openssl_pkey_new() generates a
new private and public key pair. The public component of the
key can be obtained using
openssl_pkey_get_public(). You can finetune the key
generation (such as specifying the number of bits) using configargs. See
openssl_csr_new() for more information about configargs.
注: You need to have a valid openssl.cnf installed for this function to operate correctly. See the notes under the installation section for more information.