Re: More on cert serialnumbers

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 





On 08/17/2017 10:49 AM, Karl Denninger wrote:


On 8/17/2017 09:40, Robert Moskowitz wrote:
I have been researching serial number in cert based on Jakob's comment:

"- Serial numbers are *exactly* 20 bytes (153 to 159 bits) both as standalone numbers and as DER-encoded numbers. Note that this is not the default in
 the openssl ca program.

- Serial numbers contain cryptographically strong random bits, currently at least 64 random bits, though it is best if the entire serial number looks random from the outside. This is not implemented by the openssl ca program."

And this is supposedly from the CA/B BF?

Though Erwann responded:

"There’s no such requirement. It MUST be at most 20 octets long"

I see how for all certs other than the root (get to that later), I can control this with:

openssl rand -hex 20 > serial

then use 'openssl ca ...'

But from Kyle's comment, the first bit must be ZERO.
So since the 20 octets is a maximum and not a requirement use -hex 19 instead, and if this results in DER placing a leading 0x00 byte you're still ok. This also complies with the ballot that Rich mentioned since you have more entropy than required.

At least I think that meets the requirements....

And 19 is more than 18!  And the first time I tried this I got:

a2b7499f19b3b7b4a54ccd2036d59a4a906756

And the 2nd time I tried with 20:

f7f01d018605411c8788a82e465d7991d574b08f

So that first bit can really be a problem.  Probably about 1/2 the time!  :)

Bob

--
openssl-users mailing list
To unsubscribe: https://mta.openssl.org/mailman/listinfo/openssl-users




[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[Index of Archives]     [Linux ARM Kernel]     [Linux ARM]     [Linux Omap]     [Fedora ARM]     [IETF Annouce]     [Security]     [Bugtraq]     [Linux]     [Linux OMAP]     [Linux MIPS]     [ECOS]     [Asterisk Internet PBX]     [Linux API]

  Powered by Linux