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OpenSSL::PKey::DH#public_key
static VALUE
ossl_dh_to_public_key(VALUE self)
{
DH *orig_dh, *dh;
VALUE obj;
GetDH(self, orig_dh);
dh = DHparams_dup(orig_dh); /* err check perfomed by dh_instance */
obj = dh_instance(rb_obj_class(self), dh);
if (obj == Qfalse) {
DH_free(dh);
ossl_raise(eDHError, NULL);
}
return obj;
}
Returns a new DH instance that carries just the public information, i.e. the prime p and the generator g, but no public/private key yet. Such a pair may be generated using DH#generate_key!. The “public key” needed for a key exchange with DH#compute_key is considered as per-session information and may be retrieved with DH#pub_key once a key pair has been generated. If the current instance already contains private information (and thus a valid public/private key pair), this information will no longer be present in the new instance generated by DH#public_key. This feature is helpful for publishing the Diffie-Hellman parameters without leaking any of the private per-session information.
Example
dh = OpenSSL::PKey::DH.new(2048) # has public and private key set public_key = dh.public_key # contains only prime and generator parameters = public_key.to_der # it's safe to publish this