The invention provides one or more consortia of networks that identify and share information about users and/or user devices interacting with the consortia. User devices may be identified, at least in part, by tag-based computer information. Computers and other devices accessing the Web carry device tags with date and time information describing when they were issued by a security tag server. A server time stamp may be inserted into time based computer tags such as a cookies indicating when they were created. Such time stamp information can be encrypted and analyzed during future attempts to access a secure network such as a customer attempting to log into an online banking account. When the time stamp information from the tag is compared to other selected information about the user, device and/or account, including but not limited to last account log-in date/time or account creation date, the invention may be used to detect suspicious activity. The invention may be use for identity-based applications such as network security, the detection of fraudulent transactions, identity theft, reputation-based communities, and law enforcement.