I need to use ECDH to derive the shared key using public and private key given.
On 17 December 2012 18:56, jeetendra gangele <gangele...@gmail.com> wrote: > Thanks for ur help . > > > Can you guide me how can I use ECDH for exachnaging of the secret key. > I have to implement in two phases. > 1.i have private key of 256 bit lenght need to get phase i1 value wx,wy > 2.In second I have phase1 value and private key and need to get secret > key or public key. > > > > Thanks > > > On 17 December 2012 13:55, Dave Thompson <dthomp...@prinpay.com> wrote: >>> From: owner-openssl-us...@openssl.org On Behalf Of jeetendra gangele >>> Sent: Monday, 17 December, 2012 02:48 >> >>> Yes i am talking about signature. >>> ECDSA_SIG this ouptput structure will have r and s componet >>> of 28 bytes each. [for 224-bit curve] >>> So if I merge both r and s I will get 56 bytes right? >>> These will not have any padding information?. >>> >> The struct points to two bignums, which use an internal >> format; openssl can put what it likes in there. >> If you get the (near-trivial) encoding as big-endian btyes >> using BN_bn2bin, *that* does not have padding or overhead. >> >> Note that the numbers in an ECDSA signature are effectively >> uniform random up to the field order, so they will *rarely* >> be *smaller* than the keysize (here, less then 28 bytes). >> If you want *fixed* 28 bytes each, *you* will need to pad. >> >> (I forgot to allow for this in my earlier reply. The ASN.1 >> encoding can be less than 62 bytes in these cases.) >> >> ______________________________________________________________________ >> OpenSSL Project http://www.openssl.org >> User Support Mailing List openssl-users@openssl.org >> Automated List Manager majord...@openssl.org ______________________________________________________________________ OpenSSL Project http://www.openssl.org User Support Mailing List openssl-users@openssl.org Automated List Manager majord...@openssl.org
