RFR: 8367344: Better error message when decryption of AP-REQ fails because of kvno mismatch

[Mikhail Yankelevich]

On Mon, 15 Sep 2025 15:49:11 GMT, Weijun Wang <weijun at openjdk.org> wrote:

> For interoperability, AP-REQ decryption uses the key with the highest kvno in the keytab if no exact match is found. If decryption fails, a normal "checksum failed" error is reported, which may hide the real cause that the wrong key is used. This code change throws a KRB_AP_ERR_BADKEYVER error in this case.
> 
> The change is only made in AP-REQ decryption to minimize impact. A previous test is enhanced to cover the case.

src/java.security.jgss/share/classes/sun/security/krb5/EncryptionKey.java line 578:

> 576:                     Integer kv = keys[i].getKeyVersionNumber();
> 577:                     etypeFound = true;
> 578:                     if (versionMatches(kvno, kv)) {

I believe there is no coverage for this block. Do you think expanding the test would be reasonable in this pr?

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PR Review Comment: https://git.openjdk.org/jdk/pull/27298#discussion_r2353005366