On Wed, Feb 02, 2022 at 11:40:08AM +0100, Nicolai Stange wrote: > Ephemeral key generation can be requested from any of the ffdheXYZ(dh) > variants' common ->set_secret() by passing it an (encoded) struct dh > with the key parameter being unset, i.e. with ->key_size == 0. As the > whole purpose of the ffdheXYZ(dh) templates is to fill in the group > parameters as appropriate, they expect ->p and ->g to be unset in any > input struct dh as well. This means that a user would have to encode an > all-zeroes struct dh instance via crypto_dh_encode_key() when requesting > ephemeral key generation from a ffdheXYZ(dh) instance, which is kind of > pointless. > > Make dh_safe_prime_set_secret() to decode a struct dh from the supplied > buffer only if the latter is non-NULL and initialize it with all zeroes > otherwise. > > That is, it is now possible to call > > crypto_kpp_set_secret(tfm, NULL, 0); > > on any ffdheXYZ(dh) tfm for requesting ephemeral key generation. Why do we need to support the non-NULL case? IOW what in the kernel will be using these new templates with a non-NULL parameter? Thanks, -- Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
