An authentication server authenticates a first user, and generates a voucher code that is provided to the authenticated first user. The first user may provide the voucher code to a second user, responsive to a request by the second user for the first user to vouch for the second user, to thereby allow the second user to be authenticated. The authentication server receives the voucher code from the second user, and authenticates the second user based on the voucher code. The authenticated second user may be provided with a temporary password or other type of code utilizable for at least one additional authentication.