Date: Sun, 23 Jul 2000 00:08:12 -0400 From: "Louis A. Mamakos" <louie@TransSys.COM> To: "Jeroen C. van Gelderen" <jeroen@vangelderen.org> Cc: Kris Kennaway <kris@FreeBSD.ORG>, arch@FreeBSD.ORG Subject: Re: Quantifying entropy Message-ID: <200007230408.AAA76739@whizzo.transsys.com> In-Reply-To: Your message of "Sat, 22 Jul 2000 22:51:53 EDT." <397A5DC9.91DAAD8C@vangelderen.org> References: <Pine.BSF.4.21.0007211831540.68809-200000@freefall.freebsd.org> <397A5DC9.91DAAD8C@vangelderen.org>
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> Could you make a couple of megabytes of you raw samples > available? I don't have a soundcard at hand but I do > have the FIPS-140 tests and a bunch of others. I've got some raw data sampled from my Bt848 video capture card that I'm interested in having you evaluate. You can look at http://www.transsys.com/louie/entropy and see a bunch of files: -rw-r--r-- 1 louie wheel 96384000 Jul 22 23:44 ch16.bits -rw-r--r-- 1 louie wheel 2048000 Jul 22 23:45 ch16.bits.subset -rw-r--r-- 1 louie wheel 990841 Jul 22 23:45 ch16.bits.subset.gz -rw-r--r-- 1 louie wheel 73743 Jul 22 23:40 ch16.ppm -rw-r--r-- 1 louie wheel 96192000 Jul 22 20:14 ch4.bits -rw-r--r-- 1 louie wheel 2048000 Jul 22 23:21 ch4.bits.subset -rw-r--r-- 1 louie wheel 1604791 Jul 22 23:27 ch4.bits.subset.gz -rw-r--r-- 1 louie wheel 192015 Jul 22 23:19 ch4.ppm -rw-r--r-- 1 louie wheel 96384000 Jul 22 22:01 ch47.bits -rw-r--r-- 1 louie wheel 2048000 Jul 22 23:21 ch47.bits.subset -rw-r--r-- 1 louie wheel 1767718 Jul 22 23:28 ch47.bits.subset.gz -rw-r--r-- 1 louie wheel 192015 Jul 22 23:18 ch47.ppm -rw-r--r-- 1 louie wheel 135348224 Jul 22 21:50 ch6.bits -rw-r--r-- 1 louie wheel 2048000 Jul 22 23:21 ch6.bits.subset -rw-r--r-- 1 louie wheel 1761347 Jul 22 23:28 ch6.bits.subset.gz -rw-r--r-- 1 louie wheel 192015 Jul 22 23:19 ch6.ppm There are 4 files associated with 4 different RF video sources: channel 4 - live, broadcast TV video from the local NBC affiliate. I don't know what programming was active at the time, probably some commercial :-) channel 6 - unused channel, but shows some adjacent channel interference from an in-use channel (both 5 and 7 are in use). channel 47 - unused channel, but mostly just snow on the screen with no obvious adjacent channel interference. channel 16 - live, locally generated video. This is a static display generated by a FreeBSD box connected to an VGA/baseband composite video converter, driving an RF modulator. It's an application that runs on my FreeBSD-based home automation controller, and during this run, probably only the clock is changing once per second, with the remainder of the display unchanged. (The sample image has been edited obscure phone numbers.) There are 4 files for each source: - foo.bits - the raw data captured from the Bt848 card. This was was gathered using a script something like this: for f in $(jot 450); do ./grab -width 320 -height 200 -channel 47 | tail +5 >> ch47.bits done The "./grab" program captures a video frame of the specified size and from the broadcast channel specified, and writes it to the standard output. The tail command skips over the PPM header, and the remaining image data is appended to a file. This is repeated a bunch of times to get the desired quantity of data. - The foo.subset files are simply the first two megabytes of the full-length files. - The foo.subset.gz file are run through gzip to see how compressable the data is. Interestingly, gzip isn't able to compress most of the files very much; though the mostly static video display frame is the most compressable at just over half; the ch4 data (of actual video) is somewhat more compressable than the other data which is mostly noise. - The foo.ppm files are just a representative frame of captured video, with the PPM header still intact. There is no signifcance to the different sizes of files; this is an artifact of how many frames I captured as I was hacking with the script to do it. louie To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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