Note: Descriptions are shown in the official language in which they were submitted.
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SYSTEM AND METHOD FOR
FILE ENCRYPTION AND DECRYPTION
COPYRIGHT NOTICE
[0001] A portion of the disclosure of this patent document contains material
which is subject
to copyright protection. The copyright owner has no objection to the
facsirnile reproduction
of the patent document or the patent disclosure, as it appears in the Patent
and Trademark
Office patent file or records, but otherwise reserves all copyright rights
whatsoever.
BACKGROUND
[0002] The present invention relates to systems and methods for file
encryption and
decryption.
[0003] With today's information technology (IT) systems and operations, there
is often a need
to create backup files for archival purposes and to transfer files securely
from one location to
another. Such files are often stored on portable data processor readable media
such as for
example magnetic data tapes or cartridges, and writable or rewritable optical
disks. These
media may sometimes be misplaced or become lost in transit to another
location. Files stored
on these media may contain highly sensitive infonnation such as customer
names, addresses,
bank account numbers, account balances, etc. and may need to be protected from
unauthorized access.
[0004] Various solutions for encrypting backup files have been proposed but
may exhibit
certain limitations. For example, some encryption solutions may require users
to retain
private keys, or both private and public keys, for each piece of media storing
encrypted data.
If the keys are not well managed, retrieval may become difficult or impossible
after years or
decades have passed.
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[0005] What is needed is an improved method and system for file encryption and
decryption
that may overcome some of these limitations.
SUMMARY
[0006] The present invention relates to an improved system and method for file
encryption
and decryption.
[0007] In an aspect of the invention, there is provided a method of encryptin
g a file on backup
media, comprising: encrypting clear data using a data encryption key applied
to a data
encryption algorithm and outputting encrypted data; storing the encrypted data
on the backup
media; encrypting the data encryption key using a reference cryptographic key
applied to a
key encryption algorithm and outputting an encrypted data encryption key; and
storing the
encrypted data encryption key and reconstitution data in a header of the
backup media.
[0008] In an embodiment the method further comprises storing the refererice
cryptographic
key in a reference cryptographic key data set.
[0009] In another embodiment the method further comprises storing in the
reconstitution data
the reference cryptographic key name.
[0010] In another embodiment the method further comprises storing in the
reconstitution data
the clear data characteristics and the encrypted data characteristics.
[0011] In another embodiment the method further comprises subsequently
decrypting the
encrypted data as follows: reading the reference cryptographic key name from
the
reconstitution data; identifying the reference cryptographic key in the
reference cryptographic
key data set using the reference cryptographic key name; applying the
reference cryptographic
key to a key decryption algorithm to decrypt the encrypted data encryption
lcey; and applying
the decrypted data encryption key to a data decryption algorithm to decrypt
the encrypted
data.
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[0012] In another embodiment the method further comprises utilizing the clear
data
characteristics and the encrypted data characteristics stored in the
reconstitution data to
decrypt the encrypted data.
[0013] In another embodiment the method further comprises securing the
reference
cryptographic key in cryptographic hardware during decryption of the data
enicryption key.
[0014] In another aspect of the invention, there is provided a system for
encrypting a file on
backup media, comprising: a data encryption algorithm module configured. to
encrypt clear
data using a data encryption key and to output encrypted data; encrypted data
storing means
for storing the encrypted data on the backup media; a key encryption algorithm
module
configured to encrypt the data encryption key using a reference cryptographic
key; and header
storing means for storing the encrypted data encryption key and reconstitution
data in a
header of the backup media.
[0015] In an embodiment, the system further comprises a reference
cryptographic key data set
storing the reference cryptographic key.
[0016] In another embodiment, the storing means is configured to store the
reference
cryptographic key name in the reconstitution data.
[0017] In another embodiment, the storing means is configured to store the
clear data
characteristics and the encrypted data characteristics in the reconstitution
data.
[0018] In another embodiment, the system is configured to subsequently decrypt
the
encrypted data, the system further comprising: reading means for reading the
reference
cryptographic key name from the reconstitution data stored in the backitp
media header;
identifying means for identifying the reference cryptographic key in the
reference
cryptographic key data set using the reference cryptographic key name; a key
decryption
algorithm module configured to decrypt the encrypted data encryption key by
applying the
reference cryptographic key; and a data decryption algorithm module configured
to decrypt
the encrypted data by applying the decrypted data encryption key.
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[0019] In another embodiment, the data decryption algorithm module is further
configured to
utilize the clear data characteristics and the encrypted data characteristics
stored in the
reconstitution data.
[0020] In another embodiment, the key decryption algorithm module is further
configured to
decrypt the data encryption key while securing the reference cryptographic key
in the
cryptographic hardware.
[0021] In another aspect of the invention, there is provided a data processor
readable medium
storing data processor code that when loaded into one or more data processors
adapts the
processors to provide a method of encrypting data on backup media, the data
processor
readable medium comprising: code for encrypting clear data using a data
encryption key
applied to a data encryption algorithm and outputting encrypted data; code for
storing on the
backup media; code for encrypting the data encryption key using a refererice
cryptographic
key applied to a key encryption algorithm and outputting an encrypted data
encryption key;
code for storing the encrypted data, the encrypted data encryption key and
reconstitution data
in a header of the backup media.
[0022] In an embodiment, the data processor readable medium further comprises
code for
storing the reference cryptographic key in a reference cryptographic key data
set.
[0023] In an embodiment, the data processor readable medium further comprises
code for
storing in the reconstitution data the reference cryptographic key name.
[0024] In an embodiment, the data processor readable medium further comprises
code for
storing in the reconstitution data the clear data characteristics and the
encrypted data
characteristics.
[0025] In an embodiment, the data processor readable medium further comprises
code for
subsequently decrypting the encrypted data, including: code for reading the
reference
cryptographic key name from the reconstitution data; code for identifying the
reference
cryptographic key in the reference cryptographic key data set usinig the
reference
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cryptographic key name; code for applying the reference cryptographic key to a
key
decryption algorithm to decrypt the encrypted data encryption key; and code
for applying the
decrypted data encryption key to a data decryption algorithm to decrypt the
encrypted data.
[0026] In an embodiment, the data processor readable medium further comprises
code for
utilizing the clear data characteristics and the encrypted data
characteristics stored in the
reconstitution data to decrypt the encrypted data.
[0027] In an embodiment, the data processor readable medium further comprises
code for
securing the reference cryptographic key in cryptographic hardware during
decryption of the
data encryption key.
[0028] These and other aspects of the invention will become apparent from the
following
more particular descriptions of exemplary embodiinents.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] In the figures which illustrate exemplary embodiments of the invention:
FIG. 1 shows a generic data processing system that may provide a suitable
operating
environment;
FIGS. 2A and 2B show a schematic block diagram of illustrative components of a
private key encryption system;
FIG. 3 shows a schematic block diagram of illustrative components of a public
key/private key encryption system;
FIGS. 4 shows schematic block diagrams of illustrative components of a multi-
level
encryption/decryption system in accordance with an embodiment;
FIG. 5 shows a flowchart of an illustrative method in accordance with an
embodiment;
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FIG. 6 shows a flowchart of an illustrative method in accordance with another
embodiment.
DETAILED DESCRIPTION
[0030] As noted above, the present invention relates to an improved system and
method for
file encryption and decryption.
[0031] The invention may be practiced in various embodiments. A suitably
configured data
processing system, and associated communications networks, devices, software
and finnware
may provide a platform for enabling one or more embodiments. By way of'
example, FIG. 1
shows a generic data processing system 100 that may include a central
processing unit
("CPU") 102 connected to a storage unit 104 and to a random access memory 106.
The CPU
102 may process an operating system 101, application program 103, ancl data
123. The
operating system 101, application program 103, and data 123 may be stored in
storage unit
104 and loaded into memory 106, as may be required. An operator 107 may
interact with the
data processing system 100 using a video display 108 connected by a video
interface 105, and
various input/output devices such as a keyboard 110, mouse 112, and disk drive
114
connected by an I/O interface 109. In known manner, the mouse 112 may be
configured to
control movement of a cursor in the video display 108, and to operate various
graphical user
interface ("GUI") controls appearing in the video display 108 with a mouse
button. The disk
drive 114 may be configured to accept data processing system readable media
116. The data
processing system 100 may fonn part of a network via a network interface 111,
allowing the
data processing system 100 to communicate with other suitably configured data
processing
systems (not shown). The particular configurations shown by way of example in
this
specification are not meant to be limiting. For example, in a mainframe
environment, the
video interface 105, video display 108, keyboard 110 and mouse 112 may be
provided at a
workstation operatively connected to a mainframe (not shown).
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[0032] Now referring to FIGs. 2A and 2B, shown are schematic block diagrams of
illustrative
components of a private key encryption system 200A. As shown in FIG. 2A, using
a secret
key 202, a clear data (i.e. unencrypted data) input may be encrypted at block
204 using an
encryption algorithm. The output from block 204 is an encrypted version of the
clear data
that may be stored on backup media (e.g. magnetic data tapes or cartri(Iges,
writable or
rewritable optical disks). In order to access the encrypted data on the media,
the encrypted
data is provided as an input to block 206 and the secret key 202 is used in
conjunction with
the decryption algorithm at block 206 to output the original clear data.
[0033] Shown in FIG. 3 is a schematic block diagram of illustrative components
of another
encryption system 300 using public key/private key cryptography. As shown,
Party A may
want to send certain order data 302 securely to Party B and in turn receive an
order receipt
304. An order originating from Party A's system 310 may include Party A's
digital signature
312 and the order data 302 may be encrypted using Party A's private key 314.
At Party B's
system 320, upon verification that the order data 302 from Party A is
authentic, Party B's
system 320 may receive Party A's encrypted order data 302 and decrypt the
order data 302
using Party A's public key 316.
[0034] Party B may then acknowledge receipt of the order data 302 by
gerierating the order
receipt 304, which now contains Party B's digital signature 322. The order
receipt 304 may
now be encrypted using Party B's private key 324, and upon receiving the order
receipt 304 at
Party A's system 210, the order receipt 304 may be decrypted using Party A's
private key
326.
[0035] As will be appreciated by those skilled in the art, the encryption
systems shown in
FIGs. 2A, 2B and 3 require that either a private key, or a private and public
key, be
maintained in order to decrypt and recover datasets. If there are many pieces
of media,
maintaining the private keys or private key/public key combinations for each
piece of media
may become difficult.
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[0036] In order to address this problem, the inventors have developed a multi-
level encryption
system in which there is one or perhaps a few Reference Cryptographic K:eys
that may be
used to protect and reference many unique Data Encryption Keys stored together
with the
encrypted data on the backup media. As an example, using a Reference
Cryptographic Key
having 168 bits in length, each reference cryptographic key may be used to
protect and
reference some 2168 unique Data Encryption Keys. The unique Data Encryption
Keys may be
stored, for example, as an encrypted key in a clear header on each piece of
backup media.
[0037] Now referring to FIG. 4A, shown is a schematic block diagrarn of
illustrative
components of a multi-level encryption system 400A in accordance with an
embodiment. As
shown, a Data Encryption Algorithm module 402 may be configured to utilize a
Data
Encryption Key 404, which may be unique, in order to convert Clear Data 411
(i.e.
unencrypted data) into Encrypted Data 412. The Encrypted Data 412 may be
stored on a
piece of backup media 413.
[0038] In an embodiment, the Data Encryption Key 404 used to encrypt the Clear
Data 411
may itself be encrypted before it is stored in a Header 414. For this purpose,
a Reference
Cryptographic Key 406 may be applied to a Key Encryption Algorithm module 410
to
convert the Data Encryption Key 404 into an encrypted fonn for storage in
Header 414. As
an illustrative example, the Reference Cryptographic Key 406 may be a Key
Encrypting Key
or a Rivest, Shamir and Adleman (RSA) Public Key.
[0039] As shown in FIG. 4A, Reconstitution Data 408 containing data for
reconstituting
Encrypted Data 412 may be stored in Header 414 in an unencrypted form. The
Reconstitution
Data 408 may include, for example, a Reference Cryptographic Key Name
corresponding to
the Reference Cryptographic Key 406, Source Data Characteristics for the Clear
Data 411,
and Target Data Characteristics for the Encrypted Data 412. The Reference
Cryptographic
Key Name is stored in Header 414 in an unencrypted form, such that it may be
used to
retrieve the correct Reference Cryptographic Key 406.
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[0040] In an embodiment, the Reference Cryptographic Key 406 may have a naming
convention corresponding to a file naming format for a particular client or
particular purpose:
e.g. "US.TO.CLIENT 1.KEK" or "US.TO.ARCHIVE.RSA". These file naming fonnats
are
illustrative only, and may serve to identify how and for whom the backup media
was created.
As an example, if a piece of backup media labelled "US.TO.ARCHIVE.KEK" and
created in
2006 is sent to a storage repository "A", then a Reference Cryptographic Key
404 may be
made which references that storage repository for a particular year. Such a
Reference
Cryptographic Key 404 may be named, for example, "US.TO.ARCHIVE_A.KEY.2006",
and
may be maintained in a centrally managed Cryptographic Reference Key Data Set
430. In an
embodiment, the Cryptographic Reference Key Data Set 430 may be secured using
cryptographic hardware for an additional level of security.
[0041] At some point in the future, when backup data needs to be recovered,
and backup
media 413 is retrieved from a storage repository, the label
"US.TO.ARCHIVE.KEK" and the
Reference Cryptographic Key Name may be read directly from Header 414 of the
backup
media 413. The correct Reference Cryptographic Key 404, namely
"US.TOARCHIVE A.KEY.2006", may then be retrieved from the Cryptographic
Reference
Key Data Set 430. As will be appreciated, maintaining relatively few Reference
Cryptographic Keys 404 in a central and secure location may make it
signlificantly easier to
maintain and manage the Reference Cryptographic Keys 404 over an extended
period of time.
[0042] Now referring to FIG. 4B, shown is a corresponding multi-level
decryption system
400B having a Data Decryption Algorithm module 420 that may be used to decrypt
the
Encrypted Data 412 stored on the backup media 413 back into the Clear Data
411. However,
before the Data Encryption Key 404 needed for the decryption may be used, the
Data
Encryption Key 404 needs to be retrieved from the Header 414 and decrypted.
[0043] In an embodiment, the Reference Cryptographic Key Name, stored as part
of the
Reconstituting Data 408, may be read directly from the Header 414 without any
need for
decryption. Also, as discussed earlier, a naming convention for the backup
media 413 stored
at a particular storage repository may be chosen by the user to be meaningful
and specific
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enough to identify the correct Reference Cryptographic Key 406 needed. Thus,
for any piece
of backup media 413 retrieved from a storage repository, the Encrypted I)ata
412 may be
recovered as long as the Reference Cryptographic Key 406 named in the Header
414 still
exists in the Central Reference Cryptographic Key Data Set 430.
[0044] Upon retrieving the correct Reference Cryptographic Key 406 from the
Cryptographic
Reference Key Data Set 430, the Reference Cryptographic Key 406 may be applied
to Key
Decryption Algorithm module 422 to retrieve and decrypt the Data Encryption
Key 404
originally used to encrypt the Clear Data 411. In an embodiment, the
Cryptographic
Reference Key Data Set 430 and Reference Cryptographic Key 406 inay be stored
in secure
cryptographic hardware so that the Reference Cryptographic Key 406 may be used
securely to
decrypt the Data Encryption Key 404.
[0045] As will be appreciated, much of the relevant infonnation necessary to
reconstitute
Encrypted Data may be stored directly on the backup media (i.e. as the
Reconstitution Data
408) together with the Encrypted Data 412. The user need maintain only one or
a few
Reference Cryptographic Keys 406 that are associated with many pieces of
backup media
413. With this approach, any Encrypted Data 412 may be stored with enough self-
defining
Reconstitution Data 408 such that, even years or decades into the future, the
Encrypted Data
412 may be recovered from many pieces of backup media using a Reference
Cryptographic
Key that has been centrally maintained.
[0046] FIG. 5 shows an illustrative method 500 corresponding the system
described above
with reference to FIG. 4A. Method 500 begins, and at block 502 reads various
encryption
parameters as provided by a user. At block 504, method 500 encrypts clear data
using a Data
Encryption Key applied to a Data Encryption Algorithm. Method 500 then
proceeds to block
506, where the Encrypted Data is stored onto a piece of backup media.
[0047] At block 508, method 500 encrypts the Data Encryption Key using a
Reference
Cryptographic Key applied to a Key Encryption Algorithm. Method 500 then
proceeds to
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block 510, where the encrypted Data Encryption Key is stored in the header of
the same piece
of backup media as the Encrypted Data.
[0048] At block 512, method 500 stores the Reconstitution Data, including the
Reference
Cryptographic Key Name, in the backup media header. Method 500 then proceeds
to block
514, where method 500 stores the Reference Cryptographic Key in a secure
central location to
use as necessary to decrypt the Encrypted Header at some point in the future.
Method 500
then ends.
[0049] Now referring to FIG. 6, shown is a method 600 corresponding to the
system
described above with reference to FIG. 4B. Method 600 begins and at block 602
retrieves
Reconstitution Data stored in the Header of a piece of backup media. At block
604, a
Reference Cryptographic Key Name associated with the backup media is
identified in the
Reference Cryptographic Key Data Set.
[0050] At block 606, the correct Reference Cryptographic Key is applied to a
Key Decryption
Algorithm to decrypt the encrypted Data Encryption Key.
[0051] At block 608, nlethod 600 applies the unique Data Encryption Key to a
Decryption
Algorithm to decrypt the Encrypted Data from the backup media, using the
Reconstitution
Data as may be necessary. Method 600 then ends.
[0052] While various illustrative embodiments of the invention have been
described above, it
will be appreciated by those skilled in the art that variations and
modifications may be made.
Thus, the scope of the invention is defined by the following claims.
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