blob: 092d8a7cff917e2f0c7b081de6add7614e739cee (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
|
Known security limitations
==========================
Secure memory wiping
--------------------
`Memory wiping`_ is used to protect secret data or key material from attackers
with access to deallocated memory. This is a defense-in-depth measure against
vulnerabilities that leak application memory.
Many ``cryptography`` APIs which accept ``bytes`` also accept types which
implement the buffer interface. Thus, users wishing to do so can pass
``memoryview`` or another mutable type to ``cryptography`` APIs, and overwrite
the contents once the data is no longer needed.
However, ``cryptography`` does not clear memory by default, as there is no way
to clear immutable structures such as ``bytes``. As a result, ``cryptography``,
like almost all software in Python is potentially vulnerable to this attack. The
`CERT secure coding guidelines`_ assesses this issue as "Severity: medium,
Likelihood: unlikely, Remediation Cost: expensive to repair" and we do not
consider this a high risk for most users.
.. _`Memory wiping`: https://devblogs.microsoft.com/oldnewthing/?p=4223
.. _`CERT secure coding guidelines`: https://wiki.sei.cmu.edu/confluence/display/c/MEM03-C.+Clear+sensitive+information+stored+in+reusable+resources
|
