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Authentication


The FatSecret Platform REST API allows you to access the FatSecret Platform, as long as you're signed up as a developer. To protect developers and users of the FatSecret Platform, we use Oauth. The REST API requires that developers use the OAuth protocol for securely signing all requests. Additional information on Correctly Signing your Requests with OAuth is provided below.

Note that you must be signed up as a developer, and agree to our Terms of Service in order to obtain you Consumer Key and Shared Secret, which you'll need to send requests to the REST API. If you're using the FatSecret Platform JavaScript API and you don't intend to enable deep profile integration with your site, then you don't need a Consumer Key.

There are two types of request that the REST API Supports:


Signed Requests (Consumer Key and Signature)


All requests to the to the REST API must be signed (using your pre-assigned Shared Secret).

Signed Requests, as opposed to Signed and Delegated Requests, are where you are requesting information that is not on behalf of (or specific to) any single user's profile with the FatSecret Platform. For instance, the food.get API method returns details nutritional information for a specified food. As the response of this call returns information about a shared concept (i.e.: a single food item), and there is nothing about the response that is tailored to any specific user or individual, requests to the food.get API method must be signed, so that the Platform can verify the request, but the requests do not need to include the additional credentials of the particular user on whose behalf you are making the request.

Signed and Delegated Requests (Consumer Key and Access Token and Signature)


Most requests to the REST API can be thought of as executing on behalf of an individual user. For instance, weights.get_month returns the recorded weight values for a nominated user and a nominated month, while food_entry.create records an entry in a nominated user's Food Diary.

In order to enable the recording and storage of information on a per-user basis, the FatSecret Platform provides developers with profiles. A profile is the unique identifier for an individual user in the FatSecret Platform. You can create profiles for your own users on demand, by providing your own unique identifier for each profile you create (e.g.: member name, email address, or unique member identifier) or you can create a profile without providing any user-specific information and take care of storing the profile's oauth_token and oauth_secret (the profile unique identifier and signing key) in your own system (see the profile.create method).

The Profile Management REST API methods provide you with mechanisms for generating unique OAuth access tokens for each user of your site or service and for retrieving the secret for each token so that you can sign these requests on behalf of your users. For more information see API methods: profile.create and profile.get_auth.

In addition to creating profiles for your own users, you can also use the full 3-legged OAuth provided by FatSecret.com to attain an access token for a profile that is directly linked to a user account on FatSecret.com. For more information click here.

Correctly Signing Your Requests with OAuth


While you can find protocol specifications, documentation and FAQ's, at OAuth.net please see below a summary of the main prerequisites of the OAuth Core 1.0 protocol used for signing FatSecret Platform REST API requests.

Note that we also provide Client Libraries to assist you in making JavaScript/REST profile integration API calls and additional information is available under Resources.

Some OAuth Definitions


User
You (the developer)
Consumer
Your application
Consumer Key
A value we issue to you which helps us identify you
Consumer Secret
A secret we issue to you which helps us establish that it really is you
Access Token
A value which identifies a user of your application (you use the REST API Profile Management methods to generate these)
Access Secret
A secret we issue with the Access Token which helps us establish that you can perform a request on behalf of the user identified by the Access Token (you use the REST API Profile Management methods to generate these and/or retrieve these for your users).

Making a request


The basic steps involved in correctly signing and making requests are as follows:

  1. Create a Signature Base String
  2. Calculate the Signature value
  3. Send the Request


You generate a Signature Base String by concatenating the HTTP method (GET or POST), the Request URL, and your query parameters in the following format:

<HTTP Method>&<Request URL>&<Normalized Parameters>

HTTP Method
We support both HTTP methods GET and POST.
Request URL
The URL to make API calls is http://platform.fatsecret.com/rest/server.api
Normalized Parameters
Please refer to the FatSecret REST API documentation for the full parameter list for each method, but for OAuth authentication the following parameters are required for every request:
oauth_consumer_key
Your consumer key (you can obtain one by registering here)
oauth_signature_method
We only support "HMAC-SHA1"
oauth_timestamp
The date and time, expressed in the number of seconds since January 1, 1970 00:00:00 GMT. The timestamp value must be a positive integer and must be equal or greater than the timestamp used in previous requests
oauth_nonce
A randomly generated string for a request that can be combined with the timestamp to produce a unique value
oauth_version
Must be "1.0"
Parameters are written in the format "name=value" and sorted using lexicographical byte value ordering, first by name and then by value. Finally the parameters are concatenated in their sorted order into a single string, each name-value pair separated by an '&' character (ASCII code 38).

All request parameters (i.e. the HTTP Method, Request URL and Normalized Parameters) must be encoded using the [RFC3986] percent-encoding (%xx) mechanism and concatenated by an '&' character.

E.G.: A request is made using the POST HTTP method with the following parameters:

  • oauth_consumer_key=demo
  • oauth_signature_method=HMAC-SHA1
  • oauth_timestamp=12345678
  • oauth_nonce=abc
  • oauth_version=1.0
  • a=foo
  • z=bar

The individual sections of the Signature Base String are:

Http Method
POST
Request URL
http://platform.fatsecret.com/rest/server.api is encoded to produce
http%3A%2F%2Fplatform.fatsecret.com%2Frest%2Fserver.api
Normalized Parameters
First we sort the parameters:
  1. a=foo
  2. oauth_consumer_key=demo
  3. oauth_nonce=abc
  4. oauth_signature_method=HMAC-SHA1
  5. oauth_timestamp=12345678
  6. oauth_version=1.0
  7. z=bar

Second we concatenate the parameters:
a=foo&oauth_consumer_key=demo&oauth_nonce=abc&oauth_signature_method=HMAC-SHA1&oauth_timestamp=12345678&oauth_version=1.0&z=bar

Third we encode the sorted and concatenated string:
a%3Dbar%26%26oauth_consumer_key%3Ddemo%26oauth_nonce%3Dabc%26oauth_signature_method%3DHMAC-SHA1%26oauth_timestamp%3D12345678%26oauth_version%3D1.0%26z%3Dbar

The request parameters are concatenated with the '&' to produce the Signature Base String:

POST & http%3A%2F%2Fplatform.fatsecret.com%2Frest%2Fserver.api & a%3Dbar%26%26oauth_consumer_key%3Ddemo%26oauth_nonce%3Dabc%26oauth_signature_method%3DHMAC-SHA1%26oauth_timestamp%3D12345678%26oauth_version%3D1.0%26z%3Dbar


Use the HMAC-SHA1 signature algorithm as defined by the [RFC2104] to sign the request where text is the Signature Base String and key is the concatenated values of the Consumer Secret and Access Secret separated by an '&' character (show '&' even if Access Secret is empty as some methods do not require an Access Token).

The calculated digest octet string, first base64-encoded per [RFC2045], then escaped using the [RFC3986] percent-encoding (%xx) mechanism is the oauth_signature.


Send all the parameters used to generate the Signature Base String via the HTTP method specified in the Signature Base String, with the inclusion of the oauth_signature.

That's it! We will hopefully be able to generate the same oauth_signature from our end and confirm that it is indeed you.

Happy programming!