On Mon, 25 Mar 2019 22:16:27 +0000 Rob Stradling via dev-security-policy <dev-security-policy@lists.mozilla.org> wrote:
> Even better than that (and many thanks to Andrew Ayer for suggesting > this idea)... > > To enable folks to do more thorough statistical analysis, I've > produced another, richer summary table (named > serial_number_entropy_20190325) on the crt.sh DB where each row > contains... > - the CA ID. > - a count of the total number of unique serial numbers. > - 160 counts, representing the number of times a given serial number > bit is 1. (Serial numbers of <20 octets were left-padded with 0x00 > bytes). > > This report covers all serial numbers in certs known to crt.sh where: > - there is an unrevoked serverAuthentication trust path to a Mozilla > built-in root. > - the notBefore date is between 2018-04-01 and 2019-02-22. > > Duplicate serial numbers (i.e., precertificate/certificate pairs) are > deduplicated. Thanks for creating this report Rob! I used the following query to estimate the serial number entropy of every CA which has issued more than 1,000 certificates: SELECT issuer_ca_id,(SELECT COUNT(*) FROM (SELECT unnest(bit_position_sums)/(cert_count::float) AS ratio) subq WHERE ratio >= 0.45 AND ratio <= 0.55) AS entropy_estimate FROM serial_number_entropy_20190325 WHERE cert_count > 1000 ORDER BY issuer_ca_id; (This query considers a bit "random" if it's 1 between 45% and 55% of the time.) Fortunately, this did not find any CA not already listed in Rob's spreadsheet. Regards, Andrew _______________________________________________ dev-security-policy mailing list dev-security-policy@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-security-policy
