Class: Decidim::Initiatives::PdfSignatureExample

Inherits:
Object
  • Object
show all
Defined in:
decidim-initiatives/app/services/decidim/initiatives/pdf_signature_example.rb

Overview

Example of service to add a signature to a pdf

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(args = {}) ⇒ PdfSignatureExample

Public: Initializes the service. pdf - The pdf document to be signed



14
15
16
# File 'decidim-initiatives/app/services/decidim/initiatives/pdf_signature_example.rb', line 14

def initialize(args = {})
  @pdf = args.fetch(:pdf)
end

Instance Attribute Details

#pdfObject

Returns the value of attribute pdf.



10
11
12
# File 'decidim-initiatives/app/services/decidim/initiatives/pdf_signature_example.rb', line 10

def pdf
  @pdf
end

Instance Method Details

#signed_pdfObject

Public: PDF signed using a new certificate generated by the service



19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
# File 'decidim-initiatives/app/services/decidim/initiatives/pdf_signature_example.rb', line 19

def signed_pdf
  signed_file = Tempfile.new("signed_pdf")

  doc = HexaPDF::Document.new(io: StringIO.new(pdf))

  # Prepare the document for embedding of the digital signature
  data = nil # Used for storing the to-be-signed data
  signing_mechanism = lambda do |io, byte_range|
    # Store the to-be-signed data in the local variable data
    io.pos = byte_range[0]
    data = io.read(byte_range[1])
    io.pos = byte_range[2]
    data << io.read(byte_range[3])
    ""
  end
  doc.sign(signed_file.path, signature: signature_widget(doc), reason: caption, signature_size: 10_000, external_signing: signing_mechanism)

  signature = OpenSSL::PKCS7.sign(certificate, key, data,
                                  # [HexaPDF.demo_cert.sub_ca, HexaPDF.demo_cert.root_ca],
                                  [],
                                  OpenSSL::PKCS7::DETACHED | OpenSSL::PKCS7::BINARY).to_der

  # Embed the signature
  HexaPDF::DigitalSignature::Signing.embed_signature(File.open(signed_file.path, "rb+"), signature)

  File.binread(signed_file.path)
ensure
  signed_file.close
  signed_file.unlink
end