HERE REST API OAuth 2.0 Token Request (with A 1.0 Header) Error

- 1 answer

I've been trying to get my PHP application to create a successful token request since finally managing to get it working with Postman as per the docs here

Apparently the API is using OAuth 2.0 which is why I expect to send up grant_type, client_id, client_secret and expires_in (if I don't specify one of these fields then the API will successfully tell me it is missing).

Now the problem I am having is with this OAuth 1.0 Authorization Header that I am having to generate, which Postman seems to have no issues doing so, however trying to do it in PHP I am just getting an error returned from the API about a signature mismatch:

array:6 [
  "errorId" => "ERROR-fde4f0f1-9d5c-43fd-80eb-056cbf2c3259"
  "httpStatus" => 401
  "errorCode" => 401300
  "message" => "Signature mismatch. Authorization signature or client credential is wrong."
  "error" => "invalid_client"
  "error_description" => "errorCode: '401300'. Signature mismatch. Authorization signature or client credential is wrong."

I've tried various debugging, a lot of which gives me different errors then I keep landing back on this one so the signature must be the problem.

I created the following class here to handle generating a header, getting some guidance from the class in the guzzle/oauth-subscriber package.

Here is an example of the request headers being generated:

array:2 [
  "Content-Type" => "application/x-www-form-urlencoded"
  "Authorization" => "OAuth oauth_consumer_key="XXXXXXXXXXXX",oauth_signature_method="HMAC-SHA256",oauth_timestamp="1583629976",oauth_nonce="Br2HsCVzsaEe3KswBhtCzsSxjUDWgX56",oauth_version="1.0",oauth_signature="G7%2B5f2v2Kdx3rp%2B28DcuJRBvhi9H7fHC1mFLqJIgmMc%3D""

And the request body:

array:4 [
  "grant_type" => "client_credentials"
  "client_id" => "XXXXXXXXXXXX"
  "expires_in" => 87000

Sensitive details replaced but consumer_key is correct and thats the same value as client_id and the same goes for consumer_secret and client_secret

No matter how I try and alter the signUsingHmac() method to change the signature, it doesn't work and it all looks fine to me D:

Anyone got any ideas?

If I can get this working nicely I will pull it out into package to make the auth for this API in PHP a lot less painful.


I tried forming the signature exactly like shown in the docs here but to unfortunately it still hasn't worked, this is what my $baseString looked like when passing into the hash method:


I've also created a new gist here with my updates to create this $baseString

Cheers, Matt



I created a gist that works. Some suggestion:

  • all values need to be urlenconde()
  • the string that you need to use for signign the request needs to include: method (uppercase) & URL (urlecode) & list of parameters (url encoded)
  • the signing key is your consumer key secret (urlencode) followed by &. This because usually your signing key needs to me consumer secret & secret token. In this case we don't have secret token

For the list of parameters for your signature base string you need to include all oauth_ parameter and your grant_type because you need to include also the body parameter. The sorting of these keys is crucial

some code PHP code:

$keyId = getenv('HERE_API_KEY_ID');
$keySecret = getenv('HERE_API_KEY_SECRET');

$httpBody = [
    "grant_type" => "client_credentials"
$httpMethod = "POST";
$httpUrl = '';

$oauthNonce = mt_rand();
$oauthTimestamp = time();
$oauthSignatureMethod= "HMAC-SHA256";
$oauthVersion = "1.0";

$baseString = $httpMethod."&". urlencode($httpUrl);

$oauth1Param = [
    'oauth_consumer_key' => $keyId,
    'oauth_signature_method' => $oauthSignatureMethod,
    'oauth_timestamp' => $oauthTimestamp,
    'oauth_nonce' => $oauthNonce,
    'oauth_version' => $oauthVersion

$paramString =

        "oauth_consumer_key=". urlencode($oauth1Param['oauth_consumer_key']).
        "&oauth_nonce=". urlencode($oauth1Param['oauth_nonce']).
        "&oauth_signature_method=". urlencode($oauth1Param['oauth_signature_method']).
        "&oauth_timestamp=". urlencode($oauth1Param['oauth_timestamp']).
//        "&oauth_token=".
        "&oauth_version=". urlencode($oauth1Param['oauth_version'])

echo $paramString.PHP_EOL;
$baseString = $baseString . "&" . urlencode($paramString);
echo $baseString . PHP_EOL;
$signingKey= urlencode($keySecret) . "&";
$signature = urlencode(

$oauth1Param['oauth_signature']  =  $signature;
echo "RUNTIME SIGNATURE : " . $signature .PHP_EOL;

I create a GIST that works, the only thing that you need to change is $keyId and $keySecret.

This documentation was very useful: