Does ssh-keygen really allow 521 bit ECDSA key generation?

Christian Hesse list at
Wed Feb 25 23:56:17 AEDT 2015

Eugene Bright <hexumg at> on Wed, 2015/02/25 16:12:
> Hello!
> I found strange sentence in ssh-keygen man page. There is may be a misprint.

You are referring the fact that 521 is not the power of base 2?
Looks like this is valid nevertheless.

% ssh-keygen -t ecdsa -b 512
Invalid ECDSA key length - valid lengths are 256, 384 or 521 bits
% ssh-keygen -t ecdsa -b 521
Generating public/private ecdsa key pair.

Wikipedia adds a note about this as well:
main(a){char*c=/*    Schoene Gruesse                         */"B?IJj;MEH"
"CX:;",b;for(a/*    Chris           get my mail address:    */=0;b=c[a++];)
putchar(b-1/(/*               gcc -o sig sig.c && ./sig    */b/42*2-3)*42);}
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