Open Radar

 
Summary:
Trying to add a user to FileVault2 using 'fdesetup add' exits with 17 and fails when using RecoveryKey as a user and the recoverykey as password.

Steps to Reproduce:
Enable FV2 with fdesetup enable
Create a new user with system preferences
Delete the newly added user from FV2 with fdesetup remove -user newuser
Create an inputplist where the authorizing user is RecoveryKey and the password the recoverykey as returned by fdesetup enable
cat input.plist | fdesetup add -inputplist -verbose

Expected Results:
The user foo from the attached plist is added to filevault2

Observed Results:
The command fails and returns 17
cat input.plist | fdesetup add -inputplist -verbose
fdesetup: auth info dictionary path = stdin
fdesetup: device path = /
OD user 'admin' could not be authenticated.
Adding user 'foo' to existing FileVault
Error: user could not be added (-69578).
Error: Unable to add one or more users to FileVault.

Version:
macOS 10.13 Beta3 / Build 17A306f

Notes:
The same behaviour is seen when not using an inputplist but the interactive mode with the recoverykey instead of the password 
Attached is the plist I used

Configuration:
Systemdisk is formatted with APFS