Abstract: A system (100) and method (400, 500) for data encryption and decryption are disclosed. The encryption system is operable at encryption rates in excess of 10 Mbps and is expandable to over 200 Mpbs. For encryption, plain characters are received, and a key block (120) includes key characters corresponding to the plain characters is accessed. A current key character corresponding to a current plain character is located. A next key character corresponding to a next plain character is located. An offset between the current key character and the next key character is determined to encrypt the plain characters. Aliases are used to facilitate the encryption and decryption. Vector distances of offsets are utilized for the encryption and decryption, using many variables and many dimensions, such as using coordinates.

Abstract: A data reproducing apparatus and method is provided for reproducing data that was ciphered during recording in one or more of sector forming, header appending, error correction coding, modulation, and synchronization appending operations used for processing input data to form a recording signal. Thus, deciphering requires knowledge of both the ciphering key and the aspect(s) of the recording operation in which the ciphering took place. The deciphering may also include a descrambling operation in which an initial value and/or a generating polynomial is varied in accordance with ciphering key information.

Abstract: The invention relates to a method of generating a random-number sequence, and to a random-number generator, particularly for a chip card or a smart card.

Abstract: A system and method for unique authentication of each replication of a plurality of soft-copy documents, forming a group. One soft-copy document, out of the group, becomes a carrier for an authentication code aimed at protecting the group. The authentication code is computed from the concatenation of the plurality of soft-copy documents and a key. A random number is also generated for each replication of the group of files. The random number is combined with the authentication code to mark the soft-copy document which has been selected to become the carrier. Thus, the invention introduces randomization in the insertion of the authentication code so that for each replication of an identical group of data files, unique authentication data can be associated, merged and hidden in the transmitted information.

Abstract: In accordance with the present invention, consumers and merchants use computing devices connected to a network, such as the Internet, through wired and wireless means, wherein the consumer connects to a clearing server device to purchase or retrieve previously purchased token, the consumer then connects to the merchant's computer or website to attain price quotes of goods and services, selects the goods and/or services to be purchased, and then communicates a request for purchase to the merchant. The merchant then communicates a request for an update key to the clearing server. The update key is used as an authorization to modify the value of the token. To debit the customer the decrement key is requested and to credit the customer an increment key is asked for. An overwrite key is another type of update key. Together with the overwrite key a replacement token is provided to the merchant who in turn forwards the new token to the customer.

Abstract: A key generator (51, 61) generates, from an IP-key (11) for entering a closed IP network (1), a set (52, 62) of session keys (53, 63) indexed for identification, an index pointer (71, 72) points an index (i, j) to identify a session key (53, 63), the set (52, 62) of session keys has a divergence barrier incorporated therein for barring a computational approach to any session key (53, 63), and an unbar data set (i, j, 62) unbars the divergence barrier.

Abstract: Computer methods, systems, and devices, providing automatic permutations of a programmed modified random symbol square matrix producing one time pad messages are disclosed enabling messages to be encrypted from plain text which is typed into a computer thereby selecting random symbols from the matrix. Typing in text in a continuous stream yields a continuous stream of enciphered symbols. The input into a computer via an input device activates a computer program driven device called a sliding scale whose function is to select random symbols from the matrix. The sliding scale responds to the program containing the applicable algorithms for encryption and decryption. Initiating input into the computer requires the selection of an entry point to activate the algorithms given in the Appendix herein. In the 96×96 Square described, there are 9216 entry points yielding many individual alphabets from which to select random symbols.

Abstract: A system (300, 500) for scrambling digital samples (115, 200, 250, 260, 270) of multimedia data, including audio and video data samples, such that the content of the samples is degraded but still recognizable, or otherwise provided at a desired quality level. The samples may be in any conceivable compressed or uncompressed digital format, including Pulse Code Modulation (PCM) samples, samples in floating point representation, samples in companding schemes (e.g., ?-law and A-law), and other compressed bit streams. The quality level may be associated with a particular signal to noise ratio, or quality level that is determined by objective and/or subjective tests, for example. A number of LSBs can be scrambled in successive samples in successive frames (FRAME A, FRAME B, FRAME C). Moreover, the parameters for scrambling may change from frame to frame. Furthermore, all or part of the scrambling key (310) can be embedded (340) in the scrambled data and recovered at a decoder (400, 600) to be used in descrambling.

Abstract: A method and a system for performing a transaction between at least one first party and at least one second party are disclosed. A data network connects data input/output terminals of the parties. In the data network, a secure and trusted transaction server is provided, in which a profile of the parties is registered, having a party identifier identifying a particular party, and authentication data for authenticating the party and data sent by the party. The parties communicate with each other through the transaction server by means of various transaction messages, which are digitally signed using a table of random numbers and a hashing operation, wherein the table of random numbers is generated by reading a token.

Abstract: A cryptographic key split combiner, which includes a number of key split generators for generating cryptographic key splits and a key split randomizer for randomizing the cryptographic key splits to produce a cryptographic key, and a process for forming cryptographic keys. Each of the key split generators generates key splits from seed data. The key split generators may include a random split generator for generating a random key split based on reference data. Other key split generators may include a token split generator for generating a token key split based on label data, a console split generator for generating a console key split based on maintenance data, and a biometric split generator for generating a biometric key split based on biometric data. All splits may further be based on static data, which may be updated, for example by modifying a prime number divisor of the static data. The label data may be read from a storage medium, and may include user authorization data.

Abstract: The present invention may be regarded as a digital video recorder (DVR) comprising a storage device for storing an encrypted video program, a unique ID for interlocking the encrypted video program with the digital video recorder, and a cryptography facility. The cryptography facility comprises an encoder, responsive to the unique ID, for encrypting a plaintext video program into the encrypted video program stored on the storage device, and a decoder, responsive to the unique ID, for decrypting the encrypted video program stored on the storage device into the plaintext video program during playback.

Abstract: A system and method for verifying the identification of a user and securely establishing an encryption key for a communication between the user and a verifying entity, such as a bank, which makes use of the numeric value of the user's personal identification number (PIN) known only to the user and the bank and resolves the man-in-the-middle problem. The system and method replaces a public parameter with the customer's PIN to provide an encryption mechanism that is less complex than existing protocols. Use of the protocol enables new products and improvement of existing products using a service access device and service access device interface, including, for example, self-service terminals.

Abstract: A data processing method and apparatus are proposed for used in the encryption, decryption and authentication of messages. A memory for storing input information, a set of operations and a processor for executing the operations on the stored input information are provided. The input information is utilized to select the order and number of operations performed. The operations are devised such that any possible input string will be interpreted as a valid program and the memory is extensible. Furthermore, data is output as a function of the input information. As a result the state of the memory generated during execution is indeterminate prior to execution and the process evolves differently for each possible input string. Accordingly, the process performed by the module cannot be described by an algorithm.

Abstract: An IC card having a storage memory including a program storage unit for storing a program and a data storage unit for storing data and a central processing unit for executing a predetermined process in accordance with the program to process the data, the program including one or more data process units each having a process instruction for giving an execution instruction to the central processing unit, wherein a data process order is randomly exchanged and a dummy process is added to thereby reduce the dependency of consumption current of an IC chip upon the data process.

Abstract: The random numbers are generated so as to perform an encryption processing and an authentication processing, thereby accomplishing an in-advance computation and a parallel computation. Also, the encryption processing and the authentication processing are performed, using the generated random numbers whose length is shorter than 2N with reference to the message length N. Concretely, the random numbers are generated using a pseudo random-number generator, and the generated random numbers are divided on each block basis. Also, a plaintext is divided on each block basis as well. Next, the exclusive-OR logical sums of random-number blocks Ri (1≦i≦N+1) and plaintext blocks Pi (1≦i≦N) are figured out, thereby acquiring ciphertext blocks Ci (1≦i≦N+2). Moreover, a hash function performs a key-accompanying input of the random-number blocks Ri (1≦i≦N+1), thereby generating the message authentication code of the generated ciphertext.

Abstract: A method for verifying control accesses between a device on a non-proprietary bus and a device on a proprietary bus is disclosed. A gateway controller is connected between a proprietary bus and a non-proprietary bus. A determination is made as to whether or not a non-proprietary device is registered to more than one gateway controller. In response to a determination that the non-proprietary device is registered to more than one gateway controller, another determination is made as to whether or not the non-proprietary device is a portable device. In response to a determination that the non-proprietary device is a portable device, another determination is made as to whether or not a number of acceptable duplication has been exceeded. In response to a determination that the number of acceptable duplication has been exceeded, a flag is set to indicate a control access violation has occurred.

Abstract: Service is authorized through a process that employs a randomly sequenced table lookup that is based on predetermined information that was randomly assigned. In one embodiment, a calling card is issued with a table having a plurality of entries, with each entry comprising one or more digits. When wishing to make a call, the customer enters his/her ID. That ID is communicated to the service provider, based on that ID the provider retrieves from a database a table of the information that the customer has, and proceeds to request that the customer enter information pursuant to a random selection by the service provider.

Abstract: A circuit or software generates a cipher stream. The software models components or the circuit comprises a first and a second plurality of linear feedback shift registers (LFSR). A first of the second plurality of LFSR has a clock signal as a clock input and others of the first plurality of LFSR have an output of another of the first plurality of LFSR as a clock input. A first of the first plurality of LFSR has the clock signal combined with an output of the first of the second plurality of LFSR as a clock input and others of the second plurality of LFSR have an output of one of the first plurality of LSFR combined with an output of another of the first plurality of LFSR as a clock input.

Abstract: A method for the generation of small permutations on digits, for example between 7 and 30 digits, uses basic functions that are classic, one-way functions (generally non-bijective) defined on bits, and uses these functions in a generalized Feistel scheme that has at least five rounds.

Abstract: An information encoding apparatus for encoding N pieces of information, the information encoding apparatus includes a scrambling pattern generation section for generating M scrambling patterns (N>M≧1; where M and N are each an integer); a scrambled information generation section for applying, to each of the N pieces of information, one corresponding scrambling pattern among the M scrambling patterns so as to generate N pieces of scrambled information; and an encoded information generation section for supplying the N pieces of scrambled information with N parities, respectively, so as to generate encoded information. Each of at least one of the M scrambling patterns is applied to two or more of the N pieces of information.

Abstract: A method and an apparatus of loading a pre-load seed for a test code of a physical layer device (PHY). For a physical layer device including a scrambler and a Non-Return-to-Zero/Non-Return-to-Zero-Inverted (NRZ/NRZI) converter connected to the scrambler, where the NRZ/NRZI converter receives an NRZ signal outputted by the scrambler, and outputs an NRZI signal, the method includes the following steps. (a) Determine whether a plurality of starting bits of a frame are present. (b) Repeat from step (a) if the starting bits are not present. (c) Load the pre-load seed to the scrambler and transmitting the test code. (d) Set the NRZI signal in a high level when the NRZI signal is not in the high level. On the other hand, for a physical layer device having a descrambler, the method includes the steps of: (a) determining whether a plurality of starting bits of a frame are present; and (b) loading the pre-load seed to the descrambler to retrieve the test code.

Abstract: A method and system are disclosed for adjusting the resolution or performance of digital media in a reversible manner. A mask component having a length of a predetermined number of bits is extracted from a high-resolution ordinal component of digital data having an initial state. Another non-ordered, randomly generated second component having the same predetermined number of bits is received. A logic operation using the mask component and the second, non-ordered component is performed thereby deriving a third component also having the same predetermined number of bits. The high-resolution ordinal component of digital data is altered using the derived third component, thereby adjusting the initial state of the high-resolution ordinal component to a secondary state that can be reverted to its initial state by virtue of the logic operation being reversible given the correct, corresponding operands.

Abstract: Secret material, such as a cryptographic key, that is needed for operation of a computer system (4a), can be stored under password protection on a storage medium for insertion into the computer system as required. If the password is forgotten, or the storage medium is faulty, the secret material will not be accessible. To permit secure recovery of the secret material in these or other circumstances, the secret material is encrypted using a recovery key and stored on the computer system, together with a value used in the generation of the recovery key from the secret material. The secret material is also stored on a remote secure system (5). When recovery of the secret material is required, the value for generating the recovery key is supplied to the remote system and used to generate the recovery key there. The generated recovery key is then supplied to the computer system, where it is used to decrypt the secret material.

Abstract: In this invention, a random number generation apparatus inputs unperiodic random noise n generated by a noise source 1 to a waveform shaping circuit 2 to generate a random pulse wave P1. Next, the random number generation apparatus inputs the random pulse wave P1 and a clock c1 from an oscillator 3 to a sample-and-hold circuit 4 to generate a constant periodic binary pulse sequence P2. Subsequently, the binary pulse sequence P2 and a half divided clock c2, which is the clock c1 half divided by the divider 5, are inputted to a switching circuit 6, and the polarity of the binary pulse sequence P2 is reversed at intervals of one period to output a smoothed binary pulse sequence P3 in which appearance balance of 1/0 code is smoothed.

Abstract: Encrypted e-mails that reside in e-mail service providers servers or a gateway machines can be compromised and deciphered with advances in technology for breaking encryption codes. Significant security can be achieved by encrypting the message, splitting message, and transmitting the individual fragments via a set of unique e-mail servers. At the receivers end, the message can be reconstructed from the individual pieces and then decrypted and displayed to the recipient.

Abstract: Techniques for improved handoff searching in asynchronous systems, such as W-CDMA, are disclosed. In one aspect, a two-step search procedure is used when a list of neighbor codes is known. In the first step, a received signal is correlated with a slot timing code to locate on or more pilots and the slot boundaries associated therewith. In the second step, the received signal is correlated with each of the list of codes at the slot boundaries identified with pilots in the first step to identify the pilot code and the frame timing associated with each pilot. Various other aspects of the invention are also presented. These aspects have the benefit of decreasing search time, which translates to increased acquisition speed, higher quality signal transmission, increased data throughput, decreased power, and improved overall system capacity.

Abstract: A method for the execution of an encryption program for the encryption of data in a microprocessor-based portable data carrier is described, with the encryption program comprising several parallelisationable subprograms. According to the invention the serial order of execution of at least two subprograms is randomly permuted in the execution of the encryption program under the consideration of at least one random number.

Abstract: A set of methods is specified whereby software reduces compromising electromagnetic emanations of computers that could otherwise allow eavesdroppers to reconstruct sensitive processed data using periodic averaging techniques. Fonts for screen display of text are low-pass filtered to attenuate those spectral components that radiate most strongly, without significantly affecting the readability of the text, while the character glyphs displayed are chosen at random from sets that are visually equivalent but that radiate differently. Keyboard microcontroller scan loops are also furnished with random variations that hinder reconstruction of the signal emanated by a keyboard. Drivers for hard disks and other mass-storage devices ensure that the read head is never parked over confidential data longer than necessary.

Abstract: Systems, methods and devices for scrambling/descrambling sets of data bits using subsets of a recurring sequence of scrambler bits. A self-synchronous scrambler, regardless of the generating polynomial being implemented, will generate repeating sequences of scrambler bits regardless of the initial stage of the scrambler. To implement a parallel scrambler, given a current state of the scrambler, the next n states of the scrambler are predicted based on the current state of the scrambler. The scrambling operation can then be preformed using the values in the current state—parallel logic operations between preselected bits of the current state will yield the required values to be used in scrambling an incoming parallel data set. Once these required values are generated, a parallel logical operation between the required values and the incoming data set will result in the scrambled output data.

Abstract: A system and method for the efficient encoding and decoding of protocol messages is described. In one embodiment, an offset from a beginning of a memory buffer is calculated based upon a maximum size of a header portion of the message. A variable length portion of the message is encoded beginning at the offset, and the header portion of the message is encoded based upon an encoded size of the variable portion and a size of the header portion. The encoding of the header portion begins at the offset less the encoded size of the header portion. Further, a set of object identifiers are decoded into a data structure. If a value portion corresponding to an object identifier of the set of object identifiers is variable in length, the value portion is decoded into the data structure.

Abstract: In this embodiment, a number is allocated to each packet, so that the ordinal number of a byte to be used with respect to the start of a pseudo random number bit string can be determined. The pseudo random number bit string generated by this method is repeatedly reused to some extend to make an operation speed high. A number to be allocated is adjusted, so that a repeating rate can be changed. In this manner, as in OFB, a pseudo random number bit string used in decoding can be completely prevented from being repeated, and security and a speed can be balanced as needed. In addition, since a specific position to be used of the pseudo random number bit string is managed by a number allocated to each packet, a packet loss does not affect decoding.

Abstract: Three methods are disclosed for protecting software applications from unauthorized distribution and use (piracy). The first method involves using values generated by a conventional ESD (Electronic Security Device) to encrypt and/or decrypt user data (such as a file) that is generated and used by the application. In a preferred embodiment, the user data is encrypted (such as during a write to memory) using values returned by the ESD, and the user data is later decrypted using like values returned by a software-implemented ESD simulator. The second and third methods involve the use of special development tools that make the task of analyzing the application's copy protection code (such as the code used to encrypt and/or decrypt user data) significantly more difficult. Specifically, the second method involves using pseudocode to implement some or all of the application's copy protection functions.

Abstract: A control channel in a communication system transmits messages in a one or multiple-slot format. To assure consistency of a message, a content quality indicator is included in the message. Because a terminal receiving the message does not know the number of slots comprising the message, the terminal performs blind format determination by testing hypothesis for all slot formats. Unfortunately, the content of certain control messages results in control messages that appear to be valid in a sense that, the computed CRC is equal to the interpreted CRC. Consequently, the mobile station declares a valid control message, and a false-alarm event occurs. Moreover, the same control messages always result in the same false-alarm events. To prevent such repetitive incorrect determination, the content of the message is scrambled by a time-dependent scrambling sequence before transmission. Re-generating the scrambling sequence, and performing inverse to the scrambling then unscrambles the received message.

Abstract: A method is provided for enhanced spread spectrum watermarking. The improved watermarking method includes: receiving host data which is expressed in a transform domain by a plurality of host transform parameters; reducing variance between the plurality of host transform parameters, thereby forming an enhanced sequence of host transform parameters; and adding a watermark to the enhanced sequence of host transform parameters using a spread spectrum technique. The enhanced sequence of host transform parameters may be formed by arranging the plurality of host transform parameters in at least one of an ascending order or descending order; determining a difference for each pair of consecutive host transform parameters; and alternating the sign of every other difference value, thereby forming the enhanced sequence of host transform parameters.

Abstract: A scrambler includes m serial-connected registers with reset terminals, m exclusive OR gates, and m−1 switches turned on/off according to a generating polynomial. Transmission data is input to the first exclusive OR gate. The output of the first exclusive OR gate is input to the first register. The output of the i-th register is input to the (i+1)th exclusive OR gate via the i-th switch. The output of the (i+1)th exclusive OR gate is input to the i-th exclusive OR gate. The output of the m-th register is input to the m-th exclusive OR gate. In a bypass mode of transmission data, the m registers are reset. Since reception data is directly output from the first exclusive OR gate in the bypass mode of transmission data, it is possible to confirm whether data prior to the scramble process is correct or not.

Abstract: A sequence generator for generating a pseudo random sequence for random number generation or a stream cipher engine includes a plurality of linear feedback shift registers operable to generate a plurality of binary sequences. A plurality of nonlinear functions having the binary sequences as their input and operable to generate a second plurality of binary sequences. There are at least two switches and a controller including a shift register operable to control said first and second switches. The first switch is operative to select one of the second plurality of binary sequences to the first bit of the shift register, and the second switch is operative to select one of said second plurality of binary sequences to the output of the sequence generator.

Abstract: An apparatus and method for allowing an analog scrambler using an internal digital cipher to generate a pseudo-random number stream to drive the scrambling of the analog signal to be cipher checked, to add strength to the generation of the pseudo-random number stream, and/or to allow either analog scrambling of analog signals or digital encryption of digital signals. Digital connections are made directly to internal digital cipher to allow the foregoing functions.

Abstract: Prior methods of encryption can be broken by sufficiently powerful decryption techniques. The present invention provides a method of making decryption practically extremely difficult. It involves having synchronized processors continuously calculate a defined pseudo-random number and communicate the message by adding it to the sequentially continuously calculated number.

Abstract: Transmission-based data security is provided in dense wavelength division multiplexing systems using a transmission scheme that incorporates hierarchical scrambling techniques with a unique multiplexing arrangement. Information supplied by one or more sources is multiplexed according to a predetermined scrambling pattern and transmitted in a parallel format using one or more wavelength channels in a wavelength division multiplexed signal. By transmitting the multiplexed and scrambled information in parallel, the wavelength channels effectively function as a parallel bus (a “wavelength bus”). Multiple stages of scrambling can be applied to the multiplexed and scrambled information transported in the wavelength bus. For example, individual bit streams carried within each wavelength channel of the wavelength bus can be separately scrambled according to another predetermined scrambling pattern.

Abstract: A system controls reproduction of a video transmission between a transmitter and a receiver. The system includes an encryptor with an offset generator adapted to receive the encrypted frame key and to generate a sequence, of pseudo-random values for the color component; and an adder coupled to the offset generator and to the color component signal for providing an encoded color component signal. The system also includes a decryptor with a decryptor offset generator adapted to receive the encrypted frame key and to generate a decryptor pseudo-random value for the color component; and a subtractor coupled to the offset generator and to the color component signal for subtracting the offset signal from the color component signal.

Abstract: A system and method for encrypting all channels of a wireless spread spectrum communication at the chip level. The PN sequence is encrypted with one or more encryption sequences and then used to spread the signal.

Abstract: A system for deterring unauthorized reproduction of a video presentation including a plurality of images to be displayed and method for operating the system. The system includes an encoder for encoding a signal for transmission over a vulnerable communications link to a decoder. The encoder includes: a first memory having a first plurality of addressable memory locations for storing at each of the locations data corresponding to a portion of at least one of the images to provide an array of data; and, a randomizer for pseudo-randomly addressing the first memory to provide a pseudo-random data signal corresponding to the one of the images.

Abstract: A method for scrambling a calculation involving at least one operation, of which at least one intermediary result takes into account at least one secret quantity, including modifying the intermediary result with a random quantity, carrying on the calculation with the modified result, and restoring an expected result at the end of the calculation.

Abstract: A method for analog signal scrambling and unscrambling is provided for any type of phone, including cellular phones, by way of dividing the signal to disjoint frames, scrambling these frames at the analog-signal-transmission unit connected to the transmitting phone, and unscrambling and splicing the frames at the analog-signal-reception unit connected to the receiving phone, thereby recovering a continuous replica of the original analog signal

Abstract: In the process of compressing and encrypting data, without an increase of processing time, a cipher capability is secured against the latest cryptanalysis such as differential and linear cryptanalyses. The differential and linear cryptanalyses are executed to collect plural pairs of plaintext and cryptosystem for the same key and perform the statistical operation for estimating the key. An input/output (I/O) process is executed to receive plaintext data and generate a different key for each data on the random number and set the key to a work key. The encrypted intermediate result or the pre-encrypted result is fed back to permit frequent changing of the work key. The changing operation is executed to change correspondence between the plaintext data and the compressed data in the compressing process.

Abstract: A converting processing block (4B/5B CONVERTER & ARB. SIGNAL CONVERTER) functions as a 4 bit/5 bit converting unit for performing 4 bit/5 bit conversion of data and as an arbitration signal converting unit for allocating 5-bit symbols other than 5-bit symbols allocated to data to arbitration signals to enable the sending/reception of the arbitration signals and packet data as 5-bit code data. There are also provided scrambling blocks (SCRAMBLE 1, SCRAMBLE 2) 4A, 4B and descramble blocks (DESCRAMBLE 1, DESCRAMBLE 2) 5A, 5B between the 4 bit/5 bit converting unit and the arbitration signal converting unit on one hand and the input/output port on the other hand to inhibit unneeded radiations in a transmission channel.

Abstract: Techniques are provided for generation of an RSA modulus having a predetermined portion. The predetermined portion may be the leading digits of the modulus, or split between the leading and trailing digits of the modulus. The resulting RSA modulus has the same security level as conventional RSA moduli, but requires less storage space. Significant performance improvements may be obtained for encryption, decryption, digital signature generation and digital signature verification when using RSA moduli in a specifically chosen format, as the division portion of a modulo operation is accomplished using only multiplication operations, and without using division operations.

Abstract: A data reproducing apparatus and method is provided for reproducing data that was ciphered during recording in one or more of sector forming, header appending, error correction coding, modulation, and synchronization appending operations used for processing input data to form a recording signal. Thus, deciphering requires knowledge of both the ciphering key and the aspect(s) of the recording operation in which the ciphering took place. The deciphering may also include a descrambling operation in which an initial value and/or a generating polynomial is varied in accordance with ciphering key information.

Abstract: The invention relates to a process for scrambling video data in the MPEG2 video format as well as to a process for descrambling data scrambled according to the process of the invention. The scrambled video data are the coefficients AC and/or DC arising from the “discrete cosine transform” operation which are associated with at least one block of at least one image coded in INTRA mode. The invention applies to conditional access systems such as, for example, pay television systems.

Abstract: The method is based on symmetrical encryption algorithms of variable length blocks, supported by a Pseudo-noise Sequence Generator based in its turn in one (or two) linear sequence generators (LFSR with a primitive polynomial). The basic versions of these algorithms include the plotting of a set of lines which is defined by a pole and a contour, but ensuring that the points inside the contour became inverted when plotted each time the pixel is found in one of the set of lines. Usually, two contours will be used, one of them shall act as the boundary for the data area and in a modification of the same the set of lines is created by means of unregularized contours.