290 lines
6.8 KiB
Go
290 lines
6.8 KiB
Go
package sign
|
|
|
|
import (
|
|
"crypto"
|
|
"crypto/x509"
|
|
"encoding/hex"
|
|
"io"
|
|
"os"
|
|
"time"
|
|
|
|
"bitbucket.org/digitorus/pdf"
|
|
"bitbucket.org/digitorus/pdfsign/revocation"
|
|
"github.com/digitorus/pkcs7"
|
|
"github.com/mattetti/filebuffer"
|
|
)
|
|
|
|
type CatalogData struct {
|
|
ObjectId uint32
|
|
Length int64
|
|
RootString string
|
|
}
|
|
|
|
type TSA struct {
|
|
URL string
|
|
Username string
|
|
Password string
|
|
}
|
|
|
|
type RevocationFunction func(cert, issuer *x509.Certificate, i *revocation.InfoArchival) error
|
|
|
|
type SignData struct {
|
|
ObjectId uint32
|
|
Signature SignDataSignature
|
|
Signer crypto.Signer
|
|
Certificate *x509.Certificate
|
|
CertificateChains [][]*x509.Certificate
|
|
TSA TSA
|
|
RevocationData revocation.InfoArchival
|
|
RevocationFunction RevocationFunction
|
|
}
|
|
|
|
type VisualSignData struct {
|
|
ObjectId uint32
|
|
Length int64
|
|
}
|
|
|
|
type InfoData struct {
|
|
ObjectId uint32
|
|
Length int64
|
|
}
|
|
|
|
type SignDataSignature struct {
|
|
Approval bool
|
|
CertType uint32
|
|
Info SignDataSignatureInfo
|
|
}
|
|
|
|
type SignDataSignatureInfo struct {
|
|
Name string
|
|
Location string
|
|
Reason string
|
|
ContactInfo string
|
|
Date time.Time
|
|
}
|
|
|
|
type SignContext struct {
|
|
Filesize int64
|
|
InputFile io.ReadSeeker
|
|
OutputFile io.Writer
|
|
OutputBuffer *filebuffer.Buffer
|
|
SignData SignData
|
|
CatalogData CatalogData
|
|
VisualSignData VisualSignData
|
|
InfoData InfoData
|
|
PDFReader *pdf.Reader
|
|
NewXrefStart int64
|
|
ByteRangeStartByte int64
|
|
SignatureContentsStartByte int64
|
|
ByteRangeValues []int64
|
|
SignatureMaxLength uint32
|
|
}
|
|
|
|
func SignFile(input string, output string, sign_data SignData) error {
|
|
input_file, err := os.Open(input)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
defer input_file.Close()
|
|
|
|
output_file, err := os.Create(output)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
defer output_file.Close()
|
|
|
|
finfo, err := input_file.Stat()
|
|
if err != nil {
|
|
return err
|
|
}
|
|
size := finfo.Size()
|
|
|
|
rdr, err := pdf.NewReader(input_file, size)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
return Sign(input_file, output_file, rdr, size, sign_data)
|
|
}
|
|
|
|
func Sign(input io.ReadSeeker, output io.Writer, rdr *pdf.Reader, size int64, sign_data SignData) error {
|
|
sign_data.ObjectId = uint32(rdr.XrefInformation.ItemCount) + 3
|
|
|
|
// We do size+1 because we insert a newline.
|
|
context := SignContext{
|
|
Filesize: size + 1,
|
|
PDFReader: rdr,
|
|
InputFile: input,
|
|
OutputFile: output,
|
|
VisualSignData: VisualSignData{
|
|
ObjectId: uint32(rdr.XrefInformation.ItemCount),
|
|
},
|
|
CatalogData: CatalogData{
|
|
ObjectId: uint32(rdr.XrefInformation.ItemCount) + 1,
|
|
},
|
|
InfoData: InfoData{
|
|
ObjectId: uint32(rdr.XrefInformation.ItemCount) + 2,
|
|
},
|
|
SignData: sign_data,
|
|
}
|
|
|
|
err := context.SignPDF()
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
func (context *SignContext) SignPDF() error {
|
|
context.OutputBuffer = filebuffer.New([]byte{})
|
|
|
|
// Copy old file into new file.
|
|
if _, err := io.Copy(context.OutputBuffer, context.InputFile); err != nil {
|
|
return err
|
|
}
|
|
|
|
// File always needs an empty line after %%EOF.
|
|
if _, err := context.OutputBuffer.Write([]byte("\n")); err != nil {
|
|
return err
|
|
}
|
|
|
|
// Base size for signature.
|
|
context.SignatureMaxLength = uint32(hex.EncodedLen(512))
|
|
|
|
switch string(context.SignData.Certificate.SignatureAlgorithm) {
|
|
case "SHA1-RSA":
|
|
case "ECDSA-SHA1":
|
|
case "DSA-SHA1":
|
|
context.SignatureMaxLength += uint32(hex.EncodedLen(128))
|
|
break
|
|
case "SHA256-RSA":
|
|
case "ECDSA-SHA256":
|
|
case "DSA-SHA256":
|
|
context.SignatureMaxLength += uint32(hex.EncodedLen(256))
|
|
break
|
|
case "SHA384-RSA":
|
|
case "ECDSA-SHA384":
|
|
context.SignatureMaxLength += uint32(hex.EncodedLen(384))
|
|
break
|
|
case "SHA512-RSA":
|
|
case "ECDSA-SHA512":
|
|
context.SignatureMaxLength += uint32(hex.EncodedLen(512))
|
|
break
|
|
}
|
|
|
|
// Add size for my certificate.
|
|
degenerated, err := pkcs7.DegenerateCertificate(context.SignData.Certificate.Raw)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
context.SignatureMaxLength += uint32(hex.EncodedLen(len(degenerated)))
|
|
|
|
// Add size for certificate chain.
|
|
var certificate_chain []*x509.Certificate
|
|
if len(context.SignData.CertificateChains) > 0 && len(context.SignData.CertificateChains[0]) > 1 {
|
|
certificate_chain = context.SignData.CertificateChains[0][1:]
|
|
}
|
|
|
|
if len(certificate_chain) > 0 {
|
|
for _, cert := range certificate_chain {
|
|
degenerated, err := pkcs7.DegenerateCertificate(cert.Raw)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
context.SignatureMaxLength += uint32(hex.EncodedLen(len(degenerated)))
|
|
}
|
|
}
|
|
|
|
// Add estimated size for TSA.
|
|
// We can't kow actual size of TSA until after signing.
|
|
if context.SignData.TSA.URL != "" {
|
|
context.SignatureMaxLength += uint32(hex.EncodedLen(4000))
|
|
}
|
|
|
|
// Fetch revocation data before adding signature placeholder.
|
|
// Revocation data can be quite large and we need to create enough space in the placeholder.
|
|
context.fetchRevocationData()
|
|
|
|
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.OutputBuffer.Write([]byte(visual_signature)); err != nil {
|
|
return err
|
|
}
|
|
|
|
catalog, err := context.createCatalog()
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
context.CatalogData.Length = int64(len(catalog))
|
|
|
|
// Write the new catalog object.
|
|
if _, err := context.OutputBuffer.Write([]byte(catalog)); err != nil {
|
|
return err
|
|
}
|
|
|
|
// Create the signature object
|
|
signature_object, byte_range_start_byte, signature_contents_start_byte := context.createSignaturePlaceholder()
|
|
|
|
info, err := context.createInfo()
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
context.InfoData.Length = int64(len(info))
|
|
|
|
// Write the new catalog object.
|
|
if _, err := context.OutputBuffer.Write([]byte(info)); err != nil {
|
|
return err
|
|
}
|
|
|
|
appended_bytes := context.Filesize + int64(len(catalog)) + int64(len(visual_signature)) + int64(len(info))
|
|
|
|
// Positions are relative to old start position of xref table.
|
|
byte_range_start_byte += appended_bytes
|
|
signature_contents_start_byte += appended_bytes
|
|
|
|
context.ByteRangeStartByte = byte_range_start_byte
|
|
context.SignatureContentsStartByte = signature_contents_start_byte
|
|
|
|
// Write the new signature object.
|
|
if _, err := context.OutputBuffer.Write([]byte(signature_object)); err != nil {
|
|
return err
|
|
}
|
|
|
|
// Calculate the new start position of the xref table.
|
|
context.NewXrefStart = appended_bytes + int64(len(signature_object))
|
|
|
|
if err := context.writeXref(); err != nil {
|
|
return err
|
|
}
|
|
|
|
if err := context.writeTrailer(); err != nil {
|
|
return err
|
|
}
|
|
|
|
if err := context.updateByteRange(); err != nil {
|
|
return err
|
|
}
|
|
|
|
if err := context.replaceSignature(); err != nil {
|
|
return err
|
|
}
|
|
|
|
context.OutputBuffer.Seek(0, 0)
|
|
file_content := context.OutputBuffer.Buff.Bytes()
|
|
|
|
context.OutputFile.Write(file_content)
|
|
|
|
return nil
|
|
}
|