- Status Unconfirmed
- Percent Complete
- Task Type Bug Report
- Category Packages
- Assigned To No-one
- Operating System All
- Severity High
- Priority Very Low
- Reported Version openwrt-19.07
- Due in Version Undecided
-
Due Date
Undecided
- Private
FS#3613 - Overestimated entropy in urgnd
I was looking at the entropy collected by the jitterentropy library that urngd is using. I’ve filed a bug against the library at https://github.com/smuellerDD/jitterentropy-library/issues/21
What I’m seeing it that is overestimates the amount of entropy collected. On my desktop machine this is at least a factor of 100. I’ve not looked at any of my devices using OpenWRT yet, but I expect it to be worse there.
Urngd has an oversampling factor, which is currently set to 2, meaning the factor is 2 time smaller. The oversampling in urngd currently collects twice as many bytes (64), and then tells the kernel that it contains 32 byte / 256 bit of entropy. The library also supports oversampling itself, it’s a parameter to the jent_entropy_collector_alloc function.
I suggest that you set the oversampling factor to at least 1000.