| 摘要 |
A system (10) for protecting information over the Internet (16), or other public network, is provided at a web site addressable by one or more client computer systems (18). Each client computer system connects to the web site to receive a respondent identifier and viewer software. A unique viewer identifier is generated by the viewer software at the client computer system (18) and sent to the web site for registering the viewer identifier with the respondent identifier. The web site has a database (20) and one or more web servers (12, 13, 14, 15) coupled to the database. The database (20) stores registration information including the viewer identifier and associated respondent identifiers for the client computer systems (18), encrypted conte nt information files and keys to decrypt such files, survey invitation information for each of the surveys, and exposure limit information. In response to receiving a survey in accordance with an invitation, the client computer system (18) enables the content viewer to connect to the web site o f the content protection system (10) and download a file with the encrypted content information for that survey. The viewer software then sends a reques t to the content protection system (10) for a key to decrypt the downloaded content information file. The content protection system (10) determines, bas ed on the respondent, viewer and survey identifiers and associated exposure lim it information, whether to send a decryption key. If so, a decryption key is se nt to the client computer system (18) and the viewer uses the key to decrypt th e encrypted content information file, and then opens a viewer window to show t he decrypted content information on the display of the computer system (18). During viewing on the computer system (18), the viewer limits access to the window showing the displayed content information which would typically allow the user to access information and enable copying.
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