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Authentication failures with non-default Windows Kerberos encryption types

edited Apr 19, 2020 1:43PM in Database Security Products (MOSC) 6 comments

For anyone who runs into this in the future -

Using Windows Server 2019, DBMS 19, authentication (sqlplus) fails with ORA-12638 even though all Oracle configuration appears to be correct.

SQLNET client traces (level 16) include

SSPI: 0x80090342 error in InitializeSecurityContext

This error appears to have been caused by a Windows OS configuration change made to enhance security; updating, within Local Security Policy, Local Policies->Security Options, the setting "Network security: Configure encryption types allowed for Kerberos" and removing RC4_HMAC_MD5 from the list, leaving only 'AES128_HMAC_SHA1, AES256_HMAC_SHA1, Future encryption types'.

I made this change on the client side and did not make any corresponding changes on the Oracle DBMS host, and ORA-12638 resulted with both NTS (Windows) authentication and native/database authentication.  Adding

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