Privacy advocates warn that many Websites try to collect personal information from on-line users, but few guarantee how that data will be used. They say the federal government should establish standards to protect privacy on-line. But Internet businesses and others contend that they can safeguard users' privacy without resorting to government interference. Law-enforcement agencies, meanwhile, favor government limitations on the use of sophisticated encryption technology, which makes on-line communications secure — even from the police. They fear that strong encryption software will aid criminals in hiding their activities. But privacy advocates argue that encryption technology assures companies and consumers that their on-line communications are not being tampered with.