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@ -10,20 +10,22 @@ module VerifyPdfSignature
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module_function
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def call(io, trusted_certs)
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Pdfium::Document.open_io(io) do |document|
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signatures = document.signatures.select { |e| e.byte_range.any?(&:positive?) && e.contents.present? }
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next [] if signatures.blank?
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verified_signatures = signatures.select { |e| verified_signature?(e, io, trusted_certs) }
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trusted_signatures = verified_signatures.select { |e| trusted_signature?(e, trusted_certs) }
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last_signature = (trusted_signatures.presence || verified_signatures).max_by(&:signed_end)
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has_unsigned_changes = last_signature && unsigned_changes?(document, io, last_signature.signed_end)
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signatures.map do |signature|
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build_signature(signature, trusted_certs,
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verified: verified_signatures.include?(signature),
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has_unsigned_changes: has_unsigned_changes && signature == last_signature)
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Pdfium.with_instance do
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Pdfium::Document.open_io(io) do |document|
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signatures = document.signatures.select { |e| e.byte_range.any?(&:positive?) && e.contents.present? }
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next [] if signatures.blank?
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verified_signatures = signatures.select { |e| verified_signature?(e, io, trusted_certs) }
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trusted_signatures = verified_signatures.select { |e| trusted_signature?(e, trusted_certs) }
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last_signature = (trusted_signatures.presence || verified_signatures).max_by(&:signed_end)
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has_unsigned_changes = last_signature && unsigned_changes?(document, io, last_signature.signed_end)
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signatures.map do |signature|
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build_signature(signature, trusted_certs,
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verified: verified_signatures.include?(signature),
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has_unsigned_changes: has_unsigned_changes && signature == last_signature)
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end
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end
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end
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end
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@ -31,11 +33,26 @@ module VerifyPdfSignature
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def verified_signature?(signature, io, trusted_certs)
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return false unless covers_signed_revision?(signature, io)
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verify_contents(OpenSSL::PKCS7.new(signature.contents), signed_data(io, signature.byte_range), trusted_certs)
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rescue OpenSSL::PKCS7::PKCS7Error
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pkcs7 = OpenSSL::PKCS7.new(signature.contents)
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if signature.sub_filter == 'ETSI.RFC3161'
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verify_timestamp(pkcs7, signed_data(io, signature.byte_range))
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else
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verify_contents(pkcs7, signed_data(io, signature.byte_range), trusted_certs)
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end
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rescue OpenSSL::PKCS7::PKCS7Error, OpenSSL::Timestamp::TimestampError
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false
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end
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def verify_timestamp(pkcs7, signed_data)
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return false unless pkcs7.verify(pkcs7.certificates, OpenSSL::X509::Store.new, nil,
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OpenSSL::PKCS7::NOVERIFY | OpenSSL::PKCS7::BINARY)
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token_info = OpenSSL::Timestamp::TokenInfo.new(pkcs7.data)
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token_info.message_imprint == OpenSSL::Digest.digest(token_info.algorithm, signed_data)
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end
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def build_signature(signature, trusted_certs, verified:, has_unsigned_changes:)
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pkcs7 = OpenSSL::PKCS7.new(signature.contents)
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@ -173,27 +190,8 @@ module VerifyPdfSignature
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io.seek(0)
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Pdfium::Document.open_bytes(io.read(signed_end)) do |signed_document|
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next true unless signed_document.valid_cross_reference_table?
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serialized_document(signed_document) != serialized_document(document)
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end
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end
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def serialized_document(document)
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pages = (0...document.page_count).map do |index|
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page = document.get_page(index)
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objects = page.objects.map { |object| [*object.to_a, image_digest(page, object)] }
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[page.rotation, objects, page.annotations, page.text]
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!document.only_dss_changes?(signed_document)
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end
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[pages, document.bookmarks]
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end
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def image_digest(page, object)
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return unless object.image?
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Digest::SHA256.hexdigest(page.extract_image_bitmap(object.object_ptr)[:data])
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end
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def signed_data(io, byte_range)
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Alex Turchyn
8 hours ago
committed by
GitHub