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Append instead of replace

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This commit is contained in:
Jeroen Bobbeldijk
2017-07-08 14:55:31 +02:00
parent 6d38be3f51
commit db69b6a4c0
9 changed files with 127 additions and 26 deletions
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2
sign.go
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@@ -98,6 +98,8 @@ func main() {
ContactInfo: "Geen",
Date: time.Now().Local(),
},
CertType: 2,
Approval: false,
},
Signer: pkey,
Certificate: cert,

7
sign/pdfbyterange.go
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@@ -10,8 +10,7 @@ func (context *SignContext) updateByteRange() error {
// @todo: find out of this is safe.
output_file_stat, _ := context.OutputFile.Stat()
// Don't count last newline as file length.
output_file_size := output_file_stat.Size() - 1
output_file_size := output_file_stat.Size()
// Calculate ByteRange values to replace them.
context.ByteRangeValues = make([]int64, 4)
@@ -20,10 +19,10 @@ func (context *SignContext) updateByteRange() error {
context.ByteRangeValues[0] = int64(0)
// Signature ByteRange part 1 length always stops at the actual signature start byte.
context.ByteRangeValues[1] = context.SignatureContentsStartByte
context.ByteRangeValues[1] = context.SignatureContentsStartByte - 1
// Signature ByteRange part 2 start byte directly starts after the actual signature.
context.ByteRangeValues[2] = context.ByteRangeValues[1] + int64(signatureMaxLength)
context.ByteRangeValues[2] = context.ByteRangeValues[1] + 1 + int64(signatureMaxLength) + 1
// Signature ByteRange part 2 length is everything else of the file.
context.ByteRangeValues[3] = output_file_size - context.ByteRangeValues[2]

7
sign/pdfcatalog.go
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@@ -30,7 +30,7 @@ func (context *SignContext) createCatalog() (catalog string, err error) {
pages := root.Key("Pages").GetPtr()
catalog += " /Pages " + strconv.Itoa(int(pages.GetID())) + " " + strconv.Itoa(int(pages.GetGen())) + " R"
catalog += " /AcroForm <<"
catalog += " /Fields [" + strconv.Itoa(int(context.SignData.ObjectId)) + " 0 R]"
catalog += " /Fields [" + strconv.Itoa(int(context.VisualSignData.ObjectId)) + " 0 R]"
if !context.SignData.Signature.Approval {
catalog += " /NeedAppearances false"
@@ -44,12 +44,11 @@ func (context *SignContext) createCatalog() (catalog string, err error) {
catalog += " >>"
// @todo: what do these do?
if !context.SignData.Signature.Approval {
if context.SignData.Signature.CertType > 0 {
//catalog += " /Perms << /DocMDP " + strconv.Itoa(int(context.SignData.ObjectId)) + " 0 R >>";
catalog += " /Perms << /DocMDP " + strconv.Itoa(int(context.SignData.ObjectId)) + " 0 R >>";
} else {
//catalog += " /Perms << /UR3 " + strconv.Itoa(int(context.SignData.ObjectId)) + " 0 R >>";
catalog += " /Perms << /UR3 " + strconv.Itoa(int(context.SignData.ObjectId)) + " 0 R >>";
}
}

7
sign/pdfsignature.go
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@@ -29,7 +29,7 @@ func (context *SignContext) createSignaturePlaceholder() (signature string, byte
// Create a placeholder for the actual signature content, we wil replace it later.
signature += " /Contents<" + strings.Repeat("0", int(signatureMaxLength)) + ">"
if context.SignData.Signature.Approval {
if !context.SignData.Signature.Approval {
signature += " /Reference [" // array of signature reference dictionaries
signature += " << /Type /SigRef"
if context.SignData.Signature.CertType > 0 {
@@ -77,9 +77,6 @@ func (context *SignContext) createSignature() ([]byte, error) {
io.Copy(sign_buf, context.OutputFile)
file_content := sign_buf.Bytes()
// Remove trailing newline.
file_content = file_content[:len(file_content)-1]
// Collect the parts to sign.
sign_content := make([]byte, 0)
sign_content = append(sign_content, file_content[context.ByteRangeValues[0]:(context.ByteRangeValues[0]+context.ByteRangeValues[1])]...)
@@ -111,7 +108,7 @@ func (context *SignContext) replaceSignature() error {
dst := make([]byte, hex.EncodedLen(len(signature)))
hex.Encode(dst, signature)
context.OutputFile.WriteAt(dst, context.ByteRangeValues[0]+context.ByteRangeValues[1])
context.OutputFile.WriteAt(dst, context.ByteRangeValues[0] + context.ByteRangeValues[1] + 1)
return nil
}

4
sign/pdftrailer.go
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@@ -19,7 +19,7 @@ func (context *SignContext) writeTrailer() error {
new_root := "Root " + strconv.FormatInt(int64(context.CatalogData.ObjectId), 10) + " 0 R"
size_string := "Size " + strconv.FormatInt(context.PDFReader.XrefInformation.ItemCount, 10)
new_size := "Size " + strconv.FormatInt(context.PDFReader.XrefInformation.ItemCount+2, 10)
new_size := "Size " + strconv.FormatInt(context.PDFReader.XrefInformation.ItemCount+3, 10)
trailer_string := string(trailer_buf)
trailer_string = strings.Replace(trailer_string, root_string, new_root, -1)
@@ -36,7 +36,7 @@ func (context *SignContext) writeTrailer() error {
}
// Write PDF ending.
if _, err := context.OutputFile.Write([]byte("%%EOF\n")); err != nil {
if _, err := context.OutputFile.Write([]byte("%%EOF")); err != nil {
return err
}

44
sign/pdfvisualsignature.go Normal file
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@@ -0,0 +1,44 @@
package sign
import (
"errors"
"strconv"
)
func (context *SignContext) createVisualSignature() (visual_signature string, err error) {
visual_signature = strconv.Itoa(int(context.VisualSignData.ObjectId)) + " 0 obj\n"
visual_signature += "<< /Type /Annot"
visual_signature += " /Subtype /Widget"
visual_signature += " /Rect [0 0 0 0]"
root := context.PDFReader.Trailer().Key("Root")
root_keys := root.Keys()
found_pages := false
for _, key := range root_keys {
if key == "Pages" {
found_pages = true
break
}
}
if !found_pages {
return "", errors.New("Didn't find pages in PDF trailer Root.")
}
rootPtr := root.GetPtr()
context.CatalogData.RootString = strconv.Itoa(int(rootPtr.GetID())) + " " + strconv.Itoa(int(rootPtr.GetGen())) + " R"
page := root.Key("Pages").Key("Kids").Index(0).GetPtr()
visual_signature += " /P " + strconv.Itoa(int(page.GetID())) + " " + strconv.Itoa(int(page.GetGen())) + " R"
visual_signature += " /F 4"
visual_signature += " /FT /Sig"
visual_signature += " /T " + pdfString("Signature")
visual_signature += " /Ff 0"
visual_signature += " /V " + strconv.Itoa(int(context.SignData.ObjectId)) + " 0 R"
visual_signature += " >>"
visual_signature += "\nendobj\n"
return visual_signature, nil
}

15
sign/pdfxref.go
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@@ -22,7 +22,7 @@ func (context *SignContext) writeXref() error {
func (context *SignContext) writeXrefTable() error {
xref_size := "xref\n0 " + strconv.FormatInt(context.PDFReader.XrefInformation.ItemCount, 10)
new_xref_size := "xref\n0 " + strconv.FormatInt(context.PDFReader.XrefInformation.ItemCount+2, 10)
new_xref_size := "xref\n0 " + strconv.FormatInt(context.PDFReader.XrefInformation.ItemCount+3, 10)
if _, err := context.OutputFile.Write([]byte(new_xref_size)); err != nil {
return err
@@ -34,7 +34,16 @@ func (context *SignContext) writeXrefTable() error {
}
// Create the new catalog xref line.
catalog_object_start_position := strconv.FormatInt(context.PDFReader.XrefInformation.StartPos, 10)
visual_signature_object_start_position := strconv.FormatInt(context.Filesize, 10)
visual_signature_xref_line := leftPad(visual_signature_object_start_position, "0", 10-len(visual_signature_object_start_position)) + " 00000 n\n"
// Write the new catalog xref line.
if _, err := context.OutputFile.Write([]byte(visual_signature_xref_line)); err != nil {
return err
}
// Create the new catalog xref line.
catalog_object_start_position := strconv.FormatInt(context.Filesize+context.VisualSignData.Length, 10)
catalog_xref_line := leftPad(catalog_object_start_position, "0", 10-len(catalog_object_start_position)) + " 00000 n\n"
// Write the new catalog xref line.
@@ -43,7 +52,7 @@ func (context *SignContext) writeXrefTable() error {
}
// Create the new signature xref line.
signature_object_start_position := strconv.FormatInt(context.PDFReader.XrefInformation.StartPos+context.CatalogData.Length, 10)
signature_object_start_position := strconv.FormatInt(context.Filesize+context.VisualSignData.Length+context.CatalogData.Length, 10)
signature_xref_line := leftPad(signature_object_start_position, "0", 10-len(signature_object_start_position)) + " 00000 n\n"
// Write the new signature xref line.

54
sign/sign.go
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@@ -7,6 +7,7 @@ import (
"time"
"bitbucket.org/digitorus/pdf"
"io"
)
type CatalogData struct {
@@ -23,6 +24,11 @@ type SignData struct {
CertificateChain []*x509.Certificate
}
type VisualSignData struct {
ObjectId uint32
Length int64
}
type SignDataSignature struct {
Approval bool
CertType uint32
@@ -38,10 +44,12 @@ type SignDataSignatureInfo struct {
}
type SignContext struct {
Filesize int64
InputFile *os.File
OutputFile *os.File
SignData SignData
CatalogData CatalogData
VisualSignData VisualSignData
PDFReader *pdf.Reader
NewXrefStart int64
ByteRangeStartByte int64
@@ -73,15 +81,20 @@ func SignFile(input string, output string, sign_data SignData) error {
return err
}
sign_data.ObjectId = uint32(rdr.XrefInformation.ItemCount) + 1
sign_data.ObjectId = uint32(rdr.XrefInformation.ItemCount) + 2
// We do size+1 because we insert a newline.
context := SignContext{
Filesize: size + 1,
PDFReader: rdr,
InputFile: input_file,
OutputFile: output_file,
CatalogData: CatalogData{
VisualSignData: VisualSignData{
ObjectId: uint32(rdr.XrefInformation.ItemCount),
},
CatalogData: CatalogData{
ObjectId: uint32(rdr.XrefInformation.ItemCount) + 1,
},
SignData: sign_data,
}
@@ -94,8 +107,30 @@ func SignFile(input string, output string, sign_data SignData) error {
}
func (context *SignContext) SignPDF() error {
// Write the PDF file to the output up til the xref.
if err := writePartFromSourceFileToTargetFile(context.InputFile, context.OutputFile, 0, context.PDFReader.XrefInformation.StartPos); err != nil {
// Copy old file into new file.
if _, err := io.Copy(context.OutputFile, context.InputFile); err != nil {
return err
}
err := context.OutputFile.Sync()
if err != nil {
return err
}
// File always needs an empty line after %%EOF.
if _, err := context.OutputFile.Write([]byte("\n")); err != nil {
return err
}
visual_signature, err := context.createVisualSignature()
if err != nil {
return err
}
context.VisualSignData.Length = int64(len(visual_signature))
// Write the new catalog object.
if _, err := context.OutputFile.Write([]byte(visual_signature)); err != nil {
return err
}
@@ -115,8 +150,8 @@ func (context *SignContext) SignPDF() error {
signature_object, byte_range_start_byte, signature_contents_start_byte := context.createSignaturePlaceholder()
// Positions are relative to old start position of xref table.
byte_range_start_byte += context.PDFReader.XrefInformation.StartPos + int64(len(catalog))
signature_contents_start_byte += context.PDFReader.XrefInformation.StartPos + int64(len(catalog))
byte_range_start_byte += context.Filesize + int64(len(catalog)) + int64(len(visual_signature))
signature_contents_start_byte += context.Filesize + int64(len(catalog)) + int64(len(visual_signature))
context.ByteRangeStartByte = byte_range_start_byte
context.SignatureContentsStartByte = signature_contents_start_byte
@@ -127,7 +162,7 @@ func (context *SignContext) SignPDF() error {
}
// Calculate the new start position of the xref table.
context.NewXrefStart = context.PDFReader.XrefInformation.StartPos + int64(len(signature_object)) + int64(len(catalog))
context.NewXrefStart = context.Filesize + int64(len(signature_object)) + int64(len(catalog)) + int64(len(visual_signature))
if err := context.writeXref(); err != nil {
return err
@@ -145,5 +180,10 @@ func (context *SignContext) SignPDF() error {
return err
}
err = context.OutputFile.Sync()
if err != nil {
return err
}
return nil
}

13
verify/verify.go
View File

@@ -14,6 +14,7 @@ import (
"github.com/digitorus/pkcs7"
"github.com/digitorus/timestamp"
"golang.org/x/crypto/ocsp"
"go/src/log"
)
type RevocationInfoArchival struct {
@@ -70,9 +71,11 @@ func Verify(file *os.File) (apiResp *Response, err error) {
finfo, _ := file.Stat()
size := finfo.Size()
file.Seek(0, 0)
rdr, err := pdf.NewReader(file, size)
if err != nil {
return nil, fmt.Errorf("Failed to open file")
return nil, fmt.Errorf("Failed to open file: %v", err)
}
// AcroForm will contain a SigFlags value if the form contains a digital signature
@@ -129,6 +132,12 @@ func Verify(file *os.File) (apiResp *Response, err error) {
apiResp.Error = fmt.Sprintln("Failed to get ByteRange:", i, err)
}
log.Println(v.Key("ByteRange").Index(i-1).Int64())
log.Println(v.Key("ByteRange").Index(i).Int64())
log.Println(string(content[0:60]))
log.Println(string(content[len(content)-60:len(content)]))
log.Println(len(content))
p7.Content = append(p7.Content, content...)
}
@@ -180,8 +189,10 @@ func Verify(file *os.File) (apiResp *Response, err error) {
signer.ValidSignature = true
signer.TrustedIssuer = false
}
log.Println("Invalid sig")
apiResp.Error = fmt.Sprintln("Failed to verify signature:", err)
} else {
log.Println("Valid sig")
signer.ValidSignature = true
signer.TrustedIssuer = true
}