sign-pdf-worker/pythonProject/sign.py
Julien Fastré ef32d5d91c
First commit: create mvp project
- create an orchestrator to orchestrate signature of pdf;
- create a worker to get request from amqp and resend it to amqp
2024-06-27 09:51:32 +02:00

75 lines
2.6 KiB
Python

import io
from typing import Optional
from pyhanko import stamp
from pyhanko.pdf_utils.incremental_writer import IncrementalPdfFileWriter
from pyhanko.sign import signers, timestamps, fields
from pyhanko_certvalidator import ValidationContext
from typing_extensions import Buffer
class SignOrchestrator:
"""Orchestrate the signature on document"""
def __init__(self, pkcs12_path: str, timestamp_url: str, pkcs12_password: Optional[bytes] = None):
# Load signer key material from PKCS#12 file
# This assumes that any relevant intermediate certs are also included
# in the PKCS#12 file.
self.signer = signers.SimpleSigner.load_pkcs12(
pfx_file=pkcs12_path, passphrase=pkcs12_password
)
# Set up a timestamping client to fetch timestamps tokens
self.timestamper = timestamps.HTTPTimeStamper(
url=timestamp_url,
)
self.stamp_style = stamp.TextStampStyle(
stamp_text="Signé par:\n%(signer_text)s\nLe %(ts)s",
border_width=1,
)
def _make_signature_metadata(self, reason: str, field_name: str):
# Settings for PAdES-LTA
return signers.PdfSignatureMetadata(
field_name=field_name, md_algorithm='sha256',
# Mark the signature as a PAdES signature
subfilter=fields.SigSeedSubFilter.PADES,
# We'll also need a validation context
# to fetch & embed revocation info.
# validation_context=ValidationContext(allow_fetching=True),
# Embed relevant OCSP responses / CRLs (PAdES-LT)
# embed_validation_info=True,
# Tell pyHanko to put in an extra DocumentTimeStamp
# to kick off the PAdES-LTA timestamp chain.
use_pades_lta=True,
reason=reason,
)
def sign(self, reason: str, signature_index: int, input_content: Buffer, on_page: int, box_place: (int, int, int, int), signer_text: str) -> io.BytesIO:
field_name = 'Signature' + str(signature_index)
signature_meta = self._make_signature_metadata(reason, field_name)
pdf_signer = signers.PdfSigner(
signature_meta, signer=self.signer, timestamper=self.timestamper,
stamp_style=self.stamp_style
)
inf = io.BytesIO(input_content)
w = IncrementalPdfFileWriter(inf)
fields.append_signature_field(w, sig_field_spec=fields.SigFieldSpec(
field_name, on_page=on_page, box=box_place
))
outf = io.BytesIO()
pdf_signer.sign_pdf(
w, output=outf, appearance_text_params={'signer_text': signer_text}
)
return outf