Browse Prior Art Database

Dynamic Controlling of Public-Key Operations

IP.com Disclosure Number: IPCOM000104208D
Original Publication Date: 1993-Mar-01
Included in the Prior Art Database: 2005-Mar-18
Document File: 2 page(s) / 69K

Publishing Venue

IBM

Related People

Scalzi, CA: AUTHOR [+2]

Abstract

Described is a mechanism to dynamically control the Public-Storage-Key (PSK) mode of operation. This function is controlled by a mode in the PSW, and may be made operational on an individual task basis. It also includes a new mechanism to establish and control this operational mode through PC/PR instructions, and to improve the performance of stacking PC/PR operations to make this mechanism usable for performance sensitive subsystems.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Dynamic Controlling of Public-Key Operations

      Described is a mechanism to dynamically control the
Public-Storage-Key (PSK) mode of operation.  This function is
controlled by a mode in the PSW, and may be made operational on an
individual task basis.  It also includes a new mechanism to establish
and control this operational mode through PC/PR instructions, and to
improve the performance of stacking PC/PR operations to make this
mechanism usable for performance sensitive subsystems.

      In the current S/390 architecture, bit 7 of control register 0
is the PSK mode.  When this mode is active, key controlled storage
protection is ignored for storage locations having an associated
storage-key value of 9.  This control, as defined in the current
architecture, is static, and because of the location, this capability
may not be use in the S/370 mode.  The described idea makes this mode
of operation dynamic by putting this bit in the PSW, such that it may
be made operational on an individual task-in-address-space basis,
that is, PSK authorization can be granted to specific tasks calling
specific entry points in specific address-spaces.  With this mode in
the PSW, this facility may be used in the S/370 mode also.  This mode
for each task is specified by a bit in the entry-table entry, which
is setup by the operating system.  This enables this mode to be
loaded automatically in the PSW on a PC execution with the original
state saved in the linkage-stack state entry for later restoration by
a PR operation.  This mechanism enables the saving of a SAC
execution.

      With the current S/390 architecture, in PSK mode, an
application with storage-key 9 and executing with PSK-key 9 has the
capability of changing the PSW-key if the PKM in control register 3
allows it.  This enables the application program access to other
storage data...