A digital file is associated with a security attribute in which identification data for a physical key is stored. The digital file content is encrypted, and may not be decrypted by a receiving computer unless a removable physical key that can be associated with the receiving computer includes identification data which matches the identification data stored in the file's security attribute. The digital content encrypted in the file may be compressed, and a portion of the security attribute may also be encrypted. When a portion of the security attribute is encrypted, the receiving computer may decrypt only the encrypted portion of the security attribute unless the identification data of the security attribute matches the identification data of a physical key physically or wirelessly coupled to the receiving computer. Improved security and reduction of pirating of the digital content are therefore provided.