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(Go) Sign PDF: Choosing RSASSA-PSS or PKCS1-v1_5 and Hash AlgorithmSee more PDF Signatures ExamplesThis example demonstrates how to choose between RSASSA-PSS vs. PKCS1-v1_5 and the hash algorithm when signing a PDF.
// This example requires the Chilkat API to have been previously unlocked. // See Global Unlock Sample for sample code. pdf := chilkat.NewPdf() // Load a PDF to be signed. // The "hello.pdf" is available at https://chilkatsoft.com/hello.pdf success := pdf.LoadFile("qa_data/pdf/hello.pdf") if success == false { fmt.Println(pdf.LastErrorText()) pdf.DisposePdf() return } // Options for signing are specified in JSON. json := chilkat.NewJsonObject() // In most cases, the signingCertificateV2 attribute is needed. json.UpdateInt("signingCertificateV2",1) // --------------------------------------------------------------------------------------------------------------------------- // This example is the same as the example at Sign a PDF (Simplest Example Possible) // but with the following lines added to specify the signature scheme and hash algorithm. // The signature schemes PKCS-v1_5 and RSASSA-PSS have differences. // PKCSV1_5 is deterministic. The same message and key will produce an identical signature value each time. // PSS is randomized and will produce a different signature value each time. // To choose the hash algorithm: // (The typical choices are sha1, sha256, sha384, and sha512.) json.UpdateString("hashAlgorithm","sha256") // To choose PKCSV1_5: json.UpdateString("signingAlgorithm","pkcs") // Alternatively, to choose RSASSA-PSS: json.UpdateString("signingAlgorithm","pss") // If not specified, the default is SHA256 with PKCS-v1_5. // The remainder of this example is the same as the example at Sign a PDF (Simplest Example Possible) // --------------------------------------------------------------------------------------------------------------------------- // Put the signature on page 1, top left json.UpdateInt("page",1) json.UpdateString("appearance.y","top") json.UpdateString("appearance.x","left") // Use a font scale of 10.0 json.UpdateString("appearance.fontScale","10.0") // In this example, the appearance of the digital signature will contain three lines: // 1) The signing certificate's common name // 2) The current date/time // 3) Some arbitrary text. // The keyword "cert_cn" is replaced with the Certificate's Subject Common Name. // The keyword "current_dt" is replaced with the current date/time. // Any number of appearance text lines can be added. json.UpdateString("appearance.text[0]","Digitally signed by: cert_cn") json.UpdateString("appearance.text[1]","current_dt") json.UpdateString("appearance.text[2]","The crazy brown fox jumps over the lazy dog.") // Load the signing certificate. (Use your own certificate.) cert := chilkat.NewCert() success = cert.LoadPfxFile("qa_data/pfx/myPdfSigningCert.pfx","secret") if success == false { fmt.Println(cert.LastErrorText()) pdf.DisposePdf() json.DisposeJsonObject() cert.DisposeCert() return } // Tell the pdf object to use the certificate for signing. success = pdf.SetSigningCert(cert) if success == false { fmt.Println(pdf.LastErrorText()) pdf.DisposePdf() json.DisposeJsonObject() cert.DisposeCert() return } success = pdf.SignPdf(json,"qa_output/hello_signed.pdf") if success == false { fmt.Println(pdf.LastErrorText()) pdf.DisposePdf() json.DisposeJsonObject() cert.DisposeCert() return } fmt.Println("The PDF has been successfully cryptographically signed.") // The appearance of the signature appears in Adobe Acrobat as shown here: pdf.DisposePdf() json.DisposeJsonObject() cert.DisposeCert() |
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