1 files changed, 47 insertions, 0 deletions
diff --git a/addons/l10n_it_edi/tools/remove_signature.py b/addons/l10n_it_edi/tools/remove_signature.py
new file mode 100644
index 00000000..1816b7fd
--- /dev/null
+++ b/addons/l10n_it_edi/tools/remove_signature.py
@@ -0,0 +1,47 @@
+# -*- coding:utf-8 -*-
+# Part of Odoo. See LICENSE file for full copyright and licensing details.
+
+import logging
+import warnings
+
+_logger = logging.getLogger(__name__)
+
+try:
+    from OpenSSL import crypto as ssl_crypto
+    import OpenSSL._util as ssl_util
+except ImportError:
+    ssl_crypto = None
+    _logger.warning("Cannot import library 'OpenSSL' for PKCS#7 envelope extraction.")
+
+
+def remove_signature(content):
+    """ Remove the PKCS#7 envelope from given content, making a '.xml.p7m' file content readable as it was '.xml'.
+        As OpenSSL may not be installed, in that case a warning is issued and None is returned. """
+
+    # Prevent using the library if it had import errors
+    if not ssl_crypto:
+        _logger.warning("Error reading the content, check if the OpenSSL library is installed for for PKCS#7 envelope extraction.")
+        return None
+
+    # Load some tools from the library
+    null = ssl_util.ffi.NULL
+    verify = ssl_util.lib.PKCS7_verify
+
+    # By default ignore the validity of the certificates, just validate the structure
+    flags = ssl_util.lib.PKCS7_NOVERIFY | ssl_util.lib.PKCS7_NOSIGS
+
+    # Read the signed data fron the content
+    out_buffer = ssl_crypto._new_mem_buf()
+
+    # This method is deprecated, but there are actually no alternatives
+    with warnings.catch_warnings():
+        warnings.filterwarnings("ignore", category=DeprecationWarning)
+        loaded_data = ssl_crypto.load_pkcs7_data(ssl_crypto.FILETYPE_ASN1, content)
+
+    # Verify the signature
+    if verify(loaded_data._pkcs7, null, null, null, out_buffer, flags) != 1:
+        ssl_crypto._raise_current_error()
+
+    # Get the content as a byte-string
+    decoded_content = ssl_crypto._bio_to_string(out_buffer)
+    return decoded_content