Electrical computers and digital processing systems: support – Data processing protection using cryptography – Tamper resistant
Reexamination Certificate
1999-01-27
2004-03-30
Morse, Gregory (Department: 2134)
Electrical computers and digital processing systems: support
Data processing protection using cryptography
Tamper resistant
C380S266000, C380S277000, C380S259000, C713S189000, C713S192000, C713S193000, C705S057000
Reexamination Certificate
active
06715079
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally to soft modems and relates to protection for soft modems, in particular.
BACKGROUND OF THE INVENTION
Soft modems, also known as host based modems, have been in existence since 1995. In such modems, all the required processing is done in software on the host CPU (central processing unit) of a computer, for example such as a PC (personal computer). Certain hardware is still required for soft modems, as shown in
FIG. 1
, to which reference is now made.
FIG. 1
is a schematic illustration of a prior art PC, comprising a motherboard
10
, an audio subsystem
12
and a modem subsystem
14
. The motherboard
10
comprises a main PC bus
16
, a host CPU
18
, and a memory
20
. The motherboard further comprises a first chip set
22
for interfacing to the host CPU
18
and the main PC bus
16
, and a second chip set
24
for interfacing to the main PC bus
16
and additional buses. The main PC bus
16
is, for example, a Peripheral Component Interconnect (PCI) bus or an Industry Standard Architecture (ISA) bus or any other central PC bus.
An external telephone line (not shown) is connected to the modem subsystem
14
. Electrical audio signals from the telephone line are processed by a data access arrangement (DAA)
26
and are converted from analog to digital by a modem codec (analog to digital coder and digital to analog decoder)
28
. The modem subsystem
14
also includes a digital modem interface device
30
which controls the modem codes
28
and the DAA
26
, interfaces to the main PC bus
16
, and provides signal buffering and control means.
The software instructions of a soft modem are loaded into the memory
20
, from which they are accessed and executed by the host CPU
18
. When the host CPU
18
needs to communicate with the components of the modem subsystem
14
, it sends messages via the first chip set
22
directly to the modem interface device
30
. The messages are compatible with the protocol of the main PC bus
16
.
Similarly, the audio subsystem
12
comprises an audio codec (analog to digital coder and digital to analog decoder)
32
and an audio processing device
34
which controls the audio codec
32
and interfaces to the main PC bus
16
. Applications using the components of the audio subsystem
12
include for example, recording sounds from a microphone and producing sounds through a speaker.
A soft modem manufacturer typically sells both soft modem software and a customized modem interface device to a PC manufacturer, so that the customized modem interface device may be integrated into the modem subsystem of the PC. Since the customized modem interface device is an essential hardware component, without which the soft modem software is inoperable, this arrangement provides some protection to the soft modem manufacturer.
In 1997, Intel Corporation of California, USA published a new standard, called AC′97, which establishes a standard interface, called AC-link, to audio and modem codecs. The AC′97 standard also establishes a standard way of programming the audio and modem codecs. Furthermore, Intel announced in 1998 that its future chip set, samples of which are currently available, will include an integrated modem interface device and an audio processing device, both compatible with the AC-link protocol.
This is shown in
FIG. 2
, to which reference is now made, which is a schematic illustration of an AC-link compatible PC, as described by Intel. Since the AC-link compatible PC is similar to the PC of
FIG. 1
, similar reference numerals refer to similar elements in the figure. The AC-link compatible PC comprises a motherboard
40
, an audio subsystem
42
and a modem subsystem
44
. The motherboard
40
includes a second chip set
46
for interfacing to the main PC bus
16
and additional buses. It is this second chip set
46
which includes an integrated modem interface device and an integrated audio processing device, both of which are AC-link compatible.
The modem subsystem
44
comprises only an AC-link compatible modem codec
48
and the DAA
26
. Similarly, the audio subsystem
42
includes only an AC-link compatible audio codec
50
. It will be appreciated that the modem subsystem
44
and audio subsystem
42
are expected to be smaller and less expensive than the modem subsystem
14
and audio subsystem
12
, respectively, of FIG.
1
.
There is also an option for an AC-link compatible, combined audio modem codec (AMC), in place of the separate audio codec
50
and modem codec
48
.
A soft modem implemented on a PC whose chip set includes an integrated, AC-link compatible, modem interface device does not require that the PC have additional, customized, digital interface components. Rather, the PC has a standard chip set which is sold by a third party. The modem codec, audio codec and DAA are also standard and sold by third parties. The interface to the codecs is accomplished through the AC-link protocol, which is a serial bus with a pre-determined slot allocation. Since the PC already has all the required hardware, the soft modem manufacturer needs only provide the soft modem software, which reduces the cost and eases the implementation. In this arrangement, however, the soft modem software manufacturer is vulnerable to having the software illegally reproduced.
SUMMARY OF THE INVENTION
An object of the present invention is to protect soft modem software in a computer system having a serial bus with designated time slots.
There is therefore provided in accordance with a preferred embodiment of the present invention, a system for transmitting a key for soft modem software protection over a serial bus of a computer having a CPU and a hardware device. The serial bus has designated time slots. The system includes a storage unit in the hardware device for storing a representation of the key therein, and means for transmitting the representation from the hardware device to the CPU over at least one of the designated time slots.
There is also provided in accordance with a preferred embodiment of the present invention, a system which uses a key for soft modem software protection on a computer. The computer has a CPU, a modem codec having registers, and a serial bus having designated time slots, at least one of the time slots being designated for data of the registers. The system includes bit data of the key stored in a subset of the bits of at least one of the registers, and means for transmitting the bit data from the at least one register to the CPU in the at least one register data time slot.
Moreover, in accordance with a preferred embodiment of the present invention, the key is encrypted.
Furthermore, in accordance with a preferred embodiment of the present invention, the system further includes a second key associated with the soft modem software, and means for altering operation of the soft modem software if the transmitted bit data is incompatible with the associated second key.
Additionally, in accordance with a preferred embodiment of the present invention, the means for alteration includes at least one of the following: means for stopping execution of the soft modem software, means for limiting the operation of the soft modem software to a predetermined service level, and means for changing data samples passing through the soft modem software at a predefined magnitude and frequency.
Furthermore, in accordance with a preferred embodiment of the present invention, the means for alteration is configured to become operative a predetermined amount of time after the soft modem software becomes operative.
Altematively, in accordance with a preferred embodiment of the present invention, the means for alteration is configured to become operative a random amount of time after the soft modem software becomes operative.
There is also provided in accordance with a preferred embodiment of the present invention, a system which uses a key for soft modem software protection on a computer. The computer has a CPU, a modem codec having general purpose input output (GPI/O) pins, a hardware device conn
Ben-David Shimon
Bentkovski Yacov
Maytal Binyamin
Brown Christopher J.
Eitan, Pearl, Latzer & Cohen Zedek LLP
Morse Gregory
LandOfFree
Method and system for soft modem protection does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and system for soft modem protection, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and system for soft modem protection will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3204277