From 01cd8be15ec232a669d1d6b70986ba1db5ff60b6 Mon Sep 17 00:00:00 2001
From: Jack Cushman <jcushman@law.harvard.edu>
Date: Mon, 2 Dec 2024 09:21:35 -0500
Subject: [PATCH] Update openssl flags

- include nonce in timestamp request
- explicitly specify signing algorithm
- add cades attribute and drop smimecap attribute from signature
---
 README.md             |  4 ++--
 src/nabit/lib/sign.py | 18 +++++++++++++++---
 2 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/README.md b/README.md
index dd09230..ed215bb 100644
--- a/README.md
+++ b/README.md
@@ -253,7 +253,7 @@ The signatures directory can contain two kinds of attestation files:
 * `.p7s` files are PKCS#7 signature files, which assert a domain or email address vouching for the bag contents.
   * `.p7s` files are created with the command:
     ```
-    openssl cms -sign -binary -in <original_file> -out <signature_file> -inkey <key_file> -signer <cert_chain> -certfile <cert_chain> -outform PEM
+    openssl cms -sign -binary -md sha256 -in <original_file> -out <signature_file> -inkey <key_file> -signer <first_cert> [-certfile <remaining_chain>] -outform PEM -nosmimecap -cades
     ```
   * `.p7s` files can be validated with the command:
     ```
@@ -262,7 +262,7 @@ The signatures directory can contain two kinds of attestation files:
 * `.tsr` files are timestamp response files, which assert a time before which the bag was created.
   * `.tsr` files are created with the command:
     ```
-    openssl ts -query -data <original_file> -no_nonce -sha256 -cert
+    openssl ts -query -data <original_file> -sha256 -cert
     ```
   * `.tsr` files can be validated with the commands:
     ```
diff --git a/src/nabit/lib/sign.py b/src/nabit/lib/sign.py
index 02ef7d0..b0a7252 100644
--- a/src/nabit/lib/sign.py
+++ b/src/nabit/lib/sign.py
@@ -53,8 +53,12 @@ def timestamp(file_path: str, output_path: str, url: str, cert_chain: str) -> No
     with tempfile.NamedTemporaryFile(suffix='.tsq') as tsq:
         # Generate timestamp request, capturing output
         result = run_openssl([
-            "ts", "-query", "-data", file_path,
-            "-no_nonce", "-sha256", "-cert", "-out", tsq.name
+            "ts",
+            "-query",
+            "-data", file_path,
+            "-sha256",
+            "-cert",
+            "-out", tsq.name
         ])
         
         # read timestamp query file
@@ -121,12 +125,20 @@ def sign(file_path: Path, output_path: Path, key: str, cert_chain: Path) -> None
         args = [
             "cms",
             "-sign",
-            "-binary",  # do not modify linebreaks in the original file
+            # choose explicit hash algorithm rather than default
+            "-md", "sha256",
+            # do not modify linebreaks in the original file
+            "-binary",
             "-in", file_path,
             "-out", output_path,
             "-inkey", key,
             "-signer", signer_file.name,
             "-outform", "PEM",
+            # "Exclude the list of supported algorithms from signed attributes" -- only relevant to email
+            "-nosmimecap",
+            # "add an ESS signingCertificate or ESS signingCertificateV2 signed-attribute to the SignerInfo,
+            # in order to make the signature comply with the requirements for a CAdES Basic Electronic Signature (CAdES-BES)."
+            "-cades",
         ]
         if include_chain:
             args.extend(["-certfile", cert_chain_file.name])