Abstract: Different levels of security are provided in a security system so that users can decide the security level of their own communications. Users can choose a low level of security and maintain the security overhead as low as possible. Alternatively, they can choose higher levels of security with attendant increases in security overhead. The different levels of security are created by the use of one or more of two keys: an encryption key is used to encrypt plaintext data in a delta and a message authentication key is used to authenticate and insure integrity of the data. Two keys are used to avoid re-encrypting the encrypted data for each member of the telespace. In one embodiment, the security level is determined when a telespace is created and remains fixed through out the life of the telespace. For a telespace, the security level may range from no security at all to security between the members of the telespace and outsiders to security between pairs of members of the telespace.

Abstract: The security of block cipher counter mode of operation can be improved, and stream ciphers can be converted to a “block-like” (stateless) mode of operation, by using a modified key which is a fixed secret key (K) combined with a varying random non-secret byte sequence (J) with same size as the keysize of key K. In accordance with various embodiments, the modified key can be generated by XORing the fixed secret key with a varying random sequence that is newly generated for each plaintext message. Alternatively, the fixed secret key can be modified with a variable, non-secret initialization vector and used with stream ciphers. In still another embodiment, the key and sequence are concatenated and passed through a mask generation function.

Abstract: A multiprocessor system automatically responding to a request for executing a new program to establish an extended process that spans a plurality of processors each having resources required for the execution of the new program. Initially, the extended process comprises an user process that is requesting the execution of the new program. Stub processes are created as required to gain access to the object code file of the new program, to allocate a processor to execute the new program, and to initialize the allocated processor for execution for the new program.