Patent · US Active

Branch and switch key instruction in a microprocessor that fetches and decrypts encrypted instructions

US8639945B2 · kind B2 · utility

1Cited by

29References

27Claims

0Family size

Assignee

VIA Technologies, Inc. · TW

Inventors

G. Glenn Henry · Austin, US
Terry Parks · Austin, US
Brent Bean · Austin, US
Thomas A. Crispin · Austin, US

Key dates

Filing date	Apr 21, 2011
Grant date	Jan 28, 2014
Priority date	—
Expiry date	Oct 12, 2031

Classification

Technology area (CPC H)Electricity
CPC primaryH04L2209/20
WIPO fieldComputer technology
WIPO sectorElectrical engineering

Abstract

A microprocessor includes a storage element that stores decryption key data and a fetch unit that fetches and decrypts program instructions using a value of the decryption key data stored in the storage element. The fetch unit fetches an instance of a branch and switch key instruction and decrypts it using a first value of the decryption key data stored in the storage element. If the branch is taken, the microprocessor loads the storage element with a second value of the decryption key data for subsequent use by the fetch unit to decrypt an instruction fetched at a target address specified by the branch and switch key instruction. If the branch is not taken, the microprocessor retains the first value of the decryption key data in the storage element for subsequent use by the fetch unit to decrypt an instruction sequentially following the branch and switch key instruction.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.