Crate hawk

The hawk crate provides support for Hawk authentictation. It is a low-level crate, used by higher-level crates to integrate with various Rust HTTP libraries. For example hyper-hawk integrates Hawk with Hyper.

Examples

Hawk Client

A client can attach a Hawk Authorization header to requests by providing credentials to a Request instance, which will generate the header.

use hawk::{RequestBuilder, Credentials, Key, SHA256, PayloadHasher};
use std::time::{Duration, UNIX_EPOCH};

// provide the Hawk id and key
let credentials = Credentials {
    id: "test-client".to_string(),
    key: Key::new(vec![99u8; 32], SHA256).unwrap(),
};

let payload_hash = PayloadHasher::hash("text/plain", SHA256, "request-body").unwrap();

// provide the details of the request to be authorized
 let request = RequestBuilder::new("POST", "example.com", 80, "/v1/users")
    .hash(&payload_hash[..])
    .request();

// Get the resulting header, including the calculated MAC; this involves a random
// nonce, so the MAC will be different on every request.
let header = request.make_header(&credentials).unwrap();

// the header would the be attached to the request
assert_eq!(header.id.unwrap(), "test-client");
assert_eq!(header.mac.unwrap().len(), 32);
assert_eq!(header.hash.unwrap().len(), 32);

A client that wishes to use a bewit (URL parameter) can do so as follows:

use hawk::{RequestBuilder, Credentials, Key, SHA256, Bewit};
use std::time::Duration;
use std::borrow::Cow;

let credentials = Credentials {
    id: "me".to_string(),
    key: Key::new("tok", SHA256).unwrap(),
};

let client_req = RequestBuilder::new("GET", "mysite.com", 443, "/resource").request();
let client_bewit = client_req
    .make_bewit_with_ttl(&credentials, Duration::from_secs(10))
    .unwrap();
let request_path = format!("/resource?bewit={}", client_bewit.to_str());
// .. make the request

Hawk Server

To act as a server, parse the Hawk Authorization header from the request, generate a new Request instance, and use the request to validate the header.

use hawk::{RequestBuilder, Header, Key, SHA256};
use hawk::mac::Mac;
use std::time::{Duration, UNIX_EPOCH};

let mac = Mac::from(vec![7, 22, 226, 240, 84, 78, 49, 75, 115, 144, 70,
                         106, 102, 134, 144, 128, 225, 239, 95, 132, 202,
                         154, 213, 118, 19, 63, 183, 108, 215, 134, 118, 115]);
// get the header (usually from the received request; constructed directly here)
let hdr = Header::new(Some("dh37fgj492je"),
                      Some(UNIX_EPOCH + Duration::new(1353832234, 0)),
                      Some("j4h3g2"),
                      Some(mac),
                      Some("my-ext-value"),
                      Some(vec![1, 2, 3, 4]),
                      Some("my-app"),
                      Some("my-dlg")).unwrap();

// build a request object based on what we know
let hash = vec![1, 2, 3, 4];
let request = RequestBuilder::new("GET", "localhost", 443, "/resource")
    .hash(&hash[..])
    .request();

let key = Key::new(vec![99u8; 32], SHA256).unwrap();
let one_week_in_secs = 7 * 24 * 60 * 60;
if !request.validate_header(&hdr, &key, Duration::from_secs(5200 * one_week_in_secs)) {
    panic!("header validation failed. Is it 2117 already?");
}

A server which validates bewits looks like this:

use hawk::{RequestBuilder, Credentials, Key, SHA256, Bewit};
use std::time::Duration;
use std::borrow::Cow;

let credentials = Credentials {
    id: "me".to_string(),
    key: Key::new("tok", SHA256).unwrap(),
};

// simulate the client generation of a bewit
let client_req = RequestBuilder::new("GET", "mysite.com", 443, "/resource").request();
let client_bewit = client_req
    .make_bewit_with_ttl(&credentials, Duration::from_secs(10))
    .unwrap();
let request_path = format!("/resource?bewit={}", client_bewit.to_str());

let mut maybe_bewit = None;
let server_req = RequestBuilder::new("GET", "mysite.com", 443, &request_path)
    .extract_bewit(&mut maybe_bewit).unwrap()
    .request();
let bewit = maybe_bewit.unwrap();
assert_eq!(bewit.id(), "me");
assert!(server_req.validate_bewit(&bewit, &credentials.key));

Features

By default, the use_ring feature is enabled, which means that this crate will use ring for all cryptographic operations.

Alternatively, one can configure the crate with the use_openssl feature to use the openssl crate.

If no features are enabled, you must provide a custom implementation of the [hawk::crypto::Cryptographer] trait to the set_cryptographer function, or the cryptographic operations will panic.

Attempting to configure both the use_ring and use_openssl features will result in a build error.

Modules

• crypto
  hawk must perform certain cryptographic operations in order to function, and applications may need control over which library is used for these.
• mac

Structs

• Bewit
  A Bewit is a piece of data attached to a GET request that functions in place of a Hawk Authentication header. It contains an id, a timestamp, a MAC, and an optional ext value. These are available using accessor functions.
• Credentials
  Hawk credentials: an ID and a key associated with that ID. The digest algorithm must be agreed between the server and the client, and the length of the key is specific to that algorithm.
• Header
  Representation of a Hawk Authorization header value (the part following “Hawk “).
• Key
  Hawk key.
• PayloadHasher
  A utility for hashing payloads. Feed your entity body to this, then pass the finish result to a request or response.
• Request
  Request represents a single HTTP request.
• RequestBuilder
• Response
  A Response represents a response from an HTTP server.
• ResponseBuilder

Enums

• DigestAlgorithm
• Error
• InvalidBewit

Constants

• SHA256
• SHA384
• SHA512

Type Aliases

• Result