Slide 1
Slide 1 text
Random
Under the hood of PHP 7’s
Let’s get
CSPRNG
Sammy Kaye Powers
Las Vegas, NV - 2018
Slide 2
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joind.in/talk/0e3b7
@SammyK #zcoe18
Slides
Get the
joind.in/talk/0e3b7
Slide 3
Slide 3 text
joind.in/talk/0e3b7
@SammyK #zcoe18
CSPRNG?
What is the PHP 7
Slide 4
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joind.in/talk/0e3b7
@SammyK #zcoe18
random_int()
random_bytes()
Slide 5
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joind.in/talk/0e3b7
@SammyK #zcoe18
ext/standard/random.c
Slide 6
Slide 6 text
joind.in/talk/0e3b7
@SammyK #zcoe18
The end
Slide 7
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joind.in/talk/0e3b7
@SammyK #zcoe18
Random?
What is
Slide 8
Slide 8 text
Red
Yellow
White
Red
Yellow
White
Red
Yellow
White
Period: 3
Slide 9
Slide 9 text
Jingle all the way,
Oh what fun it is to ride
In a one-horse open sleigh
Predictable seed
Jingle bells, jingle bells
Slide 10
Slide 10 text
74, 105, 110, 103, 108, 101, 32,
97, 108, 108, 32,
116, 104, 101, 32,
119, 97, 121, 44
Random, right?
Slide 11
Slide 11 text
ASCII
Slide 12
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74, 105, 110, 103, 108, 101, 32,
chr()
J, i, n, g, l, e, ,
Slide 13
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97, 108, 108, 32,
What’s the next word?
a, l, l, ,
Slide 14
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116, 104, 101, 32,
t, h, e, ,
Slide 15
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74, 105, 110, 103, 108, 101, 32,
97, 108, 108, 32,
Random, right?
116, 104, 101, 32,
nope!
Slide 16
Slide 16 text
Felt?
Remember how we
Slide 17
Slide 17 text
74, 105, 110, 103, 108, 101, 32,
97, 108, 108, 32,
116, 104, 101, 32,
119, 97, 121, 44
What’s the meaning?
ASCII codes!
Ah, right. Carry on then.
Deterministic
Slide 18
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joind.in/talk/0e3b7
@SammyK #zcoe18
Why
did we think
Slide 19
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joind.in/talk/0e3b7
@SammyK #zcoe18
•Think of a two-digit number
•Between one and one hundred
•Both digits odd
•Both digits different
Slide 20
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joind.in/talk/0e3b7
@SammyK #zcoe18
Are you thinking of…
37
Slide 21
Slide 21 text
joind.in/talk/0e3b7
@SammyK #zcoe18
Humans
are bad at being random
Slide 22
Slide 22 text
joind.in/talk/0e3b7
@SammyK #zcoe18
Environment
Can we use our
to make better random numbers?
Slide 23
Slide 23 text
joind.in/talk/0e3b7
@SammyK #zcoe18
Time?
Maybe the
Slide 24
Slide 24 text
joind.in/talk/0e3b7
@SammyK #zcoe18
12:00, 12:01, 12:02, 12:03, 12:04, 12:05, 12:06, 12:07, 12:08, 12:09, 12:10, 12:11, 12:12, 12:13, 12:14, 12:15, 12:16, 12:17, 12:18,
12:19, 12:20, 12:21, 12:22, 12:23, 12:24, 12:25, 12:26, 12:27, 12:28, 12:29, 12:30, 12:31, 12:32, 12:33, 12:34, 12:35, 12:36, 12:37,
12:38, 12:39, 12:40, 12:41, 12:42, 12:43, 12:44, 12:45, 12:46, 12:47, 12:48, 12:49, 12:50, 12:51, 12:52, 12:53, 12:54, 12:55, 12:56,
12:57, 12:58, 12:59, 1:00, 1:01, 1:02, 1:03, 1:04, 1:05, 1:06, 1:07, 1:08, 1:09, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18,
1:19, 1:20, 1:21, 1:22, 1:23, 1:24, 1:25, 1:26, 1:27, 1:28, 1:29, 1:30, 1:31, 1:32, 1:33, 1:34, 1:35, 1:36, 1:37, 1:38, 1:39, 1:40,
1:41, 1:42, 1:43, 1:44, 1:45, 1:46, 1:47, 1:48, 1:49, 1:50, 1:51, 1:52, 1:53, 1:54, 1:55, 1:56, 1:57, 1:58, 1:59, 2:00, 2:01, 2:02,
2:03, 2:04, 2:05, 2:06, 2:07, 2:08, 2:09, 2:10, 2:11, 2:12, 2:13, 2:14, 2:15, 2:16, 2:17, 2:18, 2:19, 2:20, 2:21, 2:22, 2:23, 2:24,
2:25, 2:26, 2:27, 2:28, 2:29, 2:30, 2:31, 2:32, 2:33, 2:34, 2:35, 2:36, 2:37, 2:38, 2:39, 2:40, 2:41, 2:42, 2:43, 2:44, 2:45, 2:46,
2:47, 2:48, 2:49, 2:50, 2:51, 2:52, 2:53, 2:54, 2:55, 2:56, 2:57, 2:58, 2:59, 3:00, 3:01, 3:02, 3:03, 3:04, 3:05, 3:06, 3:07, 3:08,
3:09, 3:10, 3:11, 3:12, 3:13, 3:14, 3:15, 3:16, 3:17, 3:18, 3:19, 3:20, 3:21, 3:22, 3:23, 3:24, 3:25, 3:26, 3:27, 3:28, 3:29, 3:30,
3:31, 3:32, 3:33, 3:34, 3:35, 3:36, 3:37, 3:38, 3:39, 3:40, 3:41, 3:42, 3:43, 3:44, 3:45, 3:46, 3:47, 3:48, 3:49, 3:50, 3:51, 3:52,
3:53, 3:54, 3:55, 3:56, 3:57, 3:58, 3:59, 4:00, 4:01, 4:02, 4:03, 4:04, 4:05, 4:06, 4:07, 4:08, 4:09, 4:10, 4:11, 4:12, 4:13, 4:14,
4:15, 4:16, 4:17, 4:18, 4:19, 4:20, 4:21, 4:22, 4:23, 4:24, 4:25, 4:26, 4:27, 4:28, 4:29, 4:30, 4:31, 4:32, 4:33, 4:34, 4:35, 4:36,
4:37, 4:38, 4:39, 4:40, 4:41, 4:42, 4:43, 4:44, 4:45, 4:46, 4:47, 4:48, 4:49, 4:50, 4:51, 4:52, 4:53, 4:54, 4:55, 4:56, 4:57, 4:58,
4:59, 5:00, 5:01, 5:02, 5:03, 5:04, 5:05, 5:06, 5:07, 5:08, 5:09, 5:10, 5:11, 5:12, 5:13, 5:14, 5:15, 5:16, 5:17, 5:18, 5:19, 5:20,
5:21, 5:22, 5:23, 5:24, 5:25, 5:26, 5:27, 5:28, 5:29, 5:30, 5:31, 5:32, 5:33, 5:34, 5:35, 5:36, 5:37, 5:38, 5:39, 5:40, 5:41, 5:42,
5:43, 5:44, 5:45, 5:46, 5:47, 5:48, 5:49, 5:50, 5:51, 5:52, 5:53, 5:54, 5:55, 5:56, 5:57, 5:58, 5:59, 6:00, 6:01, 6:02, 6:03, 6:04,
6:05, 6:06, 6:07, 6:08, 6:09, 6:10, 6:11, 6:12, 6:13, 6:14, 6:15, 6:16, 6:17, 6:18, 6:19, 6:20, 6:21, 6:22, 6:23, 6:24, 6:25, 6:26,
6:27, 6:28, 6:29, 6:30, 6:31, 6:32, 6:33, 6:34, 6:35, 6:36, 6:37, 6:38, 6:39, 6:40, 6:41, 6:42, 6:43, 6:44, 6:45, 6:46, 6:47, 6:48,
6:49, 6:50, 6:51, 6:52, 6:53, 6:54, 6:55, 6:56, 6:57, 6:58, 6:59, 7:00, 7:01, 7:02, 7:03, 7:04, 7:05, 7:06, 7:07, 7:08, 7:09, 7:10,
7:11, 7:12, 7:13, 7:14, 7:15, 7:16, 7:17, 7:18, 7:19, 7:20, 7:21, 7:22, 7:23, 7:24, 7:25, 7:26, 7:27, 7:28, 7:29, 7:30, 7:31, 7:32,
7:33, 7:34, 7:35, 7:36, 7:37, 7:38, 7:39, 7:40, 7:41, 7:42, 7:43, 7:44, 7:45, 7:46, 7:47, 7:48, 7:49, 7:50, 7:51, 7:52, 7:53, 7:54,
7:55, 7:56, 7:57, 7:58, 7:59, 8:00, 8:01, 8:02, 8:03, 8:04, 8:05, 8:06, 8:07, 8:08, 8:09, 8:10, 8:11, 8:12, 8:13, 8:14, 8:15, 8:16,
8:17, 8:18, 8:19, 8:20, 8:21, 8:22, 8:23, 8:24, 8:25, 8:26, 8:27, 8:28, 8:29, 8:30, 8:31, 8:32, 8:33, 8:34, 8:35, 8:36, 8:37, 8:38,
8:39, 8:40, 8:41, 8:42, 8:43, 8:44, 8:45, 8:46, 8:47, 8:48, 8:49, 8:50, 8:51, 8:52, 8:53, 8:54, 8:55, 8:56, 8:57, 8:58, 8:59, 9:00,
9:01, 9:02, 9:03, 9:04, 9:05, 9:06, 9:07, 9:08, 9:09, 9:10, 9:11, 9:12, 9:13, 9:14, 9:15, 9:16, 9:17, 9:18, 9:19, 9:20, 9:21, 9:22,
9:23, 9:24, 9:25, 9:26, 9:27, 9:28, 9:29, 9:30, 9:31, 9:32, 9:33, 9:34, 9:35, 9:36, 9:37, 9:38, 9:39, 9:40, 9:41, 9:42, 9:43, 9:44,
9:45, 9:46, 9:47, 9:48, 9:49, 9:50, 9:51, 9:52, 9:53, 9:54, 9:55, 9:56, 9:57, 9:58, 9:59, 10:00, 10:01, 10:02, 10:03, 10:04, 10:05,
10:06, 10:07, 10:08, 10:09, 10:10, 10:11, 10:12, 10:13, 10:14, 10:15, 10:16, 10:17, 10:18, 10:19, 10:20, 10:21, 10:22, 10:23, 10:24,
10:25, 10:26, 10:27, 10:28, 10:29, 10:30, 10:31, 10:32, 10:33, 10:34, 10:35, 10:36, 10:37, 10:38, 10:39, 10:40, 10:41, 10:42, 10:43,
10:44, 10:45, 10:46, 10:47, 10:48, 10:49, 10:50, 10:51, 10:52, 10:53, 10:54, 10:55, 10:56, 10:57, 10:58, 10:59, 11:00, 11:01, 11:02,
11:03, 11:04, 11:05, 11:06, 11:07, 11:08, 11:09, 11:10, 11:11, 11:12, 11:13, 11:14, 11:15, 11:16, 11:17, 11:18, 11:19, 11:20, 11:21,
11:22, 11:23, 11:24, 11:25, 11:26, 11:27, 11:28, 11:29, 11:30, 11:31, 11:32, 11:33, 11:34, 11:35, 11:36, 11:37, 11:38, 11:39, 11:40,
11:41, 11:42, 11:43, 11:44, 11:45, 11:46, 11:47, 11:48, 11:49, 11:50, 11:51, 11:52, 11:53, 11:54, 11:55, 11:56, 11:57, 11:58, 11:59
720
Slide 25
Slide 25 text
joind.in/talk/0e3b7
@SammyK #zcoe18
12:00, 12:01, 12:02, 12:03, 12:04, 12:05, 12:06, 12:07, 12:08, 12:09, 12:10, 12:11, 12:12, 12:13, 12:14, 12:15, 12:16, 12:17, 12:18,
12:19, 12:20, 12:21, 12:22, 12:23, 12:24, 12:25, 12:26, 12:27, 12:28, 12:29, 12:30, 12:31, 12:32, 12:33, 12:34, 12:35, 12:36, 12:37,
12:38, 12:39, 12:40, 12:41, 12:42, 12:43, 12:44, 12:45, 12:46, 12:47, 12:48, 12:49, 12:50, 12:51, 12:52, 12:53, 12:54, 12:55, 12:56,
12:57, 12:58, 12:59, 1:00, 1:01, 1:02, 1:03, 1:04, 1:05, 1:06, 1:07, 1:08, 1:09, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18,
1:19, 1:20, 1:21, 1:22, 1:23, 1:24, 1:25, 1:26, 1:27, 1:28, 1:29, 1:30, 1:31, 1:32, 1:33, 1:34, 1:35, 1:36, 1:37, 1:38, 1:39, 1:40,
1:41, 1:42, 1:43, 1:44, 1:45, 1:46, 1:47, 1:48, 1:49, 1:50, 1:51, 1:52, 1:53, 1:54, 1:55, 1:56, 1:57, 1:58, 1:59, 2:00, 2:01, 2:02,
2:03, 2:04, 2:05, 2:06, 2:07, 2:08, 2:09, 2:10, 2:11, 2:12, 2:13, 2:14, 2:15, 2:16, 2:17, 2:18, 2:19, 2:20, 2:21, 2:22, 2:23, 2:24,
2:25, 2:26, 2:27, 2:28, 2:29, 2:30, 2:31, 2:32, 2:33, 2:34, 2:35, 2:36, 2:37, 2:38, 2:39, 2:40, 2:41, 2:42, 2:43, 2:44, 2:45, 2:46,
2:47, 2:48, 2:49, 2:50, 2:51, 2:52, 2:53, 2:54, 2:55, 2:56, 2:57, 2:58, 2:59, 3:00, 3:01, 3:02, 3:03, 3:04, 3:05, 3:06, 3:07, 3:08,
3:09, 3:10, 3:11, 3:12, 3:13, 3:14, 3:15, 3:16, 3:17, 3:18, 3:19, 3:20, 3:21, 3:22, 3:23, 3:24, 3:25, 3:26, 3:27, 3:28, 3:29, 3:30,
3:31, 3:32, 3:33, 3:34, 3:35, 3:36, 3:37, 3:38, 3:39, 3:40, 3:41, 3:42, 3:43, 3:44, 3:45, 3:46, 3:47, 3:48, 3:49, 3:50, 3:51, 3:52,
3:53, 3:54, 3:55, 3:56, 3:57, 3:58, 3:59, 4:00, 4:01, 4:02, 4:03, 4:04, 4:05, 4:06, 4:07, 4:08, 4:09, 4:10, 4:11, 4:12, 4:13, 4:14,
4:15, 4:16, 4:17, 4:18, 4:19, 4:20, 4:21, 4:22, 4:23, 4:24, 4:25, 4:26, 4:27, 4:28, 4:29, 4:30, 4:31, 4:32, 4:33, 4:34, 4:35, 4:36,
4:37, 4:38, 4:39, 4:40, 4:41, 4:42, 4:43, 4:44, 4:45, 4:46, 4:47, 4:48, 4:49, 4:50, 4:51, 4:52, 4:53, 4:54, 4:55, 4:56, 4:57, 4:58,
4:59, 5:00, 5:01, 5:02, 5:03, 5:04, 5:05, 5:06, 5:07, 5:08, 5:09, 5:10, 5:11, 5:12, 5:13, 5:14, 5:15, 5:16, 5:17, 5:18, 5:19, 5:20,
5:21, 5:22, 5:23, 5:24, 5:25, 5:26, 5:27, 5:28, 5:29, 5:30, 5:31, 5:32, 5:33, 5:34, 5:35, 5:36, 5:37, 5:38, 5:39, 5:40, 5:41, 5:42,
5:43, 5:44, 5:45, 5:46, 5:47, 5:48, 5:49, 5:50, 5:51, 5:52, 5:53, 5:54, 5:55, 5:56, 5:57, 5:58, 5:59, 6:00, 6:01, 6:02, 6:03, 6:04,
6:05, 6:06, 6:07, 6:08, 6:09, 6:10, 6:11, 6:12, 6:13, 6:14, 6:15, 6:16, 6:17, 6:18, 6:19, 6:20, 6:21, 6:22, 6:23, 6:24, 6:25, 6:26,
6:27, 6:28, 6:29, 6:30, 6:31, 6:32, 6:33, 6:34, 6:35, 6:36, 6:37, 6:38, 6:39, 6:40, 6:41, 6:42, 6:43, 6:44, 6:45, 6:46, 6:47, 6:48,
6:49, 6:50, 6:51, 6:52, 6:53, 6:54, 6:55, 6:56, 6:57, 6:58, 6:59, 7:00, 7:01, 7:02, 7:03, 7:04, 7:05, 7:06, 7:07, 7:08, 7:09, 7:10,
7:11, 7:12, 7:13, 7:14, 7:15, 7:16, 7:17, 7:18, 7:19, 7:20, 7:21, 7:22, 7:23, 7:24, 7:25, 7:26, 7:27, 7:28, 7:29, 7:30, 7:31, 7:32,
7:33, 7:34, 7:35, 7:36, 7:37, 7:38, 7:39, 7:40, 7:41, 7:42, 7:43, 7:44, 7:45, 7:46, 7:47, 7:48, 7:49, 7:50, 7:51, 7:52, 7:53, 7:54,
7:55, 7:56, 7:57, 7:58, 7:59, 8:00, 8:01, 8:02, 8:03, 8:04, 8:05, 8:06, 8:07, 8:08, 8:09, 8:10, 8:11, 8:12, 8:13, 8:14, 8:15, 8:16,
8:17, 8:18, 8:19, 8:20, 8:21, 8:22, 8:23, 8:24, 8:25, 8:26, 8:27, 8:28, 8:29, 8:30, 8:31, 8:32, 8:33, 8:34, 8:35, 8:36, 8:37, 8:38,
8:39, 8:40, 8:41, 8:42, 8:43, 8:44, 8:45, 8:46, 8:47, 8:48, 8:49, 8:50, 8:51, 8:52, 8:53, 8:54, 8:55, 8:56, 8:57, 8:58, 8:59, 9:00,
9:01, 9:02, 9:03, 9:04, 9:05, 9:06, 9:07, 9:08, 9:09, 9:10, 9:11, 9:12, 9:13, 9:14, 9:15, 9:16, 9:17, 9:18, 9:19, 9:20, 9:21, 9:22,
9:23, 9:24, 9:25, 9:26, 9:27, 9:28, 9:29, 9:30, 9:31, 9:32, 9:33, 9:34, 9:35, 9:36, 9:37, 9:38, 9:39, 9:40, 9:41, 9:42, 9:43, 9:44,
9:45, 9:46, 9:47, 9:48, 9:49, 9:50, 9:51, 9:52, 9:53, 9:54, 9:55, 9:56, 9:57, 9:58, 9:59, 10:00, 10:01, 10:02, 10:03, 10:04, 10:05,
10:06, 10:07, 10:08, 10:09, 10:10, 10:11, 10:12, 10:13, 10:14, 10:15, 10:16, 10:17, 10:18, 10:19, 10:20, 10:21, 10:22, 10:23, 10:24,
10:25, 10:26, 10:27, 10:28, 10:29, 10:30, 10:31, 10:32, 10:33, 10:34, 10:35, 10:36, 10:37, 10:38, 10:39, 10:40, 10:41, 10:42, 10:43,
10:44, 10:45, 10:46, 10:47, 10:48, 10:49, 10:50, 10:51, 10:52, 10:53, 10:54, 10:55, 10:56, 10:57, 10:58, 10:59, 11:00, 11:01, 11:02,
11:03, 11:04, 11:05, 11:06, 11:07, 11:08, 11:09, 11:10, 11:11, 11:12, 11:13, 11:14, 11:15, 11:16, 11:17, 11:18, 11:19, 11:20, 11:21,
11:22, 11:23, 11:24, 11:25, 11:26, 11:27, 11:28, 11:29, 11:30, 11:31, 11:32, 11:33, 11:34, 11:35, 11:36, 11:37, 11:38, 11:39, 11:40,
11:41, 11:42, 11:43, 11:44, 11:45, 11:46, 11:47, 11:48, 11:49, 11:50, 11:51, 11:52, 11:53, 11:54, 11:55, 11:56, 11:57, 11:58, 11:59
BUT!
Slide 26
Slide 26 text
joind.in/talk/0e3b7
@SammyK #zcoe18
12:00, 12:01, 12:02, 12:03, 12:04, 12:05, 12:06, 12:07, 12:08, 12:09, 12:10, 12:11, 12:12, 12:13, 12:14, 12:15, 12:16, 12:17, 12:18,
12:19, 12:20, 12:21, 12:22, 12:23, 12:24, 12:25, 12:26, 12:27, 12:28, 12:29, 12:30, 12:31, 12:32, 12:33, 12:34, 12:35, 12:36, 12:37,
12:38, 12:39, 12:40, 12:41, 12:42, 12:43, 12:44, 12:45, 12:46, 12:47, 12:48, 12:49, 12:50, 12:51, 12:52, 12:53, 12:54, 12:55, 12:56,
12:57, 12:58, 12:59, 1:00, 1:01, 1:02, 1:03, 1:04, 1:05, 1:06, 1:07, 1:08, 1:09, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18,
1:19, 1:20, 1:21, 1:22, 1:23, 1:24, 1:25, 1:26, 1:27, 1:28, 1:29, 1:30, 1:31, 1:32, 1:33, 1:34, 1:35, 1:36, 1:37, 1:38, 1:39, 1:40,
1:41, 1:42, 1:43, 1:44, 1:45, 1:46, 1:47, 1:48, 1:49, 1:50, 1:51, 1:52, 1:53, 1:54, 1:55, 1:56, 1:57, 1:58, 1:59, 2:00, 2:01, 2:02,
2:03, 2:04, 2:05, 2:06, 2:07, 2:08, 2:09, 2:10, 2:11, 2:12, 2:13, 2:14, 2:15, 2:16, 2:17, 2:18, 2:19, 2:20, 2:21, 2:22, 2:23, 2:24,
2:25, 2:26, 2:27, 2:28, 2:29, 2:30, 2:31, 2:32, 2:33, 2:34, 2:35, 2:36, 2:37, 2:38, 2:39, 2:40, 2:41, 2:42, 2:43, 2:44, 2:45, 2:46,
2:47, 2:48, 2:49, 2:50, 2:51, 2:52, 2:53, 2:54, 2:55, 2:56, 2:57, 2:58, 2:59, 3:00, 3:01, 3:02, 3:03, 3:04, 3:05, 3:06, 3:07, 3:08,
3:09, 3:10, 3:11, 3:12, 3:13, 3:14, 3:15, 3:16, 3:17, 3:18, 3:19, 3:20, 3:21, 3:22, 3:23, 3:24, 3:25, 3:26, 3:27, 3:28, 3:29, 3:30,
3:31, 3:32, 3:33, 3:34, 3:35, 3:36, 3:37, 3:38, 3:39, 3:40, 3:41, 3:42, 3:43, 3:44, 3:45, 3:46, 3:47, 3:48, 3:49, 3:50, 3:51, 3:52,
3:53, 3:54, 3:55, 3:56, 3:57, 3:58, 3:59, 4:00, 4:01, 4:02, 4:03, 4:04, 4:05, 4:06, 4:07, 4:08, 4:09, 4:10, 4:11, 4:12, 4:13, 4:14,
4:15, 4:16, 4:17, 4:18, 4:19, 4:20, 4:21, 4:22, 4:23, 4:24, 4:25, 4:26, 4:27, 4:28, 4:29, 4:30, 4:31, 4:32, 4:33, 4:34, 4:35, 4:36,
4:37, 4:38, 4:39, 4:40, 4:41, 4:42, 4:43, 4:44, 4:45, 4:46, 4:47, 4:48, 4:49, 4:50, 4:51, 4:52, 4:53, 4:54, 4:55, 4:56, 4:57, 4:58,
4:59, 5:00, 5:01, 5:02, 5:03, 5:04, 5:05, 5:06, 5:07, 5:08, 5:09, 5:10, 5:11, 5:12, 5:13, 5:14, 5:15, 5:16, 5:17, 5:18, 5:19, 5:20,
5:21, 5:22, 5:23, 5:24, 5:25, 5:26, 5:27, 5:28, 5:29, 5:30, 5:31, 5:32, 5:33, 5:34, 5:35, 5:36, 5:37, 5:38, 5:39, 5:40, 5:41, 5:42,
5:43, 5:44, 5:45, 5:46, 5:47, 5:48, 5:49, 5:50, 5:51, 5:52, 5:53, 5:54, 5:55, 5:56, 5:57, 5:58, 5:59, 6:00, 6:01, 6:02, 6:03, 6:04,
6:05, 6:06, 6:07, 6:08, 6:09, 6:10, 6:11, 6:12, 6:13, 6:14, 6:15, 6:16, 6:17, 6:18, 6:19, 6:20, 6:21, 6:22, 6:23, 6:24, 6:25, 6:26,
6:27, 6:28, 6:29, 6:30, 6:31, 6:32, 6:33, 6:34, 6:35, 6:36, 6:37, 6:38, 6:39, 6:40, 6:41, 6:42, 6:43, 6:44, 6:45, 6:46, 6:47, 6:48,
6:49, 6:50, 6:51, 6:52, 6:53, 6:54, 6:55, 6:56, 6:57, 6:58, 6:59, 7:00, 7:01, 7:02, 7:03, 7:04, 7:05, 7:06, 7:07, 7:08, 7:09, 7:10,
7:11, 7:12, 7:13, 7:14, 7:15, 7:16, 7:17, 7:18, 7:19, 7:20, 7:21, 7:22, 7:23, 7:24, 7:25, 7:26, 7:27, 7:28, 7:29, 7:30, 7:31, 7:32,
7:33, 7:34, 7:35, 7:36, 7:37, 7:38, 7:39, 7:40, 7:41, 7:42, 7:43, 7:44, 7:45, 7:46, 7:47, 7:48, 7:49, 7:50, 7:51, 7:52, 7:53, 7:54,
7:55, 7:56, 7:57, 7:58, 7:59, 8:00, 8:01, 8:02, 8:03, 8:04, 8:05, 8:06, 8:07, 8:08, 8:09, 8:10, 8:11, 8:12, 8:13, 8:14, 8:15, 8:16,
8:17, 8:18, 8:19, 8:20, 8:21, 8:22, 8:23, 8:24, 8:25, 8:26, 8:27, 8:28, 8:29, 8:30, 8:31, 8:32, 8:33, 8:34, 8:35, 8:36, 8:37, 8:38,
8:39, 8:40, 8:41, 8:42, 8:43, 8:44, 8:45, 8:46, 8:47, 8:48, 8:49, 8:50, 8:51, 8:52, 8:53, 8:54, 8:55, 8:56, 8:57, 8:58, 8:59, 9:00,
9:01, 9:02, 9:03, 9:04, 9:05, 9:06, 9:07, 9:08, 9:09, 9:10, 9:11, 9:12, 9:13, 9:14, 9:15, 9:16, 9:17, 9:18, 9:19, 9:20, 9:21, 9:22,
9:23, 9:24, 9:25, 9:26, 9:27, 9:28, 9:29, 9:30, 9:31, 9:32, 9:33, 9:34, 9:35, 9:36, 9:37, 9:38, 9:39, 9:40, 9:41, 9:42, 9:43, 9:44,
9:45, 9:46, 9:47, 9:48, 9:49, 9:50, 9:51, 9:52, 9:53, 9:54, 9:55, 9:56, 9:57, 9:58, 9:59, 10:00, 10:01, 10:02, 10:03, 10:04, 10:05,
10:06, 10:07, 10:08, 10:09, 10:10, 10:11, 10:12, 10:13, 10:14, 10:15, 10:16, 10:17, 10:18, 10:19, 10:20, 10:21, 10:22, 10:23, 10:24,
10:25, 10:26, 10:27, 10:28, 10:29, 10:30, 10:31, 10:32, 10:33, 10:34, 10:35, 10:36, 10:37, 10:38, 10:39, 10:40, 10:41, 10:42, 10:43,
10:44, 10:45, 10:46, 10:47, 10:48, 10:49, 10:50, 10:51, 10:52, 10:53, 10:54, 10:55, 10:56, 10:57, 10:58, 10:59, 11:00, 11:01, 11:02,
11:03, 11:04, 11:05, 11:06, 11:07, 11:08, 11:09, 11:10, 11:11, 11:12, 11:13, 11:14, 11:15, 11:16, 11:17, 11:18, 11:19, 11:20, 11:21,
11:22, 11:23, 11:24, 11:25, 11:26, 11:27, 11:28, 11:29, 11:30, 11:31, 11:32, 11:33, 11:34, 11:35, 11:36, 11:37, 11:38, 11:39, 11:40,
11:41, 11:42, 11:43, 11:44, 11:45, 11:46, 11:47, 11:48, 11:49, 11:50, 11:51, 11:52, 11:53, 11:54, 11:55, 11:56, 11:57, 11:58, 11:59
• Session started at 4:00 pm PDT
• That was on slide #23
• If you timed my rehearsals…
Slide 27
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@SammyK #zcoe18
11
random?
What makes a number
Slide 28
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joind.in/talk/0e3b7
@SammyK #zcoe18
2, 4, 6, 8, __
10
Slide 29
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@SammyK #zcoe18
1337, 42, 0, _
?
Slide 30
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joind.in/talk/0e3b7
@SammyK #zcoe18
1337, 42, 0,
1337, 42, 0,
1337, __
42
Slide 31
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joind.in/talk/0e3b7
@SammyK #zcoe18
Random?
What is isn’t
Deterministic
Slide 32
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@SammyK #zcoe18
“True” Random
Measurement of atmospheric noise
Count of the number of electrons
coming off of a radioactive material
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No content
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joind.in/talk/0e3b7
@SammyK #zcoe18
Can I haz
random number?
Slide 35
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joind.in/talk/0e3b7
@SammyK #zcoe18
Slide 36
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joind.in/talk/0e3b7
@SammyK #zcoe18
Slide 37
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joind.in/talk/0e3b7
@SammyK #zcoe18
*sigh* Take this.
42
Slide 38
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@SammyK #zcoe18
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joind.in/talk/0e3b7
@SammyK #zcoe18
0
Slide 40
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joind.in/talk/0e3b7
@SammyK #zcoe18
2,4,8,
7,5,1
?
Slide 41
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joind.in/talk/0e3b7
@SammyK #zcoe18
Number Generator
…or “PRNG” for short
Pseudorandom
Slide 42
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joind.in/talk/0e3b7
@SammyK #zcoe18
Pseudorandom?
How’s that different than just random?
Deterministic
Slide 43
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joind.in/talk/0e3b7
@SammyK #zcoe18
2,4,8,
7,5,1
Generator
Linear Congruential
Slide 44
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joind.in/talk/0e3b7
@SammyK #zcoe18
Generator
Linear Congruential
Slide 45
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joind.in/talk/0e3b7
@SammyK #zcoe18
Slide 46
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joind.in/talk/0e3b7
@SammyK #zcoe18
The modulus
The multiplier
The increment
The seed
Slide 47
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joind.in/talk/0e3b7
@SammyK #zcoe18
Slide 48
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@SammyK #zcoe18
Slide 49
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joind.in/talk/0e3b7
@SammyK #zcoe18
2,4,8,
7,5,
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joind.in/talk/0e3b7
@SammyK #zcoe18
2,4,8,
7,5,
Deterministic
Slide 51
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joind.in/talk/0e3b7
@SammyK #zcoe18
https://xkcd.com/221/
Slide 52
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@SammyK #zcoe18
Slide 53
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@SammyK #zcoe18
Slide 54
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joind.in/talk/0e3b7
@SammyK #zcoe18
8,7,5,
1,2,
Slide 55
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joind.in/talk/0e3b7
@SammyK #zcoe18
1,2,4,
8,7,
BUT!
Slide 56
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joind.in/talk/0e3b7
@SammyK #zcoe18
Slide 57
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5,1,2,4,8,7,5,
1,2,4,8,7,5,1,
2,4,8,7,5,1,2,
4,8,7,5,1,2,4,
8,7,5,1,2,4,8,
7,5,1,2,4,
Predictable
Period: 6
Slide 58
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joind.in/talk/0e3b7
@SammyK #zcoe18
LCG
lcg_value()
PHP has a combined
Slide 59
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@SammyK #zcoe18
PRNG?
Is there a better
Slide 60
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joind.in/talk/0e3b7
@SammyK #zcoe18
Twister
Mersenne
mt_rand()
Slide 61
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joind.in/talk/0e3b7
@SammyK #zcoe18
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mt_rand()
724937621,955931554,1407935661,821438740,109344
9922,603009103,1540988686,1028238631,798475733,
1057939018,671583233,1853117923,98760648,112245
3373,534404057,900958085,1712824654,476385742,2
9956470,362833620,424798798,746223917,942003531
,320462445,673296853,1351199651,141566289,16454
09515,995047403,1216151582,1115999460,175322091
7,1312071810,1553254094,1622498991,2080099801,1
704834715,1537620663,1357630828,1317892558,
219,937-1
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joind.in/talk/0e3b7
@SammyK #zcoe18
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mt_rand(0,99)
83,9,64,28,62,48,83,47,46,53,37,26,21,91,61,32,58,1,89,60,65,97,42,56,6,47,76,1
2,98,11,36,61,62,60,43,67,6,16,73,15,39,38,56,19,66,56,98,72,91,24,57,94,8,26,7
3,55,17,14,84,89,39,11,13,48,71,98,89,63,9,95,74,9,81,85,97,24,14,14,77,22,96,4
3,61,91,61,58,19,71,8,49,18,92,38,34,9,36,91,59,14,4,58,59,29,74,52,41,36,67,82
,67,11,0,58,51,37,4,45,56,35,50,78,91,27,39,80,27,28,95,2,82,51,72,27,41,43,74,
7,82,59,89,72,9,22,61,75,27,64,16,77,57,31,29,59,47,14,67,89,33,94,33,94,22,11,
62,9,13,61,45,78,29,3,11,99,91,52,79,63,64,43,99,53,22,16,10,53,57,15,84,16,30,
17,10,3,35,0,45,83,11,70,66,37,14,59,41,46,52,53,53,62,56,41,82,40,99,8,92,96,2
2,22,43,35,60,45,77,26,96,45,51,62,77,64,23,52,17,17,97,93,57,43,56,45,62,42,24
,62,1,59,38,70,13,34,32,48,47,1,42,48,18,2,59,47,53,10,3,66,68,93,4,53,85,20,77
,63,43,45,16,15,77,73,89,11,64,76,30,46,91,1,85,96,19,63,70,62,35,58,95,63,38,7
8,83,8,97,22,2,28,51,25,29,98,62,74,59,95,79,74,66,47,35,83,56,49,25,32,25,46,1
3,69,77,30,94,24,31,68,23,64,47,28,33,65,69,16,0,98,37,85,93,60,24,10,54,50,42,
64,11,9,13,15,84,3,23,73,83,83,72,9,2,28,23,90,73,2,47,45,93,4,32,25,75,61,98,7
3,79,66,23,20,83,11,45,67,40,39,45,0,65,40,78,74,8,79,86,38,10,87,60,99,30,35,5
0,16,29,24,19,29,16,40,57,87,26,90,1,63,63,34,44,8,36,25,38,50,10,15,17,14,40,6
,53,88,18,36,46,69,2,13,0,83,59,92,59,34,34,24,40,99,41,6,79,65,98,9,36,31,8,4,
89,98,91,80,42,10,26,72,40,50,39,25,33,45,24,70,54,89,91,53,23,12,20,40,21,25,5
5,48,11,3,84,42,5,7,21,58,85,18,52,92,94,69,20,49,3,8,55,57,4,38,52,37,64,55,82
,98,5,75,84,35,14,99,74,23,41,69,55,53,22,52,6,68,35,38,73,52,22,52,86,79,15,38
,3,20,99,36,23,77,33,80,16,97,54,88,11,77,77,99,70,26,5,75,87,4,23,8,50,79,61,5
5,80,25,58,79,25,56,9,81,6,42,27,90,58,6,62,74,25,79,81,61,23,54,92,53,16,66,22
,49,77,97,84,25,49,32,49,65,51,1,93,63,68,69,67,10,44,99,44,42,89,35,24,
624 = busted
Slide 65
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echo mt_rand(0,99);
11
Slide 66
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echo mt_rand(0,99);
9
Slide 67
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echo mt_rand(0,99);
60
Slide 68
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mt_srand(10);
echo mt_rand(0,99);
21
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mt_srand(10);
echo mt_rand(0,99);
21
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mt_srand(10);
echo mt_rand(0,99);
21
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No content
Slide 72
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joind.in/talk/0e3b7
@SammyK #zcoe18
Good
randomness can be
Deterministic
(e.g. games)
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@SammyK #zcoe18
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@SammyK #zcoe18
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@SammyK #zcoe18
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joind.in/talk/0e3b7
@SammyK #zcoe18
AKA “Seed”
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@SammyK #zcoe18
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@SammyK #zcoe18
Slide 79
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joind.in/talk/0e3b7
@SammyK #zcoe18
deterministic randomness is
contexts
In cryptographic
really, really, really, really
objectively…
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@SammyK #zcoe18
BAD
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joind.in/talk/0e3b7
@SammyK #zcoe18
CSRF
Take for example
Tokens
Slide 82
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joind.in/talk/0e3b7
@SammyK #zcoe18
Cross-site request forgery
(CSRF) tokens help prevent
unauthorized requests on
a user’s behalf.
Slide 83
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joind.in/talk/0e3b7
@SammyK #zcoe18
A CSRF token must be
unique and unpredictable.
*don’t do this
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@SammyK #zcoe18
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@SammyK #zcoe18
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@SammyK #zcoe18
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joind.in/talk/0e3b7
@SammyK #zcoe18
I’ll just let PHP seed
mt_rand() for me.
Bad idea jeans
*Old SNL skit reference
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@SammyK #zcoe18
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joind.in/talk/0e3b7
@SammyK #zcoe18
What about
rand()
you ask?
Slide 90
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joind.in/talk/0e3b7
@SammyK #zcoe18
Nope
Slide 91
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joind.in/talk/0e3b7
@SammyK #zcoe18
rand()
mt_rand()
…in PHP 7.0 & below
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joind.in/talk/0e3b7
@SammyK #zcoe18
rand()
Uses the system PRNG
(unreliable & inconsistent)
Is a PRNG (totes predictable)
Uniform distribution issues
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joind.in/talk/0e3b7
@SammyK #zcoe18
Uniform
Distribution
Slide 94
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joind.in/talk/0e3b7
@SammyK #zcoe18
0
0.05
0.1
0.15
0.2
1 2 3 4 5 6
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joind.in/talk/0e3b7
@SammyK #zcoe18
0
0.1
0.2
0.3
0.4
1 2 3 4 5 6
Slide 96
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joind.in/talk/0e3b7
@SammyK #zcoe18
Uniform Distribution
==
True Random
Slide 97
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@SammyK #zcoe18
mt_rand()
Implements the MT algorithm
incorrectly
Is a PRNG (totes predictable)
Has a modulo bias
Slide 98
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joind.in/talk/0e3b7
@SammyK #zcoe18
Modulo
Bias
Slide 99
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joind.in/talk/0e3b7
@SammyK #zcoe18
6 % 3 = 0
8 % 3 = 2
Modulo Operator
Slide 100
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joind.in/talk/0e3b7
@SammyK #zcoe18
Random # between 0 & 1
n % 2 = 0 or 1
Use mod 2
Slide 101
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joind.in/talk/0e3b7
@SammyK #zcoe18
rand_src() = 1, 2, or 3
2 % 2 = 0
3 % 2 = 1
1 is
more likely
1 % 2 = 1
Slide 102
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joind.in/talk/0e3b7
@SammyK #zcoe18
rand()
mt_rand()
…in PHP 7.1 & above
Slide 103
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joind.in/talk/0e3b7
@SammyK #zcoe18
mt_rand()
Fixes bug in MT algorithm
implementation
Is a PRNG (totes predictable)
Slide 104
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joind.in/talk/0e3b7
@SammyK #zcoe18
They’re totes
samezies!
rand() mt_rand()
===
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joind.in/talk/0e3b7
@SammyK #zcoe18
Slide 106
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joind.in/talk/0e3b7
@SammyK #zcoe18
rand() mt_rand()
Both suffer from
modulo bias
&
Slide 107
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joind.in/talk/0e3b7
@SammyK #zcoe18
Seeds aren’t
impossible to predict
Slide 108
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@SammyK #zcoe18
Entropy
*Could be it’s own talk
Slide 109
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@SammyK #zcoe18
A measure of how
accurately we’re able
to predict the next
value in a sequence.*
* oversimplification
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joind.in/talk/0e3b7
@SammyK #zcoe18
High
entropy
harder
to predict
Low
entropy
easier
to predict
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joind.in/talk/0e3b7
@SammyK #zcoe18
High
entropy
harder
to predict Good for random
number generation
Slide 112
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joind.in/talk/0e3b7
@SammyK #zcoe18
Cryptographically
Pseudorandom
Secure
Number Generator
Slide 113
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joind.in/talk/0e3b7
@SammyK #zcoe18
CSPRNG
or…
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joind.in/talk/0e3b7
@SammyK #zcoe18
“See Spring”
or…
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Unicorn
Magical
Slide 116
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Uses seeds
that are really
really
really
really
ridiculously
hard to guess
Slide 117
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joind.in/talk/0e3b7
@SammyK #zcoe18
High
Entropy
wee!
Slide 118
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joind.in/talk/0e3b7
@SammyK #zcoe18
impossible
It’s values are
to predict in practice
42
82
Suitable for use in
cryptographic contexts.
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mythical
Where can we find this
creature?
Slide 120
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joind.in/talk/0e3b7
@SammyK #zcoe18
CSPRNG
options in
5.x
Slide 121
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joind.in/talk/0e3b7
@SammyK #zcoe18
openssl_random_pseudo_bytes()
mcrypt_create_iv()
/dev/urandom
Slide 122
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joind.in/talk/0e3b7
@SammyK #zcoe18
openssl_random_pseudo_bytes()
mcrypt_create_iv()
/dev/urandom
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joind.in/talk/0e3b7
@SammyK #zcoe18
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@SammyK #zcoe18
TAKE_
to_live
TAKE_
to_lie
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@SammyK #zcoe18
TAKE_
to_lie
5.6.11
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@SammyK #zcoe18
5.6.12
TAKE_
to_live
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Fails
open
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@SammyK #zcoe18
FALSE
Can return
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@SammyK #zcoe18
empty string
Can be
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@SammyK #zcoe18
Still not done!
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@SammyK #zcoe18
WRONG
Easy to get
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@SammyK #zcoe18
Worse
It gets
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@SammyK #zcoe18
Since the UNIX fork() system call
duplicates the entire process state, a
random number generator which does not
take this issue into account will produce
the same sequence of random numbers in
both the parent and the child […], leading to
cryptographic disaster…
https://wiki.openssl.org/index.php/Random_fork-safety
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@SammyK #zcoe18
OpenSSL’s
be like
42
CSPRNG
82
82
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@SammyK #zcoe18
OpenSSL cannot fix the fork-safety
problem because its not in a position
to do so. However, there are [solutions]
available and they are listed below.
https://wiki.openssl.org/index.php/Random_fork-safety
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@SammyK #zcoe18
Don't use
RAND_bytes
https://wiki.openssl.org/index.php/Random_fork-safety
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@SammyK #zcoe18
Instead, you can read directly from
/dev/random, /dev/urandom or
/dev/srandom; or use CryptGenRandom
on Windows systems.
https://wiki.openssl.org/index.php/Random_fork-safety
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@SammyK #zcoe18
Status update!
v1.1.1
(2018-09-11)
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@SammyK #zcoe18
mcrypt_create_iv()
/dev/urandom
openssl_random_pseudo_bytes()
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Fails
open
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@SammyK #zcoe18
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@SammyK #zcoe18
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@SammyK #zcoe18
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@SammyK #zcoe18
/dev/urandom
openssl_random_pseudo_bytes()
mcrypt_create_iv()
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@SammyK #zcoe18
open_basedir=/foo/dir
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@SammyK #zcoe18
openssl_random_pseudo_bytes()
mcrypt_create_iv()
/dev/urandom
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@SammyK #zcoe18
CSPRNG
New goodness
7
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@SammyK #zcoe18
CSPRNG
random_int()
random_bytes()
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random_int(0,99)
6,17,6,9,17,53,58,98,46,44,62,9,76,65,46,21,42,5,65,34,11,96,85,7,46,89,98,9,9,
80,8,76,87,18,24,68,16,61,27,39,30,32,4,83,83,23,96,27,13,47,6,99,16,40,2,75,27
,3,79,68,75,60,50,70,63,17,75,29,79,57,9,48,18,86,95,25,40,52,20,86,6,48,94,27,
76,14,9,27,62,14,68,58,12,18,63,19,84,47,7,13,63,28,66,55,2,75,44,92,11,85,51,1
7,42,57,22,4,53,7,3,76,48,55,95,7,45,33,87,36,11,17,66,6,46,87,57,48,22,31,65,5
,26,10,47,82,97,74,25,32,63,60,29,53,13,24,56,54,52,86,67,4,94,35,48,73,35,45,2
4,74,74,83,49,70,41,49,20,60,29,49,30,35,38,63,4,86,72,97,26,22,36,95,59,94,24,
89,73,46,14,73,51,93,93,39,13,80,9,30,24,20,30,63,20,64,97,29,7,2,82,96,42,61,5
3,28,49,12,90,71,58,72,63,49,32,69,76,50,62,88,31,26,72,79,19,15,3,39,27,80,16,
65,62,53,82,59,23,85,95,41,68,86,3,92,76,91,88,12,20,96,14,35,50,94,24,23,44,55
,78,65,81,7,1,86,32,58,46,97,43,78,9,51,1,6,79,73,49,13,40,21,90,14,9,70,95,88,
37,85,14,7,29,42,55,81,46,39,41,45,81,11,93,26,89,4,98,35,30,36,74,97,18,85,97,
23,52,64,88,20,89,12,25,19,21,21,50,60,50,43,84,1,52,5,19,2,86,38,51,48,30,55,9
0,93,97,52,84,29,58,96,78,37,24,14,72,81,9,82,26,83,83,17,35,15,9,87,95,51,71,4
8,9,45,13,61,98,3,18,96,99,28,74,47,58,71,89,68,57,51,86,90,38,21,72,72,30,22,1
3,88,25,48,45,62,59,81,32,10,54,82,60,90,17,98,41,73,98,60,22,99,66,32,41,82,62
,91,3,85,91,21,17,98,19,48,50,24,67,3,14,62,55,35,99,95,83,76,12,51,77,61,24,24
,60,15,31,47,24,27,97,98,70,6,24,25,20,23,67,72,55,47,19,53,50,38,22,76,37,63,8
2,67,52,3,75,84,84,71,49,79,26,89,11,77,55,92,32,81,38,23,54,9,40,80,75,20,7,58
,37,72,75,59,46,32,41,82,90,72,59,5,42,2,94,44,44,4,15,37,29,24,10,51,18,8,42,5
6,9,68,31,99,7,77,59,8,74,80,11,15,93,81,5,72,44,49,39,25,4,18,98,0,93,42,78,36
,57,47,16,49,2,85,6,31,17,81,10,54,40,95,68,31,80,29,41,86,32,9,58,96,62,79,25,
6,45,56,54,0,61,74,90,12,34,11,56,3,41,39,84,32,30,42,81,36,43,5,
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@SammyK #zcoe18
bin2hex(random_bytes(16))
f7f5289027cb6c5116d
2d3cc78e5819c
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Fails
Closed
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@SammyK #zcoe18
You’re not strong until
you’re crypto-strong!
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CSPRNG
under the hood
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No content
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@SammyK #zcoe18
On Windows: CryptGenRandom
On BSD: arc4random_buf()
On Linux: getrandom(2) syscall
Read directly from /dev/urandom
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@SammyK #zcoe18
/dev/urandom
So what is this
thing?
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/dev/urandom
Gathers environmental noise
from the system like…
…device drivers, inter-keyboard
timings, inter-interrupt timings
from some interrupts, and
other events which are both
(a) non-deterministic and
(b) hard for an outside
observer to measure.
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/char/random.c
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@SammyK #zcoe18
CSPRNG
random_bytes()
random_int()
7
/dev/urandom
Powered by
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@SammyK #zcoe18
Still on 5.x?
paragonie/random_compat
Polyfill for PHP 7 CSPRNG
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@SammyK #zcoe18
http://php.net/supported-versions.php
5.6 EOL in 75 days
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@SammyK #zcoe18
http://php.net/supported-versions.php
7.0 EOL in 47 days
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@SammyK #zcoe18
FAQ’s
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@SammyK #zcoe18
Benchmarks*
* are lies
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@SammyK #zcoe18
If random_bytes()
random_int() are…
…why not
update
mt_rand()
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@SammyK #zcoe18
TL;DR
Never use LCG, MT, or any other PRNG in
cryptographic contexts
Only use a CSPRNG like
/dev/urandom for crypto
Use random_bytes() & random_int() in
PHP (or install paragonie/random_compat)
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More Resources
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@SammyK #zcoe18
Recommendation for the
Entropy Sources Used for
Random Bit Generation
Final Draft - NIST SP 800-90B
https://csrc.nist.gov/publications/detail/sp/800-90b/final
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New & improved man pages for
/dev/urandom
http://man7.org/linux/man-pages/man7/random.7.html
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Myths about
/dev/urandom
Thomas Hühn
https://www.2uo.de/myths-about-urandom/
With pretty pictures!
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Cracking Random Number Generators
Three-part blog post series
James Roper
https://jazzy.id.au/2010/09/20/cracking_random_number_generators_part_1.html
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@SammyK #zcoe18
How I Met Your Girlfriend
DEF CON 18
Samy Kamkar
https://www.youtube.com/watch?v=fWk_rMQiDGc
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@SammyK #zcoe18
Weak RNG in PHP session ID generation
leads to session hijacking
Andreas Bogk
http://seclists.org/fulldisclosure/2010/Mar/519
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Sammy Kaye Powers
Thanks!
/talk/0e3b7
@SammyK
SammyK.me
Host of @PHPRoundtable