account migration and not force to change password

[qwerty <qwerty@seed.net.tw>]

Hi,

I'm going to migrate system accounts from flat file(passwd/shadow) to
LDAP.It would be best if not force everyone to change his password
after migration.

Yes, I can run some scripts to do the job.But as far as i know,if I'd
like to use different password hash(say SSHA,MD5....) rather than
{CRYPT} on LDAP,I must know the actual password for each account and
then generate new password into LDAP.The question is I don't know these
password and it looks as though the system password is one-way hash.

Has anyone had experience of related problem and how?

Thanks