p/pdf-simple-sign
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Go: cleanups

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This commit is contained in:
Přemysl Eric Janouch 2018-10-04 12:11:43 +02:00
parent 43ca0e5035
commit eedd9a550c
Signed by: p
GPG Key ID: A0420B94F92B9493
1 changed files with 14 additions and 12 deletions
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26
pdf/pdf.go
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@ -829,8 +829,8 @@ func (u *Updater) FlushUpdates() {
// -----------------------------------------------------------------------------
// PdfDate makes a PDF object representing the given point in time.
func PdfDate(ts time.Time) Object {
// NewDate makes a PDF object representing the given point in time.
func NewDate(ts time.Time) Object {
buf := ts.AppendFormat(nil, "D:20060102150405")
// "Z07'00'" doesn't work, we need to do some of it manually.
if _, offset := ts.Zone(); offset != 0 {
@ -842,8 +842,8 @@ func PdfDate(ts time.Time) Object {
return Object{Kind: String, String: string(buf)}
}
// PdfGetFirstPage retrieves the first page of the document or a Nil object.
func PdfGetFirstPage(pdf *Updater, nodeN, nodeGeneration uint) Object {
// GetFirstPage retrieves the first page of the document or a Nil object.
func GetFirstPage(pdf *Updater, nodeN, nodeGeneration uint) Object {
obj := pdf.Get(nodeN, nodeGeneration)
if obj.Kind != Dict {
return Object{Kind: Nil}
@ -871,7 +871,7 @@ func PdfGetFirstPage(pdf *Updater, nodeN, nodeGeneration uint) Object {
}
// XXX: Nothing prevents us from recursing in an evil circular graph.
return PdfGetFirstPage(pdf, kids.Array[0].N, kids.Array[0].Generation)
return GetFirstPage(pdf, kids.Array[0].N, kids.Array[0].Generation)
}
// -----------------------------------------------------------------------------
@ -1039,7 +1039,13 @@ func FillInSignature(document []byte, signOff, signLen int,
return nil
}
// https://www.adobe.com/devnet-docs/acrobatetk/tools/DigSig/Acrobat_DigitalSignatures_in_PDF.pdf
// https://www.adobe.com/content/dam/acom/en/devnet/acrobat/pdfs/pdf_reference_1-7.pdf
// https://www.adobe.com/content/dam/acom/en/devnet/acrobat/pdfs/PPKAppearances.pdf
// Sign signs the given document, growing and returning the passed-in slice.
// There must be at least one certificate, matching the private key.
// The certificates must form a chain.
//
// The presumption here is that the document is valid and that it doesn't
// employ cross-reference streams from PDF 1.5, or at least constitutes
@ -1048,11 +1054,7 @@ func FillInSignature(document []byte, signOff, signLen int,
//
// Carelessly assumes that the version of the original document is at most
// PDF 1.6.
//
// https://www.adobe.com/devnet-docs/acrobatetk/tools/DigSig/Acrobat_DigitalSignatures_in_PDF.pdf
// https://www.adobe.com/content/dam/acom/en/devnet/acrobat/pdfs/pdf_reference_1-7.pdf
// https://www.adobe.com/content/dam/acom/en/devnet/acrobat/pdfs/PPKAppearances.pdf
func Sign(document []byte, key crypto.PublicKey, certs []*x509.Certificate) (
func Sign(document []byte, key crypto.PrivateKey, certs []*x509.Certificate) (
[]byte, error) {
pdf := &Updater{Document: document}
if err := pdf.Initialize(); err != nil {
@ -1074,7 +1076,7 @@ func Sign(document []byte, key crypto.PublicKey, certs []*x509.Certificate) (
pdf.Update(sigdictN, func(buf BytesWriter) {
// The timestamp is important for Adobe Acrobat Reader DC.
// The ideal would be to use RFC 3161.
now := PdfDate(time.Now())
now := NewDate(time.Now())
buf.WriteString("<< /Type/Sig /Filter/Adobe.PPKLite" +
" /SubFilter/adbe.pkcs7.detached\n" +
" /M" + now.Serialize() + " /ByteRange ")
@ -1120,7 +1122,7 @@ func Sign(document []byte, key crypto.PublicKey, certs []*x509.Certificate) (
if !ok || pagesRef.Kind != Reference {
return nil, errors.New("invalid Pages reference")
}
page := PdfGetFirstPage(pdf, pagesRef.N, pagesRef.Generation)
page := GetFirstPage(pdf, pagesRef.N, pagesRef.Generation)
if page.Kind != Dict {
return nil, errors.New("invalid or unsupported page tree")
}