[openssl-users] What does EC_KEY_get0_public_key deliver?

Christian Weber weber at infotech.de
Fri Jan 9 10:55:46 UTC 2015

Am 09.01.2015 um 01:11 schrieb Matt Caswell: On 09/01/15 00:05, 
Christian Weber wrote:
>> Thanks Matt, i just assumed the BIGNUMs were the coordinates without any projection - obviously that assumption was wrong - mislead by the funtions name.
> What interests me is to how you accessed the BIGNUMs in the first place!
> The EC_POINT structure is opaque and is defined in an internal header
> file!! Applications shouldn't be reaching into those.
> Matt
Actually i imported the internal header so the structure was known. I 
marked the import as HACK to access exactly that EC_POINT structure. The 
hack was carried out because of the lack of knowledge about how to 
access the public key.

I yust did not understand the intention for hiding the EC_POINT 
structure and didn't find information about how to access the coordinate 
values which i need to compare with coordinates from other sources (XML 
Dsig, Element <ds:KeyValue>) or placing them elsewhere.

So could you please give a hint or a pointer to where the intended 
access can be found?

BTW: How does one find out which type of ECC is being used (binary or 
BTW2: Which compact representation of any public key would you recommend 
(for program internal comparisons)?

Surely i will ban the internal header from my sources as they are not 


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