On Tue, Jul 19, 2016 at 4:46 PM, Mark Watson <watsonm@netflix.com> wrote: > Hi Charles, > > Thanks - that explanation makes sense: there are two ways to do ECDH > defined in SEC1, the RFC uses one of them and X9.62 uses the other and they > are the same for curves with cofactor 1. > > So, then, can anyone tell me what is the co-factor of the curves we > defined in the WebCrypto specification ? If that is 1, then I am convinced > that the RFC and X9.62 are the same and we can safely switch. > SEC 2: Recommended Elliptic Curve Domain Parameters ( http://www.secg.org/SEC2-Ver-1.0.pdf) defines secp256r1, secp384r1, and secp521r1, which are alternate names for P-256, P-384, and P-521. According to this PDF, all three curves have cofactor h=1.
Received on Tuesday, 19 July 2016 20:59:39 UTC