src/Hmac.php
public static function shaHashBase64($signature, $secret)
    {
        return base64_encode(
            hash_hmac(Hmac::ALGORITHM_SHA256, $signature, $secret, true)
        );
    }
public static function shaHashBase64($signature, $secret)
    {
        return base64_encode(
            hash_hmac(Hmac::ALGORITHM_SHA256, $signature, $secret, true)
        );
    }
public static function shaHashBase64 ( $ signature , $ secret ) { return base64_encode ( hash_hmac ( Hmac :: ALGORITHM_SHA256 , $ signature , $ secret , true ) ) ; }
Base64 of signature hashed with HMAC using SHA hash.

@param string $signature String composed of specific headers.
@param string $secret Secret part of credentials.
@return string Base64 string.
Base64 of signature hashed with HMAC using SHA hash .