Difference between revisions of "How to control a RNG in userspace"

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1 Purpose[edit]

Hardware random framework offers the interface to control RNG devices from userspace.
This article shows two ways to control a RNG in userspace:

  • using /dev/random command to generate a random number
  • using rng-tools to validate the RNG

2 RNG control through /dev/random[edit]

/dev/random is a special file that can be used to generate random numbers. It uses noise collected from device drivers and hardware random sources to generate data. od (octal dump) command is used to extract the number of bytes and display the decimal number.
Ex: - Random number (0 - 255):

Board $> od -An -N1 -i /dev/random
        172

- Random number (0 - 65535):

Board $> od -An -N2 -i /dev/random
        20041

3 RNG control through rng-tools[edit]

rng_tools[1] is a set of tools related to random number generation.
rngtest is a basic test that checks data using FIPS 140-2 tests[2] which is a security requirement test for cryptographic module compliance.

Board $> rngtest -c 100 </dev/hwrng                                                                                                                                           
rngtest 5
Copyright (c) 2004 by Henrique de Moraes Holschuh
This is free software; see the source for copying conditions.  There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

rngtest: starting FIPS tests...
rngtest: bits received from input: 2000032
rngtest: FIPS 140-2 successes: 100
rngtest: FIPS 140-2 failures: 0
rngtest: FIPS 140-2(2001-10-10) Monobit: 0
rngtest: FIPS 140-2(2001-10-10) Poker: 0
rngtest: FIPS 140-2(2001-10-10) Runs: 0
rngtest: FIPS 140-2(2001-10-10) Long run: 0
rngtest: FIPS 140-2(2001-10-10) Continuous run: 0
rngtest: input channel speed: (min=33.154; avg=33.656; max=34.217) Kibits/s
rngtest: FIPS tests speed: (min=21.193; avg=23.180; max=23.403) Mibits/s
rngtest: Program run time: 58114432 microseconds

It is normal for any random generator to fail in small number of tests, but failures must not exceed around 10.

4 References[edit]

<noinclude>

{{ArticleMainWriter | LionelD}}
{{ArticleApprovedVersion | LionelD | JeromeB(Passed, 7Jan'19) | No previous approved version | AlainF - 15Jan'19 - 10272 | 13Dec'18}}
[[Category:Security]]</noinclude>


==Purpose==
[[Hardware_random_overview|Hardware random framework]] offers the interface to control RNG devices from userspace. <br>

This article shows two ways to control a RNG in userspace:
*using /dev/random command to generate a random number
*using rng-tools to validate the RNG

==RNG control through /dev/random ==
/dev/random is a special file that can be used to generate random numbers. It uses noise collected from device drivers and hardware random sources to generate data.
od (octal dump) command is used to extract the number of bytes and display the decimal number.<br>

Ex: 
- Random number (0 - 255):
 {{Board$}} od -An -N1 -i /dev/random
         172
- Random number (0 - 65535):
 {{Board$}} od -An -N2 -i /dev/random
         20041
{{ReviewsComments | OVI w2619 - you start the page with /dev/random and now you switch to /dev/hwrng without any explanation. could you explain why we have /dev/random and /dev/hwrng ? }}==RNG control through rng-tools==
rng_tools<ref name="rngtools">https://git.kernel.org/pub/scm/utils/kernel/rng-tools/rng-tools.git/</ref> is a set of tools related to random number generation.<br>

rngtest is a basic test that checks data using FIPS 140-2 tests<ref>https://en.wikipedia.org/wiki/FIPS_140-2</ref> which is a security requirement test for cryptographic module compliance.

 {{Board$}} rngtest -c 100 </dev/hwrng                                                                                                                                           
 rngtest 5
 Copyright (c) 2004 by Henrique de Moraes Holschuh
 This is free software; see the source for copying conditions.  There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

 rngtest: starting FIPS tests...
 rngtest: bits received from input: 2000032
 rngtest: FIPS 140-2 successes: 100
 rngtest: FIPS 140-2 failures: 0
 rngtest: FIPS 140-2(2001-10-10) Monobit: 0
 rngtest: FIPS 140-2(2001-10-10) Poker: 0
 rngtest: FIPS 140-2(2001-10-10) Runs: 0
 rngtest: FIPS 140-2(2001-10-10) Long run: 0
 rngtest: FIPS 140-2(2001-10-10) Continuous run: 0
 rngtest: input channel speed: (min=33.154; avg=33.656; max=34.217) Kibits/s
 rngtest: FIPS tests speed: (min=21.193; avg=23.180; max=23.403) Mibits/s
 rngtest: Program run time: 58114432 microseconds

It is normal for any random generator to fail in small number of tests, but failures must not exceed around 10.

==References==
<references/>
Line 21: Line 21:
 
  {{Board$}} od -An -N2 -i /dev/random
 
  {{Board$}} od -An -N2 -i /dev/random
 
         20041
 
         20041
 
+
{{ReviewsComments | OVI w2619 - you start the page with /dev/random and now you switch to /dev/hwrng without any explanation. could you explain why we have /dev/random and /dev/hwrng ? }}
 
==RNG control through rng-tools==
 
==RNG control through rng-tools==
 
rng_tools<ref name="rngtools">https://git.kernel.org/pub/scm/utils/kernel/rng-tools/rng-tools.git/</ref> is a set of tools related to random number generation.<br>
 
rng_tools<ref name="rngtools">https://git.kernel.org/pub/scm/utils/kernel/rng-tools/rng-tools.git/</ref> is a set of tools related to random number generation.<br>

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