Minimum CA Requirements
Here we discuss the
minimum requirements for traditional online PKI CAs. These have evolved over a
period of three years in an iterative discursive fashion – largely as a result
of the numerous difficulties that arise when interoperating between different
linguistic, administrative, networking and security domains as occur over
national boundaries. In this section, the key words `must', `must not',
`required', `shall', `shall not', `should', `should not', `recommended', `may',
and `optional' in this document are to be interpreted as described in RFC 2119.
Due to certain idiosyncrasies of the Grid
middleware, the PKI structure within each country should should not follow the
conventional hierarchical
model, where there is a chain of CAs. The model followed
simulates the hierarchical model , but there should by having be one a single Certification
Authority (CA) per country or , large region (5-20M people) or international
organization. and aA wide network of Registration Authorities
(RA) for each CA
is preferred. The RAs will handle the tasks of validating the identity of
the end entities and authenticating their requests, which will then be
forwarded at to the national/regional CA.
The CA will handle the actual tasks of issuing CRLs, signing Certificates/CRLS
and revoking Certificates when necessary.
The CA computer,
where the signing of the certificates will take place, needs to be a dedicated machine, running no other services
than those needed for the CA operations. The CA computer must be located in a
secure environment where access is controlled, limited to specific trained
personnel and must be kept disconnected from any kind of networks at all times.
In case the CA computer is equipped with at least a FIPS 140-1 level 3 Hardware
Security Module or
equivalent , to protect the CA’s private key,
the CA computer can be connected to a highly protected/monitored network,
possibly accessible from the Internet. The secure environment must be documented that are
available to the PMA.
Each CA must
sign only a well defined namespace that does not clash with any other CA.
Every CA must have a Certification Policy and Certificate
Practice Statement (CP/CPS Document) and assign it an O.I.D. Whenever there is
a change in the CP/CPS the O.I.D. of the document must change and the major changes must be announced to the
euGridPMA for and approvedal before
signing any certs under the new CP/CPs. All the CP/CPS under which valid certs are issued MUST be
available on the web.
The CA Key must have a minimum length of 2048 bits and for CAs that issue
end-entity certificates the a lifetime must be no longer of 5 years and no less than
two times of the maximum life time of an end entity certificate.
The private key
of the CA must be protected with a pass phrase of at least 15 elements which is
known only by specific personnel of the Certification Authority.
Copies of the encrypted private key must be kept on offline mediums in secure
places where access is controlled.
The pass phrase of the encrypted private must be kept
also on an offline medium, separated from the encrypted keys and guarded in a
safe place where only the autorized personnel of the Certification Authority
have access.
The
CA certificate must have the extensions keyUsage and basicConstraints marked as
critical.
The maximum CRL lifetime must be at most 30 days and the
CA must issue a new CRL at least 7 days before expiration and immediatelly
after a revocation. The CRLS must be published in a repository at least
accessible via the World Wide Web, as soon as issued.
The CA must record and archive all requests for
certificates, along with all the issued certificates, all the request for
revocation, all the issued CRLs and the login/logout/reboot of the issuing
machine.
The CA's private signing key must be changed
periodically; from that time on only the new key will be used for certificate
signing purposes. The
overlap of the old and new key must be at least the longest time an end-entity
cert can be valid.The period of changing the CA’s private key must
not be longer than the CA Key lifetime minus the maximum life time of an end entity
certificate. The older , but
still valid certificate, must be available to verify old
signatures – and
the secret key to sign CRLs – until all the certificates
signed using the associated private key have also expired.
The repository must be run at least on a best-effort
basis, with an intended availability of 24x7.
Each CA must accept being audited by other trusted
accredited
CAs to verify its compliance with the rules and procedures specified in
its CP/CPS document.
The CA must perform operational audits of the CA/RA staff
at least once per year.
In order for an
RA to validate the identity of a person, the subject must contact the RA
personally and present photo-id and/or valid official documents
showing that the subject is an acceptable end entity as defined in the CP/CPS
document of the CA.
In case of host
or service certificate requests, the CSR be delivered to the RA by the person
in charge of the specific entities using a secure method.
The subject name listed in a
certificate must be unambiguous and unique for all certificates issued to the same entity by
the CA.
The RAs must
record and archive all requests and confirmations.
The RA must communicate with the CA with secure methods
that are clearly defined in the CP/CPS. (e.g. Signed emails, voice
conversations with a known person, SSL protected private web pages that are
bi-directionally authenticated)
The EE keys must be at least 1024
bits long and must not be generated by the CA or the RA. The EE certificates
must have a maximum lifetime of 1 year and must not be shared among end
entities. The EE certificate must contain information to identify which CP/CPS
was used to issue the certificate (e.g. OID or by date). The extensions basicConstraints and
keyUsage must be marked as critical and the basicConstraints must be set to “CA: False”.
The CA should make a reasonable effort to make sure
that end-entities realize the importance of properly protecting their private
data. It’s
upon the user to protect his private key with a pass phrase at least 12
characters long.