[gentoo-user] Re: [OT] RSA Vs DSA keys for SSH authentication

[Remy Blank]

Mick wrote:
> I have looked around and have found confusing info regarding which is a better
> key cipher to use for ssh authentication.  Some say that RSA is widely
> considered more secure than DSA.  Some say that it doesn't really matter, as
> long as you use a large enough bits setting in creating your key.  RSA takes
> longer to create but it takes less time to authenticate on the server and DSA
> is the other way around.  Not sure what to believe and I'd rather not be
> guessing which one is best

DSA keys are always 1024 bits, as this is mandated by the standard. RSA
keys can have variable length. From "man ssh-keygen":

  -b bits
    Specifies the number of bits in the key to create.  For RSA keys,
    the minimum size is 768 bits and the default is 2048 bits.  Gen-
    erally, 2048 bits is considered sufficient.  DSA keys must be
    exactly 1024 bits as specified by FIPS 186-2.

Another argument in favor of RSA is mentioned in the PuTTY FAQ:

  http://www.chiark.greenend.org.uk/~sgtatham/putty/faq.html#faq-dsa

Personally, I use RSA keys because I want to use a 2048 bit key length.

-- Remy


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