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

pythonProject/sign.py

@@ -0,0 +1,74 @@
+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
+
+
+
+
+