Generating the corresponding public key of a private key

[Ángel González]

On 13/10/14 12:12, Angelos Ching wrote:
> Hi,
>
> Can I always expect the following commands, when given the same
> private key, to generate the same public key albeit in different format?
> # ssh-keygen -y -f id_rsa
> # ssh-keygen -e -f id_rsa
Both commands are defined as outputting the public key for id_rsa, so yes.
Otherwise, it's a bug.

> Because I'm dealing with one private key that is generating different
> public key when the above commands were executed.
How are you detecting that it is a different public key?

-e by default uses RFC4716, so other than the wrapping, it should be the 
same content.

You should be able to go from -e format to -y one with:
> echo ssh-rsa $(echo $(ssh-keygen -e -f id_rsa | sed 
> '/--/d;/^Comment:/d') | tr -d \ )


> The output between the 2 commands are different, but they are
> consistent for any number of runs.
> Moreover, if I copy id_rsa to, say, id_rsa.priv:
> # ssh-keygen -y -f id_rsa.priv
> # ssh-keygen -e -f id_rsa.priv
> would generate the same public key output.
Are you saying that the output is different if you rename the file to 
id_rsa.priv ??

> Running OpenSSL 1.0.0-fips 29 Mar 2010
May I also ask for the openssh version, too? :)

>
> Best regards,
> Angelos

Cheers