Abstract: In a packet based communication network 10, a key management center 20 is used to distribute cryptographic keys for either a switched virtual circuit or a permanent virtual circuit. The disclosed methods allow the key management center 20 to communicate directly with the data encryption/decryption devices (DE's) 14 even though they operate in a transparent mode (rather than a store and forward mode). This is accomplished by balancing link counters with calls to fictitious addresses and/or use of interrupt packets transferred between the DTE 12 and the DE 14. In permanent virtual circuits, the MAC of the last packet transmitted under the old cryptographic key is exchanged to synchronize the key change.

Abstract: In a packet based communication network 10, a key management center 20 is used to distribute cryptographic keys for either a switched virtual circuit or a permanent virtual circuit. The disclosed methods allow the key management center 20 to communicate directly with the data encryption/decryption devices (DE's) 14 even though they operate in a transparent mode (rather than a store and forward mode). This is accomplished by balancing link counters with calls to fictitious addresses and/or use of interrupt packets transferred between the DTE 12 and the DE 14. In permanent virtual circuits, the MAC of the last packet transmitted under the cold cryptographic key is exchanged to synchronize the key change.

Abstract: Apparatus for precision positioning of guide bushings for roughing tools and for finishing tools so that preformed holes in workpieces may be initially subjected to a roughing operation by roughing tools and subsequently to a finishing operation by finishing tools. The guide bushings are mounted on the ends of carrier arms. The carrier arms encircle a workpiece holder. Each carrier arm is mounted for swinging movement on a pivot axis spaced radially from the workpiece holder. The carrier arms are swingable from a position in which the bushings on one end of the arms are aligned with holes in a workpiece mounted on the workpiece holder, to another position in which the guide bushings on the other end of the arms are aligned with holes in the workpiece. Power is provided for simultaneously swinging all of the carrier arms.

Abstract: Apparatus for use in cutting a workpiece on different centers. The workpiece is mounted in a chuck on a spindle top. The spindle top is mounted on the upper end of a rotatable, vertical spindle shaft adjacent to a cutting tool in different positions spaced apart laterally relative to the spindle shaft axis. When the spindle shaft is rotated with the spindle top in one position, the tool will cut the workpiece on one center. In another position of the spindle top, the tool will cut on a different center.