Hi Christian,
Marcel has upload a version of ECB which does not generate negative parameters.
Jeff
On 9/27/07, Jeffrey Walton <[EMAIL PROTECTED]> wrote:
> Hi Christian,
>
> > a %= p; ----- why is this done?
> > b %= p; ----- why is this done?
> > x %= p;
> > y %= p;
>
> Certicom requirements. Domain Parameters are in the interval [0, p-1].
> Some programs used to create curves use negative values.
>
> Jeff
>
> On 9/27/07, greatx <[EMAIL PROTECTED]> wrote:
> >
> > I still have my questions about the domain parameters.
> >
> > Question 1:
> > -----------------
> > >From the DPVal example (thanks Jeffrey) they mention the 'p', but is
> > this the same as the prime 'p' from my ASN1 data (in the first
> > posting)?
> > DPVal sample code:
> > // This is Curve P-112 from NIST
> > CryptoPP::Integer
> > p("6277101735386680763835789423207666416083908700390324961279");
> >
> > Given ASN1 data:
> > ... OBJECT IDENTIFIER prime-field (1 2 840 10045 1 1)
> > INTEGER -----> prime 'p'
> > 00 D7 C1 34 AA 26 43 66 86 2A 18 30 25 75 D1 D7
> > 87 B0 9F 07 57 97 DA 89 F5 7E C8 C0 FF
> > ...
> > ...
> >
> >
> >
> > Question 2:
> > -----------------
> > Based on the sample code from DPVal:
> > Integer p; ------ load prime 'p' here
> > Integer a; ------ load curve equation parameter 'a' here
> > Integer b; ------ load curve equation parameter 'b' here
> > Integer f; ------ load the cofactor 'f' here
> > Integer n; ------- load the group order 'n' here
> > a %= p; ----- why is this done?
> > b %= p; ----- why is this done?
> > x %= p;
> > y %= p;
> > ECP ec( p, a, b ); // is 'ec' the curve equation?
> > PrivateKey.Initialize( ec, ECP::Point( x, y ), n, f );
> >
> > In my ASN1 data, 'a' and 'b' are in an OCTET STRING form. Can I pass
> > that instead of an INTEGER? or do I have to convert from the OCTET to
> > INTEGER before giving it to crypto++?
> > In my ASN1 data, 'G' is the encoded Group Generator. Is this needed to
> > be passed? What about:
> > DL_GroupParameters_EC<ECP> gp;
> > gp.Initialize(ec, G, n, f); ----- is G the same as ECP::Point( x,
> > y )? if so, my G is given as an OCTET, how do I pass it in here? is
> > the last parameter k the same as the cofactor 'f'??
> >
> >
> > Thanks.
> > Christian
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