Abstract: Data security is provided using an encryption/decryption algorithm which attaches at the primitive BIOS level of the operating system automatically during the power-on self-test routines. The encryption/decryption process is implemented by intercepting the removable media or floppy diskette interrupt in order to add additionasl interrupt ahandling routing instructions which perform the encryption and decryption of data passed between the diskette controller and the data transfer buffer area within system RAM. Bitwise alteratio of the data in a predefined relationship is used to encrypt and decrypt. The encryption/decryption system sttaches before the computer power-up sequence renders data entry hardware active, hence the user cannot readily override the secrity system. Data stored on nonremovable media such as hard disk media is not encrypted, thereby preserving the integrity of more permanent data.

Abstract: Data security is provided using an encryption/decryption algorithm which attaches at the primitive BIOS level of the operating system automatically during the power-on self-test routines. The encryption/decryption process is implemented by intercepting the removable media or floppy diskette interrupt in order to add additional interrupt handling routing instructions which perform the encryption and decryption of data passed between the diskette controller and the data transfer buffer area within system RAM. Bitwise alteration of the data in a predefined relationship is used to encrypt and decrypt. The encryption/decryption system attaches before the computer power-up sequence renders data entry hardward active, hence the user cannot readily override the security system. Data stored on nonremovable media such as hard disk media is not encrypted, thereby preserving the integrity of more permanent data.