.NET Core C#

Sign PDF using PAdES-Baseline-B

See more PDF Signatures Examples

PAdES-Baseline-B is the most basic, entry-level profile of the PDF Advanced Electronic Signatures (PAdES) standard.

It means:

• A PDF contains a CMS/PKCS#7 detached signature over the document’s byte range.
• /SubFilter must be ETSI.CAdES.detached.
• The signer’s X.509 certificate is included inside the signature.
• The signature uses recognized secure algorithms (e.g., SHA-256 with RSA/ECDSA).
• It proves document integrity (no changes since signing) and signer authenticity (certificate identifies who signed).
• It does not include time-stamps, revocation data (CRL/OCSP), or long-term validation information — those appear only in higher levels (PAdES-Baseline-T, -LT, -LTA).

In short: Baseline-B = a standard PDF digital signature that ensures integrity and origin, but without time or revocation guarantees.

.NET Core C#

bool success = false;

Chilkat.Pdf pdf = new Chilkat.Pdf();

// Load a PDF to be signed.
success = pdf.LoadFile("c:/someDir/my.pdf");
if (success == false) {
    Debug.WriteLine(pdf.LastErrorText);
    return;
}

// Options for signing are specified in JSON.
Chilkat.JsonObject json = new Chilkat.JsonObject();

json.UpdateString("subFilter","/ETSI.CAdES.detached");
json.UpdateBool("signingCertificateV2",true);
json.UpdateBool("signingTime",true);
json.UpdateString("signingAlgorithm","pkcs");
json.UpdateString("hashAlgorithm","sha256");

// -----------------------------------------------------------
// The following JSON settings define the signature appearance.
json.UpdateInt("page",1);
json.UpdateString("appearance.y","top");
json.UpdateString("appearance.x","left");
json.UpdateString("appearance.fontScale","10.0");
json.UpdateString("appearance.text[0]","Digitally signed by: cert_cn");
json.UpdateString("appearance.text[1]","current_dt");
json.UpdateString("appearance.text[2]","Hello 123 ABC");

// --------------------------------------------------------------
// Load the signing certificate. (Use your own certificate.)
// Note: There are other methods for using a certificate on an HSM (smartcard or token)
// or from other sources, such as a cloud HSM, a Windows installed certificate,
// or other file formats.
Chilkat.Cert cert = new Chilkat.Cert();
success = cert.LoadPfxFile("c:/myPfxFiles/myPdfSigningCert.pfx","pfxPassword");
if (success == false) {
    Debug.WriteLine(cert.LastErrorText);
    return;
}

// Once we have the certificate object, tell the PDF object to use it for signing
success = pdf.SetSigningCert(cert);
if (success == false) {
    Debug.WriteLine(pdf.LastErrorText);
    return;
}

// Sign the PDF, creating the output file.
string outFilePath = "c:/someDir/mySigned.pdf";
success = pdf.SignPdf(json,outFilePath);
if (success == false) {
    Debug.WriteLine(pdf.LastErrorText);
    return;
}

Debug.WriteLine("Success.");