Compute EC_KEY starting from X or Y coordinate only

[Luca Di Mauro]

I think it is correct because I extracted the hexadecimal string from  
a packet contained in a pcap.

This compressed point is created following the ETSI TS 103 097 v1.3.1  
standard for secured communications in the vehicular communication  
context  
(https://www.etsi.org/deliver/etsi_ts/103000_103099/103097/01.03.01_60/ts_103097v010301p.pdf).

I notice that the point 'pubPoint' that I created is empty when I try  
to call 'EC_POINT_set_compressed_coordinates_GFp' function. How can I  
put a BIGNUM into an EC_POINT?

Luca

Billy Brumley <bbrumley at gmail.com> ha scritto:

>>         EC_GROUP* group         = EC_GROUP_new_by_curve_name  
>> (NID_secp256k1);
>
>> "c16b4ce0532f5dc9d09114fe121d3956ae84f9eb677a0d4bdac1d3af7a91950c";
>
> I don't believe there's a point on secp256k1 with that x-coordinate.
> If you check the failure reason for
> EC_POINT_set_compressed_coordinates_GFp in the debugger, that is
> probably what it is telling you.
>
> Where did this curve / x-coord pair come from?
>
> BBB