1 =================================
2 Hardware random number generators
3 =================================
4
5 Introduction
6 ============
7
8 The hw_random framework is software that makes
9 special hardware feature on your CPU or mother
10 a Random Number Generator (RNG). The software
11 a core providing the /dev/hwrng character devi
12 sysfs support, plus a hardware-specific driver
13 into that core.
14
15 To make the most effective use of these mechan
16 should download the support software as well.
17 latest version of the "rng-tools" package from
18
19 https://github.com/nhorman/rng-tools
20
21 Those tools use /dev/hwrng to fill the kernel
22 which is used internally and exported by the /
23 /dev/random special files.
24
25 Theory of operation
26 ===================
27
28 CHARACTER DEVICE. Using the standard open()
29 and read() system calls, you can read random d
30 the hardware RNG device. This data is NOT CHE
31 fitness tests, and could potentially be bogus
32 hardware is faulty or has been tampered with).
33 output if the hardware "has-data" flag is set,
34 a security-conscious person would run fitness
35 data before assuming it is truly random.
36
37 The rng-tools package uses such tests in "rngd
38 run them by hand with a "rngtest" utility.
39
40 /dev/hwrng is char device major 10, minor 183.
41
42 CLASS DEVICE. There is a /sys/class/misc/hw_r
43 two unique attributes, "rng_available" and "rn
44 "rng_available" attribute lists the hardware-s
45 available, while "rng_current" lists the one w
46 connected to /dev/hwrng. If your system has m
47 RNG available, you may change the one used by
48 the list in "rng_available" into "rng_current"
49
50 ==============================================
51
52
53 Hardware driver for Intel/AMD/VIA Random Numbe
54 - Copyright 2000,2001 Jeff Garzik <jgar
55 - Copyright 2000,2001 Philipp Rumpf <pr
56
57
58 About the Intel RNG hardware, from the firmwar
59 ==============================================
60
61 The Firmware Hub integrates a Random Number Ge
62 using thermal noise generated from inherently
63 mechanical properties of silicon. When not gen
64 bits the RNG circuitry will enter a low power
65 provide a binary software driver to give third
66 access to our RNG for use as a security featur
67 the RNG is only to be used with a system in an
68
69 Intel RNG Driver notes
70 ======================
71
72 FIXME: support poll(2)
73
74 .. note::
75
76 request_mem_region was removed, for th
77
78 1) Only one RNG is supported by this d
79 2) The location used by the RNG is a f
80 MMIO-addressable memory;
81 3) users with properly working BIOS e8
82 have the region in which the RNG is
83 request_mem_region calls always fai
84 However, for people who use mem=XX,
85 **not** in /proc/iomem, and request
86 succeed.
87
88 Driver details
89 ==============
90
91 Based on:
92 Intel 82802AB/82802AC Firmware Hub (FW
93 May 1999 Order Number: 290658-002 R
94
95 Intel 82802 Firmware Hub:
96 Random Number Generator
97 Programmer's Reference Manual
98 December 1999 Order Number: 298029-001
99
100 Intel 82802 Firmware HUB Random Number Generat
101 Copyright (c) 2000 Matt Sottek <msottek
102
103 Special thanks to Matt Sottek. I did the "gut
104 did the "brains" and all the testing.
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