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    • New note by bobjonkman 26 June 2022
      I've never played #Minecraft - Is this #Federated software? Is it #FreeSoftware? If so, how can Microsoft control what's happening on someone's private server? Even if such code existed in a #FreeSoftware application, I would have thought there'd be a fork that eliminates that external control. It's time for that now. But if #Minecraft isn't […]
    • bobjonkman repeated a notice by lnxw48a1 26 June 2022
      RT @lnxw48a1 Seen via @sullybiker https://freeradical.zone/@thenewoil/108539077382008407 Microsoft bans in #Minecraft will soon carry over to privately run servers as well. One commenter said "Seems like there is a really simple solution here: Don't be a toxic asshole on a public server." But once $CORPORATION starts interfering with privately hosted servers in any way, those servers' […]
    • New note by bobjonkman 27 May 2022
      Mind you, there's something charming and soporific about listening to a professional baseball game with an old-fashioned, laid-back announcer. But most of those have retired... #ASMR
    • New note by bobjonkman 27 May 2022
      Applies to all professional #Sportsball: begging to see overpaid drug-users doing something that the rest of us would gladly do for free. When I walked our dog we'd pass the local baseball field, and we'd stop and watch the game for hours. But the one time I went to a professional baseball match (Toronto Blue […]
    • New note by bobjonkman 19 May 2022
      I've had all my clocks and watches on 24hr time ever since...
    • New note by bobjonkman 19 May 2022
      When I was a young pup, just started my first job. Woke up at 4:30 one day, panicked, "I've slept through the whole day, I'll get fired!!" It was 4:30am, of course. Don't recall if I got back to sleep or not.
    • bobjonkman repeated a notice by lnxw48a1 19 May 2022
      RT @lnxw48a1 I woke up around 02:45, thinking it was 07:45. Before 03:00, I realized it wasn’t time to get up. I still really feel the lack of #sleep 💤.
    • Favorite 19 May 2022
      bobjonkman favorited something by lnxw48a1: I woke up around 02:45, thinking it was 07:45. Before 03:00, I realized it wasn’t time to get up. I still really feel the lack of #sleep 💤.
    • New note by bobjonkman 14 May 2022
      "A Supreme Court that doesn't give a damn what the public wants ... is exactly what a Supreme Court is for, actually." True enough. But elected representatives in government *are* supposed to do what people want, that's why they get elected. If they had fulfilled their obligations to actually represent the citizens' wants then the […]
    • bobjonkman repeated a notice by clacke 14 May 2022
      RT @clacke People, not all people but most people, are angry about the wrong thing. I agree that Roe v Wade being canceled is a bad outcome. I agree that women should have the right to their bodies, but here's my possibly unpopular take: A Supreme Court that doesn't give a damn what the public […]

Archive for March, 2014

The cost of long GnuPG/PGP keys

Posted by Bob Jonkman on 25th March 2014

Never Eat That Green Food At The Back Of The Fridge

Never Trust Anyone Over Thirty

and

Never Sign A GnuPG/PGP Key That’s Older Than You Are

Face peeking into fridge

Looking for green food at the back of the fridge

OK, only one of those is true, and it’s not the last one. At the University of Waterloo Keysigning Party last fall, some of the people signing my key were younger than the key they were signing!

At the keysigning I was having a discussion with someone about key lengths. In particular, choosing 4096 bits instead of 2048. I was reading that GnuPG has a limit of 4096 bits, but that 4096 should be enough for all time to come.

I’ve read online that GnuPG does actually support larger key sizes but that there is a const in the source code limiting it to 4096. The reasons for doing so are supposedly speed, 4096 would be very slow to generate and use, and comparability with other implementations that may not support larger keys. Personally I think it’s an inevitability that this will be increased in time but we’re not there yet.

In 1996 when I started with PGP a 1024 bit key was considered adequate, by 1999 a 2048 bit key was still considered large.

Consider Moore’s Law: every 18 months computing capacity doubles and costs halve. I’m not sure if that means that over 18 months x flops increases to 2x flops at the same price, or that in 18 months the cost of x flops is half of today’s cost, or if it means that in 18 months the cost of 2x flops will be half the cost of x flops today. If the latter, then today’s x flops/$ is x/4 flops/$ in 18 months. That factor of four is an increase of two bits every 18 months, or four bits every 3 years.

So, the cost in 1996 to brute-force crack a 1024 bit key is the same as the cost in 1999 to crack a 1028 bit key. And in 2014, 18 years later, it’s the same cost as cracking a 1048 bit key (an additional 24 bits).

An increase in key size from 1024 bits to 2048 bits buys an additional 768 years of Moore’s Law. And going from 2048 bits to 4096 bits buys an additional 1536 years of Moore’s Law.

Is Moore’s Law overestimating the cost of cracking keys? Are there fundamental advances in math that have dropped the cost of cracking 1024 bit keys to near-zero? What’s the economic justification for crippling keysizes in GnuPG, anyway?

–Bob, who is not trolling but really wants to know.

Day 57 / 365 – refrigerator by Jason Rogers is used under a CC BYCC BY license.

This post is based on a message to the KWCrypto Mailing List.

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