Motivation:
SSLContext.buildTrustManagerFactory(...) builds a KeyStore to
initialize the TrustManagerFactory from an array of X509Certificates,
assuming that array is a chain and that each certificate will have a
unique Subject Distinguised Name.
However, the collection of certificates used as trust anchors is generally
not a chain (it is an unordered collection), and it is legitimate for it
to contain multiple certificates with the same Subject DN.
The existing code uses the Subject DN as the alias name when filling in
the `KeyStore`, thereby overwriting other certificates with the same
Subject DN in this collection, so some certificates may be discarded.
In addition, the code related to building trust managers can take an array of
X509Certificate instances to use as trust anchors. The variable name is
usually trustCertChain, and the documentation refers to them as a "chain".
However, while it makes sense to talk about a "chain" from a keymanager
point of view, these certificates are just an unordered collection in a
trust manager. (There is no chaining requirement, having the Subject DN
matching its predecessor's Issuer DN.)
This can create confusion to for users not used with PKI concepts.
Modifications:
SSLContext.buildTrustManagerFactory(...) now uses a distinct alias for each
array (simply using a counter, since this name is never used for reference
later). This patch also includes a unit test with CA certificates using the
same Subject DN.
Also renamed trustCertChain into trustCertCollection, and changed the
references to "chain" in the Javadoc.
Result:
Each loaded certificate now has a unique identifier when loaded, so it is
now possible to use multiple certificates with the same Subject DN as
trust anchors.
Hopefully, renaming the parameter should also reduce confusion around PKI
concepts.
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