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Authlogic plugin to allow API requests to be authenticated automatically by using an api_key/signature mechanism

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authlogic-api

github.com/phurni/authlogic_api

DESCRIPTION:

This is a plugin for Authlogic to allow API requests to be authenticated automatically by using an api_key/signature mechanism. The plugin will automatically compute the hashed sum of the request params and compare it to the passed signature.

REQUIREMENTS:

  • authlogic

INSTALL:

  • script/plugin install git://github.com/phurni/authlogic_api.git

  • optionally create a migration for an application_accounts table.

  • create an application session model and configure it with Authlogic.

EXAMPLE:

You certainly want to separate User sessions from Application sessions. You'll have to create say an ApplicationSession like this:

class ApplicationSession < Authlogic::Session::Base
  authenticate_with ApplicationAccount

  api_key_param 'app_key'
end

Because Authlogic will infer the model holding the credentials from the session class name, which would result in Application, we explicitely tell it to use our ApplicationAccount model.

Then to enable API access, we tell AuthlogicApi the name of the param key which will get the application id.

The ApplicationAccount model will look like:

class ApplicationAccount < ActiveRecord::Base
  acts_as_authentic do |config|
  end # the configuration block is optional
end

The table should have a api_key field and also a api_secret field. You can change these default names with the config block on the acts_as_authentic call.

Everything is now setup to authenticate API request. Note that it's up to you to create your controllers, configure them to respond with your prefered data format and all the other stuff.

Read the AuthlogicApi::ActsAsAuthentic::Config portion for config options.

Client side

I'll describe here what the client has to do to create requests that will be authenticated by the AuthlogicApi backend.

GET requests

Every parameter given in the query string will be summed and hashed to form a signature. Here is the pseudo-code to use:

args = array of arguments for the request, each argument is a key/value pair
args += app_key
sorted_args = alphabetically_sort_array_by_keys(args);
request_str = concatenate_in_order(sorted_args);
signature = md5(concatenate(request_str, secret))

Let's take an example:

here is the original URL of the request:
  http://montain.mil/private/rockets/launch?rocket_id=42&speed=5

The args with the app_key:
  rocket_id: 42
  speed: 5
  app_key: A6G87bqY

The sorted args
  app_key: A6G87bqY
  rocket_id: 42
  speed: 5

The request string (note that there is no delimiter between key/value, neither between arguments)
  app_keyA6G87bqYrocket_id42speed5

Now the client has to know the application secret, it must add it to the request string:
  app_keyA6G87bqYrocket_id42speed5SECRET

Hash this with MD5:
  5266bf02b183ffac3898b802e62d45d6

here is the URL for the signed request:
  http://montain.mil/private/rockets/launch?rocket_id=42&speed=5&app_key=A6G87bqY&signature=5266bf02b183ffac3898b802e62d45d6

POST requests

The principle is the same, but only the POST data is hased. The app_key and the signature are passed into the query string.

Example:

here is the original URL of the request:
  http://montain.mil/private/rockets/launch

the POST data:
  <?xml version="1.0" encoding="UTF-8"?>
  <rocket>
    <id>42</id>
    <speed>5</speed>
  </rocket>

Now the client has to know the application secret, it must add it to the POST data:
  <?xml version="1.0" encoding="UTF-8"?>
  <rocket>
    <id>42</id>
    <speed>5</speed>
  </rocket>
  SECRET

the MD5 hash of the post data with secret:
  82f5aef6d4a4ad710a60b74e0355b74d

here is the URL for the signed request:
  http://montain.mil/private/rockets/launch?app_key=A6G87bqY&signature=82f5aef6d4a4ad710a60b74e0355b74d

Note that the POST data is left untouched. (Do not send the secret)

LICENSE:

(The MIT License)

Copyright © 2010 Pascal Hurni

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

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