If you are worried about security set up public/private keys which avoid the problem of passwords and I think use 128bit encryption but even so this
...Finally, if other authentication methods fail, ssh prompts the user for a
password. The password is sent to the remote host for checking; however,
since all communications are encrypted, the password cannot be seen by
someone listening on the network...
from the man page would point to paswwords being reasonably secure ( depending on the password of course "abc123" is NOT a good password ).
In these situations the manpage is your friend!