The online surveillance bill was effectively a digital key to determining someone's leanings, the people they know and where they travel, says the office of Privacy Commissioner Jennifer Stoddart.
"What's more, each of these pieces of information can be used to uncover further information about an individual," concludes the study.
"As information technologies become more and more common in our lives, and the more they become an extension of our very selves, the more sensitive and revealing subscriber identification information becomes."
The Conservative government abandoned the legislation in February following a public outcry.
The bill would have allowed police, intelligence agents and competition bureau officers access to Internet subscriber information — including name, address, telephone number, email address and Internet Protocol (IP) address — without a warrant.
Currently, the release of such data held by Internet service providers is voluntary.
Opponents of the bill said allowing authorities access to Internet subscriber information without a court-approved warrant would be a worrisome erosion of privacy because even that limited data can help paint a candid picture.
The federal government, on the other hand, likened the information in question to a listing in a public phone book.
The privacy commissioner's study, initiated while the bill was still before Parliament, says the government's characterization "grossly misconstrues and underestimates" what can be gleaned from the data with a bit of additional effort.
"In general, the findings lead to the conclusion that, unlike simple phone book information, the elements examined can be used to develop very detailed portraits of individuals providing insight into one's activities, tastes, leanings and lives."
Assistant privacy commissioner Chantal Bernier said Canadians are protective about their Internet activities.
"We should be extremely careful about granting unwarranted access about basic subscriber information," she said Wednesday in an interview.
"The challenge is to ensure privacy on the Internet while at the same time not creating a space for anonymity for criminals."
In its study, the privacy commissioner's office focused on elements covered by the bill which are not found in a phone book — email address, mobile phone number and IP address, the numerical sequence assigned to an online device.
Taking the actual mobile phone number of a staff member in the privacy commissioner's office, the researchers used commonly available Internet tools such as search engines to reveal the individual's full name, their phone service provider, two personal web sites and their domain registrations, an affiliation with a university and contributions to online discussion forums.
Similar to a phone number, an email address can lead to a variety of information about someone, says the study, including friends on social network services and previous employers.
An IP address can help divulge someone's personal interests and even point to their physical location, the privacy commissioner added.
A service provider may assign a temporary IP address to a computer for anywhere from a few days to a few months, notes the study.
The authors looked at one IP address shown by Wikipedia, the online encyclopedia site, to reveal that the person behind the address had edited hundreds of entries about television shows and history topics, taken part in a discussion board about a TV channel and visited a site devoted to sexual preferences.
The study points to the case of David Petraeus, the U.S. Central Intelligence Agency director who resigned over revelation of an extramarital affair. His indiscretions came to light after the Federal Bureau of Investigation used IP addresses to trace harassing emails his mistress had sent to another woman.
In dropping the online surveillance bill, Justice Minister Rob Nicholson said the government would not include mandatory disclosure of basic subscriber information in future revisions of the Criminal Code.
Bernier said while she hopes the study's findings turn out to be moot, the privacy commissioner's office has received no direct assurances about the federal legislative intentions.
"We really have no idea, we have had no communication about that one way or another."
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