From b1be80b8485116e0d3dca85e2ccd655e374d7702 Mon Sep 17 00:00:00 2001
From: David Ormsbee <dave@edx.org>
Date: Mon, 16 Sep 2013 01:59:26 -0400
Subject: [PATCH] Extend message signing code to work with dicts, lists.
---
lms/djangoapps/verify_student/ssencrypt.py | 33 +++++++++++++++++-----
1 file changed, 26 insertions(+), 7 deletions(-)
diff --git a/lms/djangoapps/verify_student/ssencrypt.py b/lms/djangoapps/verify_student/ssencrypt.py
index 862c5aa0218..3a110b8d046 100644
--- a/lms/djangoapps/verify_student/ssencrypt.py
+++ b/lms/djangoapps/verify_student/ssencrypt.py
@@ -127,9 +127,7 @@ def generate_signed_message(method, headers_dict, body_dict, access_key, secret_
"""
Returns a (message, signature) pair.
"""
- headers_str = "{}\n\n{}".format(method, header_string(headers_dict))
- body_str = body_string(body_dict)
- message = headers_str + body_str
+ message = signing_format_message(method, headers_dict, body_dict)
# hmac needs a byte string for it's starting key, can't be unicode.
hashed = hmac.new(secret_key.encode('utf-8'), message, sha256)
@@ -139,6 +137,18 @@ def generate_signed_message(method, headers_dict, body_dict, access_key, secret_
message += '\n'
return message, signature, authorization_header
+def signing_format_message(method, headers_dict, body_dict):
+ """
+ Given a dictionary of headers and a dictionary of the JSON for the body,
+ will return a str that represents the normalized version of this messsage
+ that will be used to generate a signature.
+ """
+ headers_str = "{}\n\n{}".format(method, header_string(headers_dict))
+ body_str = body_string(body_dict)
+ message = headers_str + body_str
+
+ return message
+
def header_string(headers_dict):
"""Given a dictionary of headers, return a canonical string representation."""
header_list = []
@@ -152,7 +162,7 @@ def header_string(headers_dict):
return "".join(header_list) # Note that trailing \n's are important
-def body_string(body_dict):
+def body_string(body_dict, prefix=""):
"""
This version actually doesn't support nested lists and dicts. The code for
that was a little gnarly and we don't use that functionality, so there's no
@@ -160,9 +170,18 @@ def body_string(body_dict):
"""
body_list = []
for key, value in sorted(body_dict.items()):
- if value is None:
- value = "null"
- body_list.append(u"{}:{}\n".format(key, value).encode('utf-8'))
+ if isinstance(value, (list, tuple)):
+ for i, arr in enumerate(value):
+ if isinstance(arr, dict):
+ body_list.append(body_string(arr, u"{}.{}.".format(key, i)))
+ else:
+ body_list.append(u"{}.{}:{}\n".format(key, i, arr).encode('utf-8'))
+ elif isinstance(value, dict):
+ body_list.append(body_string(value, key + ":"))
+ else:
+ if value is None:
+ value = "null"
+ body_list.append(u"{}{}:{}\n".format(prefix, key, value).encode('utf-8'))
return "".join(body_list) # Note that trailing \n's are important
--
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