blob: e4ea9629b657b9aa9a7b8180bbd94c83c9ccf246 (
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
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
|
Encryption & authentication methods
===================================
fastd supports various combinations of ciphers and authentication schemes using
different method providers. All ciphers, message authentication codes (MACs) and
method providers can be disabled during compilation to reduce the binary size.
See `Benchmarks <https://projects.universe-factory.net/projects/fastd/wiki/Benchmarks>`_ for an
overview of the performance of the different methods.
Recommended methods
~~~~~~~~~~~~~~~~~~~
The method ``salsa2012+umac`` is recommended for authenticated encyption. ``null+salsa2012+umac`` is the
recommended method for authenticated-only operation.
Salsa20/12 is a stream cipher with very high speed and a very comfortable security margin.
It has been chosed for the software profile in the `eSTREAM <http://en.wikipedia.org/wiki/ESTREAM>`_ project in 2008.
`UMAC <http://en.wikipedia.org/wiki/UMAC>`_ is an extremely fast message authentication code which is provably
secure and optimized for software implementations.
OpenWrt
-------
Too keep the binary as small as possible, only the following methods are enabled on OpenWrt
by default:
* ``salsa2012+gmac``
* ``salsa2012+umac``
* ``null+salsa2012+gmac``
* ``null+salsa2012+umac``
* ``null``
Of these, the GMAC-based methods may be dropped in the future to further reduce the binary size, as UMAC is
the superior authentication scheme (it is faster than GMAC, provably secure and its software implementation
isn't suspect to timing side channels).
List of methods
~~~~~~~~~~~~~~~
Encrypted methods
-----------------
======================= ================ ========== ========= ======
Method Method provider Cipher MAC Notes
======================= ================ ========== ========= ======
``aes128-gcm`` generic-gmac aes128-ctr ghash [2]_
``salsa20+gmac`` generic-gmac salsa20 ghash
``salsa2012+gmac`` generic-gmac salsa2012 ghash
``aes128-ctr+umac`` generic-umac aes128-ctr uhash [2]_
``salsa20+umac`` generic-umac salsa20 uhash
``salsa2012+umac`` generic-umac salsa2012 uhash
``aes128-ctr+poly1305`` generic-poly1305 aes128-ctr none [1]_ [2]_, [3]_
``salsa20+poly1305`` generic-poly1305 salsa20 none [1]_ [3]_
``salsa2012+poly1305`` generic-poly1305 salsa2012 none [1]_ [3]_
======================= ================ ========== ========= ======
This list is not exhaustive. It is possible to combine different ciphers for
data and authentication tag encryption using the *composed-gmac* and *composed-umac*
method providers; these methods aren't listed here as this is not very useful.
Authenticated-only methods
--------------------------
======================== ================ ========== ===== ======
Method Method provider Cipher MAC Notes
======================== ================ ========== ===== ======
``null+aes128-gmac`` composed-gmac aes128-ctr ghash [2]_, [4]_
``null+salsa20+gmac`` composed-gmac salsa20 ghash [4]_
``null+salsa2012+gmac`` composed-gmac salsa2012 ghash [4]_
``null+aes128-ctr+umac`` composed-umac aes128-ctr uhash [2]_, [4]_
``null+salsa20+umac`` composed-umac salsa20 uhash [4]_
``null+salsa2012+umac`` composed-umac salsa2012 uhash [4]_
======================== ================ ========== ===== ======
Methods without security
------------------------
======== =============== ====== ==== =====
Method Method provider Cipher MAC Notes
======== =============== ====== ==== =====
``null`` null none none [5]_
======== =============== ====== ==== =====
Deprecated methods
------------------
======================== ================= ========== ===== ======
Method Method provider Cipher MAC Notes
======================== ================= ========== ===== ======
``xsalsa20-poly1305`` xsalsa20-poly1305 none none [6]_
======================== ================= ========== ===== ======
Since fastd v11 ``salsa20+poly1305`` should be used instead (or even better a more performant
method like salsa2012+gmac); ``xsalsa20-poly1305`` will be removed eventually.
.. [1] The MAC is integrated in the method provider.
.. [2] AES is very slow without OpenSSL support. OpenSSL's AES implementation may be suspect to cache timing side channels when no hardware support like AES-NI is available.
.. [3] Poly1305 is very slow on embedded systems.
.. [4] The cipher is used to encrypt the authentication tag only, the actual data is transmitted unencrypted.
.. [5] Only authentication of peers' IP addresses, but no encryption or authentication of any data is provided.
.. [6] Both the cipher and the MAC are integrated in the method provider.
|
