CA2243093C - Confusion data generator - Google Patents
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- CA2243093C CA2243093C CA 2243093 CA2243093A CA2243093C CA 2243093 C CA2243093 C CA 2243093C CA 2243093 CA2243093 CA 2243093 CA 2243093 A CA2243093 A CA 2243093A CA 2243093 C CA2243093 C CA 2243093C
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
- H04L9/06—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols the encryption apparatus using shift registers or memories for block-wise or stream coding, e.g. DES systems or RC4; Hash functions; Pseudorandom sequence generators
- H04L9/065—Encryption by serially and continuously modifying data stream elements, e.g. stream cipher systems, RC4, SEAL or A5/3
- H04L9/0656—Pseudorandom key sequence combined element-for-element with data sequence, e.g. one-time-pad [OTP] or Vernam's cipher
- H04L9/0662—Pseudorandom key sequence combined element-for-element with data sequence, e.g. one-time-pad [OTP] or Vernam's cipher with particular pseudorandom sequence generator
- H04L9/0668—Pseudorandom key sequence combined element-for-element with data sequence, e.g. one-time-pad [OTP] or Vernam's cipher with particular pseudorandom sequence generator producing a non-linear pseudorandom sequence
Abstract
A confusion data generator for the generation of non-linear confusion data utilizes a plurality of arrays acting as non-linear state machines to generate a stream of confusion data of a certain width. Each non-linear state machine contributes equally to the overall width of the confusion data. The output bit stream from the confusion data generator is then used with a combiner such as an XOR combiner to generate secure text from plaintext. The confusion data generator can be used to securely store data on a storage medium or transmit data over a communication medium. The confusion data generator is computationally inexpensive, scalable and provides good security when used with a combiner, such as an XOR combiner, to generate secure text.
Description
CONFUSION DATA GENERATOR
FIELD OF INVENTION
The present invention relates to a method and apparatus for the generation of confusion data.
More particularly, the invention relates to a confusion data generator for generating non-linear confusion data for use with a combiner to store plaintext data on a storage medium or to transmit data over a communication medium in a secure fashion.
BACKGROUND OF THE INVENTION
In this application, the phrases "application of data to a medium" or "applying data to a medium" refer to the act of putting the data on a communication medium or mediums, or a storage medium or mediums. This involves the act of generating physical signals (i.e.
electrical, electromagnetic, light, or other) which are sent (for a communication medium) or stored (for a storage medium).
Whether data is transmitted or stored, it is susceptible to unauthorized observation. Security is becoming particularly difficult as computers are increasingly networked, thus increasing potential access to stored or transmitted confidential data. Therefore, to transmit or store data in a secure fashion, the data must be encrypted.
One of the main objectives of the field of data encryption is to transform plaintext data into ciphertext data in a way to conceal the information content of the original data. For the transformation to be of any value, it should be reversible, meaning that an inverse transformation should exist that enables the user to obtain the original plaintext from the ciphertext (i.e. decryption). In general, the process involves the use of a secret key in the encryption and decryption phases.
There are many encryption techniques that can be used to transfer plaintext into ciphertext.
Such techniques generally utilize block ciphers, substitution ciphers, stream ciphers or random number generators. However, due to the ease of their implementation in software and hardware, stream ciphers have gained popularity as fast encryptor devices.
Hence, many popular encryption techniques are based on stream ciphers.
In general, a stream cipher combines plaintext data with pseudo-random confusion data to produce ciphertext data. Hence, a stream cipher can be thought of as a confusion data generator and a combiner. An important combiner is based on the binary bit-by-bit addition mod 2, which is also known as the Boolean logic exclusive-OR (XOR) function.
Hence, the confusion data would be combined with the plaintext data by using the XOR
function in order to encrypt the plaintext. In the decryption process, the same confusion data would be XORed with the ciphertext data in order to recover the original plaintext.
The design of ciphers must assume that the cipher must be able to confront an unauthorized attacker who seeks the information contained in the ciphertext. In this regard, the use of the XOR function is useful in the encryption process. This is because the task of XORing the plaintext with pseudo-random bytes generally results in the generation of pseudo-random bytes. This helps to disguise the frequency statistics of the plaintext data.
Furthermore, the use of the XOR function has the advantage of making the decrypting process simple. This is because it is possible to extract the plaintext from the ciphertext by simply XORing the ciphertext with the confusion data.
The use of the XOR function as a combiner has a major drawback: the use of the XOR
function allows an unauthorized analyst to cryptoanalyze the confusion stream.
This can be done by using plaintext attacks. If an analyst is able to obtain some amount of plaintext and the matching ciphertext, the analyst can recover that portion of the confusion data. In the worst case scenario, the unauthorized attacker could analyse the confusion data and manage to reproduce the pseudo-random source, thus making the decryption of all subsequent messages possible. Therefore, designers must develop confusion generators or random number generators which are exceedingly difficult for a cryptanalyst to analyse successfully.
SIJMMtIRY OF THE INVL;NTION
Accordingly, an important object of the present invention is tc:~ provide a confusion data generator for generating confusion data which is difficult to cryptomalyze when used ~-ith a combiner, such as an XOIZ combiner.
A second object of the in~~en ion is to provide a confusion data generator that is scalable and capable of being implemented in hardware and soirt~.~~~re of various complexities.
FIELD OF INVENTION
The present invention relates to a method and apparatus for the generation of confusion data.
More particularly, the invention relates to a confusion data generator for generating non-linear confusion data for use with a combiner to store plaintext data on a storage medium or to transmit data over a communication medium in a secure fashion.
BACKGROUND OF THE INVENTION
In this application, the phrases "application of data to a medium" or "applying data to a medium" refer to the act of putting the data on a communication medium or mediums, or a storage medium or mediums. This involves the act of generating physical signals (i.e.
electrical, electromagnetic, light, or other) which are sent (for a communication medium) or stored (for a storage medium).
Whether data is transmitted or stored, it is susceptible to unauthorized observation. Security is becoming particularly difficult as computers are increasingly networked, thus increasing potential access to stored or transmitted confidential data. Therefore, to transmit or store data in a secure fashion, the data must be encrypted.
One of the main objectives of the field of data encryption is to transform plaintext data into ciphertext data in a way to conceal the information content of the original data. For the transformation to be of any value, it should be reversible, meaning that an inverse transformation should exist that enables the user to obtain the original plaintext from the ciphertext (i.e. decryption). In general, the process involves the use of a secret key in the encryption and decryption phases.
There are many encryption techniques that can be used to transfer plaintext into ciphertext.
Such techniques generally utilize block ciphers, substitution ciphers, stream ciphers or random number generators. However, due to the ease of their implementation in software and hardware, stream ciphers have gained popularity as fast encryptor devices.
Hence, many popular encryption techniques are based on stream ciphers.
In general, a stream cipher combines plaintext data with pseudo-random confusion data to produce ciphertext data. Hence, a stream cipher can be thought of as a confusion data generator and a combiner. An important combiner is based on the binary bit-by-bit addition mod 2, which is also known as the Boolean logic exclusive-OR (XOR) function.
Hence, the confusion data would be combined with the plaintext data by using the XOR
function in order to encrypt the plaintext. In the decryption process, the same confusion data would be XORed with the ciphertext data in order to recover the original plaintext.
The design of ciphers must assume that the cipher must be able to confront an unauthorized attacker who seeks the information contained in the ciphertext. In this regard, the use of the XOR function is useful in the encryption process. This is because the task of XORing the plaintext with pseudo-random bytes generally results in the generation of pseudo-random bytes. This helps to disguise the frequency statistics of the plaintext data.
Furthermore, the use of the XOR function has the advantage of making the decrypting process simple. This is because it is possible to extract the plaintext from the ciphertext by simply XORing the ciphertext with the confusion data.
The use of the XOR function as a combiner has a major drawback: the use of the XOR
function allows an unauthorized analyst to cryptoanalyze the confusion stream.
This can be done by using plaintext attacks. If an analyst is able to obtain some amount of plaintext and the matching ciphertext, the analyst can recover that portion of the confusion data. In the worst case scenario, the unauthorized attacker could analyse the confusion data and manage to reproduce the pseudo-random source, thus making the decryption of all subsequent messages possible. Therefore, designers must develop confusion generators or random number generators which are exceedingly difficult for a cryptanalyst to analyse successfully.
SIJMMtIRY OF THE INVL;NTION
Accordingly, an important object of the present invention is tc:~ provide a confusion data generator for generating confusion data which is difficult to cryptomalyze when used ~-ith a combiner, such as an XOIZ combiner.
A second object of the in~~en ion is to provide a confusion data generator that is scalable and capable of being implemented in hardware and soirt~.~~~re of various complexities.
t'1 third object of the inven ion is to provide a confiasic>n data generator that is fast and therefore computationally inexpensive.
'l'he confusion data gcneratc>r of the present invention generates non-linear confusion data.
In one embodiment, the confusion data generator uses a plurality of arrays, i.e. at least two arrays, acaing as non-linear state machines to generate a stream of confusion data made up of blacks r>f confusion bits. Each non-linear state machine produces sub-blocks ofeonfusion hits and thereby contributes equally to the overall width of the confusion data.
The state machines drive each other in a feed fbmard and feed back fashion. 'fhe output bit stream from the confusion data generator is then used with a combiner such as an XUR combincr to generate secure text from plainlext. The confusion data generator can be used to securely store data on a storage mediLnn or transmit data over a communication medium. The cc>nfusic.m data generator is ccnnl?utationally inexpensive, scalable and provides good security ~~~hen used wi th a combines, such as an XOR combines, to fenerate secure text.
t2ccording to the invention, there is further provided a confusion data generator comprising:
(aj a first state machine, the .first state machine corn.prising: a first series of data elements w%hose values are unidue: first mein~s to randomize the first state machine by exchanging two data elements from the rust set of data elements within the first state machine; (b) a second state machine, the second state machine comprising: a second series c>f data elements whose ~%alues are unique; second means to randomize the second state machine by exchanging two data elements fiom the second set of da a elements within the second state machine; and wherein the second state machine drives the first state machine in a feedback fashion in order to generate co~~fusion data as a :(unction o('the state machines.
According to tine invention, there is further provided a confusion data generator further comprising: a plurality of state machW es between the first and second state machines, each state machine driving the next state machine in a forward fashion, and a last state machine driving the first state machine in a feedback fashion.
according to the invention, there is further provided anon-linear confusion data generator for generating a number of blocks o:f.'confusion bits, the confusion data generator comprising: (a) a location counter having a value corresponding to the number of blocks of confusion hits generated; (b) a first array comprising a series of data elements, each of which has a value:
~c) a :first index having a value corresponding to a da a element in the first array; td) a second index having a ~-~alue corresponding to a data element in the first array; (e) a second array comprising a series of da a elements, each of which has a value; (t) a third index having a value corresponding to a data element in the second array; (g) a fourth index hawing a value coy°responding to a data elemetnt in the second array; (h) me~n~s fbr inerernenting the value of the location counter; (i) means for updating the vahue of tlve first index as a function of the value of the first index, the value of the data elemen of the first array corresponding to the value of the location counter, anal the value of the data element of the second. array corresponding to the vane of the location counter; (j) means for updating the value crf the second index as a function of the v=alue of the data elemen in the first array corresponding to the value of the first index, and the value of the data elemen-t in the first array corresponding to the value of the location counter; (k) means for exchanging the value of the data element in the first ax-ray corresponding to the value of the first index and the value of the data element in the first array corresponding to the valme of the location counter; (1) means for updating the value of the third index as a function of the value of the third index, the value of the data element of the first array corresponding to value of the lc}cation counter, acid the value of the data element of the second array corresponding to the value of the location counter; (m) means for updating th a value of the fourth index as a function o Fthe value of the data element in floe second ~u-ray corresponding to the value of th.e third index, and the value of the data element i.n the second array corresponding to tile value of the location counter; (n) means for exchanging the valzae of the data element in the second array corresponding to the value o f the third index acid the value of the data element in the second array corresponding to the value of the location eoimter; (o) means for generating from the first aT-ray a first sub-block of confusion bits equal to the value of'the data element in the lust array corresponding to the value of the second index; (p) means for generating from the second array a second sub-block of coWiasion bits equal to the value o f the data element in the second array eorrespcmdin.g to the value of Che fcmuth ilndex; (q) means for generatislg a hloek of confusion bits comprising the first and secand sub-blocks of confusion bits; and (r) means fbr applying the block of confusion bits to a medium.
According to the invention, there is further provided a non-linear confusion data generator for generating a number of blocks of confusioln bits, the confusion data generator comprising:
(a) a location counter having a value corresponding to tl~e nmnber of blocks of confusion bits generated; (L~) a plurality of arrays,, each array comprising: (i) a series of data elements, each data f:lel'llent haV111g a ~'alllf:; ( 11) a first llldex having a value COCreSpOndln~ to a data element In tile array: fllld (Ill) a seCOlld 111t1ex llavlng ii value eC)rrespOnc'llng to a data elerl'1e11t In the array; (c) means jor incrementing the value of the location colnnter; (d) means for Updating the value of the first index in each array as a Function of tile value of~ the first index c)f such array. the value of the data element of such alrray corresponding to the value of'tile location coup er, alld the value c~f the data element of at least one other array ec:)rresponding to the value of tile location counter; (e) means for updating the value of the second index in each array as a Function of the value of the data element in such array corresponding to the value of the first index in such array, and the value oFthe data element in such array corresponding to the value of the location counter; (f) means for exchanging the value of the data element in each array corresponding to the value of the first index in such array and the value of the data element in such array correspondinb to the value of the Location counter;
(g) means For generating from the each array a sub-block of confilsion bits equal to tile value of the data element in such array corresponding to the value of the secc)nd index in such array; (h) meatls lbr generating a block of'confusion bits comprising the sub-bl ocl;s o f conf usion bi s generated by the arrays; and (i) means For applying the block of confusion bits to a medium.
According to the invention. there is Further provided a lnetllod for generating a number c)f blocks of confusion bits. tile method Utilizing a non-linear confusion data generator comprising: a location counter having a value corresponding to the number of blocks of c.on:Fusion bits genera ed; a f first array comprising a series of data elements, each oi'which has a value; a first index having a value cor~~espallding to a data element in the first array; a second index having a value corresponding to a data element in the first ~rrl~a~~; a second array comprising a series of da a elements, each of which has a value; a third index having a value corresponding to a data element in the second array; and a fourth index having a value corresponding to a data element iv the second wray; the method comprising: ta) u~cromenting the value of the location co enter; (b) updating the value of the first index as a li~.nctior~ of the value of the first index, the value of the data element of the first array corresponding to the value of 'the location c.oun er, and the value of~ the data element of the second array corresponding to the value of the location counter; (c) updating the value of the second index as a lunetion ol'the value caf the data elemen in the first array corresponding to the value of the first index, and the value oi~the data element in the first array corresponding to the value of the location counter; (d) exchanging the value of the data element in the first array corresponding to the value oi~the first index and the value oi~the data element in the first array c.ortespondin.g to the value of the location counCer; (e) updating the value of the third index as a function of t(e value ol'the third index, the value ovf~the data element of the tirst array corresponding to value of'the location coLUrter, and the value of the data element of the second array corresponding to the value of the location counter; (f) updating the value oC the fourth index as a function. of~ the value of the data element i1n the second array car~-espondinlg to the value of'the third index, and the value of floe data element in the second array corresponding tc~ the value of the location counter; (g) exchanging the value caf the data element in the second array corresponding to the value of the third index and the value of'the data element in the second array corresponding to the value of'tht location counter; (11) the first array generating a first sub-blc?clc of confusion bits equal to the value of the data element in the first array corresponding to the value of the second index; (i) the second ~~rray generating a second sub-block ofi confusion bits equal to the value of the data element in the second array corresponding to the value of the fourth index; (;j) generating a block o:f' confusion hits cocnhrising the first and second sub-blocks of confusion bits; and (k) applying the hloch of confusion bits to a medium.
;'lccordinn to the invention. Chore is further provided a method for generating a number of blocks of confusion hits. the method utilizing a non-linear confusion data generator ecnnprisil~g: a locatican ccmmter having a value comes,ponding to the number crf t~lachs of confusion bits generated; a plurality of arrays. each array con uprising a series of data elements, each data element having a value a first index Having a value corresponding to a data element in the array and a second index having a value corresponding to a data element in the array; (a) incrementing the value of the location counter; (b) updating the value of the Lust index in each array as a function of the value of the first index o:f' such array, the value of the data element of such array corresponding to the value of the location counter, and the val~.te oPtHe data element of at least one other array corr espondW g to the value of the location counter; (c) updating the value of the second index in each wray as a function of the ~~alue of the data element in such array corresponding to the value of the foist index.
in such array., and the value of the data element in such array corresponding to the value of the location counter;
(d) exchanging the value o:f'the data element i.n each array corresponding to the value ovf'the tirsC index in such array and the value of the data elemen-t in such array corresponding to the value o.f.'the location counter; (e) generating frcnn the each array a sub-block of confusion bits eilual to the value of the data element in such array corresponding to the value of the second index in such array; and (f°~ generating a block oi~con:fusion bits comprising the sub-blocks of confusion bits generated by flue arrays; and (g) applying the block of conli~sion hits to a medium.
Among the advantages of the present invention are that the confusion data generator of the present invention: generates highly non-linear or complex confusion data that is difficult to cryptoanalyze (whether used with an XOR combiner or another combiner); is scalable and capable of being implemented in hardware and software of various complexities;
and is fast and therefore computationally inexpensive.
Other advantages, objects and features of the present invention will be readily apparent to those skilled in the art from a review of the following detailed description of preferred embodiments in conjunction with the accompanying drawings and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
The embodiments of the invention will now be described with reference to the accompanying drawings, in which:
Figure 1 is a block diagram of a Local Area Network (LAN) to LAN communication network over a Wide Area Network (WAN) link;
Figure 2 is a block diagram of the main processor of Figure 2;
Figure 3 is a block diagram showing major hardware components of the processor of Figure 3;
Figure 4 is a block diagram of step 1 of the initialization sequence of the method applied by the processor of Figure 3;
l0A
Figure S is a block diagram of step 2 of the initialization sequence of the method applied by the processor of Figure 3; and Figure 6 is a block diagram of the confusion data generator of the method applied by the processor of Figure 3.
Similar references are used in different figures to denote similar components.
DETAILED DESCRIPTION OF THE INVENTION
The present invention presents a method and apparatus for developing highly non-linear or complex confusion data generators (CDG) that can be used to securely store data on a storage medium or transmit data over a communication medium. The invention allows the development of scalable confusion data generators that generate a stream of confusion data of user defined width (such as 4 bit, 6 bit, 12 bit, etc.), thus resulting in the ability to efficiently implement the confusion data generator in hardware and software to minimize development costs.
The following is a description of preferred embodiments of the invention. The embodiments employ a system that performs data encryption and data decryption based on an encryption key or a seed. The system introduces randomness into the data such that it can only be decrypted by a system that uses the same confusion data generator and the same key.
Refernng to Figure 1, a pair of Local Area Networks (LANs), namely LAN A and LAN B, are shown. LAN A is located in Boston, and LAN B is located in Ottawa. Each LAN has attached thereto various devices which are well known in the art. In general, for security purposes, there may be a need for data encryption within each of LAN A and LAN
B.
However, there is a greater need to encrypt the data during its transport from LAN A to LAN B over the unprotected public network. Hence, when data is transmitted from LAN A
to LAN B, it will pass through LANBRII?GE 110 processor, where the user portion of the data packets appearing on LAN A is encrypted in accordance with the teachings of the present invention. The data is then transmitted by modem 11 S over Wide Area Network (WAN) link 120 to modem 125. The received user data packets are then decrypted by and the packets appearing at the input to LANBRIDGE 130 are reconstructed and placed on LAN B.
In Figure 2, a block diagram of LANBRIDGE 110 is shown. Data packets appearing on LAN A are received by LAN interface device 135 and passed into LANBRIDGE 110 processor 140. Within the processor 140 is bridge software 142 which, in addition to performing routing and other functions, also performs data encryption and decryption on the data portion of the packets.
A high level block diagram of LANBRIDGE 110 processor is shown in Figure 3. A
central processing unit (CPU) 155 forms the heart of LANBRIDGE 110. The CPU 155 communicates with other elements of the system via bus 170. The LAN interface 135 is connected to its bus 170, as is WAN interface 145 which provides a gateway for data to and from modem 11 S. An electrically alterable programmable read only memory (EPROM) 150 and random access memory (RAM) 160 provide storage functions for CPU 155.
Within RAM 160 are tables 165 that are employed by the encryption software 142. In Figure 3, the processor 140 includes EPROM 150, CPU 155 and RAM 160. Alternatively, the CPU
may be any special hardware device.
Before introducing the confusion data generator (CDG) as developed in this invention, it is beneficial to introduce some basic notations. In particular, we make reference of the use of the mathematical modulo operation (mod), which gives the remainder of dividing one number by the other. The term exchange means that the contents of two data variables is interchanged. The term array is used in the context of the C programming language which indicates a set of elements having the same data type that could be referenced by indexing them. Hence, an array R is a one dimensional entity of certain size or dimension, such as 'b', with elements assuming locations zero to 'b-1'. In this invention an array is viewed as a state machine that could transform from one state to another. The order of elements in an array defines the state of the array at a given time. Hence, if two elements of an array are exchanged, then the state of the array is changed, since the new order of elements in the array is different from the old order of elements in the array.
The confusion data generator of the invention uses at least two arrays acting as non-linear state machines to generate the confusion data. Herein, such arrays are termed cipher arrays.
The next state of a cipher array is determined as a function of its present state and the states of one or more other cipher an:ays. The transition process is determined in a non-linear fashion based on the mathematical concept of randomization by non-linear exchange. The initialization of the cipher arrays is performed as a function of all the cipher arrays and a secret key array. The secret key array holds the user seed.
The design of the confusion data generator of the present invention requires that the total width 'm' in bits of the confusion data and the number of cipher arrays 'n' be specified by the designer. This in turn determines the width 'w' of random bits and the dimension of each of the cipher arrays that are used in the design. For the following analysis, and without limiting the generality of the foregoing, it is assumed that the dimension of each cipher arrays is an integral power of two and that the width 'm' of the confusion data is a multiple of two.
Before the confusion data of this invention is used, a three step initialization process is performed. The first step of the initialization process consists of setting up the secret key array. In this step, the user seed is used to initialize each location in the secret key array. This is done by replicating the user seed to fill all the locations in the secret key array.
The second step of the initialization process consists of filling the cipher arrays with data elements whose values are unique. The simplest way to achieve this objective is to fill each cipher array with data that range from zero to 'c-1', where 'c' is the dimension of the cipher arrays.
The concepts are better illustrated in the following example. In this regard, let the width of the confusion data in bits be 'm'=24, and let the number of cipher arrays that are used in the design of the confusion data generator be 'n'=3. Hence, each cipher array must generate 8 bits of random data per iteration. Thus, the dimension of each cipher array is 'c'=8.
Let Array_1, Array 2 and Array 3 be the three cipher arrays that would be used in the design of the confusion data generator. Furthermore, let the secret key array be Key whose dimension is the same as the dimension of each of the cipher arrays and is equal to 'c'=8.
In Figure 4, the details of initializing the secret key array and the cipher arrays are depicted.
In step 300, the secret array Key is initialized with the user seed starting at location zero. The seed is replicated to fill all the locations in the array. In step 310 the cipher array Array_1 is filled with data elements starting at location zero. In step 320 and 330, the same process is repeated to cipher array Array_2 and Array_3.
The third step in the initialization process consists of shuffling the contents of the cipher arrays as a function of the secret key array in a non-linear fashion. This step uses the mathematical modulo operation 'mod'. In Figure 5, the details of the non-linear shuffling operation are depicted. Steps 470 and 480 ensure that all the elements of the cipher arrays are shuffled. In step 400, the variables '1', 'pos_1', 'pos 2' and 'pos_3' are initialized to zero.
The variable '1' indicates the current location within the cipher array that must be shuffled.
Variables 'pos_1', 'pos 2' and 'pos 3' are computed in a non-linear fashion and point to the location within a cipher array that must be exchanged with the '1'th location.
In step 410, the new value of 'pos_1' is computed as a function 'Key[l]', 'Array_1[1]', 'Array_2[1]', 'Array_3 [1]' and itself modulo 'c', where 'c' is the dimension of the cipher array. In step 420, the elements in location '1' and 'pos-1' in Array-1 are exchanged. The same processing is performed on the elements of Array_2 and Array_3 in steps 430, 440, 450 and 460.
The initialization process of Figure 5 ensures that the contents of the cipher arrays are randomized in a non-linear fashion. The randomization process is a function of all the cipher arrays that are used in the design of the confusion data generator. Hence, although the same Key array is used in the randomization process, the technique of Figure 5 ensures that the state of each cipher array is different after the completion of the initialization process. Therefore, this methodology results in the ability to generate a stream of cipher bits that is more secure for applications that use short size user seeds. Alternatively, multiple key arrays can be used in the randomization stage, whereby a different key array is associated with each cipher array.
In Figure 6, the details of the actual generation of the confusion data are depicted. In step 600, the variables 'LC', 'Index__1' , 'Index 2' and 'Index 3' are initialized to zero. Here, 'LC' acts as a data counter, it basically counts the number of data items that have been processed. The variables 'Index_1', 'Index 2' and 'Index 3' are used as indices to Array_l, Array 2 and Array 3, whereby the location that they point to is exchanged with location 'LC' in preparation for the next output sequence of the confusion data. In the example of Figure 6, 'Index_1' is used to compute the lower 'c' bits of the confusion data. 'Index 2' is used to compute the middle 'c' bits of the confusion data and 'Index 3' is used to compute the upper 'c' bits of the confusion data. The order of the indices can vary from one application to another and is user specified. In step 610, 'LC' is incremented to indicate that one piece of data is processed. The process is performed as a modulo 'c' operation. In step 620, the new value of 'Index-1' is computed as a modulo 'c' operation consisting of the previous value of 'Index-1', the 'LC' position of Array_l, Array_2, and Array_3. In step 630, the 'LC' element and the 'Index_1' element of Array_1 are exchanged. In step 631, the index of the lower 'c' bits of the confusion data is computed and stored in the variable 'I'. Here 'I' is computed as a modulo 'c' operation of the addition of 'Array 1 [Index_1 ]' and 'Array 1 [LC]'.
In step 640, the lower 'c' bits of confusion data are generated by outputting the Ith location of Array_1.
In step 650, the new value of 'Index_2' is computed as a modulo 'c' operation consisting of the previous value of 'Index 2', the 'LC' position of Array-1, Array_2 and Array_3. In step 660, the 'Index 2' elements and the 'LC' location of Array_2 are exchanged. In step 661, the index of the middle 'c' bits of the confusion data is computed and stored in the variable 'I'. Here 'I' is computed as a modulo 'c' operation of the addition of 'Array_2[Index 2]' and 'Array 2[LC]'. In step 670, the middle 'c' bits of confusion data are generated by outputting the Ith location of Array 2.
In step 680, the new value of Index 3 is computed as a modulo 'c' operation consisting of the previous value of 'Index 3', the 'LC' position of Array_1, Array 2 and Array_3. In step 690, the 'Index 3' elements and the 'LC' element of Array_3 are exchanged. In step 700, the index of the upper 'c' bits of the confusion data is computed and stored in the variable 'I'. Here 'I' is computed as a modulo 'c' operation of the addition of 'Array 3[Index 3]' and 'Array 3[LC]'. In step 710, the upper 'c' bits of the confusion data are generated by outputting the Ith location of Array 3.
The technique of Figure 6 utilizes multiple cipher arrays to generate a block of cipher bits as a collection of smaller size sub-blocks. The technique requires that at least two sub-blocks be used to generate a cipher block. The cipher bits from a block can be used to secure at least a sub-block of text.
The technique of Figure 6 presents a methodology for the non-linear generation of sub-blocks of cipher bits as a function of multiple cipher arrays acting as state machines. The methodology uses the cipher arrays in a feed forward and feed backward fashion to generate sub-blocks of cipher bits in a non-linear fashion. For each iteration the procedure of Figure 6 computes an index to a cipher array as a function of the previous value of that index and the current location of all cipher arrays. The procedure then randomizes the cipher array by exchanging the contents of the two locations. The procedure then computes in a non-linear fashion the index of the next sub-block of cipher bits as a function of the two locations.
Hence, per iteration all cipher arrays contribute to the randomization process.
In Figure 6, the value of the location counter LC was incremented once per iteration.
Alternatively, the value of LC could also be incremented after the generation of each sub-block of cipher bits or after any combination of sub-blocks.
The confusion data generator of this invention could be used to generate a m=n*w bits stream of cipher bits that could be used with an XOR combiner to encrypt 'm' bits of data.
Furthermore, it could also be used in an effective way to minimize the limitation of the XOR
combiner. In this regard, the confusion data generator could be used as a 'w' bit encryptor, whereby the lower, middle and upper 'w' bits are XORed together and the result is used to encrypt 'w' bits of data. Similarly, the confusion data generator could be used to encrypt 2*w' bits of data whereby, the lower and middle 'w' bits are XORed together and then used with the upper 'w' bits to encrypt the data. Any other combination could also be used. Such modifications give the designer the ability to hide the internal states of the confusion data generator from a cryptanalyst.
The confusion data generator of the present invention provides a mechanism for generating a confusion data stream that is highly non-linear or complex in nature.
Advantages of the invention include the use of the non-linear mathematical modulo operation to combine the operation of the cipher arrays in a non-linear fashion. The invention has provided a novice mechanism for developing feed forward and feed backward state machines that are highly non-linear. The invention overcomes one of the basic limitations of the XOR
combiner by developing a confusion data generator that generates a block of 'm' bits of confusion data per each iteration that can be used to generate a 'k'<'m' bit cipher stream that does not reveal the internal states of the confusion data generator. The invention results in the ability to design confusion data generators that are scalable, fast and secure.
Numerous modifications, variations and adaptations may be made to the particular embodiments of the invention described above without departing from the scope of the invention, which is defined in the claims.
'l'he confusion data gcneratc>r of the present invention generates non-linear confusion data.
In one embodiment, the confusion data generator uses a plurality of arrays, i.e. at least two arrays, acaing as non-linear state machines to generate a stream of confusion data made up of blacks r>f confusion bits. Each non-linear state machine produces sub-blocks ofeonfusion hits and thereby contributes equally to the overall width of the confusion data.
The state machines drive each other in a feed fbmard and feed back fashion. 'fhe output bit stream from the confusion data generator is then used with a combiner such as an XUR combincr to generate secure text from plainlext. The confusion data generator can be used to securely store data on a storage mediLnn or transmit data over a communication medium. The cc>nfusic.m data generator is ccnnl?utationally inexpensive, scalable and provides good security ~~~hen used wi th a combines, such as an XOR combines, to fenerate secure text.
t2ccording to the invention, there is further provided a confusion data generator comprising:
(aj a first state machine, the .first state machine corn.prising: a first series of data elements w%hose values are unidue: first mein~s to randomize the first state machine by exchanging two data elements from the rust set of data elements within the first state machine; (b) a second state machine, the second state machine comprising: a second series c>f data elements whose ~%alues are unique; second means to randomize the second state machine by exchanging two data elements fiom the second set of da a elements within the second state machine; and wherein the second state machine drives the first state machine in a feedback fashion in order to generate co~~fusion data as a :(unction o('the state machines.
According to tine invention, there is further provided a confusion data generator further comprising: a plurality of state machW es between the first and second state machines, each state machine driving the next state machine in a forward fashion, and a last state machine driving the first state machine in a feedback fashion.
according to the invention, there is further provided anon-linear confusion data generator for generating a number of blocks o:f.'confusion bits, the confusion data generator comprising: (a) a location counter having a value corresponding to the number of blocks of confusion hits generated; (b) a first array comprising a series of data elements, each of which has a value:
~c) a :first index having a value corresponding to a da a element in the first array; td) a second index having a ~-~alue corresponding to a data element in the first array; (e) a second array comprising a series of da a elements, each of which has a value; (t) a third index having a value corresponding to a data element in the second array; (g) a fourth index hawing a value coy°responding to a data elemetnt in the second array; (h) me~n~s fbr inerernenting the value of the location counter; (i) means for updating the vahue of tlve first index as a function of the value of the first index, the value of the data elemen of the first array corresponding to the value of the location counter, anal the value of the data element of the second. array corresponding to the vane of the location counter; (j) means for updating the value crf the second index as a function of the v=alue of the data elemen in the first array corresponding to the value of the first index, and the value of the data elemen-t in the first array corresponding to the value of the location counter; (k) means for exchanging the value of the data element in the first ax-ray corresponding to the value of the first index and the value of the data element in the first array corresponding to the valme of the location counter; (1) means for updating the value of the third index as a function of the value of the third index, the value of the data element of the first array corresponding to value of the lc}cation counter, acid the value of the data element of the second array corresponding to the value of the location counter; (m) means for updating th a value of the fourth index as a function o Fthe value of the data element in floe second ~u-ray corresponding to the value of th.e third index, and the value of the data element i.n the second array corresponding to tile value of the location counter; (n) means for exchanging the valzae of the data element in the second array corresponding to the value o f the third index acid the value of the data element in the second array corresponding to the value of the location eoimter; (o) means for generating from the first aT-ray a first sub-block of confusion bits equal to the value of'the data element in the lust array corresponding to the value of the second index; (p) means for generating from the second array a second sub-block of coWiasion bits equal to the value o f the data element in the second array eorrespcmdin.g to the value of Che fcmuth ilndex; (q) means for generatislg a hloek of confusion bits comprising the first and secand sub-blocks of confusion bits; and (r) means fbr applying the block of confusion bits to a medium.
According to the invention, there is further provided a non-linear confusion data generator for generating a number of blocks of confusioln bits, the confusion data generator comprising:
(a) a location counter having a value corresponding to tl~e nmnber of blocks of confusion bits generated; (L~) a plurality of arrays,, each array comprising: (i) a series of data elements, each data f:lel'llent haV111g a ~'alllf:; ( 11) a first llldex having a value COCreSpOndln~ to a data element In tile array: fllld (Ill) a seCOlld 111t1ex llavlng ii value eC)rrespOnc'llng to a data elerl'1e11t In the array; (c) means jor incrementing the value of the location colnnter; (d) means for Updating the value of the first index in each array as a Function of tile value of~ the first index c)f such array. the value of the data element of such alrray corresponding to the value of'tile location coup er, alld the value c~f the data element of at least one other array ec:)rresponding to the value of tile location counter; (e) means for updating the value of the second index in each array as a Function of the value of the data element in such array corresponding to the value of the first index in such array, and the value oFthe data element in such array corresponding to the value of the location counter; (f) means for exchanging the value of the data element in each array corresponding to the value of the first index in such array and the value of the data element in such array correspondinb to the value of the Location counter;
(g) means For generating from the each array a sub-block of confilsion bits equal to tile value of the data element in such array corresponding to the value of the secc)nd index in such array; (h) meatls lbr generating a block of'confusion bits comprising the sub-bl ocl;s o f conf usion bi s generated by the arrays; and (i) means For applying the block of confusion bits to a medium.
According to the invention. there is Further provided a lnetllod for generating a number c)f blocks of confusion bits. tile method Utilizing a non-linear confusion data generator comprising: a location counter having a value corresponding to the number of blocks of c.on:Fusion bits genera ed; a f first array comprising a series of data elements, each oi'which has a value; a first index having a value cor~~espallding to a data element in the first array; a second index having a value corresponding to a data element in the first ~rrl~a~~; a second array comprising a series of da a elements, each of which has a value; a third index having a value corresponding to a data element in the second array; and a fourth index having a value corresponding to a data element iv the second wray; the method comprising: ta) u~cromenting the value of the location co enter; (b) updating the value of the first index as a li~.nctior~ of the value of the first index, the value of the data element of the first array corresponding to the value of 'the location c.oun er, and the value of~ the data element of the second array corresponding to the value of the location counter; (c) updating the value of the second index as a lunetion ol'the value caf the data elemen in the first array corresponding to the value of the first index, and the value oi~the data element in the first array corresponding to the value of the location counter; (d) exchanging the value of the data element in the first array corresponding to the value oi~the first index and the value oi~the data element in the first array c.ortespondin.g to the value of the location counCer; (e) updating the value of the third index as a function of t(e value ol'the third index, the value ovf~the data element of the tirst array corresponding to value of'the location coLUrter, and the value of the data element of the second array corresponding to the value of the location counter; (f) updating the value oC the fourth index as a function. of~ the value of the data element i1n the second array car~-espondinlg to the value of'the third index, and the value of floe data element in the second array corresponding tc~ the value of the location counter; (g) exchanging the value caf the data element in the second array corresponding to the value of the third index and the value of'the data element in the second array corresponding to the value of'tht location counter; (11) the first array generating a first sub-blc?clc of confusion bits equal to the value of the data element in the first array corresponding to the value of the second index; (i) the second ~~rray generating a second sub-block ofi confusion bits equal to the value of the data element in the second array corresponding to the value of the fourth index; (;j) generating a block o:f' confusion hits cocnhrising the first and second sub-blocks of confusion bits; and (k) applying the hloch of confusion bits to a medium.
;'lccordinn to the invention. Chore is further provided a method for generating a number of blocks of confusion hits. the method utilizing a non-linear confusion data generator ecnnprisil~g: a locatican ccmmter having a value comes,ponding to the number crf t~lachs of confusion bits generated; a plurality of arrays. each array con uprising a series of data elements, each data element having a value a first index Having a value corresponding to a data element in the array and a second index having a value corresponding to a data element in the array; (a) incrementing the value of the location counter; (b) updating the value of the Lust index in each array as a function of the value of the first index o:f' such array, the value of the data element of such array corresponding to the value of the location counter, and the val~.te oPtHe data element of at least one other array corr espondW g to the value of the location counter; (c) updating the value of the second index in each wray as a function of the ~~alue of the data element in such array corresponding to the value of the foist index.
in such array., and the value of the data element in such array corresponding to the value of the location counter;
(d) exchanging the value o:f'the data element i.n each array corresponding to the value ovf'the tirsC index in such array and the value of the data elemen-t in such array corresponding to the value o.f.'the location counter; (e) generating frcnn the each array a sub-block of confusion bits eilual to the value of the data element in such array corresponding to the value of the second index in such array; and (f°~ generating a block oi~con:fusion bits comprising the sub-blocks of confusion bits generated by flue arrays; and (g) applying the block of conli~sion hits to a medium.
Among the advantages of the present invention are that the confusion data generator of the present invention: generates highly non-linear or complex confusion data that is difficult to cryptoanalyze (whether used with an XOR combiner or another combiner); is scalable and capable of being implemented in hardware and software of various complexities;
and is fast and therefore computationally inexpensive.
Other advantages, objects and features of the present invention will be readily apparent to those skilled in the art from a review of the following detailed description of preferred embodiments in conjunction with the accompanying drawings and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
The embodiments of the invention will now be described with reference to the accompanying drawings, in which:
Figure 1 is a block diagram of a Local Area Network (LAN) to LAN communication network over a Wide Area Network (WAN) link;
Figure 2 is a block diagram of the main processor of Figure 2;
Figure 3 is a block diagram showing major hardware components of the processor of Figure 3;
Figure 4 is a block diagram of step 1 of the initialization sequence of the method applied by the processor of Figure 3;
l0A
Figure S is a block diagram of step 2 of the initialization sequence of the method applied by the processor of Figure 3; and Figure 6 is a block diagram of the confusion data generator of the method applied by the processor of Figure 3.
Similar references are used in different figures to denote similar components.
DETAILED DESCRIPTION OF THE INVENTION
The present invention presents a method and apparatus for developing highly non-linear or complex confusion data generators (CDG) that can be used to securely store data on a storage medium or transmit data over a communication medium. The invention allows the development of scalable confusion data generators that generate a stream of confusion data of user defined width (such as 4 bit, 6 bit, 12 bit, etc.), thus resulting in the ability to efficiently implement the confusion data generator in hardware and software to minimize development costs.
The following is a description of preferred embodiments of the invention. The embodiments employ a system that performs data encryption and data decryption based on an encryption key or a seed. The system introduces randomness into the data such that it can only be decrypted by a system that uses the same confusion data generator and the same key.
Refernng to Figure 1, a pair of Local Area Networks (LANs), namely LAN A and LAN B, are shown. LAN A is located in Boston, and LAN B is located in Ottawa. Each LAN has attached thereto various devices which are well known in the art. In general, for security purposes, there may be a need for data encryption within each of LAN A and LAN
B.
However, there is a greater need to encrypt the data during its transport from LAN A to LAN B over the unprotected public network. Hence, when data is transmitted from LAN A
to LAN B, it will pass through LANBRII?GE 110 processor, where the user portion of the data packets appearing on LAN A is encrypted in accordance with the teachings of the present invention. The data is then transmitted by modem 11 S over Wide Area Network (WAN) link 120 to modem 125. The received user data packets are then decrypted by and the packets appearing at the input to LANBRIDGE 130 are reconstructed and placed on LAN B.
In Figure 2, a block diagram of LANBRIDGE 110 is shown. Data packets appearing on LAN A are received by LAN interface device 135 and passed into LANBRIDGE 110 processor 140. Within the processor 140 is bridge software 142 which, in addition to performing routing and other functions, also performs data encryption and decryption on the data portion of the packets.
A high level block diagram of LANBRIDGE 110 processor is shown in Figure 3. A
central processing unit (CPU) 155 forms the heart of LANBRIDGE 110. The CPU 155 communicates with other elements of the system via bus 170. The LAN interface 135 is connected to its bus 170, as is WAN interface 145 which provides a gateway for data to and from modem 11 S. An electrically alterable programmable read only memory (EPROM) 150 and random access memory (RAM) 160 provide storage functions for CPU 155.
Within RAM 160 are tables 165 that are employed by the encryption software 142. In Figure 3, the processor 140 includes EPROM 150, CPU 155 and RAM 160. Alternatively, the CPU
may be any special hardware device.
Before introducing the confusion data generator (CDG) as developed in this invention, it is beneficial to introduce some basic notations. In particular, we make reference of the use of the mathematical modulo operation (mod), which gives the remainder of dividing one number by the other. The term exchange means that the contents of two data variables is interchanged. The term array is used in the context of the C programming language which indicates a set of elements having the same data type that could be referenced by indexing them. Hence, an array R is a one dimensional entity of certain size or dimension, such as 'b', with elements assuming locations zero to 'b-1'. In this invention an array is viewed as a state machine that could transform from one state to another. The order of elements in an array defines the state of the array at a given time. Hence, if two elements of an array are exchanged, then the state of the array is changed, since the new order of elements in the array is different from the old order of elements in the array.
The confusion data generator of the invention uses at least two arrays acting as non-linear state machines to generate the confusion data. Herein, such arrays are termed cipher arrays.
The next state of a cipher array is determined as a function of its present state and the states of one or more other cipher an:ays. The transition process is determined in a non-linear fashion based on the mathematical concept of randomization by non-linear exchange. The initialization of the cipher arrays is performed as a function of all the cipher arrays and a secret key array. The secret key array holds the user seed.
The design of the confusion data generator of the present invention requires that the total width 'm' in bits of the confusion data and the number of cipher arrays 'n' be specified by the designer. This in turn determines the width 'w' of random bits and the dimension of each of the cipher arrays that are used in the design. For the following analysis, and without limiting the generality of the foregoing, it is assumed that the dimension of each cipher arrays is an integral power of two and that the width 'm' of the confusion data is a multiple of two.
Before the confusion data of this invention is used, a three step initialization process is performed. The first step of the initialization process consists of setting up the secret key array. In this step, the user seed is used to initialize each location in the secret key array. This is done by replicating the user seed to fill all the locations in the secret key array.
The second step of the initialization process consists of filling the cipher arrays with data elements whose values are unique. The simplest way to achieve this objective is to fill each cipher array with data that range from zero to 'c-1', where 'c' is the dimension of the cipher arrays.
The concepts are better illustrated in the following example. In this regard, let the width of the confusion data in bits be 'm'=24, and let the number of cipher arrays that are used in the design of the confusion data generator be 'n'=3. Hence, each cipher array must generate 8 bits of random data per iteration. Thus, the dimension of each cipher array is 'c'=8.
Let Array_1, Array 2 and Array 3 be the three cipher arrays that would be used in the design of the confusion data generator. Furthermore, let the secret key array be Key whose dimension is the same as the dimension of each of the cipher arrays and is equal to 'c'=8.
In Figure 4, the details of initializing the secret key array and the cipher arrays are depicted.
In step 300, the secret array Key is initialized with the user seed starting at location zero. The seed is replicated to fill all the locations in the array. In step 310 the cipher array Array_1 is filled with data elements starting at location zero. In step 320 and 330, the same process is repeated to cipher array Array_2 and Array_3.
The third step in the initialization process consists of shuffling the contents of the cipher arrays as a function of the secret key array in a non-linear fashion. This step uses the mathematical modulo operation 'mod'. In Figure 5, the details of the non-linear shuffling operation are depicted. Steps 470 and 480 ensure that all the elements of the cipher arrays are shuffled. In step 400, the variables '1', 'pos_1', 'pos 2' and 'pos_3' are initialized to zero.
The variable '1' indicates the current location within the cipher array that must be shuffled.
Variables 'pos_1', 'pos 2' and 'pos 3' are computed in a non-linear fashion and point to the location within a cipher array that must be exchanged with the '1'th location.
In step 410, the new value of 'pos_1' is computed as a function 'Key[l]', 'Array_1[1]', 'Array_2[1]', 'Array_3 [1]' and itself modulo 'c', where 'c' is the dimension of the cipher array. In step 420, the elements in location '1' and 'pos-1' in Array-1 are exchanged. The same processing is performed on the elements of Array_2 and Array_3 in steps 430, 440, 450 and 460.
The initialization process of Figure 5 ensures that the contents of the cipher arrays are randomized in a non-linear fashion. The randomization process is a function of all the cipher arrays that are used in the design of the confusion data generator. Hence, although the same Key array is used in the randomization process, the technique of Figure 5 ensures that the state of each cipher array is different after the completion of the initialization process. Therefore, this methodology results in the ability to generate a stream of cipher bits that is more secure for applications that use short size user seeds. Alternatively, multiple key arrays can be used in the randomization stage, whereby a different key array is associated with each cipher array.
In Figure 6, the details of the actual generation of the confusion data are depicted. In step 600, the variables 'LC', 'Index__1' , 'Index 2' and 'Index 3' are initialized to zero. Here, 'LC' acts as a data counter, it basically counts the number of data items that have been processed. The variables 'Index_1', 'Index 2' and 'Index 3' are used as indices to Array_l, Array 2 and Array 3, whereby the location that they point to is exchanged with location 'LC' in preparation for the next output sequence of the confusion data. In the example of Figure 6, 'Index_1' is used to compute the lower 'c' bits of the confusion data. 'Index 2' is used to compute the middle 'c' bits of the confusion data and 'Index 3' is used to compute the upper 'c' bits of the confusion data. The order of the indices can vary from one application to another and is user specified. In step 610, 'LC' is incremented to indicate that one piece of data is processed. The process is performed as a modulo 'c' operation. In step 620, the new value of 'Index-1' is computed as a modulo 'c' operation consisting of the previous value of 'Index-1', the 'LC' position of Array_l, Array_2, and Array_3. In step 630, the 'LC' element and the 'Index_1' element of Array_1 are exchanged. In step 631, the index of the lower 'c' bits of the confusion data is computed and stored in the variable 'I'. Here 'I' is computed as a modulo 'c' operation of the addition of 'Array 1 [Index_1 ]' and 'Array 1 [LC]'.
In step 640, the lower 'c' bits of confusion data are generated by outputting the Ith location of Array_1.
In step 650, the new value of 'Index_2' is computed as a modulo 'c' operation consisting of the previous value of 'Index 2', the 'LC' position of Array-1, Array_2 and Array_3. In step 660, the 'Index 2' elements and the 'LC' location of Array_2 are exchanged. In step 661, the index of the middle 'c' bits of the confusion data is computed and stored in the variable 'I'. Here 'I' is computed as a modulo 'c' operation of the addition of 'Array_2[Index 2]' and 'Array 2[LC]'. In step 670, the middle 'c' bits of confusion data are generated by outputting the Ith location of Array 2.
In step 680, the new value of Index 3 is computed as a modulo 'c' operation consisting of the previous value of 'Index 3', the 'LC' position of Array_1, Array 2 and Array_3. In step 690, the 'Index 3' elements and the 'LC' element of Array_3 are exchanged. In step 700, the index of the upper 'c' bits of the confusion data is computed and stored in the variable 'I'. Here 'I' is computed as a modulo 'c' operation of the addition of 'Array 3[Index 3]' and 'Array 3[LC]'. In step 710, the upper 'c' bits of the confusion data are generated by outputting the Ith location of Array 3.
The technique of Figure 6 utilizes multiple cipher arrays to generate a block of cipher bits as a collection of smaller size sub-blocks. The technique requires that at least two sub-blocks be used to generate a cipher block. The cipher bits from a block can be used to secure at least a sub-block of text.
The technique of Figure 6 presents a methodology for the non-linear generation of sub-blocks of cipher bits as a function of multiple cipher arrays acting as state machines. The methodology uses the cipher arrays in a feed forward and feed backward fashion to generate sub-blocks of cipher bits in a non-linear fashion. For each iteration the procedure of Figure 6 computes an index to a cipher array as a function of the previous value of that index and the current location of all cipher arrays. The procedure then randomizes the cipher array by exchanging the contents of the two locations. The procedure then computes in a non-linear fashion the index of the next sub-block of cipher bits as a function of the two locations.
Hence, per iteration all cipher arrays contribute to the randomization process.
In Figure 6, the value of the location counter LC was incremented once per iteration.
Alternatively, the value of LC could also be incremented after the generation of each sub-block of cipher bits or after any combination of sub-blocks.
The confusion data generator of this invention could be used to generate a m=n*w bits stream of cipher bits that could be used with an XOR combiner to encrypt 'm' bits of data.
Furthermore, it could also be used in an effective way to minimize the limitation of the XOR
combiner. In this regard, the confusion data generator could be used as a 'w' bit encryptor, whereby the lower, middle and upper 'w' bits are XORed together and the result is used to encrypt 'w' bits of data. Similarly, the confusion data generator could be used to encrypt 2*w' bits of data whereby, the lower and middle 'w' bits are XORed together and then used with the upper 'w' bits to encrypt the data. Any other combination could also be used. Such modifications give the designer the ability to hide the internal states of the confusion data generator from a cryptanalyst.
The confusion data generator of the present invention provides a mechanism for generating a confusion data stream that is highly non-linear or complex in nature.
Advantages of the invention include the use of the non-linear mathematical modulo operation to combine the operation of the cipher arrays in a non-linear fashion. The invention has provided a novice mechanism for developing feed forward and feed backward state machines that are highly non-linear. The invention overcomes one of the basic limitations of the XOR
combiner by developing a confusion data generator that generates a block of 'm' bits of confusion data per each iteration that can be used to generate a 'k'<'m' bit cipher stream that does not reveal the internal states of the confusion data generator. The invention results in the ability to design confusion data generators that are scalable, fast and secure.
Numerous modifications, variations and adaptations may be made to the particular embodiments of the invention described above without departing from the scope of the invention, which is defined in the claims.
Claims (17)
1. A confusion data generator comprising:
(a) a first state machine, the first state machine comprising:
a first series of data elements whose values are unique;
first means to randomize the first state machine by exchanging two data elements from the first set of data elements within the first state machine;
and (b) a second state machine, the second state machine comprising:
a second series of data elements whose values are unique;
second means to randomize the second state machine by exchanging two data elements from the second set of data elements within the second state machine;
whereby the second state machine drives the first state machine in a feedback fashion to generate confusion data as a function of the state machines.
(a) a first state machine, the first state machine comprising:
a first series of data elements whose values are unique;
first means to randomize the first state machine by exchanging two data elements from the first set of data elements within the first state machine;
and (b) a second state machine, the second state machine comprising:
a second series of data elements whose values are unique;
second means to randomize the second state machine by exchanging two data elements from the second set of data elements within the second state machine;
whereby the second state machine drives the first state machine in a feedback fashion to generate confusion data as a function of the state machines.
2. A confusion data generator as defined in claim 1 further comprising: at least one state machine between the first and second state machines, each state machine driving the next state machine in a feed forward fashion, and a second state machine driving the first state machine in a feedback fashion.
3. A confusion data generator as claimed in claim 2, wherein each state machine drives itself and every other state machine such that all state machines contribute to the confusion data generator.
4. A confusion data generator as claimed in claim 2, wherein each state machine drives itself and every other state machine such that some state machines contribute to the confusion data generator.
5. A confusion data generator as defined in claim 1, wherein the first state machine drives the second state machine in a feed forward fashion, and the second state machine drives the first state machine in a feedback fashion.
6. A confusion data generator as defined in claim 5, wherein the first state machine drives itself and the second state machine, and the second state machine drives itself and the first state machine such that the first and second state machines contribute to the confusion data generator.
7. A confusion data generator as defined in claim 5, wherein each state machine drives itself and every other state machine such that some state machines contribute to the confusion data generator.
8. A confusion data generator as defined in claim 1, wherein the second state machine drives the first state machine in a non-linear feedback fashion.
9. A confusion data generator as defined in claim 1, wherein each state machine comprises an array and an index therefor, each index corresponding to a location in its array.
10. A confusion data generator as defined in claim 9, wherein the location of each index in its array is dependent upon the location of another index in its array.
11. A confusion data generator as defined in claim 9, further comprising:
a data counter; and means for incrementing the value of the data counter, wherein the values of the first and second sets of data elements correspond to the value of the data counter.
a data counter; and means for incrementing the value of the data counter, wherein the values of the first and second sets of data elements correspond to the value of the data counter.
12. A confusion data generator as defined in claim 1, further comprising a combiner.
13. A confusion data generator as defined in claim 12, wherein the combiner is an XOR
combiner.
combiner.
14. A non-linear confusion data generator for generating a number of blocks of confusion bits, the confusion data generator comprising:
(a) a location counter having a value corresponding to the number of blocks of confusion bits to be generated;
(b) a first array comprising a series of data elements, each of which has a value:
(c) a first index having a value corresponding to a data element in the first array;
(d) a second index having a value corresponding to a data element in the first array:
(e) a second array comprising a series of data elements, each of which has a value;
(f) a third index having a value corresponding to a data element in the second array;
(g) a fourth index having a value corresponding to a data element in the second array:
(h) means for incrementing the value of the location counter;
(i) means for updating the value of the first index as a function of the value of the first index, the value of the data element of the first array corresponding to the value of the location counter, and the value of the data element of the second array corresponding to the value of the location counter;
(j) means for updating the value of the second index as a function of the value of the data element in the first array corresponding to the value of the first index, and the value of the data element in the first array corresponding to the value of the location counter;
(k) means for exchanging the value of the data element in the first array corresponding to the value of the first index and the value of the data element in the first array corresponding to the value of the location counter;
(l) means for updating the value of the third index as a function of the value of the third index, the value of the data element of the first array corresponding to value of the location counter, and the value of the data element of the second array corresponding to the value of the location counter;
(m) means for updating the value of the fourth index as a function of the value of the data element in the second array corresponding to the value of the third index, and the value of the data element in the second array corresponding to the value of the location counter;
(n) means for exchanging the value of the data element in the second array corresponding to the value of the third index and the value of the data element in the second array corresponding to the value of the location counter;
(o) means for generating from the first array a first sub-block of confusion bits equal to the value of the data element in the first array corresponding to the value of the second index;
(p) means for generating from the second array a second sub-block of confusion bits equal to the value of the data element in the second an array corresponding to the value of the fourth index;
(q) means for generating a block of confusion bits comprising the first and second sub-blocks of confusion bits; and (r) means for applying the block of confusion bits to a medium.
(a) a location counter having a value corresponding to the number of blocks of confusion bits to be generated;
(b) a first array comprising a series of data elements, each of which has a value:
(c) a first index having a value corresponding to a data element in the first array;
(d) a second index having a value corresponding to a data element in the first array:
(e) a second array comprising a series of data elements, each of which has a value;
(f) a third index having a value corresponding to a data element in the second array;
(g) a fourth index having a value corresponding to a data element in the second array:
(h) means for incrementing the value of the location counter;
(i) means for updating the value of the first index as a function of the value of the first index, the value of the data element of the first array corresponding to the value of the location counter, and the value of the data element of the second array corresponding to the value of the location counter;
(j) means for updating the value of the second index as a function of the value of the data element in the first array corresponding to the value of the first index, and the value of the data element in the first array corresponding to the value of the location counter;
(k) means for exchanging the value of the data element in the first array corresponding to the value of the first index and the value of the data element in the first array corresponding to the value of the location counter;
(l) means for updating the value of the third index as a function of the value of the third index, the value of the data element of the first array corresponding to value of the location counter, and the value of the data element of the second array corresponding to the value of the location counter;
(m) means for updating the value of the fourth index as a function of the value of the data element in the second array corresponding to the value of the third index, and the value of the data element in the second array corresponding to the value of the location counter;
(n) means for exchanging the value of the data element in the second array corresponding to the value of the third index and the value of the data element in the second array corresponding to the value of the location counter;
(o) means for generating from the first array a first sub-block of confusion bits equal to the value of the data element in the first array corresponding to the value of the second index;
(p) means for generating from the second array a second sub-block of confusion bits equal to the value of the data element in the second an array corresponding to the value of the fourth index;
(q) means for generating a block of confusion bits comprising the first and second sub-blocks of confusion bits; and (r) means for applying the block of confusion bits to a medium.
15. A non-linear confusion data generator for generating a number of blocks of confusion bits as defined in claim 14, the confusion data generator comprising:
(a) a location counter having a value corresponding to the number of blocks of confusion bits generated;
(b) a plurality of arrays, each array comprising:
(i) a series of data elements, each data element having a value;
(ii) a first index having a value corresponding to a data element in the array; and (iii) a second index having a value corresponding to a data element in the array;
(c) means for incrementing the value of the location counter;
(d) means for updating the value of the first index in each array as a function of the value of the first index of such array, the value of the data element of such array corresponding to the value of the location counter, and the value of the data element of at least one other array corresponding to the value of the location counter;
(e) means for updating the valve of the second index in each array as a function of the value of the data element in such array corresponding to the value of the first index in such array, and the value of the data element in such array corresponding to the value of the location counter;
(f) means for exchanging the value of the data element in each array corresponding to the value of the first index in such array and the value of the data element in such array corresponding to the value of the location counter;
(g) means for generating from the each array a sub-block of confusion bits equal to the value of the data element in such array corresponding to the value of the second index in such array;
(h) means for generating a block of confusion bits comprising the sub-blocks of confusion bits generated by the arrays; and (i) means for applying the block of confusion bits to a medium.
(a) a location counter having a value corresponding to the number of blocks of confusion bits generated;
(b) a plurality of arrays, each array comprising:
(i) a series of data elements, each data element having a value;
(ii) a first index having a value corresponding to a data element in the array; and (iii) a second index having a value corresponding to a data element in the array;
(c) means for incrementing the value of the location counter;
(d) means for updating the value of the first index in each array as a function of the value of the first index of such array, the value of the data element of such array corresponding to the value of the location counter, and the value of the data element of at least one other array corresponding to the value of the location counter;
(e) means for updating the valve of the second index in each array as a function of the value of the data element in such array corresponding to the value of the first index in such array, and the value of the data element in such array corresponding to the value of the location counter;
(f) means for exchanging the value of the data element in each array corresponding to the value of the first index in such array and the value of the data element in such array corresponding to the value of the location counter;
(g) means for generating from the each array a sub-block of confusion bits equal to the value of the data element in such array corresponding to the value of the second index in such array;
(h) means for generating a block of confusion bits comprising the sub-blocks of confusion bits generated by the arrays; and (i) means for applying the block of confusion bits to a medium.
16. A method for generating a number of blocks of confusion bits, the method utilizing a non-linear confusion data generator comprising: a location counter having a value corresponding to the number of blocks of confusion bits generated; a first array comprising a series of data elements, each of which has a value; a first index having a value corresponding to a data element in the first array; a second index having a value corresponding to a data element in the first array; a second array comprising a series of data elements, each of which has a value; a third index having a value corresponding to a data element in the second array; and a fourth index having a value corresponding to a data element in the second array; the method comprising:
(a) incrementing the value of the location counter;
(b) updating the value of the first index as a function of the value of the first index, the value of the data element of the first array corresponding to the value of the location counter. and the value of the data element of the second array corresponding to the value of the location counter;
(c) updating the value of the second index as a function of the value of the data element in the first array corresponding to the value of the first index, and the value of the data element in the first array corresponding to the value of the location counter;
(d) exchanging the value of the data element in the first array corresponding to the value of the first index and the value of the data element in the first array corresponding to the value of the location counter;
(e) updating the value of the third index as a function of the value of the third index, the value of the data element of the first array corresponding to value of the location counter, and the value of the data element of the second array corresponding to the value of the location counter;
(f) updating the value of the fourth index as a function of the value of the data element to the second array corresponding to the value of the third index, and the value of the data element in the second array corresponding to the value of the location counter;
(g) exchanging the value of the data element in the second array corresponding to the value of the third index and the value of the data element in the second array corresponding to the value of the location counter;
(h) the first array generating a first sub-block of confusion bits equal to the value of the data element in the first array corresponding to the value of the second index;
(i) the second array generating a second sub-block of confusion bits equal to the value of the data element in the second array corresponding to the value of the fourth index:
(j) generating a block of confusion bits comprising the first and second sub-blocks of confusion bits; and (k) applying the block of confusion bits to a medium.
(a) incrementing the value of the location counter;
(b) updating the value of the first index as a function of the value of the first index, the value of the data element of the first array corresponding to the value of the location counter. and the value of the data element of the second array corresponding to the value of the location counter;
(c) updating the value of the second index as a function of the value of the data element in the first array corresponding to the value of the first index, and the value of the data element in the first array corresponding to the value of the location counter;
(d) exchanging the value of the data element in the first array corresponding to the value of the first index and the value of the data element in the first array corresponding to the value of the location counter;
(e) updating the value of the third index as a function of the value of the third index, the value of the data element of the first array corresponding to value of the location counter, and the value of the data element of the second array corresponding to the value of the location counter;
(f) updating the value of the fourth index as a function of the value of the data element to the second array corresponding to the value of the third index, and the value of the data element in the second array corresponding to the value of the location counter;
(g) exchanging the value of the data element in the second array corresponding to the value of the third index and the value of the data element in the second array corresponding to the value of the location counter;
(h) the first array generating a first sub-block of confusion bits equal to the value of the data element in the first array corresponding to the value of the second index;
(i) the second array generating a second sub-block of confusion bits equal to the value of the data element in the second array corresponding to the value of the fourth index:
(j) generating a block of confusion bits comprising the first and second sub-blocks of confusion bits; and (k) applying the block of confusion bits to a medium.
17. A method for generating a number of blocks of confusion bits, the method utilizing a non-linear confusion data generator comprising: a location counter having a value corresponding to the number of blocks of confusion bits generated; a plurality of arrays, each array comprising a series of data elements, each data element having a value a first index having a value corresponding to a data element in the array and a second index having a value corresponding to a data element in the array:
(a) incrementing the value of the location counter;
(b) updating the value of the first index in each array as a function of the value of the first index of such array, the value of the data element of such array corresponding to the value of the location counter, and the value of the data element of at least one other array corresponding to the value of the location counter:
(c) updating the value of the second index in each array as a function of the value of the data element in such array corresponding to the value of the first index in such array, and the value of the data element in such array corresponding to the value of the location counter;
(d) exchanging the value of the data element in each array corresponding to the value of the first index in such array and the value of the data element in such array corresponding to the value of the location counter;
(e) generating from the each array a sub-block of confusion bits equal to the value of the data element in such array corresponding to the value of the second index in such array; and (f) generating a block of confusion bits comprising the sub-blocks of confusion bits generated by the arrays; and (g) applying the block of confusion bits to a medium.
(a) incrementing the value of the location counter;
(b) updating the value of the first index in each array as a function of the value of the first index of such array, the value of the data element of such array corresponding to the value of the location counter, and the value of the data element of at least one other array corresponding to the value of the location counter:
(c) updating the value of the second index in each array as a function of the value of the data element in such array corresponding to the value of the first index in such array, and the value of the data element in such array corresponding to the value of the location counter;
(d) exchanging the value of the data element in each array corresponding to the value of the first index in such array and the value of the data element in such array corresponding to the value of the location counter;
(e) generating from the each array a sub-block of confusion bits equal to the value of the data element in such array corresponding to the value of the second index in such array; and (f) generating a block of confusion bits comprising the sub-blocks of confusion bits generated by the arrays; and (g) applying the block of confusion bits to a medium.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2243093 CA2243093C (en) | 1997-07-11 | 1998-07-10 | Confusion data generator |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002210199A CA2210199A1 (en) | 1997-07-11 | 1997-07-11 | Method and apparatus for the generation of non-linear confusion data |
| CA2,210,199 | 1997-07-11 | ||
| CA 2243093 CA2243093C (en) | 1997-07-11 | 1998-07-10 | Confusion data generator |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2243093A1 CA2243093A1 (en) | 1999-01-11 |
| CA2243093C true CA2243093C (en) | 2001-05-01 |
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ID=25679480
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2243093 Expired - Fee Related CA2243093C (en) | 1997-07-11 | 1998-07-10 | Confusion data generator |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2243093C (en) |
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1998
- 1998-07-10 CA CA 2243093 patent/CA2243093C/en not_active Expired - Fee Related
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| Publication number | Publication date |
|---|---|
| CA2243093A1 (en) | 1999-01-11 |
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