When a principal logs in, the login process prompts for a password. That password is used to pass the user through the login security gate and give the user access to the network. The login process also decrypts the user's private key stored in the user's home domain cred table and passes that private key to the keyserver. The keyserver then uses that decrypted private key to authenticate the user each time the user accesses an NIS+ object.
Normally, this is the only time the principal is asked to provide a password. However, if the principal's private key in the cred table was encrypted with a password that was different from the user's login password, login cannot decrypt it using the login password at login time, and thus cannot provide a decrypted private key to the keyserver. (This most often occurs when a user's private key in the cred table was encrypted with a Secure RPC password different from the user's login password.)
In this context, network password is sometimes used as a synonym for Secure RPC password.
To temporarily remedy this problem, the principal must perform a keylogin, using the keylogin command, after every login. (The -r flag is used to keylogin the superuser principal and to store the superuser's key in /etc/.rootkey on a host.)
For a principal user
For a principal machine (only once)
Note, however, that performing an explicit keylogin with the original password provides only a temporary solution good for the current login session only. The private key in the cred table is still encrypted with a password different than the user's login password so the next time the user logs in the problem will reoccur. To permanently solve this problem, the user must run chkey to change the password used to encrypt the private key to the user's login password (see Changing Keys for an NIS+ Principal).