Compilers
Widgets - Security

Sphere Engine Compilers Widget provides mechanisms for secure integration. A fully secured widget can be embedded only on selected websites (i.e., on websites in an appropriate domain) and the communication between the client's system and the Sphere Engine system is fully reliable (i.e., unauthorized people are unable to falsify or fabricate communication).

Signature

In a production environment, we recommend using the signature security measure that fully protects the widget from unauthorized use. The signature verification feature must be enabled in advance by selecting the Secure the widget option in Sphere Engine client panel: Menu > Compilers > Widgets > WIDGET HASH > Widget settings.

The use of a signature for communication between the client's system and the Sphere Engine system increases the overall security level. It eliminates the possibility of unauthorized access to the widget (preventing even complex and difficult attempts at acquiring access by preparing fake HTTP requests) and guarantees the reliability of transmitted data.

Signature parameters

Signature generation is based on selected widget parameters and additional signature parameters:

  • hash - unique widget ID in the Sphere Engine system. It can be found in the Unique hash field in Sphere Engine client panel: Menu > Compilers > Widgets > WIDGET HASH > Widget settings,
  • se_secret - secret key which is the basis for the security of the signature. It can be found in the Shared secret field in Sphere Engine client panel: Menu > Compilers > Widgets > WIDGET HASH > Widget settings,
  • se_nonce (optional) - unique session ID for a given widget.

Important: The se_secret parameter is the basis for the security of the signature and should remain a secret. Do not send it in messages between systems.

Important: The procedure of signature generation in the client's system should not be performed on the front-end side of the application (e.g., using a JavaScript function) due to the se_secret parameter being disclosed.

Note: The use of an optional se_nonce parameter ensures that each session of the end-user (i.e., every situation in which the widget has been initialized) is a one-off. It is impossible to re-initialize the widget using the se_nonce parameter with the same value. Using this parameter provides full protection against unauthorized use of the widget.

Signature generation algorithm

The signature generation procedure can be divided into the following steps:

  • Normalization by sorting parameter names in alphabetical order. For example:
    [hash, se_secret, se_nonce] ➡ [hash, se_nonce, se_secret],
  • Conjunction by saving the parameters and their values ​​in the form of a string in the following format:
    param1=value1&param2=value2&...&paramN=valueN
    for example:
    hash=XYZ&se_nonce=12345&se_secret=CIPHER,
  • Encoding to the application/x-www-form-urlencoded format using UTF-8 encoding,
  • Hashing using the SHA-256 algorithm which is available for the majority of popular programming languages ​​(in the standard library or as part of an additional library).

Pseudocode of the algorithm that generates the signature

generate_signature(params) {
    // Normalization
    params = sort(params);

    // Conjunction with Encoding
    seq = [];
    foreach p in params {
        seq += key(p) + "=" + urlencode(value(p), "utf-8"); 
    }

    // Hashing
    return sha256(join("&", seq));
}

Implementation of the algorithm that generates the signature in PHP

function generate_signature($params) {
    ksort($params);

    $seq = [];
    foreach ($params as $k => $v) {
        $seq[] = $k . "=" . urlencode($v);
    }

    return hash("sha256", implode("&", $seq));
}

Implementation of the algorithm that generates the signature in Python

def generate_signature(params):
    keys = sorted(params.keys())

    seq = []
    for k in keys :
        seq.append(k + "=" + urllib.parse.quote_plus(params[k]))

    return hashlib.sha256("&".join(seq).encode('utf-8')).hexdigest()

Attaching a signature

The signature and the values ​​of all parameters used to generate it (except the se_secret parameter which should remain secret) should be attached to the embedded widget in the form of the appropriate HTML attributes with the data- prefix:

  • data-widget for the hash parameter,
  • data-nonce for the se_nonce parameter,
  • date-signature for the signature.

An example of HTML code used to embed a widget prepared to support the signature

<div class="sec-widget"
    data-id="widget-secured-by-signature"
    data-widget="XYZ"
    data-signature="e85b12137f76526ca6804625fc4e2093a0750fc6c6c158fc2be210ac5"
    data-nonce="e9838cc0819d713b3670df7adb0079a3">
</div>

Note: The general scheme for securing communication with the signature assumes that both communicating parties share a secret key (a shared secret).

The sender uses the selected parameters of the message (or even the entire message) along with the key when creating the signature. The generated signature is attached to the message and sent to the recipient.

The recipient, who also has access to the key, repeats the procedure of creating the signature. The received message is authorized, if the signature sent by the sender is identical to the signature generated by the recipient.

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