title: 7digital API : OAuth authentication error: Invalid signature
body: <p>I have problems with the authentication, i am doing this steps:</p>
  
  <p><strong>1. First time I get the oauth_signature by using this site url with following details:</strong>
  <a href="http://7digital.github.io/oauth-reference-page/" rel="nofollow">http://7digital.github.io/oauth-reference-page/</a></p>
  
  <p><strong>url:</strong> <a href="https://api.7digital.com/1.2/oauth/requesttoken" rel="nofollow">https://api.7digital.com/1.2/oauth/requesttoken</a></p>
  
  <p><strong>consumer key:</strong> MY_KEY</p>
  
  <p><strong>consumer secret:</strong> MY_SECRET_KEY</p>
  
  <p><strong>nonce:</strong> 814629426</p>
  
  <p>*<strong>*timestamp:</strong> 1383291284</p>
  
  <p>body encoding:** application/json</p>
  
  <p>and them send request to get the oauth_token for the 7digital API:
  <a href="https://api.7digital.com/1.2/oauth/requesttoken?oauth_consumer_key=MY_KEY&amp;oauth_nonce=184615245&amp;oauth_signature_method=HMAC-SHA1&amp;oauth_timestamp=1383144733&amp;oauth_version=1.0&amp;oauth_signature=sJ%2B%2BPq2i9LfC1xGG1EHx2DrTBxg%3D" rel="nofollow">https://api.7digital.com/1.2/oauth/requesttoken?oauth_consumer_key=MY_KEY&amp;oauth_nonce=184615245&amp;oauth_signature_method=HMAC-SHA1&amp;oauth_timestamp=1383144733&amp;oauth_version=1.0&amp;oauth_signature=sJ%2B%2BPq2i9LfC1xGG1EHx2DrTBxg%3D</a></p>
  
  <p>This request gets the oauth_token and the oauth_token_secret.</p>
  
  <p><strong>2. I need to authorize the oauth_token with the client key:</strong></p>
  
  <p><a href="https://account.7digital.com/7dysvzdxkkmf/oauth/authorise?oauth_token=7EP6KGD" rel="nofollow">https://account.7digital.com/7dysvzdxkkmf/oauth/authorise?oauth_token=7EP6KGD</a>
  The request responses  a page to registration or login if i have a 7digital account. </p>
  
  <p><strong>3. I need to access token:</strong></p>
  
  <p><a href="https://api.7digital.com/1.2/oauth/accesstoken?oauth_token=JXLDXZY&amp;oauth_consumer_key=MY_KEY&amp;oauth_signature=uJ8jUSre5%2Fe5qiJsA5jeN54143M%3D&amp;oauth_timestamp=1383204749&amp;oauth_nonce=558206579" rel="nofollow">https://api.7digital.com/1.2/oauth/accesstoken?oauth_token=JXLDXZY&amp;oauth_consumer_key=MY_KEY&amp;oauth_signature=uJ8jUSre5%2Fe5qiJsA5jeN54143M%3D&amp;oauth_timestamp=1383204749&amp;oauth_nonce=558206579</a></p>
  
  <p>But on step 3 i got error message:
  OAuth authentication error: Invalid signature.</p>
  
  <p>What's wrong in my code?</p>