CREATE_DH_PARAMETERS(key_len)

Creates a shared secret for generating a DH private/public key pair and
returns a binary string that can be passed to
CREATE_ASYMMETRIC_PRIV_KEY(). If secret generation fails, the result is
null.

Supported key_len values: The minimum and maximum key lengths in bits
are 1024 and 10,000. These lengths are constraints imposed by OpenSSL.

For an example showing how to use the return value for generating
symmetric keys, see the description of ASYMMETRIC_DERIVE().

URL: http://dev.mysql.com/doc/refman/5.7/en/enterprise-encryption-functions.html

