"Credential retrieval failed" during recovery of an Oracle database When starting up automatic instance INSTANCE:

RMAN-00571: =========================================================== 
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS =============== 
RMAN-00571: =========================================================== 
RMAN-03002: failure of recover command at 06/19/2015 15:40:19 
RMAN-04006: error from auxiliary database: 
    ORA-12638: Credential retrieval failed


I created an Oracle 12c database with 1 CDB and 2 PDB and told Oracle to create a user for me and also added this user in the registry to have access to the eventlog. I don't have any problem in restore but recovery is giving the above error. I am doing PIT restore and then recovery using these commands:

shutdown immediate;
startup;
RUN {
configure default device type to SBT_TAPE;
set until SCN = 2259403;
restore pluggable database PDB1;
recover pluggable database PDB1 auxiliary destination='C:\oracle\12.1.0\dbhome_1\temp';
[STDIN]: }
alter pluggable database PDB1 open resetlogs;
EXIT;
I've just solved the same error on Oracle12c under Windows on my test enviroment.
The Oracle service was running under oracle user local account but I was trying the PITR with my domain user. Even if my domain user was member of ORADBA group I've got the same nasty ORA-12638 error.

I've changed the user account of the Oracle Service and got it finally working.
I guess if you use SYSTEM account it will work as well.

Regards,
Daniel.