Dear openssl team,
While migrating from 1.0.2 to 3.0, we found that
DH_generate_key() has be deprecated. And as per the man page, it is advised to
use
EVP_PKEY_derive_init<https://www.openssl.org/docs/manmaster/man3/EVP_PKEY_derive_init.html>
&
EVP_PKEY_derive<https://www.openssl.org/docs/manmaster/man3/EVP_PKEY_derive.html>
our application creates a new DH and using DH_generate_key() creates
pub_key/priv_key and uses it. how can we replace this exactly with EVP.
And please suggest what EVP API’s should we use to generate pub/priv keys ?
Application code
dh = DH_new();
dh->p = BN_bin2bn(modSize, octet_len, NULL);
dh->g = BN_bin2bn(H235Bits_generator, H235Bits_generator_len / 8, NULL);
if ( ! DH_generate_key(dh) )
{
return FAILURE;
}
n = (unsigned) BN_num_bytes(dh->pub_key);
BN_bn2bin(dh->pub_key, p);
n = (unsigned) BN_num_bytes(dh->priv_key);
Instead above logic can we do this ? is derive generated pub/priv keys ?
The man page in section 7 (EVP_PKEY_DH) has examples for generating using safe
primes or using probable primes. Seems better since you don’t have to use the
BN API anymore, but a little more complicated because you have to call
OSSL_PARAM_construct_xxx for parameters and assign them to an array.
From there, you can use EVP_PKEY_derive_init, EVP_PKEY_derive_set_peer, and
EVP_PKEY_derive to get your shared secret. See apps/speed.c in the OSSL3
source code for an example. Look for the text EVP_PKEY_DH
