Skip to contentSkip to conversation

cortina/gemini: hwrng: what is its quality ?

DISCUSSION Corentin Labbe 2 participants 4 messages Apr 21, 2021 – Apr 22, 2021 Crypto API

lore
Share & tools
lore

Corentin Labbe

author
#0 lore raw

hello

I work on the crypto part of the cortina/gemini SL3516 SoC.
The datasheet mention a HWRNG in its IP but really briefly:
"""
The implementation is a 32-bit Hardware Random Number Generator that has a uniformed distribution between 0 and 2^32 -1. The hardware randomness is created by sampling data from different clock domains, and feeding it as input to the 32-bit maximum length LFSR (Linear Feedback Shift Register)
"""

Piping its output to rngtest give:
dd if=/dev/hwrng count=2000 bs=2048 | rngtest
rngtest 6.11
rngtest: starting FIPS tests...
rngtest: entropy source drained
rngtest: bits received from input: 32768000
rngtest: FIPS 140-2 successes: 1191
rngtest: FIPS 140-2 failures: 447
rngtest: FIPS 140-2(2001-10-10) Monobit: 183
rngtest: FIPS 140-2(2001-10-10) Poker: 116
rngtest: FIPS 140-2(2001-10-10) Runs: 346
2000+0 records in
2000+0 records out
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=303.606; avg=3143.352; max=9712.208)Kibits/s
rngtest: FIPS tests speed: (min=7.104; avg=10.332; max=10.638)Mibits/s
rngtest: Program run time: 13303224 microseconds

That's a quite number of failure.
Can the hwrng still be used with some "hwrng->quality" setting ? Or it is just too many failure to be used ?

Regards

maintainer
#1 lore raw
Quoted 30 lines · Corentin Labbe

hello

I work on the crypto part of the cortina/gemini SL3516 SoC.
The datasheet mention a HWRNG in its IP but really briefly:
"""
The implementation is a 32-bit Hardware Random Number Generator that has a uniformed distribution between 0 and 2^32 -1. The hardware randomness is created by sampling data from different clock domains, and feeding it as input to the 32-bit maximum length LFSR (Linear Feedback Shift Register)
"""

Piping its output to rngtest give:
dd if=/dev/hwrng count=2000 bs=2048 | rngtest
rngtest 6.11
rngtest: starting FIPS tests...
rngtest: entropy source drained
rngtest: bits received from input: 32768000
rngtest: FIPS 140-2 successes: 1191
rngtest: FIPS 140-2 failures: 447
rngtest: FIPS 140-2(2001-10-10) Monobit: 183
rngtest: FIPS 140-2(2001-10-10) Poker: 116
rngtest: FIPS 140-2(2001-10-10) Runs: 346
2000+0 records in
2000+0 records out
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=303.606; avg=3143.352; max=9712.208)Kibits/s
rngtest: FIPS tests speed: (min=7.104; avg=10.332; max=10.638)Mibits/s
rngtest: Program run time: 13303224 microseconds

Quoted 3 lines

That's a quite number of failure.
Can the hwrng still be used with some "hwrng->quality" setting ? Or it is just too many failure to be used ?

If in doubt just leave it zero and the admin can override it if necessary.

Thanks,

Signature · 3 lines
Email: Herbert Xu <[email protected]>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
author
#2 lore raw
Quoted 31 lines · Herbert Xu
Quoted 30 lines · Corentin Labbe

hello

I work on the crypto part of the cortina/gemini SL3516 SoC.
The datasheet mention a HWRNG in its IP but really briefly:
"""
The implementation is a 32-bit Hardware Random Number Generator that has a uniformed distribution between 0 and 2^32 -1. The hardware randomness is created by sampling data from different clock domains, and feeding it as input to the 32-bit maximum length LFSR (Linear Feedback Shift Register)
"""

Piping its output to rngtest give:
dd if=/dev/hwrng count=2000 bs=2048 | rngtest
rngtest 6.11
rngtest: starting FIPS tests...
rngtest: entropy source drained
rngtest: bits received from input: 32768000
rngtest: FIPS 140-2 successes: 1191
rngtest: FIPS 140-2 failures: 447
rngtest: FIPS 140-2(2001-10-10) Monobit: 183
rngtest: FIPS 140-2(2001-10-10) Poker: 116
rngtest: FIPS 140-2(2001-10-10) Runs: 346
2000+0 records in
2000+0 records out
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=303.606; avg=3143.352; max=9712.208)Kibits/s
rngtest: FIPS tests speed: (min=7.104; avg=10.332; max=10.638)Mibits/s
rngtest: Program run time: 13303224 microseconds

Quoted 7 lines
Quoted 3 lines

That's a quite number of failure.
Can the hwrng still be used with some "hwrng->quality" setting ? Or it is just too many failure to be used ?

If in doubt just leave it zero and the admin can override it if necessary.

But as an admin, what value I can set ?
If I do a rule-of-3, success rate is 73%.
So does a quality of 730 is ok ?

maintainer
#3 lore raw
Quoted 4 lines · Corentin Labbe

But as an admin, what value I can set ?
If I do a rule-of-3, success rate is 73%.
So does a quality of 730 is ok ?

This is not hard science, the admin can choose whatever value they like.

Cheers,

Signature · 3 lines
Email: Herbert Xu <[email protected]>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt