thanks Jeff, will take a look. Regarding Key Length of the private key component of e.g. a secp112r1 based EC key, is it actually a 112 Bit number? Or is it longer?
Chris On 16 Mrz., 18:11, Jeffrey Walton <[email protected]> wrote: > On Mar 16, 11:08 am, Chris Garbers <[email protected]> wrote:> cannot talk > much about the application as such, but I have a byte- > > oriented structure which is limited in size, and need to ensure that > > the structure is authentic to the originator. Thus I thought EC > > signature was about the only thing appropriate, however even that > > seems to be too long, as I only have 20 bytes space left for the > > signature. > > Also > seehttp://www.cryptopp.com/wiki/Elliptic_Curve_Digital_Signature_Algorithm > andhttp://www.cryptopp.com/wiki/Elliptic_Curve_Builder. The ECB page > shows how to generate non-standard domain parameters. But the > parameters will not meet modern security level recommendations. > > > > > The counterpart verifying it, must not have possession any secret key, > > thus I thought HMAC would be out of question. > > Jeff > > > > > > > > > On 16 Mrz., 13:52, Geoff Beier <[email protected]> wrote: > > > > Can you talk about what you're trying to accomplish? It sounds like > > > maybe you're trying to use a signature where a truncated HMAC would be > > > more appropriate. > > > > Geoff > > > > On Wed, Mar 16, 2011 at 07:24, Chris Garbers <[email protected]> wrote: > > > > My bad. I think signatures cannot be shorter than the key, thus in the > > > > example the signature will always be 28 bytes regardless of the hash > > > > digest. > > > > > Instead, one would have to use a different curve definition with a > > > > shorter key. > > > > > Chris > > > > > [SNIP] -- You received this message because you are subscribed to the "Crypto++ Users" Google Group. To unsubscribe, send an email to [email protected]. More information about Crypto++ and this group is available at http://www.cryptopp.com.
