rocket-sig-auth

Authentication library for Rocket. Supports Bearer Auth and secp256k1 Public key auth.

Permission and aliases

Typically permissions are simple enums. The library passes permission as a const u8 type parameter to permission provider to check. Because of that, permissions are supposed to have TryFrom trait.

To efficiently use type aliases, Permission must have

pub const fn as_u8(p: Permission) -> u8

const is important, otherwise the function can't be used in types.

Requires

#![allow(incomplete_features)]
#![feature(generic_const_exprs)]
#![feature(adt_const_params)]

Example alias:

#[derive(Debug, Clone, PartialEq, Eq, Copy)]
pub enum UserPermission {
  Read,
  Write,
  Sudo
}

impl UserPermission {
    pub const fn as_u8(perm: UserPermission) -> u8 {
        match perm {
            UserPermission::Read => 0,
            UserPermission::Write => 1,
            UserPermission::Sudo => 2,
        }
    }
}

impl TryFrom<u8> for UserPermission {
    type Error = ();

    fn try_from(value: u8) -> Result<Self, Self::Error> {
        match value {
            0 => Ok(UserPermission::Read),
            1 => Ok(UserPermission::Write),
            2 => Ok(UserPermission::Sudo),
            _ => Err(()),
        }
    }
}

type AuthSignature<const PERM: UserPermission, T> =
    PublicKeyAuth<UserPermission, AuthInfo, AuthDb, { UserPermission::as_u8(PERM) }, T>;

Alias usage in handles:

#[openapi(tag = "example")]
#[post("/signature/read", data = "<req>")]
pub async fn signature_read(
  req: AuthSignature<{ UserPermission::Read }, String>
) -> Json<String> {
    log::info!("User id {}", req.auth);
    Json(req.data.to_string())
}

Permission provider

We do not specify the container for actual permission provider, so the traits must be implemented for a type, which implements Send and Copy

For example, sqlx Postgres Pool must be wraped in an Arc to pass to the rocket state. The library doesn't know about the Arc and rust doesn't allow implementing traits for Arc in different crates, so the user has to create a wrapper:

pub struct AuthPool(pub Pool)

and implement authorization traits for AuthPool

In a different example, rusqlite Connection has to be wrapped into Arc<Mutex<Connection>>. Same idea: wrap the resulting container into a newtype and implement traits for it.

Nonce handling

Authorization scheme uses UTC timestamps (in seconds!) as a nonce.

The library doesn't cache nonces (yet?) and implements stateless authorization scheme. To limit the possibility of repeating attacks nonces have expiration.

Permission provider gives nonce_timeout. If current UTC timestamp on the server differs from provided nonce timestamp for more than nonce_timeout seconds, the request is invalid and no further checks are made.