title: Bittrex API call with powershell fails with INVALID_SIGNATURE
body: <p>I haven't been successful in getting a response from the Bittrex API with the following powershell code:</p>
  
  <pre><code>Function Crypto($secret, $message)
  {
  $hmacsha = New-Object System.Security.Cryptography.HMACSHA512(,[System.Text.Encoding]::ASCII.GetBytes($secret))
  $hashmessage = $hmacsha.ComputeHash([System.Text.Encoding]::ASCII.GetBytes($message))
  $signature = [Convert]::ToBase64String($hashmessage)
  return $signature
  }
  $apiKey = "key"
  $secretApiKey = "secret"
  $nonce = [Math]::Round((([DateTime]::UtcNow - [DateTime]::new(1970, 1, 1, 0, 0, 0, 0, 'Utc')).TotalSeconds),0)
  $uri = "https://bittrex.com/api/v1.1/account/getbalances?apikey=$apiKey&amp;nonce=$nonce"
  $signature = Crypto $secretApiKey $uri
  Invoke-RestMethod -Uri $uri -Method Get -Headers @{"apisign"="$signature"}
  </code></pre>
  
  <p>The response is</p>
  
  <pre><code>success message           result
  ------- -------           ------
    False INVALID_SIGNATURE 
  </code></pre>
  
  <p>Any ideas what's missing?</p>