Viewing file:  WebhookSignature.php (2.18 KB) -rwxr-xr-x
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<?php
namespace Telnyx;
abstract class WebhookSignature
{
/**
* Verifies the signature header sent by Telnyx. Throws an
* Exception\SignatureVerificationException exception if the verification fails for
* any reason.
*
* @param string $payload the payload sent by Telnyx
* @param string $header the contents of the signature header sent by
* Telnyx
* @param string $public_key secret used to generate the signature
* @param int $tolerance maximum difference allowed between the header's
* timestamp and the current time
*
* @throws Exception\SignatureVerificationException if the verification fails
*
* @return bool
*/
public static function verifyHeader($payload, $signature_header, $timestamp, $public_key = '', $tolerance = null)
{
// Typecast timestamp to int for comparisons
$timestamp = (int)$timestamp;
// If it is empty, then maybe we need to get the $public_key from the Telnyx object.
if (empty($public_key)) {
$my_public_key = Telnyx::$publicKey;
}
else {
$my_public_key = $public_key;
}
// Check if timestamp is within tolerance
if (($tolerance > 0) && (\abs(\time() - $timestamp) > $tolerance)) {
throw Exception\SignatureVerificationException::factory(
'Timestamp outside the tolerance zone',
$payload,
$signature_header
);
}
// Convert base64 string to bytes for sodium crypto functions
$public_key_bytes = base64_decode($my_public_key);
$signature_header_bytes = base64_decode($signature_header);
// Construct a message to test against the signature header using the timestamp and payload
$signed_payload = $timestamp . '|' . $payload;
if (!\sodium_crypto_sign_verify_detached($signature_header_bytes, $signed_payload, $public_key_bytes)) {
throw Exception\SignatureVerificationException::factory(
'Signature is invalid and does not match the payload',
$payload,
$signature_header
);
}
return true;
}
}
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