From 20d9ca1e1c2ce1fe4bb4b8b52c423de816aaebd7 Mon Sep 17 00:00:00 2001
From: Spitap <dev@asdrip.fr>
Date: Sun, 31 Jul 2022 11:49:58 +0200
Subject: [PATCH] Enabled PKCS#8 for private keys

---
 dkim/asn1.py   |  3 +++
 dkim/crypto.py | 15 ++++++++++++++-
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/dkim/asn1.py b/dkim/asn1.py
index 4cc3167..9d8bf2b 100644
--- a/dkim/asn1.py
+++ b/dkim/asn1.py
@@ -84,6 +84,9 @@ def asn1_parse(template, data):
               elif tag == SEQUENCE:
                   r.append(asn1_parse(t[1], data[i:i+length]))
                   i += length
+              elif tag == OCTET_STRING:
+                  r.append(data[i:i+length])
+                  i += length
               else:
                   raise ASN1FormatError(
                       "Unexpected tag in template: %02x" % tag)
diff --git a/dkim/crypto.py b/dkim/crypto.py
index 10e3e5a..3c5d685 100644
--- a/dkim/crypto.py
+++ b/dkim/crypto.py
@@ -48,6 +48,13 @@ from dkim.asn1 import (
     NULL,
     )
 
+ASN1_PKCS8_PrivateKey = [
+    (SEQUENCE, [
+        (INTEGER,),
+        (SEQUENCE, [ (OBJECT_IDENTIFIER,), (NULL,),]),
+        (OCTET_STRING,),
+    ]) 
+]
 
 ASN1_Object = [
     (SEQUENCE, [
@@ -167,7 +174,13 @@ def parse_pem_private_key(data):
         pkdata = base64.b64decode(m.group(1))
     except TypeError as e:
         raise UnparsableKeyError(str(e))
-    return parse_private_key(pkdata)
+    try:
+        pk = parse_private_key(pkdata)
+    except UnparsableKeyError:
+        #If it fails it might be because of PKCS#8 (key generated with openSSL 3.X)
+        pka = asn1_parse(ASN1_PKCS8_PrivateKey, pkdata)
+        pk = parse_private_key(pka[0][2])
+    return pk
 
 
 def EMSA_PKCS1_v1_5_encode(hash, mlen):