oysteikt/heimdal
0
0
Fork 0
Code Issues 5 Pull Requests Releases Activity

Merge documentation update from Mustafa Hashmi.

Browse Source 
git-svn-id: svn://svn.h5l.se/heimdal/trunk/heimdal@23522 ec53bebd-3082-4978-b11e-865c3cabbd6b
This commit is contained in:
Love Hörnquist Åstrand
2008-08-11 10:02:08 +00:00
parent e112c2f9aa
commit 742ade64a2
1 changed files with 197 additions and 118 deletions
Download Patch File Download Diff File Expand all files Collapse all files

315
doc/hx509.texi
View File

@@ -220,32 +220,55 @@ Software PKCS 11 module
@node Introduction, What is X.509 ?, Top, Top
@chapter Introduction
hx509 is a somewhat complete X.509 stack that can handle CMS messages
(crypto system used in S/MIME and Kerberos PK-INIT) and basic
certificate processing tasks, path construction, path validation, OCSP
and CRL validation, PKCS10 message construction, CMS Encrypted (shared
secret encrypted), CMS SignedData (certificate signed), and CMS
EnvelopedData (certificate encrypted).
The goals of a PKI infrastructure (as defined in
<a href="http://www.ietf.org/rfc/rfc3280.txt">RFC 3280</a>) is to meet
@emph{the needs of deterministic, automated identification, authentication, access control, and authorization}.
hx509 can use PKCS11 tokens, PKCS12 files, PEM files, DER encoded files.
The administrator should be aware of certain terminologies as explained by the aforementioned
RFC before attemping to put in place a PKI infrastructure. Briefly, these are:
@itemize @bullet
@item CA
Certificate Authority
@item RA
Registration Authority, i.e., an optional system to which a CA delegates certain management functions.
@item CRL Issuer
An optional system to which a CA delegates the publication of certificate revocation lists.
@item Repository
A system or collection of distributed systems that stores certificates and CRLs
and serves as a means of distributing these certificates and CRLs to end entities
@end itemize
hx509 (Heimdal x509 support) is a near complete X.509 stack that can
handle CMS messages (crypto system used in S/MIME and Kerberos PK-INIT)
and basic certificate processing tasks, path construction, path
validation, OCSP and CRL validation, PKCS10 message construction, CMS
Encrypted (shared secret encrypted), CMS SignedData (certificate
signed), and CMS EnvelopedData (certificate encrypted).
hx509 can use PKCS11 tokens, PKCS12 files, PEM files, and/or DER encoded
files.
@node What is X.509 ?, Setting up a CA, Introduction, Top
@chapter What is X.509, PKIX, PKCS7 and CMS ?
X.509 is from the beginning created by CCITT (later ITU) for the X.500
directory service. But today when people are talking about X.509 they
are commonly referring to IETF's PKIX Certificate and CRL Profile of the
X.509 v3 certificate standard, as specified in RFC 3280.
X.509 was created by CCITT (later ITU) for the X.500 directory
service. Today, X.509 discussions and implementations commonly reference
the IETF's PKIX Certificate and CRL Profile of the X.509 v3 certificate
standard, as specified in RFC 3280.
ITU continues to develop the X.509 standard together in a complicated
dance with IETF.
ITU continues to develop the X.509 standard together with the IETF in a
rather complicated dance.
X.509 is public key based security system that have associated data
stored within a so called certificate. From the beginning X.509 was a
strict hierarchical system with one root. This didn't not work so over
time X.509 got support for multiple policy roots, bridges, and mesh
solutions. You can even use it as a peer to peer system, but this is not
very common.
X.509 is a public key based security system that has associated data
stored within a so called certificate. Initially, X.509 was a strict
hierarchical system with one root. However, ever evolving requiments and
technology advancements saw the inclusion of multiple policy roots,
bridges and mesh solutions.
x.509 can also be used as a peer to peer system, though often seen as a
common scenario.
@section Type of certificates
@@ -255,36 +278,36 @@ There are several flavors of certificate in X.509.
@item Trust anchors
Trust anchors are strictly not certificate, but commonly stored in
certificate since they are easier to handle then. Trust anchor are the
keys that you trust to validate other certificate. This is done by
building a path from the certificate you wan to validate to to any of
the trust anchors you have.
Trust anchors are strictly not certificates, but commonly stored in a
certificate format as they become easier to manage. Trust anchors are
the keys that an end entity would trust to validate other certificates.
This is done by building a path from the certificate you want to
validate to to any of the trust anchors you have.
@item End Entity (EE) certificates
End entity certificates is the most common type of certificate. End
entity certificates can't issue certificate them-self and is used to
authenticate and authorize user and services.
End entity certificates are the most common types of certificates. End
entity certificates cannot issue (sign) certificate themselves and are generally
used to authenticate and authorize users and services.
@item Certification Authority (CA) certificates
Certificate authority are certificates that have the right to issue
other certificate, they may be End entity certificates or Certificate
Authority certificates. There is no limit to how many certificates a CA
Certificate authority certificates have the right to issue additional
certificates (be it sub-ordinate CA certificates to build an trust anchors
or end entity certificates). There is no limit to how many certificates a CA
may issue, but there might other restrictions, like the maximum path
depth.
@item Proxy certificates
Remember that End Entity can't issue certificates by them own, it's not
really true. There there is an extension called proxy certificates,
defined in RFC3820, that allows certificates to be issued by end entity
certificates. The service that receives the proxy certificates must have
explicitly turned on support for proxy certificates, so their use is
somewhat limited.
Remember the statement "End Entity certificates cannot issue
certificates"? Well that statement is not entirely true. There is an
extension called proxy certificates defined in RFC3820, that allows
certificates to be issued by end entity certificates. The service that
receives the proxy certificates must have explicitly turned on support
for proxy certificates, so their use is somewhat limited.
Proxy certificates can be limited by policy stored in the certificate to
Proxy certificates can be limited by policies stored in the certificate to
what they can be used for. This allows users to delegate the proxy
certificate to services (by sending over the certificate and private
key) so the service can access services on behalf of the user.
@@ -294,59 +317,52 @@ large job in the middle of the night when the printer isn't used that
much, so the user creates a proxy certificate with the policy that it
can only be used to access files related to this print job, creates the
print job description and send both the description and proxy
certificate with key over to print service. Later at night will the
print service, without the help of the user, access the files for the
the print job using the proxy certificate and print the job. Because of
the policy (limitation) in the proxy certificate, it can't be used for
any other purposes.
certificate with key over to print service. Later at night when the
print service initializes (without any user intervention), access to the files
for the print job is granted via the proxy certificate. As a result of (in-place)
policy limitations, the certificate cannot be used for any other purposes.
@end itemize
@section Building a path
Before validating a path the path must be constructed. Given a
certificate (EE, CA, Proxy, or any other type), the path construction
algorithm will try to find a path to one of the trust anchors.
Before validating a certificate path (or chain), the path needs to be
constructed. Given a certificate (EE, CA, Proxy, or any other type),
the path construction algorithm will try to find a path to one of the
trust anchors.
It start with looking at whom issued the certificate, by name or Key
Identifier, and tries to find that certificate while at the same time
evaluates the policy.
The process starts by looking at the issuing CA of the certificate, by
Name or Key Identifier, and tries to find that certificate while at the
same time evaluting any policies in-place.
@node Setting up a CA, Creating a CA certificate, What is X.509 ?, Top
@chapter Setting up a CA
Do not let this chapter scare you off, it's just to give you an idea how
to complicated setting up a CA can be. If you are just playing around,
skip all this and go to the next chapter, @pxref{Creating a CA
certificate}.
Do not let information overload scare you off! If you are simply testing
or getting started with a PKI infrastructure, skip all this and go to
the next chapter (see: @pxref{Creating a CA certificate}).
Creating a CA certificate should be more the just creating a
certificate, there is the policy of the CA. If it's just you and your
friend that is playing around then it probably doesn't matter what the
policy is. But then it comes to trust in an organisation, it will
probably matter more whom your users and sysadmins will find it
acceptable to trust.
certificate, CA's should define a policy. Again, if you are simply
testing a PKI, policies do not matter so much. However, when it comes to
trust in an organisation, it will probably matter more whom your users
and sysadmins will find it acceptable to trust.
At the same time, try to keep thing simple, it's not very hard to run a
Certificate authority and the process to get new certificates should
simple.
At the same time, try to keep things simple, it's not very hard to run a
Certificate authority and the process to get new certificates should be simple.
Fill all this in later.
You may find it helpful to answer the following policy questions for
your organization at a later stage:
How do you trust your CA.
What is the CA responsibility.
Review of CA activity.
How much process should it be to issue certificate.
Who is allowed to issue certificates.
Who is allowed to requests certificates.
How to handle certificate revocation, issuing CRLs and maintain OCSP
services.
@itemize @bullet
@item How do you trust your CA.
@item What is the CA responsibility.
@item Review of CA activity.
@item How much process should it be to issue certificate.
@item Who is allowed to issue certificates.
@item Who is allowed to requests certificates.
@item How to handle certificate revocation, issuing CRLs and maintain OCSP services.
@end itemize
@node Creating a CA certificate, Issuing certificates, Setting up a CA, Top
@section Creating a CA certificate
@@ -357,10 +373,10 @@ about.
@subsection Lifetime CA certificate
You probably want to create a CA certificate with a long lifetime, 10
years at the shortest. This because you don't want to push out the
certificate (as a trust anchor) to all you users once again when the old
one just expired. A trust anchor can't really expire, but not all
software works that way.
years at the very minimum. This is because you don't want to push out the
certificate (as a trust anchor) to all you users again when the old
CA certificate expires. Although a trust anchor can't really expire, not all
software works in accordance with published standards.
Keep in mind the security requirements might be different 10-20 years
into the future. For example, SHA1 is going to be withdrawn in 2010, so
@@ -369,7 +385,7 @@ algorithms, signature algorithms and key lengths.
@subsection Create a CA certificate
This command below will create a CA certificate in the file ca.pem.
This command below can be used to generate a self-signed CA certificate.
@example
hxtool issue-certificate \
@@ -381,14 +397,14 @@ hxtool issue-certificate \
--certificate="FILE:ca.pem"
@end example
@subsection Extending lifetime of a CA certificate
@subsection Extending the lifetime of a CA certificate
You just realised that your CA certificate is going to expire soon and
that you need replace it with something else, the easiest way to do that
is to extend the lifetime of your CA certificate.
that you need replace it with a new CA. The easiest way to do that
is to extend the lifetime of your existing CA certificate.
The example below will extend the CA certificate 10 years into the
future. You should compare this new certificate if it contains all the
The example below will extend the CA certificate's lifetime by 10 years.
You should compare this new certificate if it contains all the
special tweaks as the old certificate had.
@example
@@ -404,7 +420,7 @@ hxtool issue-certificate \
@subsection Subordinate CA
This example create a new subordinate certificate authority.
This example below creates a new subordinate certificate authority.
@example
hxtool issue-certificate \
@@ -420,17 +436,34 @@ hxtool issue-certificate \
@section Issuing certificates
First you'll create a CA certificate, after that you have to deal with
your users and servers and issue certificate to them.
your users and servers and issue certificates to them.
CA can generate the key for the user.
@c I think this section needs a bit of clarity. Can I add a separate
@c section which explains CSRs as well?
Can receive PKCS10 certificate requests from the users. PKCS10 is a
request for a certificate. The user can specified what DN the user wants
and what public key. To prove the user have the key, the whole request
is signed by the private key of the user.
@itemize @bullet
@item Do all the work themself
Generate the key for the user. This has the problme that the the CA
knows the private key of the user. For a paranoid user this might leave
feeling of disconfort.
@item Have the user do part of the work
Receive PKCS10 certificate requests fromusers. PKCS10 is a request for a
certificate. The user may specify what DN they want as well as provide
a certificate signing request (CSR). To prove the user have the key,
the whole request is signed by the private key of the user.
@end itemize
@subsection Name space management
@c The explanation given below is slightly unclear. I will re-read the
@c RFC and document accordingly
What people might want to see.
Re-issue certificates just because people moved within the organization.
@@ -441,22 +474,43 @@ Using Sub-component name (+ notation).
@subsection Certificate Revocation, CRL and OCSP
Sonetimes people loose smartcard or computers and certificates have to
be make not valid any more, this is called revoking certificates. There
are two main protocols for doing this Certificate Revocations Lists
(CRL) and Online Certificate Status Protocol (OCSP).
Certificates that a CA issues may need to be revoked at some stage. As
an example, an employee leaves the organization and does not bother
handing in his smart card (or even if the smart card is handed back --
the certificate on it must no longer be acceptable to services; the
employee has left).
If you know that the certificate is destroyed then there is no need to
revoke the certificate because it can not be used by someone else.
You may also want to revoke a certificate for a service which is no
longer being offered on your network. Overlooking these scenarios can
lead to security holes which will quickly become a nightmare to deal
with.
There are two primary protocols for dealing with certificate
revokation. Namely:
@itemize @bullet
@item Certificate Revocation List (CRL)
@item Online Certificate Status Protocol (OCSP)
@end itemize
If however the certificate in qeustion has been destroyed, there is no
need to revoke the certificate because it can not be used by someone
else. This matter since for each certificate you add to CRL, the
download time and processing time for clients are longer.
CRLs and OCSP responders however greatly help manage compatible services
which may authenticate and authorize users (or services) on an on-going
basis. As an example, VPN connectivity established via certificates for
connecting clients would require your VPN software to make use of a CRL
or an OCSP service to ensure revoked certificates belonging to former
clients are not allowed access to (formerly subscribed) network
services.
The main reason you as a CA administrator have to deal with CRLs however
will be that some software require there to be CRLs. Example of this is
Windows, so you have to deal with this somehow.
@node Issuing CRLs, Application requirements, Issuing certificates, Top
@section Issuing CRLs
Create an empty CRL with not certificates revoked. Default expiration
Create an empty CRL with no certificates revoked. Default expiration
value is one year from now.
@example
@@ -480,7 +534,7 @@ hxtool crl-sign \
@node Application requirements, CMS signing and encryption, Issuing CRLs, Top
@section Application requirements
Application have different requirements on certificates. This section
Application place different requirements on certificates. This section
tries to expand what they are and how to use hxtool to generate
certificates for those services.
@@ -513,14 +567,14 @@ The email address format used in S/MIME certificates is defined in
RFC2822, section 3.4.1 and it should be an ``addr-spec''.
There are two ways to specifify email address in certificates. The old
ways is in the subject distinguished name, this should not be used. The
way is in the subject distinguished name, @emph{this should not be used}. The
new way is using a Subject Alternative Name (SAN).
But even though email address is stored in certificates, they don't need
to, email reader programs are required to accept certificates that
doesn't have either of the two methods of storing email in certificates.
In that case, they try to protect the user by printing the name of the
certificate instead.
Even though the email address is stored in certificates, they don't need
to be, email reader programs are required to accept certificates that
doesn't have either of the two methods of storing email in certificates
-- in which case, the email client will try to protect the user by
printing the name of the certificate instead.
S/MIME certificate can be used in another special way. They can be
issued with a NULL subject distinguished name plus the email in SAN,
@@ -553,26 +607,51 @@ hxtool issue-certificate \
@subsection PK-INIT
How to create a certificate for a KDC.
A PK-INIT infrastructure allows users and services to pick up kerberos
credentials (tickets) based on their certificate. This, for example,
allows users to authenticate to their desktops using smartcards while
acquiring kerberos tickets in the process.
As an example, an office network which offers centrally controlled
desktop logins, mail, messaging (xmpp) and openafs would give users
single sign-on facilities via smartcard based logins. Once the kerberos
ticket has been acquired, all kerberized services would immediately
become accessible based on deployed security policies.
Let's go over the process of initializing a demo PK-INIT framework:
@example
hxtool issue-certificate \
--type="pkinit-kdc" \
--pk-init-principal="krbtgt/TEST.H5L.SE@@TEST.H5L.SE" \
--hostname kerberos.test.h5l.se \
--hostname pal.test.h5l.se \
...
--type="pkinit-kdc" \
--pk-init-principal="krbtgt/TEST.H5L.SE@@TEST.H5L.SE" \
--hostname=kerberos.test.h5l.se \
--ca-certificate="FILE:ca.pem,ca.key" \
--generate-key=rsa \
--certificate="FILE:kdc.pem" \
--subject="cn=kdc"
@end example
How to create a certificate for a user.
@example
hxtool issue-certificate \
--type="pkinit-client" \
--pk-init-principal="user@@TEST.H5L.SE" \
...
--type="pkinit-client" \
--pk-init-principal="user@@TEST.H5L.SE" \
--ca-certificate="FILE:ca.pem,ca.key" \
--generate-key=rsa \
--subject="cn=Test User" \
--certificate="FILE:user.pem"
@end example
The --type field can be specified multiple times. The same certificate
can hence house extensions for both pkinit-client as well as S/MIME.
To use the PKCS11 module, please see the section:
@pxref{How to use the PKCS11 module}.
More about how to configure the KDC, see the documentation in the
Heimdal manual to set up the KDC.
@subsection XMPP/Jabber
The jabber server certificate should have a dNSname that is the same as