[openssl-users] RDRAND and engine (was: how to generate EC public key from EC private key)

Blumenthal, Uri - 0553 - MITLL uri at ll.mit.edu
Thu Mar 24 17:28:25 UTC 2016

Thank you - employing the pointers (no pun intended :) that you gave, the
code now is doing exactly what’s needed, and utilizes RDRAND (as required
by the specs I have, and my personal preferences as well).

>	set the default RAND_method to the engine

This is what I did not do originally - fixed now.

P.S. I wonder if there’s a way for the application (that did NOT set the
environment by itself - think a function or a module called by somebody
else) can verify that, e.g., RAND_METHOD is what it wants (say, RDRAND in
my case), rather than what it is NOT (e.g., not RAND_SSLeay()).
Uri Blumenthal

On 3/22/16, 20:11 , "openssl-users on behalf of Jeffrey Walton"
<openssl-users-bounces at openssl.org on behalf of noloader at gmail.com> wrote:

>On Tue, Mar 22, 2016 at 6:54 PM, Jeffrey Walton <noloader at gmail.com>
>>> Now one small question: how do I ensure that ‎RAND_engine (and
>>>therefore Intel RDRAND output) is being used for the key generation in
>>>    EVP_PKEY_keygen(ctx, &newkey);
>>> Is just loading RAND_engine enough for that?‎
>> To verify it, I think you need to inspect the default RAND method. Its
>> going to look something like:
>>   RAND_METHOD* rm = RAND_get_rand_method();
>>   if(rm == RAND_SSLeay())
>>   {
>>       printf("Using default generator\n");
>>   }
>> Also see https://wiki.openssl.org/index.php/Random_Numbers#Generators.
>> RDRAND is discussed there, too. But I don't recall how much detail is
>> provided.
>Ah, its right there. I should have checked earlier
>To ensure RAND_bytes uses the [RDRAND] hardware engine, you must
>perform three steps:
>   * load the rdrand engine
>   * acquire a handle to the engine
>   * set the default RAND_method to the engine
>It also provides the sample code.
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