3-Legged OAuth problem

[leocelis]

To be able to extract a user's data, the first step was to create the
signature with the url http://www.fatsecret.com/oauth/request_token.

Although I did get a response with the signature (by using the php
lib), FatSecret keeps saying that the signature is invalid.

Also, I can't get the token to redirect the user to
http://www.fatsecret.com/oauth/authorize.

I encoded all the params with base64_encode (like the php lib), send
the signature to the /request_token url via oauth_signature params,
but we are still getting invalid signature.

Does anyone have sample PHP code of how to use the 3-legged OAuth
authorization that you can share with me?