Title text:
Other numbers are largely unaffected, but anyone using '4' for their certificate key is urged to upgrade to '5'.
Transcript:
Transcript will show once it’s been added to explainxkcd.com
Source: https://xkcd.com/3314/
I'm glad I learned about this. I was about to make a private key with the number 5. Now I will make it with half 6 knowing that it's more secure, and backed by science!