Abstract: In a method for producing an encrypted method payload data stream comprising a header and a block containing encrypted payload data, a payload data key for a payload data encryption algorithm for encrypting payload data is generated. The payload data is encrypted using the generated payload data key and the payload data encryption algorithm to obtain the block containing the encrypted payload data of the payload stream. A part of the payload data stream is processed to deduce information marking the part of the payload data stream. The information is linked with the payload data by means of an invertible logic linkage to obtain a basic value. This basic value is finally encrypted using a key of two keys being different from each other by an asymmetrical encryption method, the two different keys being the public and the private keys respectively for the asymmetrical encryption method to obtain an output value being an encrypted version of the payload data key.

Abstract: A method includes receiving an authentication request from a mobile station (401) and determining whether to forward the request to an authentication agent. When it is determined to forward the request, the request is forwarded to the authentication agent (107). A random number and a random seed are received from the authentication agent (107). The random number and the random seed are forwarded to the mobile station (401). A response to the random number and the random seed from the mobile station (401) is received and forwarded to the authentication agent (107). The authentication agent (107) compares the response with an expected response. When the authentication agent (107) authenticates the mobile station (401), a derived cipher key is received from the authentication agent (107).

Abstract: The present invention relate to systems and methods for conducting secured telephony and transaction authentication via electronic devices. More specifically, the embodiments of the present invention relate to systems and methods for conducting secure networked telephony, including but not limited to communications over the internet, other computer networks, wired or wireless networks, or audio, video or multi-media.

Abstract: A trusted authentication chip for use in authenticating an untrusted authentication chip; the trusted authentication chip including a random number generator, a symmetric encryption function and two secret keys for the function, a signature function and a test function; wherein the trusted authentication chip generates test data including a random number and its signature, encrypted using a first of said secret keys and transmits the test data to the untrusted authentication chip, wherein the trusted authentication chip receives a data message and an encrypted version of the data message in combination with the random number from the untrusted authentication chip, the data message being encrypted using a second of said secret keys, wherein the test function operates to encrypt the random number together with the data message by the symmetric encryption function using the second secret key, compare the two versions of the random number encrypted together with the data message using the second key, and in the e

Abstract: A method and an arrangement maintain end-to-end synchronization on a telecommunications connection transmitting data in frames substantially in real time and using synchronized end-to-end encryption, wherein at least a part of the telecommunications connection is a packet-switched connection, in which case the reproduction delay of the data to be transmitted can be increased by adding one or more extra frames to the frame string being transmitted, wherein the arrangement defines, based on the number of received frames, an initialization vector value corresponding to a frame received at the receiving end of the telecommunications connection and used in decrypting the frame, adjusts the reproduction delay to mark the frame to be added to increase the reproduction delay as an extra frame, and defines the initialization vector value to count only the frames not marked as extra frames in the number of received frames.

Abstract: Detecting loss of stream cipher synchronization between a transmitter and a receiver in a video processing system may be achieved by receiving, by the receiver, an encrypted video frame from the transmitter, obtaining an encrypted value for a selected pixel in the encrypted video frame, decrypting the encrypted pixel value using a first portion of the receiver's current key stream, re-encrypting the pixel value using a second portion of the receiver's current key stream, sending the re-encrypted pixel value from the receiver to the transmitter, obtaining, by the transmitter, a plaintext value for the selected pixel from a corresponding original video frame and encrypting the plaintext pixel value using a second portion of the transmitter's current key stream, and comparing the re-encrypted pixel value received from the receiver with the encrypted pixel value generated by the transmitter and detecting a loss of cipher synchronization when the values do not match.

Abstract: A system, protocol and related methods for providing secure manageability are generally described. In this regard, a communication protocol is introduced comprising an authentication protocol, responsive to an initialization event in a host device, to authenticate a remote device and establish an initial anti-replay value, and a secure communication protocol, selectively invoked upon authentication of the remote device, to facilitate subsequent communications between at least the host device and the authenticated remote device utilizing the initial anti-replay value in at least a first of said subsequent communications.

Abstract: A method of synchronizing the encryption/decryption functions of an AlphaEta physical-layer encryption or key generation system. The method includes the insertion of a header to indicate the start of encryption after clock-synchronization has been established. The method also allows for a side-channel to signal other useful information, such as a loss-of-syncrhonization signal from Bob or to synchronize a dynamic key change.

Abstract: A method for accessing discrete data includes transmitting a write command to a memory, determining whether each data following a header of the file needs to be encrypted according to a data format of a file that is to be written into the memory, transmitting the file header and each data following the file header to a logic unit, turning on the logic unit for encrypting the data determined to be encrypted and writing the encrypted data into the memory, turning off the logic unit for writing the data determined not to be encrypted into the memory directly, and sending a first response signal from the memory when the writing of the file is finished.

Abstract: Framing transmit encoded output data begins by determining a scrambling remainder between scrambling of an input code word in accordance with a 1st scrambling protocol and the scrambling of the input code word in accordance with an adjustable scrambling protocol. The processing continues by adjusting the adjustable scrambling protocol based on the scrambling remainder to produce an adjusted scrambling protocol. The processing continues by scrambling the input code word in accordance with the 1st scrambling protocol to produce a 1st scrambled code word. The processing continues by scrambling the input code word in accordance with the adjusted scrambling protocol to produce a scrambled partial code word. The processing continues by determining a portion of the 1st scrambled code word based on the scrambling remainder. The process continues by combining the scrambled partial code word with the portion of the 1st scrambled code word to produce the transmit encoded output data.

Abstract: In an electronic component including a two-way bus through which data elements travel between peripherals and a central processing unit at the rate of a clock signal, the central processing unit and at least one of the peripherals each includes a data encryption/decryption cell. Each data encryption/decryption cell uses the same secret key. The secret key is produced locally at each clock cycle in each cell from a random signal synchronous with the clock signal, and is applied to each of the cells by a one-way transmission line.

Abstract: Methods, computer-readable media, and apparati for securely distributing a cryptographic key (C) from a first party(s) to a second party(s). A method embodiment of the present invention comprises the steps of combining (steps 1 and 2) the cryptographic key (C) with a transport key (T) to form a key set; encrypting (step 7) the key set to form an encrypted key set; distributing (step 8) the encrypted key set across a medium (3); and decrypting (step 9) the encrypted key set to reconstitute the cryptographic key (C) and the transport key (T).

Abstract: Techniques for securely and adaptively delivering multimedia content. It is assumed that a set of alternate access units for each time slot is obtained. Then, the encryption stream index of each access unit from the set of alternate access units of the previous time slot are obtained. An encryption stream index is then assigned to each access unit in the set of alternate access units in the current time slot, such that the encryption index increases over time. Thus, the invention overcomes the problem of encrypting a multimedia stream that may have multiple access units for each time slot by selecting the encryption index for each access unit such that the encryption index increases, regardless of which access unit the delivery system (e.g., server) selects for transmission.

Abstract: An encrypting keypad module (30) comprising a keypad (40) and an encryption unit (42) is described. The encryption unit (42) includes an interpreter (56) for receiving a file (150) containing data and instructions for processing the data. The encryption unit (42) is operable to process the data in the file (150) by interpreting the instructions in the file (150). This enables a file (150) to be used to instruct the encryption unit (42) about the data that is to be operated on and the type of operations to be performed on the data.

Abstract: A method for protecting traffic in a radio access network connected to at least two core networks. The method includes maintaining a core-network-specific authentication protocol and a radio-bearer-specific ciphering process, and generating, for each ciphering process, a count parameter including a cyclical sequence number and a hyperframe number (HFN) which is incremented each time the cyclical sequence number completes one cycle. For each core network or authentication protocol, a first radio bearer of a session is initialized with a HFN exceeding the highest HFN used during the previous session. When a new radio bearer is established, the mobile station selects the highest HFN used during the session for the core network in question, increments it and uses it for initializing the count parameter for the new radio bearer. At the end of a session, the mobile station stores at least part of the highest HFN used during the session.

Abstract: An authentication method for establishing a connection between devices that want to communicate data in a communication environment using communication specification such as Bluetooth is provided. In the authentication method, it is determined whether the authentication procedure for establishing a connection between devices that want to communicate data is performed as a unilateral authentication procedure or as a mutual authentication procedure, according to the condition of one of the two devices that can communicate data and receives an authentication request, and performing the authentication procedure. Therefore, the authentication method more reliably and precisely establishes a connection between devices that want to communicate data in a communication environment operating based on communication specifications such as Bluetooth.

Abstract: An observation unit of an authentication apparatus and an observation unit of an authentication target apparatus observe a radio wave from a common radio star at a common observation time. A sending unit sends information message including information on the observed radio wave, and an information reception unit receives it. An estimation unit estimates a position of the authentication target apparatus based on “the information on the radio wave observed by the observation unit” and “information on the radio wave observed by the observation unit”. A retaining unit pre-retains positions of one or more authentication target apparatus(s). A determination unit checks whether a position of the authentication target apparatus pre-retained in the retaining unit and the estimated position correspond within a predetermined error range, and settles authentication for the information message as a success in a case where the positions correspond.

Abstract: A system and method for protecting data transmitted across a private network is disclosed. A secure channel is established so that the client computer can securely transmit a password to the server computer. Once the password has been transmitted, future transmissions use the password to encrypt data by the sending computer and decipher the data at the receiving computer. In one embodiment, passwords expire after a certain amount of time and are thereafter renegotiated. In another embodiment, the password is successively modified by a counter value further preventing unauthorized persons from discovering the password used to encrypt the data. By using passwords rather than public-key encryption methods, less system resources are required to maintain data confidentiality. An information handling system securely transmitting data within a private network as well as a computer program product programmed to perform the encryption processing are further disclosed.

Abstract: A method and apparatus that uses the dynamics of chaotic systems for the remote generation of a digital key, for use in any encryption algorithm. After initialization, the dynamics of a chaotic system are allowed to generate the 0 and 1 bits of a key bitstream. An initialization bitstream is transmitted, using conventional transmission technologies, to an identical chaotic system. This chaotic system is driven into synchrony and allowed to generate a key bitstream, which is identical to the other bitstream because the chaotic systems have been synchronized.

Abstract: This invention concerns a consumable authentication protocol for validating the existence of an untrusted authentication chip, as well as ensuring that the authentication chip lasts only as long as the consumable. In a further aspect it concerns a consumable authentication system for the protocol. A trusted authentication chip has a test function; and the untrusted authentication chip has a read function to test data from the trusted chip, including a random number and its signature, encrypted using a first key, by comparing the decrypted signature with a signature calculated from the decrypted random number. In the event that the two signatures match, it returns a data message and an encrypted version of the data message in combination with the random number, encrypted using the second key.

Abstract: A method and system are provided to permit a network operator to capture transaction data relating to transactions between a subscriber and a service provider that are conducted via a communications network established by the network operator, such as a cable television network. In operation, the subscribers are provided with information relating to items offered by one or more service providers. The subscriber can transmit a purchase order. A headend of the communications network receives and analyzes the purchase order to capture transaction data. If the service provider is different than the network operator, the headend also relays a copy of the purchase order to the third party service provider such that the purchase order can be filled. Since the network operator has captured information relating to the purchase order, however, the network operator can charge the service provider and/or the subscriber for utilizing its network to facilitate the transaction.

Abstract: A method of electronically signing a document includes initializing a user, including generating an asymmetric key pair including a private signing key and a public signing key, and storing the private signing key and the public signing key; and providing an electronic signature, including receiving document data corresponding to at least one selected portion of the document, binding the stored private signing key and the document data to create an electronic signature, and providing the electronic signature for a recipient.

Abstract: A method and apparatus for re-synchronizing a stream cipher during soft handoff. Transmitted quasi-secret keying information is used with a secret key to reinitialize a stream cipher generator located in a base station and a stream cipher generator located in a travelling mobile station. Since the quasi-secret keying information is uniquely determined according to each base station in the wireless telephone system, a base station's quasi-secret keying information and a shared secret key can also be used to create a new key. Thus, as the mobile station travels from one base station to another base station, a unique new key is generated for each base station.

Abstract: Dynamic varying of encrypting of a stream of data at an encryption unit based on data content is disclosed. The dynamic varying of the encrypting, which can be responsive to passage of a predefined number of units of physical data or passage of a predefined number of conceptual units of data, is accomplished by changing at least one encryption parameter over different portions of the data. The at least one encryption parameter can comprise one or more of an encryption key, an encryption granularity, an encryption density scale, an encryption density, an encryption delay, an encryption key update variable, and an encryption key update data trigger. The change in encryption parameter is signaled to a receiver's decryption unit and used by the decryption unit in decrypting the dynamically varied encrypted stream of data. The stream of data may comprise, e.g., MPEG compressed video or audio.

Abstract: A method and apparatus for reducing perceived latency in a group communication network provides for receiving a request from a user of a communication device wishing to initiate a group call, receiving media from the user before completely processing the request, and buffering the received media for later transmission.

Abstract: Encryption and decryption sites are initially assigned identical one time Vernam like pads, (OTP), and each site is provided with identical compendiums of byte modifying instructions identified by instruction IDs. Encryption is implemented by a random first subset of instructions applied to the current OTP to generate a new OTP. A second subset of random instructions is applied to the message for encryption. The list of IDs of the first subset of instructions is XORed with the current OTP. The list of IDs of the second subset of instructions and the encrypted message are each XORed with the new OTP and all XORed outputs are concatenated into the payload. Decryption is implemented by applying the encryption steps to the payload in reverse order to recover the message and new OTP. A secure, new OTP is therefore available both at the encryption and decryption sites without having been transmitted.

Abstract: A method for encryption and decryption of data items is provided by defining a cipher key based on variables in a Chaotic Equation. The method includes selecting a Chaotic Equation (110) from a set of Chaotic Equations, defining starting conditions of the variables of the equation (140), and applying the equation to each data item (120). The real and imaginary parts of the result of the iteration of the Chaotic Equation are combined with the data item by an arithmetic operation, for example, an XOR operation (120). Data items in a continuous stream with a rate dependency can be encrypted and decrypted on an item by item basis. The input or cipher key changes for each byte of the data encryption. Blocks of data (700, 701, 702, 703, 704) can be encrypted using the method with an identifier of the order of the blocks in the data stream. If blocks are received out of sequence, the identifiers can be used to maintain the correct decryption order.

Abstract: A receiver sends a first random number to a transmitter. The transmitter generates a sync signal in response to the first random number sent from the receiver. The transmitter embeds the sync signal and key information in a second random number to generate a composite signal. In the composite signal, the sync signal is a position indicator for the key information. The transmitter sends the composite signal to the receiver. The transmitter generates an encryption key from the key information. The receiver detects the sync signal in the composite signal sent from the transmitter. The receiver extracts the key information from the composite signal in response to the detected sync signal. The receiver generates an encryption key from the extracted key information. The encryption key generated by the receiver is equal to that generated by the transmitter. Thus, the transmitter and the receiver hold the same encryption key in common.

Abstract: An apparatus and method for generating pseudo-random cryptographic keys in a cryptographic communications system, whereby, given a common set of initializing configuration data, the pseudo-random cryptographic keys can be duplicatively generated by various independent pseudo-random key generators of the cryptographic communications system. In accordance with the preferred embodiment of the present invention, users of the communications system can each possess an independent pseudo-random key generator to securely communicate with other users also holding independent pseudo-random key generator that share the same initialization configuration data, no matter where the other users are located or whether the users are connected via wire or wireless communication network. The present invention facilitates secure communication without the need to transport decryption keys in advanced, thereby reducing the risk of the secure communication becoming compromised via interception of decryption keys.

Abstract: In a communication system for a secure transfer of information from a source device to a sink device in a communication session in the form of a plurality of packets from the source device to the sink device, a packet structure is used with a key check block field. During the session, the source device can change the session key used to encrypt data (including the key check block) in the packet. The sink device detects a change of session key by decrypting only the key check block field with a plurality of candidate keys. The key that gave a valid decryption is used for decrypting the remainder of the packet.

Abstract: A method and apparatus for providing security in a group communication network provides for receiving an encryption key, encrypting media for transmission to a controller using the received encryption key, the encrypted media being directed to another communication device, and communicating the encrypted media to the controller. In one embodiment, the communicating includes wireless communication. The method and apparatus further provides for receiving encrypted media from a controller and blocking the encrypted media if the communication device is not enabled to receive encrypted-media transmission, or if the media is not encrypted based on an encryption key previously specified by the communication device. In another aspect, the communication device is a push-to-talk (PTT) device.

Abstract: A transmitter adds packet transmission order information to transmitted packets using a forward error device (416) and a masking device (420). The masking device (420) receives ordering masks (610) from a mask store (424). The ordering masks (610) are maintained in a known order, and the ordering masks (610) and the known order are known to both the transmitter and the receiver. The receiver includes an unmasking device (504) that applies ordering masks to unmask the packets, and then an error detection device checks for errors. The ordering masks (610) are applied in the known order until errors are below an acceptable limit. When errors are below an acceptable limit, the relative packet order is determined from the known order of the ordering masks.

Abstract: A closed system meter that secures the link between the accounting device and printer utilizing a Linear Feedback Shift Register (LFSR) based stream encryption is provided. The accounting device includes an LFSR that comprises a plurality of stages, with one or more taps that are passed through a logic gate to provide a “feedback” signal to the input of the LFSR, to generate a pseudo-random pattern output. Preferably, a Shrinking Key Generator (SKG) is utilized to further ensure privacy of the data. The output data from the accounting unit is encrypted utilizing the output from the LFSR and sent to the printing device. The printing device includes a similar LFSR, which is utilized to decrypt the output data from the accounting unit and enable printing.

Abstract: Arbitrary quantum information is input. The information of a quantum two-state system is acquired as a qubit by performing a computation in consideration of a physical system. The acquired qubit is encrypted. A quantum system having signature information for guaranteeing that the qubit is really transferred from a sender to a recipient is added to the encrypted qubit. The qubit to which the quantum system having the signature information is added is further encrypted. In this manner, an arbitrary quantum state can be encrypted and transmitted without letting the sender and recipient share an entangled pair of qubits in advance.

Abstract: Method for providing database content usage. The database content can be a digital work having one or more rights associated therewith. The method can be effected within a system having at least one repository configured to enforce use of the content in accordance with the one or more usage rights. A usage right is associated with database content, the usage right specifying rights for the usage of database content and usage fees for exercise of such usage. The database content is provided in accordance with the usage right, and the usage fees are reported as a transaction.

Abstract: A system and method for encryption, transmission and decryption of data based on a publicly or other wide area broadcast random number sequence. Encryption is by a selected subsequence from the broadcast random number sequence, the selection being at a sample time relative to a synchronization event, with the sample time calculated based on a private key. Decryption uses the same private key to select the same subsequence from the broadcast random number sequence, as detection by the sender and receiver of the synchronization event and a sampling time based on a commonly known private key allows the sampling to be synchronous. Alternative embodiments employ trusted agents if the tender and receiver do not have a common private key.

Abstract: Disclosed is a computer-readable medium containing program instructions for configuring a first computer so that a first telephony client on the first computer may securely communicate with a second telephony client on a second computer via a communication path. The computer-readable medium includes computer code for inserting a security algorithm within the communication path. The security algorithm facilitates secure communication between the first and second telephony clients such that more than a single type of telephony client may be implemented. In a specific embodiment, the security algorithm is inserted within the first computer's operating system kernel.

Abstract: At the time when generating a secret key of each entity by using each divided identification information (ID division vector) obtained by dividing identification information (ID vector) of each entity into a plurality of blocks and by using a secret symmetric matrix of each key generating agency (center), a part of the components of the symmetric matrix is extracted in accordance with each divided identification information (ID division vector) so that the extracted components are synthesized with a random number particular to each entity so as to generate a secret key of each entity.

Abstract: In an interface security system between a plurality of devices mutually connected and transmitting/receiving a signal, the respective devices include respective selectors selecting a connection pattern between signals transmitted/received and external terminals for transmitting/receiving the signals and switching connections between the signals and the external terminals in accordance with a connection pattern selected, and the selectors of the respective devices select a connection pattern and switch the connections in synchronization between the respective devices.

Abstract: A chaotic communication system employs transmitting and receiving chaotic oscillating circuits. One improvement to first-generation systems is the ability to modulate a nonreactive element in the transmitting circuit, thus increasing modulation bandwidth. Other features include insertion of a gain control amplifier in a chaotic receiver; signal filtering in chaotic transmitters and receivers; use of chaotic modulation techniques for cellular telephony applications; dual-transmitter and receiver systems; a dual receiver synchronization detector; interfaces to communication systems; analog chaotic signal modulation; use of multiple chaotic transmitters and receivers; digital algorithm improvement using a cube-law nonlinear component; a Gb-only receiver; a Gb-only transmitter; and positive slope transmitter and receiver systems.

Abstract: A key management scheme for managing encryption keys in a cryptographic co-processor includes the first step of selecting a key from one of a symmetrical key type and an asymmetrical key type. Then, the key bit length is selected. The key is then generated and, lastly, the key is represented in either an external form or an internal form.

Abstract: A secure wireless local or metropolitan area network and data communications device therefor are provided, where the device transmits plain text in an encrypted message including cipher text and an initialization vector. The device may include a seed generator for performing a one-way algorithm using a secret key, a device address, and a changing reference value for generating a seed. Further, a random initialization vector (IV) generator may be included for generating a random IV, and a key encryptor may generate a key sequence based upon the seed and the random IV. Additionally, a logic circuit may be included for generating cipher text based upon the key sequence and plain text, and a wireless communications device may be connected to the logic circuit and the random IV generator for wirelessly transmitting the encrypted message.

Abstract: A method and apparatus for efficiently synchronizing a stream cipher. State information is transmitted that will allow the intended recipient of the encrypted data stream to set a stream cipher generator to the correct state from which to start generating the stream cipher. A cycle number indicating the current state of a linear feedback shift register and a stutter number indicating whether an output of the linear feedback shift register is dropped are both transmitted to a remote station along with the encrypted data stream.

Abstract: This invention report describes the architecture of a system, which undertakes in a new way the dynamic generation of symmetrical keys and the confidential synchronization of encryption components which use these keys. The basis is formed by the principle of the one-time-pad, with which absolute confidentiality can be ensured in theory. The difficulties with practical implementation of a pure one-time-pad can be avoided by expansions.

Abstract: A composite cellular terminal providing various service options issues different call termination alert tones and different call termination display messages according to types of terminated calls. The cellular terminal sets and stores the call termination alert tones and the call termination display messages according to those service options which are available for the composite cellular terminal. Upon reception of a paging message, If the terminal recognizes the service option contained within the paging message, the terminal then retreives a call termination alert tone corresponding to the recognized service option and generates the call termination alert tone. The terminal then retreives a call termination display message corresponding to the recognized service option and displays the read call termination display message.

Abstract: There is provided a method of encoding a data word. The method includes (a) scrambling a data word to generate a scrambled data word, and (b) encoding the scrambled data word so that a first occurrence of the scrambled data word is encoded to produce a first code word, and a subsequent occurrence of the scrambled data word is encoded to produce a second code word. The second code word is different from the first code word.

Abstract: A communication system (10) has a portion (28) of a transmitter controller (14) that provides a message package. An encryption portion (36) of the controller (14) encrypts a first fraction of the message package (e.g., a first portion of the message package and a first part of a second portion of the message package) using a second fraction of the message package (e.g., a second part of the second portion of the message package) as an encryption key. Transmitter components (32 and 34) output a signal (18) that conveys the encrypted first fraction of the message package. Receiver components (56 and 58) receive the signal (18). A decryption portion (60) of a receiver/controller unit (16) decrypts the signal using a decryption key, and reassembles the message package using the decryption key as the second fraction of the message package. Preferably, the communication system (10) is a remote convenience system for remotely controlling a convenience function.

Abstract: A method and system for emulating a secret code between a first hardware module to a second hardware module. First, the secret code that is initially stored in the first hardware module is transformed into a transformed secret code according to a transformation pattern randomly selected from a set of possible transformation patterns. Then the transformed secret code is transferred to the second hardware module. Next, the second hardware module can repeatedly guess a hypothetical secret code from the transformed secret code by using a transformation pattern selected from the possible transformation patterns and reversing the effect of the selected transformation pattern on the transformed secret code. In addition, the hypothetical secret code is used to encode a test sample, and the encoded test sample is sent back to the first hardware module. Accordingly, the first hardware module can verify the validity of the current hypothetical secret code by checking the encoded test sample.

Abstract: This invention concerns a consumable authentication protocol for validating the existence of an untrusted authentication chip, as well as ensuring that the authentication chip lasts only as long as the consumable. In a further aspect it concerns a consumable authentication system for the protocol. A trusted authentication chip has a test function; and the untrusted authentication chip has a read function to test data from the trusted chip, including a random number and its signature, encrypted using a first key, by comparing the decrypted signature with a signature calculated from the decrypted random number. In the event that the two signatures match, it returns a data message and an encrypted version of the data message in combination with the random number, encrypted using the second key.

Abstract: Blind inverse halftoning on a digital image is performed by applying a robust convolution filter to the digital image.