Abstract: A simple and efficient method for producing an obfuscated speech signal which may be used to mask a stream of speech, is disclosed. A speech signal representing the speech stream to be masked is obtained. The speech signal is then temporally partitioned into segments, preferably corresponding to phonemes within the speech stream. The segments are then stored in a memory, and some or all of the segments are subsequently selected, retrieved, and assembled into an obfuscated speech signal representing an unintelligble speech stream that, when combined with the speech signal or reproduced and combined with the speech stream, provides a masking effect. While the presently preferred embodiment finds application most readily in an open plan office, embodiments suitable for use in restaurants, classrooms, and in telecommunications systems are also disclosed.

Abstract: The present invention is a data processing apparatus and method for encrypting, sending, receiving, and decrypting secure transmissions using a cellular telephone. The user may either purchase a cellular telephone which contains the encryption and decryption software, download the encryption and decryption software to an existing cellular telephone, or may purchase an encryption component which is adaptable to a conventional cellular telephone. Additionally, the described system of encryption and decryption can be used for secure communications in PDA/cellular telephones combinations and any other type of portable communications device. The encryption process is a Java application which converts the user's audio signal into a wav file. The encryption program then creates a second wav file using the first wav file header. The encryption program then converts the data in the first wav file into encrypted data in the second wav file using public key encryption and a series of data manipulations.

Abstract: The device and method for scrambling/descrambling voice/data in a mobile communication system involves vocoding or bypassing a signal received from a radio channel interval, scrambling the vocoded or bypassed signal using a random number, sending the scrambled signal to a cable channel interval, descrambles the scrambled signal received from the cable channel interval, vocoding or bypassing the descrambled signal, and sending the vocoded or bypassed signal to the radio channel interval, thereby dramatically security of the data in the cable channel interval between the system vocoders and preventing overhearing of the voice.

Abstract: Techniques for providing secure processing and data storage for a wireless communication device. In one specific design, a remote terminal includes a data processing unit, a main processor, and a secure unit. The data processing unit processes data for a communication over a wireless link. The main processor provides control for the remote terminal. The secure unit includes a secure processor that performs the secure processing for the remote terminal (e.g., using public-key cryptography) and a memory that provides secure storage of data (e.g., electronics funds, personal data, certificates, and so on). The secure processor may include an embedded ROM that stores program instructions and parameters used for the secure processing. For enhanced security, the secure processor and memory may be implemented within a single integrated circuit. Messaging and data may be exchanged with the secure unit via a single entry point provided by a bus.

Abstract: Apparatus and methods for including a code having at least one code frequency component in an audio signal are provided. The abilities of various frequency components in the audio signal to mask the code frequency component to human hearing are evaluated and based on these evaluations an amplitude is assigned to the code frequency component. Methods and apparatus for detecting a code in an encoded audio signal are also provided. A code frequency component in the encoded audio signal is detected based on an expected code amplitude or on a noise amplitude within a range of audio frequencies including the frequency of the code component.

Abstract: A system and method for maintaining privacy in transmission of a high bandwidth analog signal. A preferred system and method breaks an input signal into bands and then uses Walsh codes to overlay many signals on top of each other with a set of phase modulators to establish scrambling of the input signal. The scrambled signal is then transmitted. The received scrambled signal has the phase modulation removed and an inverse Walsh transform recovers the original bands. The recovered bands are added together to recover the original signal. The system and method use techniques that establish synchronization and phase coherency complete the process.

Abstract: A secure real time voice communication system 70 is provided that allows for the secure transmission of voice communications between a sending device 72 and a receiving device 78 through the public switch telephone network 76. The device 72 uses an encryption decryption engine 30 which is capable of executing a number of encryption algorithms which are selected using an encryption selection table 80. An encryption key can be calculated from a periodic key value and a public variable key value. Further, the encryption algorithm used can be periodically changed during a voice communication session so that multiple encryption techniques can be used within the same communication session.

Abstract: A technique is described to change the codec or MAC (message authentication code) size in a packet security unit for PacketCable communications during realtime voice transmissions is described. An algorithm that provides fast RC4 key advancing to prevent MIPS (millions of instruction cycles per second) overflow is used to perform codec or MAC size changes. The invention is performed without changing the keying material, where the sender and receiver must continue the RC4 encryption process from its state prior to the codec or MAC size change. A sender needs to preserve continuity of the timestamp across a codec change, since the timestamp reflects realtime. Changing the codec or MAC size is likely to change the frame parameters. To preserve continuity of the RC4 state and the timestamp across the codec/MAC size change, the sender TX and receiver RX generates a new frame number. The new frame number is applied to the first frame generated by the new codec or MAC size.

Abstract: A voice decoder detects channel errors and loss of cryptographic synchronization using the change in spectral energy between sequential frames. The change in energy between frames is determined between corresponding LSP's of said successive frames and summed together. A running average of the change in energy for a predetermined number of frames is maintained. Current voice frames are eliminated based on the difference between the change in energy associated with the current frame and the running average. Accordingly, offensive audio associated with such channel errors or cryptographic synchronization loss is eliminated.

Abstract: A modulated symbol domain data scrambling/descrambling method overcomes modulated signal non-uniform distribution problem associated with higher order M-ary QAM and M-ary PSK modulation. Since the descrambling is performed in the symbol domain, it has the flexibility to place the descrambler outside and before the QAM demapper. By doing so, it is not necessary for QAM demapper or the blocks after QAM demapper to have the knowledge of the scrambling code. The scrambling technique is also backward compatible with most of the current CDMA standards, such as IS 95 and IS-2000 standards.

Abstract: Apparatus and methods for including a code having at least one code frequency component in an audio signal are provided. The abilities of various frequency components in the audio signal to mask the code frequency component to human hearing are evaluated and based on these evaluations an amplitude is assigned to the code frequency component. Methods and apparatus for detecting a code in an encoded audio signal are also provided. A code frequency component in the encoded audio signal is detected based on an expected code amplitude or on a noise amplitude within a range of audio frequencies including the frequency of the code component.

Abstract: An interface between a digital communication system and a PSTN establishes a user configurable secure encrypted link to a digital subscriber unit through the digital communication system, and provides clear (unencrypted) voice to telephone sets through the PSTN. The interface includes a security module for encrypting and decrypting information with user specific algorithms and keys, a transcoder for converting modulated voice to digital voice and a modem for modulating and demodulating data and encrypted voice. Accordingly, the wireline interface allows for user specified security over a digital wireless portion of an end-to-end communication channel. The interface also provides for the communication of unencrypted voice followed by secure voice or secure data.

Abstract: The downlink channelization code limitation problem encountered in spread spectrum or CDMA cellular systems is resolved by using codes from a different, non-orthogonal code set when operating in the slotted mode. The non-orthogonal code sets can be constructed by using the same channelization code tree, but applying a different scrambling code.

Abstract: This disclosure describes systems and methods for processing voice data for secure transmission and secure receipt over a network, such as the Internet. The systems and methods include the processing of analog voice and digital information, including conversion of a voice signal into digital information (or of digital information into a voice signal) and transmission of digital information representing voice data over a network. The analog-to-digital conversion (and digital-to-analog conversion) includes coding and decoding digital information according to voice coding techniques and encrypting and decrypting digital information according to encryption techniques. The transmission of the digital information includes creation of a secure voice frame.

Abstract: Disclosed is an encrypting speech processor architecture that provides enhanced security without the use of external cryptosync and with minimal speech degradation. This is accomplished by incorporating a block encryptor and a keystream generator (instead of a fixed secret mask encryption scheme, such as those implemented in voice ciphers) for encrypting blocks of encoded speech bits at a transmitter side. The block encryptor employs an invertible cryptographic algorithm and internal cryptosync to convert a first block of encoded speech bits into a first ciphertext block. The first ciphertext block is used to generate a keystream, which is then used to encrypt a second ciphertext block.

Abstract: An encryption device for a telephone having a handset and a base unit is disclosed. The device includes a handset interface, a first converter, an encryption processor, a second converter, and a host interface. The handset interface receives analog output signals from the handset. The first converter converts the analog output signals into digital output signals. The encryption processor includes a compressor, a key manager, an encryptor, and a modulator. The key manager generates key material for encrypting the digital output signals. The compressor compresses the digital output signals, the encryptor encrypts the digital output signals based on the key material, and the modulator modulates the encrypted digital output signals. The second converter converts the encrypted digital output signals into encrypted analog output signals. The host interface receives the encrypted analog output signals from the encryption processor, and forwards the encrypted analog output signals to the base unit.

Abstract: A method and system of read-ahead caching for use in a DVD player utilizing CSS titles is disclosed. The caching system is a host-based read-ahead caching system that utilizes a threaded architecture for caching. One thread is dedicated to retrieving data from the cache and a second thread is dedicated to reading data from the cache. The producer thread is intelligent enough to cache only within a title boundary, thus preventing costly re-authentication steps.

Abstract: An apparatus and method for security of individual communications over a composite communications channel such as T1 or E1. The composite channel is digitized. Individual channels are separated, but identifying information of each channel is retained. A level of security can be chosen for each channel by digitally processing the selected call with a selected level of scrambling or encryption prior to passing the call to an end-user.

Abstract: An apparatus and method for concealing data bursts in an analog scrambler using audio repetition. What otherwise would be periodic data bursts appearing at the audio output are replaced with samples from audio portions of the multiplexed signal. Preferably the replaced audio samples come from immediately past portions of the audio of the signal. The data bursts are therefore effectively concealed from the audio output which improves on the degradation of audio otherwise caused by the data bursts that are mixed in periodically with the audio portions of the signal.