Digital Envelope Research Articles

Реалізація криптографічних алгоритмів на основі ПЛІС для цифрових розподілених систем

This paper presents a single chip efficient FPGA implementation of RSA and DES for Digital Envelope Scheme that targets the Altera Apex 20KE EP20k200EBC356. Implementation of cryptographic algorithms on programmable devices like FPGAs run much faster than on software while preserving physical security of hardware solutions. The high throughput in the implementation of cryptographic algorithms for digital envelope scheme is achieved by means of exploiting the parallelism present in the DES and RSA operations as well as the features of Altera Apex 20KE device family which best suit for system-on-a-programmable-chip (SOPC) applications. The parallelized single chip implementation of DES and RSA for performing the Encryption/Decryption for the Digital envelope scheme offers a throughput of 3.5 Gbits/sec at a system clock rate of 54.7 MHz. This implementation even provides a means for using the DES and RSA separately.

An adaptive digital processor for power efficiency enhancement in hybrid supply modulators

SummaryA novel digital envelope modulator for envelope tracking radio frequency power amplifier is presented in this paper. The proposed modulator consists of a parallel combination of linear class AB and switching class D power amplifiers that are controlled digitally. In the previous analog architectures, the requirements needed for the AB operational amplifier such as high‐current driving capability, high bandwidth and large output swing is usually obtainable at high overall static power dissipation. The digitally controlled power opamp presented here not only provides the aforementioned requirements but also reduces power dissipation compared with previous work. Furthermore, the digital control of the modulator makes it adaptive to the input signal variations in comparison with conventional analog parallel hybrid envelope modulators. The digital processor of the modulator is evaluated with a 45‐nm complementary metal oxide semiconductor technology. The overall power consumption of the digital processor is around 142 mW at 1.5‐GHz clock frequency. As an application, the designed digital class AB is incorporated in a complete envelope modulator architecture. The overall efficiency of the modulator, including the digital processor power consumption, is around 82% at an average 32 dBm output power for a 5‐MHz input signal. Copyright © 2015 John Wiley & Sons, Ltd.

A 2.4-GHz low power polar transmitter for wireless body area network applications

A 2.4 GHz low power polar transmitter is proposed in this paper. A dynamic biasing circuit, controlled by a digital envelope signal, is used as a direct digital-to-RF envelope converter. It effectively linearizes the input-output characteristic of the overdriven cascode class-C power amplifier used as the output stage, by dynamically adjusting the bias voltage of the cascode transistor. An equivalent baseband model of the transmitter is presented and used to optimize system parameters and give initial assessment of the achievable performance in terms of efficiency and linearity. Based on these simulations, parameters for transistor-level implementation of the bias circuit are derived. The transmitter is designed in a 65 nm CMOS technology. The post layout simulations indicate that the transmitter successfully meets the requirements of the IEEE 802.15.6 standard for wireless body area networks. The simulated amplifier consumes 4.75 mA from a 1.2 V supply while delivering 1.45 dBm of output power with a peak efficiency of 24 %. The entire transmitter, including the PLL, consumes 7.5 mA.

Fast digital envelope detector based on generalized harmonic wavelet transform for BOTDR performance improvement

We propose a fast digital envelope detector (DED) based on the generalized harmonic wavelet transform to improve the performance of coherent heterodyne Brillouin optical time domain reflectometry. The proposed DED can obtain undistorted envelopes due to the zero phase-shift ideal bandpass filter (BPF) characteristics of the generalized harmonic wavelet (GHW). Its envelope average ability benefits from the passband designing flexibility of the GHW, and its demodulation speed can be accelerated by using a fast algorithm that only analyses signals of interest within the passband of the GHW with reduced computational complexity. The feasibility and advantage of the proposed DED are verified by simulations and experiments. With an optimized bandwidth, Brillouin frequency shift accuracy improvements of 19.4% and 11.14%, as well as envelope demodulation speed increases of 39.1% and 24.9%, are experimentally attained by the proposed DED over Hilbert transform (HT) and Morlet wavelet transform (MWT) based DEDs, respectively. Spatial resolution by the proposed DED is undegraded, which is identical to the undegraded value by HT-DED with an allpass filter characteristic and better than the degraded value by MWT-DED with a Gaussian BPF characteristic.

A Secure Scheme for Storage, Retrieval, and Sharing of Digital Documents in Cloud Computing Using Attribute-Based Encryption on Mobile Devices

ABSTRACT This work describes the analysis, design, and implementation of a secure scheme for storage, retrieval, and fine-grained sharing of digital documents in cloud computing using mobile devices. Confidentiality of digital documents stored in public clouds from a mobile device is achieved by implementing the digital envelope concept. Data are encrypted using AES, and the session key is encrypted using ciphertext-policy attribute based encryption (CP-ABE). CP-ABE also provides access control mechanisms at a fine-grain level, allowing the decryption of the AES key only to those users having the correct set of attributes. The encryption and decryption processes are carried out in a mobile device that interacts with a cloud provider, a trust server, and a key server. For practical implementation of CP-ABE, the Tate pairing was used on elliptic curves type A and F over prime fields, using affine and projective coordinates for the security levels 80, 112, and 128 bits. After evaluating the proposed system for different CP-ABE implementation options, it was observed that the elliptic curves type A allow execution times 18 times faster compared with the use of elliptic curves type F, achieving processing times that ensures the deployment of the proposed secure scheme.

AUTHENTICATION AND ENCRYPTION FOR MEDICAL IMAGE SECURITY SYSTEM

Significant advancements in information and communication technologies have made remarkable developments in many fields including health care delivery, computer-aided diagnosis and medical data management. In this work Digital Envelope (DE) method is used to assure data integrity and security. DE includes the digital signature of the image and encrypted patient information from the Digital Imaging and Communication in Medicine image header. It is encrypted and embedded in the background area of the image as an invisible permanent watermark. To increase the trustworthiness, the DE-embedded image is then encrypted using Rivest Shamir Adleman and Advanced Encryption Standard algorithms. The encrypted images are also tested with common attacks like flipping, filtering, noise, rotation and contrast. A qualitative comparative analysis is done for medical images with and without tampering using performance measures such as peak signal-to-noise ratio, correlation coefficient and Tamper Assessment Factor to evaluate the behaviour of the algorithm.

A secure and timestamp-based communication scheme for cloud environment

Cloud computing provides the capability to use computing and storage resources on a rented basis and reduce the investments in an organisation's computing infrastructure. With all its benefits, cloud computing also brings with it concerns about the security and privacy of information extant on the cloud as a result of its size, structure, and geographical dispersion. Secure communication in cloud environment is necessary to access remote resources in a controlled and efficient way. For validation and authentication digital signatures using public key cryptography is extensively used in cloud computing. Further to keep confidentiality, digital envelope which is the combination of the encrypted message and signature with the encrypted symmetric key is also used. In this paper we propose a timestamp-based authentication scheme for cloud client with a modified digital envelope. As hyperelliptic curve cryptosystem (HECC) is known for its small key size and high security, we have taken HECC encryption technique. We have also presented a security analysis to show that our scheme can resist various attacks related to cloud environment.

0.7–1.8 GHz multiband digital polar transmitter using watt-class current-mode class-D CMOS power amplifier and digital envelope modulation technique for reduced spurious emissions

A polar transmitter driven by digital input signals for envelope and phase is demonstrated, using a band-switching output resonator to achieve multiband operation. A new digital pulse width modulation algorithm is also shown to partially suppress spurious signals associated with the digital input envelope signal. The transmitter consists of a current-mode class-D (CMCD) CMOS power amplifier (PA), together with a buck converter with a dead-time generator for improved efficiency. The CMCD PA is tuned by band-switching capacitors that can handle up to 9 V, and is measured to have approximately 30 dBm output power with 31–35% drain efficiency under single-tone testing. The proposed spurious signal reduction technique works to partially suppress quantization noise without increasing power consumption. Overall efficiencies of 27.1/25.6% are obtained at 30.2/28.9 dBm continuous wave (CW) output powers and 0.85/1.75 GHz carrier frequencies, respectively. Spur suppression of 9–10 dB peak is achieved when the proposed algorithm is applied with wideband code division multiple access (WCDMA) modulation.

Secure Message Transmission using Lagrange Polynomial Interpolation and Huffman Coding

In this paper, an algorithm for secure transmission of message is proposed based on Lagrange's interpolation. The message is viewed as a polynomial of degree n where n is kept secret and transmitted to the receiver's side using the concept of a digital envelope. As any nth degree polynomial is uniquely determined by n+1 points, n +1 points are communicated to the other side, where the polynomial and hence the message is reconstructed. Padding of length m is added to the message to overcome the message length issue. Although any coding scheme may be used, in this paper Huffman coding is used for converting the plaintext into binary form. Finally, the proposed algorithm is compared with the performance of RSA algorithm and found to be efficient.

A Palmar Approach for Insertion of a Free, Nonvascularized Phalangeal Transfer

Free nonvascularized phalangeal transfer from a toe to congenitally hypoplastic digits, is an established procedure in the repertoire of digit reconstruction. The hypoplastic digit is frequently flexed, due to shortage of palmar soft tissues. The phalanx must be transferred intact, with a complete periosteal covering. A new technique of incision and dissection is described utilizing a palmar V approach, closed after skin advancement, as a Y. This permits ample visualization of the digital envelope to receive the phalanx, protection under direct vision of the digital bundles, and simultaneous correction of the deficient palmar skin, without tension.

Timestamp-Based Digital Envelope for Secure Communication Using HECC

ABSTRACT Secure communication in wireless network is necessary to access remote resources in a controlled and efficient way. For validation and authentication in e-banking and e-commerce transactions, digital signatures using public key cryptography is extensively employed. To maintain confidentiality, Digital Envelope, which is the combination of the encrypted message and signature with the encrypted symmetric key, is also used. In this paper we propose a timestamp-based authentication scheme with a modified Digital Envelope using hyperelliptic curve cryptosystem. HECC have advantages over the existing public key cryptosystems for its small key size and high security in wireless networks where resources are constrained. We have compared the performance of the proposed scheme with that of ECC and present a security analysis to show that our scheme can resist various attacks related to wireless networks.

202pJ/bit area-efficient ASK demodulator for high-density visual prostheses

A fully integrated low-power and area-efficient ASK demodulator is presented. By using a controllable digital envelope detector and a self-biased clock extractor, the threshold-detection level of the demodulator can be adjusted and the clock from the wireless power carrier can be recovered. This implantable demodulator was fabricated in a 0.35 µm CMOS process and tested using inductively-coupled coils with a resonant frequency of 13.56 MHz.

An Effective Mutual Authentication Scheme for Hierarchical Mobile IP

In order to improve the efficiency and security of the authentication for Hierarchical Mobile IP protocol, we propose a novel authentication scheme, which introduced identity signature and digital envelope to authenticate the sender and receiver of the registration packet. Theoretically prove that the scheme is an effective mutual authentication scheme, and improve the security and resist security attacks.

Analysis and Optimization of Transformer-Based Series Power Combining for Reconfigurable Power Amplifiers

Transformer-based series power combiners are analyzed within the context of reconfigurable, watt-level, wideband digital envelope tracking transmitters. A model is developed for designing and analyzing transformer-based switchable series combiners. This model takes into account losses in the windings and nonideal mutual coupling, as well as the effect of switching and scaling the input amplifiers on the combiner efficiency, input impedance, and power combining ratio. Optimum combining efficiency is derived for a combiner with scaled sources. Based on the developed model, a four-element 29.5-dBm power amplifier with 31% peak efficiency at 1.9 GHz, using a 1.5-V supply is designed and simulated in IBM 130-nm CMOS technology. The efficiency drops to 14% at 12 dB power back-off when elements are turned off. The amplifier maintains an output power >; 25 dBm from 1.8 GHz to 2.5 GHz. The studies presented in this paper can be extended to any series combiner implementation and any frequency range, which can be effective in the design of watt-level power amplifiers in submicrometer CMOS technologies.

A Novel Digital Envelope Approach for a Secure E-Commerce Channel

Data privacy and integrity will be the crucial and significant factors in recent times for trade which will be transacted over the Internet through e-commerce and m-commerce channels. To deal with these anxieties, various security etiquette related to symmetric and asymmetric key types have been framed. Digital Envelope is one of the practices to attain Privacy, Authentication, Integrity maintenance, and Non-Repudiation in e-commerce channels. In this paper, we suggest a software implementation of a digital envelope for a secure e-commerce channel that combines the hashing algorithm of MD5, the symmetric key algorithm of AES and the asymmetric key algorithm of Hyper Elliptic Curve Cryptography (HECC). The result illustrates that HECC is the best alternative asymmetric key technique rather than ECC and RSA in the digital envelope hybrid cryptosystem.

A Digital Envelope Combiner for Switching Power Amplifier Linearization

A digital envelope combiner (DEC) technique that employs an open-loop transformer-based combination of a bank of two-level polar switching power amplifiers to generate wide-bandwidth modulated radio frequency signals with simultaneously high efficiency and good linearity is presented. The application of the DEC is illustrated by the design and simulation-based verification of a 2.4-GHz 0.13-?m complementary metal-oxide-semiconductor power amplifier that achieves EVM < -25 dBc, ACPR < -40 dBc, and an average drain efficiency of 37% while generating a 16.25-MHz-bandwidth 8.9-dB-peak-to-average signal power ratio (PAR) 64-state quadrature amplitude modulation signal.

Ten Good Years

I take this opportunity to look back at the 10 years of my editorship. Circulation Research has been a force to be reckoned with in my life and career for the last 10 eventful years. Much has been accomplished, much has changed: in the journal, as in cardiovascular science. We, my Associate Editors, and I have done our best to usher in the new millennium, while remaining true stewards of this venerable publication. Circulation Research had another banner year in 2008. In total, we received 1983 manuscript submissions in 2008, a 53% increase in manuscript submissions over those received in 1999, when the Marban editorship began. Figure 1 tracks the steadily increasing manuscript submissions received since 1990. Submissions are tracking on course in 2009 to date. As in past years, the Editors of Circulation Research have maintained a competitively low acceptance rate, now 15% (Figure 2). When we took over the reins in July 1999, the acceptance rate was 22%. We sought to continue to improve the journal by tightening the acceptance rate; corollary efforts included determinations to reduce the reject de novo rate, to triage inappropriate papers at an early editorial stage, and to give authors meaningful feedback in our decision letters. Figure 3 highlights the trends in acceptance rates for the last 10 years, noting the steady decrease from 22% in 1999% to 16% in 2008. Figure 1. Annual manuscript submissions to Circulation Research for 1990 to 2008. Figure 2. Percentage of final decisions rendered by Circulation Research 2009 to date. Figure 3. Trends in annual acceptance rates for 1998 to 2009 to date. Circulation Research has an unmistakable global presence, evidenced by the diverse geographic distribution of manuscripts submitted to the journal in 2008 (Figure 4 …

Design and Linearization of Class-E Power Amplifier for Nonconstant Envelope Modulation

This paper presents design and linearization techniques for a highly efficient, but nonlinear Class-E power amplifier (PA) applied to linear RF transmitters. To achieve maximum efficiency for Class-E PA operating above gigahertz frequencies, the proposed design theory modifies the classic Class-E condition and considers switch-on and switch-off resistances in deriving the analytical solution. For linearization, a digital envelope predistorter (DEP) is used to provide predistorted envelope modulation for the RF-input and supply-voltage signals fed to the Class-E PA. This DEP can successfully compensate for AM/AM and AM/PM distortions such that the Class-E PA, although classified as a switching-mode PA, can act as a linear PA. A cdma2000 1 times transmitter incorporating this Class-E PA and DEP is demonstrated to simultaneously achieve high efficiency and high modulation quality.

Fingerprint verification on medical image reporting system

The healthcare industry is recently going through extensive changes, through adoption of robust, interoperable healthcare information technology by means of electronic medical records (EMR). However, a major concern of EMR is adequate confidentiality of the individual records being managed electronically. Multiple access points over an open network like the Internet increases possible patient data interception. The obligation is on healthcare providers to procure information security solutions that do not hamper patient care while still providing the confidentiality of patient information. Medical images are also part of the EMR which need to be protected from unauthorized users. This study integrates the techniques of fingerprint verification, DICOM object, digital signature and digital envelope in order to ensure that access to the hospital Picture Archiving and Communication System (PACS) or radiology information system (RIS) is only by certified parties.

A Digital Envelope Modulator for a WLAN OFDM Polar Transmitter in 90 nm CMOS

A digital envelope modulator as part of a polar transmitter architecture for the 802.11a/g WLAN OFDM standards is investigated. The digital envelope modulator is quite similar to a state-of-the-art DAC design, but now it has been optimized to deal with envelope signals. A thermometer-coded envelope DAC has been implemented in a 90 nm digital CMOS process. Measurements of a test chip show the digital envelope modulator to reach an OFDM output power of 5 dBm for 54 Mb/s using 64 QAM at 2.45 GHz and fulfilling EVM specifications and in-band spectral mask requirements using just 12.7 mW from a 1.2 V supply. Combining the digital envelope modulator with an off-chip power amplifier gives an output power of 20.4 dBm, while fulfilling EVM specifications and in-band spectral mask requirements. The output power of the presented envelope DAC can be increased in a re-design by scaling device sizes. The envelope DAC is a key component in a software-defined-radio transmitter.