An immutable sequence of certificates (a certification path).
This is an abstract class that defines the methods common to all
CertPath
s. Subclasses can handle different kinds of
certificates (X.509, PGP, etc.).
All CertPath
objects have a type, a list of
Certificate
s, and one or more supported encodings. Because the
CertPath
class is immutable, a CertPath
cannot
change in any externally visible way after being constructed. This
stipulation applies to all public fields and methods of this class and any
added or overridden by subclasses.
The type is a String
that identifies the type of
Certificate
s in the certification path. For each
certificate cert
in a certification path certPath
,
cert.getType().equals(certPath.getType())
must be
true
.
The list of Certificate
s is an ordered List
of
zero or more Certificate
s. This List
and all
of the Certificate
s contained in it must be immutable.
Each CertPath
object must support one or more encodings
so that the object can be translated into a byte array for storage or
transmission to other parties. Preferably, these encodings should be
well-documented standards (such as PKCS#7). One of the encodings supported
by a CertPath
is considered the default encoding. This
encoding is used if no encoding is explicitly requested (for the
getEncoded()
method, for instance).
All CertPath
objects are also Serializable
.
CertPath
objects are resolved into an alternate
CertPathRep
object during serialization. This allows
a CertPath
object to be serialized into an equivalent
representation regardless of its underlying implementation.
CertPath
objects can be created with a
CertificateFactory
or they can be returned by other classes,
such as a CertPathBuilder
.
By convention, X.509 CertPath
s (consisting of
X509Certificate
s), are ordered starting with the target
certificate and ending with a certificate issued by the trust anchor. That
is, the issuer of one certificate is the subject of the following one. The
certificate representing the TrustAnchor
should not be
included in the certification path. Unvalidated X.509 CertPath
s
may not follow these conventions. PKIX CertPathValidator
s will
detect any departure from these conventions that cause the certification
path to be invalid and throw a CertPathValidatorException
.
Concurrent Access
All CertPath
objects must be thread-safe. That is, multiple
threads may concurrently invoke the methods defined in this class on a
single CertPath
object (or more than one) with no
ill effects. This is also true for the List
returned by
CertPath.getCertificates
.
Requiring CertPath
objects to be immutable and thread-safe
allows them to be passed around to various pieces of code without worrying
about coordinating access. Providing this thread-safety is
generally not difficult, since the CertPath
and
List
objects in question are immutable.