Facebook Inc. next week plans to roll out a new ad targeting feature that enables advertisers to target shoppers based on their e-mail addresses, phone numbers and, for game and application developers, their user names. The feature, which at first will only be available to marketers that work with a Facebook sales representative, will eventually also offer targeting based on a consumer’s address and other information, says a Facebook spokeswoman.

Marketers will only be able to use the new feature to target consumers who have previously shared that information with the marketer off of Facebook. For instance, a retailer could use consumers’ e-mail addresses that it gathered from sign-ups to its e-mail newsletter to place a Facebook ad asking them to Like its page. “This gives advertisers a new way to go and reach their customers on Facebook,” the spokeswoman says.

The social network says it has safeguards in place to protect consumers’ personal information. “We’re not giving access to any information from Facebook nor is the tool allowing advertisers to provide Facebook with any of their customers’ personally identifiable information,” she says.

The safeguard Facebook is referring to is hashing technology, which is found in its Power Editor ad management tool. Hashing technology takes an e-mail address or other information and converts it into a string of numbers and letters that cannot be reversed to create the original information.

The hashing technology enables the marketer to share the hashed version of its customers’ personal information, like their e-mail addresses, with Facebook, which hashes its own users’ information. The marketer can then target any of the consumers whose hashes match. The marketer can then use the matched list to target consumers any time it places an ad on the social network. Marketers will be able to target ads to their entire matched list or further refine who will see their ad by targeting shoppers based on information consumers have shared on Facebook, such as what they have Liked and their demographic information.