Serial signatures

Serial signatures are the PAdES mechanism for multiple signatures. After a first signature of the PDF document, the flow moves on to the next signer, who signs not just the document but the document with the previous signature, and so on.

A serial PAdES signature needs no changes in the SDK: just pass an already signed PDF to the next signer's signer object. The example below makes a serial signature on an already signed PDF:

// PDF document already signed
byte[] signedPdf1 = ...

// Certificate of signer 2
PKCertificateWithKey signingCert2 = ...

var signer2 = new PadesSigner();
signer2.SetPdfToSign(signedPdf1);               // signed PDF 1
signer2.SetSigningCertificate(signingCert2);
signer2.SetPolicy(policy);
signer2.ComputeSignature();
byte[] signedPdf2 = signer2.GetPadesSignature();      // returns the signed PDF with 2 signatures

See also​

See also