A content server provides a browser of a client with encrypted content and with obfuscated browser-executable code for decrypting and displaying the content within the browser. Both the encrypted content and the obfuscated browser-executable code are generated based at least in part on an identity of the user requesting the content, and thus are different from encrypted content and obfuscated browser-executable code provided to other users. Further, in one embodiment the browser-executable code provided by the server changes periodically, such as weekly, thereby rendering ineffective any malicious software tools that obtain decrypted content by calling expected functions of the code. In one embodiment, the obfuscated browser-executable code for a user is pre-computed before that user makes a request for content.