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From George Stanchev <George.Stanc...@microfocus.com>
Subject TLS key management
Date Mon, 11 Nov 2019 23:40:28 GMT
Currently, (in most cases) Tomcat creates an in-memory keystore and initializes kmf as follows:
KeyManagementFactory.getInstance(algo).init(keystore, kspass). The in-memory keystore has
the key, the certificate and the chain and nothing else. This works fine in most cases but
we've ran into a situation where this is not sufficient. I am running TC with BC as JSSE provider
in FIPS-approved only mode and in certain use cases we're running into issues with RSA key
reuse. FIPS states that an RSA key should be used for encryption/decryption or for signature/verification
but not for both. So when one browser (in our case it was FF) selects TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
BC's key manager marks and remembers the key usage, then another browser (Chrome) settles
for TLS_RSA_WITH_AES_128_GCM_SHA256 BC throws an key-reuse exception since the latter suite
uses RSA for key exchange and the former for authentication. The BC key manager has the ability
to select a different key based on KeyUsage extension, so it is possible to have multiple
RSA keys in memory that would be used according to their certificates KeyUsage policy. However
TC feeds only one certificate to the KM.

Here is a thread [1] that I ran into that shows someone else running into the issue and response
from BC developer.

To be fair, BCFIPS does have a -D override for the key usage override for RSA keys in approved-only
mode but according to this thread [2], the property is there for completely different purpose
and running it to get around the TC issue is not FIPS compliant.

So having looked at the code in SSLUtilBase#getKeyManagers(), is it worth opening a BZ request
to have some solution to this issue - perhaps if alias is omitted in configuration and the
keystore is of transferrable type (not ms, hardware, etc) then transfer all entries to the
KM and let it do the selection?

George


[1] http://bouncy-castle.1462172.n4.nabble.com/Using-different-cipher-suites-in-a-BCFIPS-JDK-triggers-RSA-key-reuse-td4659354.html
[2] http://bouncy-castle.1462172.n4.nabble.com/Modulus-reuse-in-FIPS-td4659219.html

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