1. Data Security: Introduction and Motivation. - 2. Statistical Database Security. - 2. 1. Introduction. - 2. 2. Security with Characteristic-Specified Queries. - 2. 3. Security in the Key-Specified Model. - 2. 4. Conclusion. - 3. Authorization Mechanisms. - 3. 1. Introduction. - 3. 2. The Undecidability of the Safety Problem for General Authorization Systems. - 3. 3. Authorization Systems with Tractable Safety Problem. - 3. 4. Overview of a Practical Implementation. - 4. Cryptosystems. - 4. 1. Introduction and Motivation. - 4. 2. Symmetric Cryptosystems. - 4. 3. Public Key Cryptosystems. - 4. 4. Authentication and Digital Signatures. - 4. 5. Protecting Ownership of Proprietary Data and Software. - References. Language: English