GST / MCA / GeM / eTender

Portal-specific signing integration guides.

GST Portal

GST returns and filings use hash signing on return XML. Generate the hash server-side, then redirect the user to the SecureSign deep link.

1. Server generates SHA-256 hash of return XML (base64)
2. Redirect browser to securesign://sign with documentType=hash
3. Mobile App or Desktop Software signs and returns to callbackUrl
4. Upload signatureBase64 to GST API

$params = http_build_query([
  'requestId' => bin2hex(random_bytes(16)),
  'hashBase64' => base64_encode(hash('sha256', $doc, true)),
  'hashAlgo' => 'SHA256',
  'documentType' => 'hash',
  'callbackUrl' => 'https://portal.example.gov.in/sign/callback',
  'apiKey' => 'ss_live_abc123xyz'
]);
header('Location: securesign://sign?' . $params);

MCA Portal

MCA filings use PDF and XML signing. Use the same deep link with documentType=pdf or documentType=xml and include documentBase64 when required.

GeM Portal

GeM bid submissions typically require PDF signing with visible signature appearance. Pass documentType=pdf and appearance parameters via deep link query string. See Signature Customization.

eTender Portals

eTender workflows combine hash signing for bid hashes and PDF signing for tender documents. Use documentType=hash or documentType=pdf on the same securesign://sign handoff.