The report by University of Toronto researchers gives low marks to all 20 providers ranked in 10 categories of transparency.
They looked at how much information the companies posted on their websites about how and when they give personal data to authorities, where and how long information is stored, and whether data is routed through the United States.
The report comes amid widespread concern about surveillance by western security agencies and a legislative move by the federal government to make it easier for authorities to find out more about Internet users.
The researchers, Andrew Clement and Jonathan Obar, say it is very difficult for Canadians to protect their personal privacy online unless companies reveal how they treat customer information.
They recommend that Internet providers and law-enforcement and security agencies do more to inform the public.
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