Sign a CSR with another certificate (or itself) and generate a certificate
Function csr_sign (csr, cacert, priv_key, days As Long, [configargs], [serial]) As Object
csr_sign generates an x509 certificate resource
from the csr previously generated by csr_new,
but it can also be the path to a PEM encoded CSR when specified as file://path/to/csr
or an exported string generated by csr_export.
The generated certificate will be signed by cacert.
If cacert is NULL,
the generated certificate will be a self-signed certificate. priv_key
is the private key that corresponds to cacert.
days specifies the length of time for which
the generated certificate will be valid, in days.
Returns an x509 certificate resource on success, FALSE
Note: You need to have a valid openssl.cnf
installed for this function to operate correctly.