Note: Descriptions are shown in the official language in which they were submitted.
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AUTOMATED KEY MANAGEMENT SYSTEM AND METHOD
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to mobile wireless communications
devices
capable of processing cryptographically secure messages and information. In
particular, the
disclosure is directed to a mobile wireless communications device having
cryptographic
messaging capability in which automatic key detection and synchronization are
provided.
2. Related Art
Exchanging cryptographically secured electronic messages and data, such as,
for
example, e-mail messages, is well known. Cryptographically secured electronic
messaging
typically requires the use of cryptographic keys to perform various
cryptographic functions
relating to secured electronic messages. In order to ensure that a user is
able to perform
cryptographic functions, such as, for example, signing, verifying, encrypting,
decrypting, etc.,
secure e-mail messages, users are typically required to transfer their
cryptographic keys from, for
example, a desktop PC or the like, to the mobile wireless communications
device. This transfer
is typically accomplished via a hard-wired serial connection that accommodates
a mobile
wireless communications device and provides an interface to the user's desktop
PC. When the
mobile device is in communication with the user's desktop, a utility, such as,
for example, the
Certificate Synchronization (sometimes referred to as "Cert Sync") running on
the user's desktop
is used to allow the user to choose which keys to synchronize to the mobile
wireless
communications device.
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Periodically, users get issued new signing/decryption keys, for example, for
use in secure
e-mail messaging. This may be done fairly frequently in some systems, for
example automatic
key rollover systems such as that employed by EntrustTM, or less frequently if
the users keys only
expire every couple of years or so.
When a new key or keys are issued, the user must load these new keys onto the
user's
mobile wireless communications devices in order to be able to sign and decrypt
secured
messages with the new keys. Typically, the process of updating the keys for
the mobile wireless
communications device involves running Cert Sync on the user's desktop;
manually identifying
which keys are new; manually selecting keys to download; and synchronizing
with the mobile
wireless communications device. Users may not realize that new keys have been
issued in which
case they will not be able to read encrypted e-mail until they synchronize
with their desktop and
update the device key store.
This method of key management for mobile wireless communications devices is
cumbersome, inefficient, subject to widespread inaccuracies and is difficult
to implement. As
discussed above, it is difficult to identify which keys are new keys even when
the user is aware
of the issuance of new keys.
BRIEF SUMMARY OF THE INVENTION
In view of the foregoing, we have now identified an efficient, accurate and
easy to
implement method for key management in devices that are capable of processing
cryptographically secured electronic messages, such as, for example, mobile
wireless
communications devices.
According to a preferred embodiment of the present disclosure, a list of keys
that have
been used or seen in the past is generated. This list is referred to herein as
the history list. Every
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time Cert Sync is started, the list of keys on the user's desktop is compared
with the history list.
If new keys have been added to the system since the last update (or last
cradling of the mobile
wireless communications device), they will not appear on the history list. At
this point, the user
is informed of the detection of newly issued keys, and prompted to download
the new keys, if
desired.
If the user elects to download the new keys, the new keys are automatically
marked for
download. The new keys are then added to the history list so that the user is
not prompted with
respect to these keys in the future.
Of course, the first time a user starts Cert Sync with this automated key
management
feature, the history list is empty. Thus, the user will initially be prompted
to mark all of the keys
for download.
In an alternative embodiment, certificates may be synchronized automatically
when the
user puts his or her mobile wireless communications device in communication
with a desktop
without having the user start the Cert Sync utility. In this exemplary
embodiment, when the
device is put in communication with a desktop, new certificates are checked
for by comparing
the desktop keys to the history list. If new keys are present, the user is
prompted to download
keys, and if the user accepts, the new keys are downloaded automatically.
In a further alternative embodiment, automatic downloading of new keys that
replace
expired keys on the device is contemplated. In this embodiment, when the user
puts his or her
mobile wireless communications device in communication with a desktop, a check
is
automatically made for new keys. For each new key, if the corresponding
certificate matches a
certificate on the device, the new certificate is automatically downloaded
without prompting the
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user. A matching certificate is one that appears to replace an existing
certificate, as the old
expired certificate has the same common name and issuer name as the new
certificate.
SUMMARY OF INVENTION
In one aspect of the invention, there is provided a system for processing
electronic
messages, comprising: a base computer comprising a first memory for storing a
first set of
keys for use in secure electronic messages; a mobile communications device
comprising a
second memory for storing a second set of keys for use in secure electronic
messages; and
program logic, stored on said mobile communication device, for enabling a user
to select
keys in said first memory for downloading to said second memory, said
selection of keys
being based on a new key indicator generated by said program logic, said new
key indicator
marking keys that have not been previously available to the user, wherein said
new key
indicator is generated by comparing a list of previously available keys with a
current list of
keys in said first memory.
Furthermore, there is a method for updating a cryptographic key store of a
mobile
communications device comprising:maintaining a current key inventory in a
memory of a
base computer; establishing a communications connection between the base
computer and the
mobile communications device; identifying new keys in the current key
inventory by
comparing a list of previously available keys to the keys stored in the
current key inventory;
marking the new keys identified by the identifying step for downloading; and
downloading
the marked new keys to the mobile communications device.
Furthermore, there is a system for updating a cryptographic key store of a
mobile
communications device comprising: means for maintaining a current key
inventory in a
memory of a base computer; means for establishing a communications connection
between
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the base computer and the mobile communications device; means for identifying
new
keys in the current key inventory by comparing a list of previously available
keys to the keys
stored in the current key inventory; means for marking the new keys identified
by the
identifying means for downloading; and means for downloading the marked new
keys to the
mobile communications device.
Furthermore, there is a system for processing electronic messages, comprising:
a base
computer comprising a first memory for storing certificates for use in at
least one of
decrypting and signing secure electronic messages; a mobile communications
device
comprising a second memory for storing certificates for use in secure
electronic messages;
and program logic, stored on said mobile communication device, for
automatically identifing
certificates corresponding to new keys in said first memory for downloading to
said second
memory, said identification of certificates being based on detection of new
keys and
certificates corresponding to the new keys, said program logic marking
certificates
corresponding to the new keys that match existing certificates, wherein said
new keys are
determined by comparing a list of previously available keys with a current
list of keys in said
first memory, said program logic automatically downloading said identified
certificates to
said mobile device.
Furthermore, there is a method for updating a cryptographic certificate store
of a
mobile communications device comprising: establishing an interface between a
base
computer and said communications device; detecting new keys by comparing a
list of
previously available keys with keys in a key store of the base computer;
determining whether
a certificate corresponding to a new key matches an existing certificate; and
downloading the
certificate corresponding to the new key if a match between the corresponding
certificate and
an existing certificate is determined.
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Furthermore, there is a method for automated key maintenance comprising:
generating a history list that includes a list of previously available keys;
comparing said
history list to a list of currently stored keys to identify new keys; and
marking the new keys
for downloading to an electronic communications device.
The advantages attendant with the various embodiments of the invention
described
above are provided by the method and system of automated key management
disclosed and
described herein with reference to the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other objects and advantages of exemplary embodiments of the present
invention will be better understood and appreciated in conjunction with the
following detailed
description of exemplary embodiments taken together with the accompanying
drawings, in
which:
FIG. 1 is an overall system wide schematic view of an exemplary wireless e-
mail
communication system incorporating a mobile wireless communications device
with the
descriptive error messaging in accordance with an exemplary embodiment of the
present
invention;
FIG. 2 is a block diagram of a further examplary communication system
including
multiple networks and multiple mobile communication devices;
FIG. 3 is an abbreviated schematic diagram of hardware included within an
exemplary mobile wireless communications device;
FIG. 4 is an abbreviated schematic functional diagram of the hardware/software
utilized to achieve updating of the mobile wireless communication device
key/certificate
store in the exemplary embodiment of FIG. 1; and
4b
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FIG. 5 is an exemplary abbreviated schematic flow diagram of an automated key
management system according to an exemplary embodiment of the present
invention;
4c
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FIG. 6 is an exemplary abbreviated schematic flow diagram of an automated key
management system according to another exemplary embodiment of the present
invention; and
FIG. 7 is an exemplary abbreviated schematic flow diagram of an automated key
management system according to yet another exemplary embodiment of the present
invention;
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
FIG. 1 is an overview of an example communication system in which a wireless
communication device may be used. One skilled in the art will appreciate that
there may be
hundreds of different topologies, but the system shown in FIG.1 helps
demonstrate the operation
of the encoded message processing systems and methods described in the present
application.
There may also be many message senders and recipients. The simple system shown
in FIG.1 is
for illustrative purposes only, and shows perhaps the rnDst prevalent Internet
e-mail environment
where security is not generally used.
FIG. 1 shows an e-mail sender 10, the Intern.et 20, a message server system
40, a wireless
gateway 85, wireless infrastructure 90, a wireless network 105 and a mobile
communication
device 100.
An e-mail sender system 10 may, for example, be connected to an ISP (Internet
Service
Provider) on which a user of the system 10 has an account, located within a
company, possibly
connected to a local area network (LAN), and connected to the Internet20, or
connected to the
Internet 20 through a large ASP (application service provider) such as America
Online (AOL).
Those skilled in the art will appreciate that the systems shown in FIG. 1 may
instead be
connected to a wide area network (WAN) other than the Internet, although e-
mail transfers are
commonly accomplished through Internet-connected arrangements as shown in FIG.
1.
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The message server 40 may be implemented, for example, on a network computer
within
the firewall of a corporation, a computer within an ISP or ASP system or the
like, and acts as the
main interface for e-mail exchange over the Internet 20. Although other
messaging systems
might not require a message server system 40, a mobile device 100 configured
for receiving and
possibly sending e-mail will normally be associated with an account on a
message server.
Perhaps the two most common message servers are Microsoft ExchangeTM and Lotus
DominoTM.
These products are often used in conjunction with Internet mail routers that
route and deliver
mail. These intermediate components are not shown in FIG. 1, as they do not
directly play a role
in the secure message processing described below. Message servers such as
server 40 typically
extend beyond just e-mail sending and receiving; they also include dynamic
database storage
engines that have predefined database formats for data like calendars, to-do
lists, task lists, e-
mail and documentation.
The wireless gateway 85 and infrastructure 90 provide a link between the
Internet 20 and
wireless network 105. The wireless infrastructure 90 determines the most
likely network for
locating a given user and tracks the user as they roam between countries or
networks. A message
is then delivered to the mobile device 100 via wireless transmission,
typically at a radio
frequency (RF), from a base station in the wireless network 105 to the mobile
device 100. The
particular network 105 may be virtually any wireless network over which
messages may be
exchanged with a mobile communication device.
As shown in FIG. 1, a composed e-mail message 15 is sent by the e-mail sender
10,
located somewhere on the Internet 20. This message 15 is normally fully in the
clear and uses
traditional Simple Mail Transfer Protocol (SMTP), RFC822 headers and
Multipurpose Internet
Mail Extension (MIME) body parts to defme the format of the mail message.
These techniques
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are all well known to those skilled in the art. The message 15 ar.rives at the
message server 40
and is normally stored in a message store. Most known messaging systems
support a so-called
"pull" message access scheme, wherein the mobile device 100 must request that
stored messages
be forwarded by the message server to the mobile device 100. Some systems
provide for
automatic routing of such messages which are addressed using a specific e-mail
address
associated with the mobile device 100. In a preferred embodiment described in
further detail
below, messages addressed to a message server account associated with a host
system such as a
home computer or office computer which belongs to the user of a mobile device
100 are
redirected from the message server 40 to the mobile device 100 as they are
received.
Regardless of the specific mechanism controlling the forwarding of messages to
the
mobile device 100, the message 15, or possibly a translated or reformatted
version thereof, is
sent to the wireless gateway 85. The wireless infrastructure 90 includes a
series of connections
to wireless network 105. These connections could be Integrated Services
Digital Network
(ISDN), Frame Relay or T1 connections using the TCP/IP protocol used
throughout the Internet.
As used herein, the term "wireless network" is intended to include at least
one of three different
types of networks, those being (1) data-centric wireless networks, (2) voice-
centric wireless
networks and (3) dual-mode networks that can support both voice and data
communications over
the same physical base stations. Combined dual-mode networks include, but are
not limited to,
(1) Code Division Multiple Access (CDMA) networks, (2) the Groupe Special
Mobile or the
Global System for Mobile Communications (GSM) and the General Packet Radio
Service
(GPRS) networks, and (3) future third-generation (3G) networks like Enhanced
Data-rates for
Global Evolution (EDGE) and Universal Mobile Telecommunications Systems
(UMTS). Some
older examples of data-centric network include the Mobitexm Radio Network and
the
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DataTACTM Radio Network. Examples of older voice-centric data netvvorks
include Personal
Communication Systems (PCS) networks like GSM, and TDMA systerns.
FIG. 2 is a block diagram of a further example communication system including
multiple
networks and multiple mobile communication devices. The system of FIG. 2 is
substantially
similar to the FIG. 1 system, but includes a host system 300, a redirection
program 45, a mobile
device cradle 65, a wireless virtual private network (VPN) router 75, an
additional wireless
network 110 and multiple mobile communication devices 100. As described above
in conjunction
with FIG. 1, FIG. 2 represents an overview of a sample network topology.
Although the encoded
message processing systems and methods described herein may be applied to
networks having
many different topologies, the network of FIG. 2 is useful in understanding an
automatic e-mail
redirection system mentioned briefly above.
The central host system 300 will typically be a corporate office or other LAN,
but may
instead be a home office computer or some other private system where mail
messages are being
exchanged. Within the host system 300 is the message server 400, running on
some computer
within the firewall of the host system, that acts as the main interface for
the host system to
exchange e-mail with the Internet 20. In the system of FIG. 2, the redirection
program 45
enables redirection of data items from the server 400 to a mobile
communication device 100.
Although the redirection program 45 is shown to reside on the same machine as
the message
server 400 for ease of presentation, there is no requirement that it must
reside on the message
server. The redirection program 45 and the message server 400 are designed to
co-operate and
interact to allow the pushing of information to mobile devices 100. In this
installation, the
redirection program 45 takes confidential and non-confidential corporate
information for a
specific user and redirects it out through the corporate firewall to mobile
devices 100. A more
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detailed description of the redirection software 45 may be found in the
commonly assigned
United States Patent 6,219,694 ("the '694 Patent"), entitled "System and
Method for Pushing
Information From A Host System To A Mobile Data Communication Device Having A
Shared Electronic Address", and issued to the assi gnee of the instant
application on April 17,
2001. This push technique may use a wireless friendly encoding, compression
and
encryption technique to deliver all information to a mobile device, thus
effectively extending
the security firewall to include each mobile device 100 associated with the
host system 300.
As shown in FIG. 2, there may be many alternative paths for getting
information to the
mobile device 100. One method for loading information onto the mobile device
100 is
through a port designated 50, using a device cradle 65. This method tends to
be useful for
bulk information updates often performed at initialization of a mobile device
100 with the
host system 300 or a computer 35 within the system 300. The other main method
for data
exchange is over-the-air using wireless networks to deliver the information.
As shown in
FIG. 2, this may be accomplished through a wireless VPN router 75 or through a
traditional
Internet connection 95 to a wireless gateway 85 and a wireless infrastructure
90, as described
above. The concept of a wireless VPN router 75 is new in the wireless industry
and implies
that a VPN connection could be established directly through a specific
wireless network 110
to a mobile device 100. The possibility of using a wireless VPN router 75 has
only recently
been available and could be used when the new Internet Protocol (IP) Version 6
(IPV6)
arrives into IP-based wireless networks. This new protocol will provide enough
IP addresses
to dedicate an IP address to every mobile device 100 and thus make it possible
to push
information to a mobile device 100 at any time. A principal advantage of using
this wireless
VPN router 75 is that it could be an off-the-shelf VPN
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component, thus it would not require a separate wireless gateway 85 and
wireless infrastructure
90 to be used. A VPN connection would preferably be a Transmission Control
Protocol
(TCP)/IP or User Datagram Protocol (UDP)/IP connection to deliver the messages
directly to the
mobile device 100. If a wireless VPN 75 is not available then a link 95 to the
Internet 20 is the
most common connection mechanism available and has been described above.
In the automatic redirection system of FIG. 2, a composed e-mail message 15
leaving the
e-mail sender 10 arrives at the message server 400 and is redirected by the
redirection program
45 to the mobile device 100. As this redirection takes place the message 15 is
re-enveloped, as
indicated at 80, and a possibly proprietary compression and encryption
algorithm can then be
applied to the original message 15. In this way, messages being read on the
mobile device 100
are no less secure than if they were read on a desktop workstation such as 35
within the firewall.
All messages exchanged between the redirection program 45 and the mobile
device 100
preferably use this message repackaging technique. Another goal of this outer
envelope is to
maintain the addressing information of the original message except the
sender's and the
receiver's address. This allows reply messages to reach the appropriate
destination, and also
allows the "from" field to reflect the mobile user's desktop address. Using
the user's e-mail
address from the mobile device 100 allows the received message to appear as
though the
message originated from the user's desktop system 35 rather than the mobile
device 100.
With reference back to the port 50 and cradle 65 connectivity to the mobile
device 100,
this connection path offers many advantages for enabling one-time data
exchange of large items.
For those skilled in the art of personal digital assistants (PDAs) and
synchronization, the most
common data exchanged over this link is Personal Inforniation Management (PIM)
data 55.
When exchanged for the first time this data tends to be large in quantity,
bulky in nature and
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requires a large bandwidth to get loaded onto the mobile device 100 where it
can be used on
the road. This serial link may also be used for other purposes, including
setting up a private
security key 210 such as an S/MIME or PGP specific private key, the
Certificate (Cert) of the
user and their Certificate Revocation Lists (CRLs) 60. The private key is
preferably
exchanged so that the desktop 35 and mobile device 100 share one personality
and one
method for accessing all mail. The Cert and CRLs are normally exchanged over
such a link
because they represent a large amount of the data that is required by the
device for S/MIME,
PGP and other public key security methods.
As depicted in FIG. 3, mobile communications device 100 includes a suitable RF
antenna 102 for wireless communication to/from wireless network 20.
Conventional RF,
demodulation/ modulation and decoding/coding circuits 104 are provided. As
those in the art
will appreciate, such circuits may involve possibly many digital signal
processors (DSPs),
microprocessors, filters, analog and digital circuits and the like. However,
since such
circuitry is well known in the art, it is not further described herein.
The mobile communications device 100 will also typically include a main
control
CPU 106 that operates under the control of a stored program in program memory
108, and
which has access to data memory 110. CPU 106 also communicates with a
conventional
keyboard 112 and display 114 (for example, a liquid crystal display or LCD)
and audio
transducer or speaker 116. A portion of the data memory 310 is available for
storing data
required for decrypting encrypted messages, such as, for example, private
keys, digital
certificates, and the like. Suitable computer program executable code is
stored in portions of
the program memory 108 to constitute stored program logic for receiving and
using new or
added private keys and/or digital certificates or the like as described below
(for example, via
a wired serial I/O port or the wireless RF antenna 102).
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As depicted in FIG. 1, a secure wired synchronization connection 26 (for
example,
between serial UO ports of the user's base unit 24 and the wireless device
100) is typically
provided for normal data synchronization purposes (for example, to synchronize
databases in
the two devices with respect to such things as calendars, to-do lists, task
lists, address books,
etc.). Part of prior data synchronization processes has included a program
logic such as Cert
Sync for maintaining synchronization between cryptographic message
certificates. If a
secure over the air (OTA) synchronization connection 28 is available, it may
also be used by
Cert Sync to maintain synchronization of cryptographic message certificates.
As previously described, there is a communications link (for example, depicted
in
dotted lines in FIG. 1) typically found between the device user's base unit 24
and a system
message server 40. Accordingly, there is an existing communication path that
may be
utilized for passing synchronization data from the user's base unit 24 via
channel 30, the
server 40, Internet 20, wireless gateway 85 and wireless infrastructure 90 via
the OTA
synchronization connection 28.
As depicted in FIG. 4, the user's base unit 24 may be used to update the
mobile
wireless communications device 100 with information including, for example,
private key
information and digital certificate information. The user's base station 24 is
typically a
desktop PC, and may be of conventional hardware and operating system design.
It will
typically include desktop manager program logic 304 (in the form of, for
example, executable
computer program logic) for managing, among other things, a normal data
synchronization
connection to device 100. As previously mentioned, in the environment of
mobile wireless
communications systems, such a desktop manager may typically include logic for
synchronizing cryptographic message certificates. Such logic is denoted here
as Cert Sync.
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E-mail messages generated using the S/MIME and PGP techniques may include
encrypted information, a digital signature on the message contents, or both.
In signed S/MIME
operations the sender takes a digest of a message and signs the digest using
the sender's private
key. A digest is essentially a checksum, CRC or other preferably non-
reversible operation such
as a hash of the message, which is then signed. The signed digest is appended
to the outgoing
message, possibly along with the certificate of the sender and possibly any
required certificates
or CRLs. The receiver of this signed message must also take a digest of the
message, compare
this digest with the digest appended to the message, retrieve the sender's
public key, and verify
the signature on the appended digest. If the message content has been changed,
the digests will
be different or the signature on the digest will not verify properly. If the
message is not
encrypted, this signature does not prevent anyone from seeing the contents of
the message, but
does ensure that the message has not been tampered with and is from the actual
person as
indicated on the "from" field of the message.
The receiver may also verify the certificate and CRL if they were appended to
the
message. A certificate chain is a certificate along with a number of other
certificates required to
verify that the original certificate is authentic. While verifying the
signature on a signed
message, the receiver of the message will also typically obtain a certificate
chain for the signing
certificate and verify that each certificate in the chain was signed by the
next certificate in the
chain, until a certificate is found that was signed by a root certificate from
a trusted source, such
as, for example, a large Public Key Server (PKS) associated with a Certificate
Authority (CA),
such as, for example, Verisign or Entrust, both prominent companies in the
field of public key
cryptography. Once such a root certificate is found, a signature can be
verified and trusted, since
both the sender and receiver trust the source of the root certificate.
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In encrypted S/MIME message operations, a one time session key is generated
and used
to encrypt the body of the message, typically with a symmetric cipher, such
as, for example,
Triple DES. The session key is then encrypted using the receiver's public key,
typically with a
public key encryption algorithm like RSA. If the message is addressed to more
than one
receiver, the same session key is encrypted using the public key of each
receiver. The encrypted
message body, as well as all encrypted session keys, is sent to every
receiver. Each receiver
must then locate its own session key, possibly based on a generated Recipient
Info summary of
the receivers that may be attached to the message, and decrypt the session key
using its private
key. Once the session key is decrypted, it is then used to decrypt the message
body. The
S/MIME Recipient Info attachment can also specify the particular encryption
scheme that must
be used to decrypt the message. This information is normally placed in the
header of the
S/MIME message. Those skilled in the art will appreciate that these operations
relate to an
illustrative example of S/MIME messaging and its associated encoding
operations, namely
encryption. It will also be understood that the instant disclosure is in no
way limited thereto.
FIG. 5 illustrates an exemplary embodiment of the present disclosure showing
one form
of automated key management according to the present disclosure. At the
outset, a history list of
keys that have been seen or used in the past is generated 500. Each time the
device is put in
conununication with a desktop 502, Cert Sync (or any similar application) is
automatically
invoked and begins running 504. Cert Sync compares the history list with the
list of keys on the
user's desktop 506. If new keys have been added to the system since the last
update (or last
communication of the mobile wireless communications device with the desktop)
they will not
appear on the history list, and will thus be detected at step 507. If new keys
are detected 507, the
user will be prompted to mark the new keys for downloading 508. If the user
elects to mark the
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new keys 510, they new keys are marked for download 514. The next time the
user elects to
download keys to his mobile device, any keys that were previously marked for
download in step
514 will be downloaded to the user's device. Once the new keys have been
marked, the history
list is updated with the newly downloaded key list 512. At step 510, if the
user elects not to
mark the new keys, the history list is nevertheless updated with the new key
information 512.
In an alternative embodiment illustrated in FIG. 6, certificates may be
synchronized
automatically when the user puts his or her mobile wireless communications
device in
communication with the desktop 602 after the history list has been generated
600. In this
embodiment, the keys of the mobile wireless communication device are updated
without running
the Cert Sync application. According to this alternative embodiment, new
certificates are
checked for by comparing the desktop keys to the history keys 606. If new keys
are detected
607, the user is prompted to download the new keys 608. If the user elects to
download the new
keys 610, the new keys are downloaded 614, and the history list updated 616.
If the user elects
not to download the new keys at 610, the history list is nevertheless updated
with the new key
information 612. Alternatively, when new keys are detected, the user may be
prompted to run,
for example, the Cert Sync application to mark and download the new keys, and
these new keys
may be downloaded, for example, as set forth above with reference to FIG. 5.
According to yet another embodiment, illustrated in FIG. 7, automatic
downloading of
new keys that replace expired keys on the device is disclosed. In this
embodiment, when the
user puts the mobile wireless communications device in communication with the
desktop 700, a
check is automatically made for new keys 702 by comparing the history list
with the list of keys
at the desktop. For each new key, if the corresponding certificate matches an
existing certificate
704, the new certificate is automatically downloaded 706 without prompting the
user. Once the
CA 02476919 2004-08-09
download is completed, the history list is updated 710. Thus, the process is
entirely transparent
to the user. It is noted that a matching certificate is one that appears to
replace an existing
certificate, as the old expired certificate has the same common name and
issuer name as the new
certificate.
It will be understood that the above described key management system has been
described with respect to mobile wireless communications devices, and is
intended to be
illustrative only. It will be apparent to those skilled in the art that this
type of key management
system has wide ranging application in unlimited and innumerable systems,
especially those
encountered in the computer and electronics fields.
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