||The SSH Cryptosystem|
|Subject:||Pass phrase prompt at each login|
Response to: Pass phrase prompt at each login
That is probably because you used a passphrase when generating your key.
The purpose of the passphrase is so that if someone were to steal your identity key (by booting up on a recovery floppy e.g., and snagging your key) it wouldn't be of any use to them if they didnt know your passphrase too. This is what they call 2 tier authentication, both a key and a passphrase are required ...