Category Archives: Security

Weak ssh public keys in github

A presentation slide, named “Attacking against 5 millions SSH public keys – 偶然にも500万個のSSH公開鍵を手に入れた俺たちは” is published, it is a lightning talk in “Edomae security seminar” in Jan 24, 2015.

 He grabbed ssh public keys with  GitHub API (https://github.com/${user}.key), the API is obsoleted, but not closed.

He found short (<= 512 bit) DSA/RSA keys and can solve prime decomposition 256bit RSA key in 3 seconds.

And he repoted there are 208 weak ssh keys generated by Debian/Ubuntu (CVE-2008-0166). It was already announced  by GitHub.

On the other hand, such ssh keys couldn’t solve prime decomposition with fastgcd. It means almost ssh keys in GitHub has no bias in almost random number generators implementations, it is a good news.