g46hh6j8&apiKey=Fgae35h6j78_vbsddgs34th6h6hhekj97gfj&lang=en&continueUrl=www.test.com/sign-in\"\n}\n"}
```

* Verify user's ID token

```ex
# Fetch the id_token generated by firebase client for the user and pass to to verify_token(id_token, allow_unverified \\ true). It checks for valid certificate, issuer, audience, expiry and optionally if the user has a verified email address.
#Returns user object with token details on successful verification.

#Valid id token
iex(5)> id_token = "eyJhbGciOiJSUzI1NiIsImtpZCI6ImQ1OThkYjVjZjE1ZWNhOTI0OWJhZTUzMDYzOWVkYzUzNmMzYzViYjUiLCJ0eXAiOiJKV1QifQ"
iex(6)> FirebaseAdminEx.Auth.verify_token(id_token)
{:ok,
%{
"aud" => "YOUR-FIREBASE-PROJECT",
"auth_time" => 1577079586,
"email" => "[email protected]",
"email_verified" => false,
"exp" => 1577087136,
"firebase" => %{
"identities" => %{"email" => ["[email protected]"]},
"sign_in_provider" => "password"
},
"iat" => 1577083536,
"iss" => "https://securetoken.google.com/YOUR-FIREBASE-PROJECT",
"sub" => "xxxxxxxxxxxxxxxxxxxx",
"user_id" => "USER-UID-ON-FIREBASE"
}}

#Expired id_token
iex(7)> id_token = "eyJhbGciOiJSUzI1NiIsImtpZCI6ImQ1OThkYjVjZjE1ZWNhOTI0OWJhZTUzMDYzOWVkYzUzNmMzYzViYjUiLCJ0eXAiOiJKtyerdf"
iex(8)> FirebaseAdminEx.Auth.verify_token(id_token)
{:error, "Token has passed it's expiry time"}

#Force check for verified email address
iex(9)> id_token = "eyJhbGciOiJSUzI1NiIsImtpZCI6ImQ1OThkYjVjZjE1ZWNhOTI0OWJhZTUzMDYzOWVkYzUzNmMzYzViYjUiLCJ0eXAiOiJKV1QifQ"
iex(10)> FirebaseAdminEx.Auth.verify_token(id_token,false)
{:error, "Email is not verified"}
```


## Firebase Documentation

* [Setup Guide](https://firebase.google.com/docs/admin/setup/)
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114 changes: 114 additions & 0 deletions lib/auth.ex
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Expand Up @@ -5,6 +5,7 @@ defmodule FirebaseAdminEx.Auth do
@auth_endpoint "https://www.googleapis.com/identitytoolkit/v3/relyingparty/"
@auth_endpoint_account "https://identitytoolkit.googleapis.com/v1/projects/"
@auth_scope "https://www.googleapis.com/auth/cloud-platform"
@auth_cert_url "https://www.googleapis.com/robot/v1/metadata/x509/[email protected]"
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i worked on something similar, can you check this code, maybe you can use it

Suggested change
@auth_cert_url "https://www.googleapis.com/robot/v1/metadata/x509/[email protected]"
@public_keys "https://www.googleapis.com/robot/v1/metadata/x509/[email protected]"
@header_claims ["alg", "kid", "typ"]
@payload_claims ["exp", "iat", "aud", "iss", "sub", "auth_time"]
@doc """
Verifica si un token jwt de firebase es válido
"""
@spec verify_id_token(String.t()) :: tuple
def verify_id_token(token) do
with [header, payload, _signature] <- String.split(token, ".") do
# Certificados y llaves públicas de google
public_keys =
@public_keys
|> HTTPoison.get!()
|> Map.get(:body)
|> Poison.decode!()
# Credenciales para verificar los claims del token
firebase_credentials =
:goth
|> Application.get_env(:json)
|> Poison.decode!()
|> List.last()
# Validar claims del header
valid_header? =
header
|> Base.decode64!(padding: false)
|> Poison.decode!()
|> Map.take(@header_claims)
|> Enum.all?(fn {k, v} ->
_valid_claim?(k, v, public_keys, firebase_credentials)
end)
# Validar claims del payload
valid_payload? =
payload
|> Base.decode64!(padding: false)
|> Poison.decode!()
|> Map.take(@payload_claims)
|> Enum.all?(fn {k, v} ->
_valid_claim?(k, v, public_keys, firebase_credentials)
end)
if valid_header? and valid_payload? do
# Validar si el token jwk fue firmado con la llave privada de google
# haciendo uso de la llave publica
kid =
header
|> Base.decode64!(padding: false)
|> Poison.decode!()
|> Map.get("kid")
cert =
public_keys
|> Map.get(kid)
|> JOSE.JWK.from_pem()
{valid_signature?, claims, _jws} = JOSE.JWK.verify(token, cert)
if valid_signature? do
{:ok, Poison.decode!(claims)}
else
{:error, "La firma del token no es válida"}
end
else
{:error, "El header o el payload del token no es válido"}
end
else
_ -> {:error, "Token no válido"}
end
end
# Valida si los claims del header/payload son válidos
@spec _valid_claim?(String.t(), String.t() | integer, map, map) :: boolean
defp _valid_claim?("alg", "RS256", _, _), do: true
defp _valid_claim?("alg", _, _, _), do: false
defp _valid_claim?("kid", kid, public_keys, _), do: Map.has_key?(public_keys, kid)
defp _valid_claim?("typ", "JWT", _, _), do: true
defp _valid_claim?("typ", _, _, _), do: false
defp _valid_claim?("exp", exp, _, _) do
exp > DateTime.diff(Timex.now(), DateTime.from_unix!(0))
end
defp _valid_claim?("iat", iat, _, _) do
iat < DateTime.diff(Timex.now(), DateTime.from_unix!(0))
end
defp _valid_claim?("aud", aud, _, firebase_credentials) do
aud == Map.get(firebase_credentials, "project_id")
end
defp _valid_claim?("iss", iss, _, firebase_credentials) do
project_id = Map.get(firebase_credentials, "project_id")
iss == "https://securetoken.google.com/#{project_id}"
end
defp _valid_claim?("sub", sub, _, _), do: sub not in ["", nil]
defp _valid_claim?("auth_time", auth_time, _, _) do
auth_time < DateTime.diff(Timex.now(), DateTime.from_unix!(0))
end
# Obtiene los datos del cliente de firebase
@spec _get_client_data(String.t()) :: String.t()
defp _get_client_data(key) do
:goth
|> Application.get_env(:json)
|> Poison.decode!()
|> List.last()
|> Map.get(key)
end

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@bernardd @nitinstp23


@doc """
Get a user's info by UID
Expand Down Expand Up @@ -36,6 +37,20 @@ defmodule FirebaseAdminEx.Auth do
def delete_user(uid, client_email \\ nil),
do: do_request("deleteAccount", %{localId: uid}, client_email)

@doc """
Update an existing user by UID
Pick one or more fields that require updation.
Passing the firebase UID as local_id is mandatory, force check this in the client before using update_user api.
iex(9)> request_body = %{email_verified: true, local_id: "iD1vovu1QsOcOFrkB2XBw2F4jsZ2"}
%{email_verified: true, local_id: "iD1vovu1QsOcOFrkB2XBw2F4jsZ2"}
iex(10)> FirebaseAdminEx.Auth.update_user(request_body)
{:ok, _UPDATED_USER_BODY_RESPONSE}

"""
@spec update_user(map, String.t() | nil) :: tuple()
def update_user(request_body, client_email \\ nil),
do: do_request("setAccountInfo", request_body, client_email)

# TODO: Add other commands:
# list_users
# create_user
Expand Down Expand Up @@ -67,6 +82,105 @@ defmodule FirebaseAdminEx.Auth do
end
end

@doc """
Fetch environment specific Firebase project_id
"""
def firebase_project_id() do
Goth.Config.get(:project_id) |> elem(1)
end

@doc """
Verify id token based on certificate, token issuer and timestamp
"""
@spec verify_token(String.t(), boolean()) :: tuple()
def verify_token(id_token, allow_unverified \\ true) do
with {:ok, fields} <- resolve_token_firebase(id_token, @auth_cert_url),
{true,_} <- check_payload_email_verified(fields["email_verified"],allow_unverified),
{true,_} <- check_payload_audience(fields["aud"]),
{true,_} <- check_payload_issuer(fields["iss"]),
{true,_} <- check_payload_expiry(fields["exp"]) do
{:ok, fields}
else
{:error, reason} -> {:error, reason}
{false, reason} -> {:error, reason}
end
end

@doc """
Resolve id token based on certificate into firebase user data
"""
@spec resolve_token_firebase(String.t(), String.t()) :: tuple()
def resolve_token_firebase(id_token, cert_url) do
with true <- !is_nil(id_token),
{:ok, response} <- HTTPoison.get(cert_url),
%{body: body} = response,
certs = Poison.Parser.parse!(body, %{}),
{:ok, header} <- Joken.peek_header(id_token),
jwks = JOSE.JWK.from_firebase(certs),
true <- !is_nil(jwks[header["kid"]]),
jwk = jwks[header["kid"]] |> JOSE.JWK.to_map |> elem(1),
{true, jose_jwt, _} = JOSE.JWT.verify(jwk, id_token) do
fields = JOSE.JWT.to_map(jose_jwt) |> elem(1)
{:ok, fields}
else
false -> {:error, "id_token is nil"}
{:error, _} -> {:error, "Unable to resolve id_token error"}
{false,_} -> {:error, "Unable to resolve id_token due to certificate mismatch"}
end
end

@doc """
Check if the email in the payload is verified. If client allows unverified users,
set allow_unverified to true
"""
@spec check_payload_email_verified(String.t(), boolean()) :: tuple()
def check_payload_email_verified(field_value, allow_unverified) do
if field_value || allow_unverified do
{true, "Email is verified"}
else
{false, "Email is not verified"}
end
end

@doc """
Check if the issuer in the payload matches client's firebase project
"""
@spec check_payload_issuer(String.t()) :: tuple()
def check_payload_issuer(field_value) do
firebase_project_id = firebase_project_id()
if field_value == "https://securetoken.google.com/" <> firebase_project_id do
{true, "Issuer matches client's firebase project"}
else
{false, "Token issuer does not match client's firebase project"}
end
end

@doc """
Check if the audience in the payload matches client's firebase project
"""
@spec check_payload_audience(String.t()) :: tuple()
def check_payload_audience(field_value) do
firebase_project_id = firebase_project_id()
if field_value == firebase_project_id do
{true, "Audience matches client's firebase project"}
else
{false, "Token aud does not match client's firebase project"}
end
end

@doc """
Check that the token expiry time has not passed.
"""
@spec check_payload_expiry(integer()) :: tuple()
def check_payload_expiry(field_value) do
current_datetime = DateTime.utc_now |> DateTime.to_unix
if field_value > current_datetime do
{true, "Token is valid"}
else
{false, "Token has passed it's expiry time"}
end
end

defp do_request(url_suffix, payload, client_email, project_id) do
with {:ok, response} <-
Request.request(
Expand Down
2 changes: 1 addition & 1 deletion mix.exs
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Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,7 @@ defmodule FirebaseAdminEx.MixProject do
def project do
[
app: :firebase_admin_ex,
version: "0.2.0",
version: "0.2.3",
elixir: "~> 1.6",
start_permanent: Mix.env() == :prod,
deps: deps(),
Expand Down