Private Messages Research Articles

Capacity Results for Classes of Partially Ordered $K$ -User Broadcast Channels With Two Nested Multicast Messages

The $K$ -user discrete memoryless (DM) broadcast channel (BC) with two nested multicast messages is studied in which one common message is to be multicast to all receivers and the second private message to a subset of receivers. The receivers that must decode both messages are referred to as private receivers and the others that must decode only the common message as common receivers. For two nested multicast messages, we establish the capacity region for several classes of partially ordered DM BCs characterized by the respective associated sets of pair-wise relationships between and among the common and private receivers, each described by the well-known pair-wise more capable or less noisy condition. For three classes of partially ordered DM BCs, the capacity region is shown to be simply achieved by two-level superposition coding and the proofs of the converses rely on a recently found information inequality. The rate region achievable by two-level superposition coding is then enhanced through a multi-level superposition coding scheme after splitting the private message into as many parts as there are common receivers and indirect decoding. A closed-form two-dimensional polyhedral (polygonal) description is obtained for it for a given coding distribution in spite of the indeterminate number of split rates via a structured form of Fourier-Motzkin elimination. Through a converse result that relies on the Csiszar sum lemma and that information inequality, a specialization of this region that corresponds to splitting the private message into just two sub-messages is proved to be the capacity region for several classes of partially ordered DM BCs beyond those for which two-level superposition coding is capacity optimal, thereby underscoring the benefit of rate-splitting. All previously known capacity results for partially ordered DM BCs with two nested multicast messages for the two and three-receiver DM BCs as well as DM BCs with one private or one common receiver are subsumed in the general results obtained in this work.

Emerging Adults’ Public and Private Discussions of Substance Use on Social Media

Substance use increases during emerging adulthood and may relate to higher concurrent and future problems. For a community sample of 140 emerging adults, this study explores the associations between reported alcohol, marijuana, and tobacco use in 12th grade, the content of public posts and private messaging on Facebook during the fall after 12th grade, and self-reported substance use 1 year after high school. About one quarter of participants discussed substances publicly, and nearly half discussed substances privately on Facebook as observationally coded by researchers. Twelfth-grade substance use predicted the probability of engaging in public and private substance-related discussions. Tobacco and marijuana use predicted the frequency of private messaging about substances. Public and private online substance discussions predicted positive changes in marijuana use 1 year later. Results from this study suggest that social media discussions about substances, particularly private messages, may signal and shape emerging adults’ substance use behaviors.

A Mobile Health Intervention to Improve Hepatitis C Outcomes Among People With Opioid Use Disorder: Protocol for a Randomized Controlled Trial.

BackgroundPeople who inject drugs are at a disproportionate risk for contracting hepatitis C virus (HCV). However, use of HCV prevention and treatment services remains suboptimal among people with substance use disorders due to various health system, societal, and individual barriers. Mobile health applications offer promising strategies to support people in recovery from substance use disorders. We sought to determine whether the Addiction-Comprehensive Health Enhancement Support System (A-CHESS), an existing mobile health application for opioid use disorder, could be adapted to improve HCV screening and treatment.ObjectiveThe goals of this paper are to describe: (1) the components and functionality of an HCV intervention incorporated into the existing A-CHESS system; and (2) how data are collected and will be used to evaluate HCV testing, linkage to care, and treatment.MethodsPeople with recent opioid use were enrolled in a randomized controlled trial to test whether A-CHESS reduced relapse. We developed and implemented HCV intervention content within the A-CHESS platform to simultaneously evaluate whether A-CHESS improved secondary outcomes related to HCV care. All A-CHESS users received the HCV intervention content, which includes educational information, private messages tailored to an individual’s stage of HCV care, and a public discussion forum. Data on patients’ HCV risk behaviors and stage of care were collected through quarterly telephone interviews and weekly surveys delivered through A-CHESS. The proportion of people with opioid use disorder who are HCV untested, HCV-negative, HCV antibody-positive, or HCV RNA–positive, as well as linked to care, treated and cured at baseline is described here. The 24-month follow-up is ongoing and will be completed in April 2020. Survey data will then be used to assess whether individuals who received the HCV-enhanced A-CHESS intervention were more likely to reduce risky injection behaviors, receive HCV testing, link to medical care, initiate treatment, and be cured of HCV compared to the control group.ResultsBetween April 2016 and April 2018, 416 individuals were enrolled and completed the baseline interview. Of these individuals, 207 were then randomly assigned to the control arm and 209 were assigned to the intervention arm. At baseline, 202 individuals (49%) self-reported ever testing HCV antibody-positive. Of those, 179 (89%) reported receiving HCV RNA confirmatory testing, 134 (66%) tested HCV RNA–positive, 125 (62%) were linked to medical care and 27 (13%) were treated and cured of HCV. Of the remaining 214 individuals who had never tested HCV antibody–positive, 129 (31%) had tested HCV antibody–negative within the past year and 85 (20%) had not been tested within the past year.ConclusionsThe A-CHESS mobile health system allows for the implementation of a bundle of services as well as the collection of longitudinal data related to drug use and HCV care among people with opioid use disorders. This study will provide preliminary evidence to determine whether HCV-specific services embedded into the A-CHESS program can improve HCV outcomes for people engaged in addiction treatment.Trial RegistrationClinicalTrials.gov NCT02712034; https://clinicaltrials.gov/ct2/show/NCT02712034International Registered Report Identifier (IRRID)DERR1-10.2196/12620

Semi-Robust Communications Over a Broadcast Channel

We establish the deterministic-code capacity region of a network with one transmitter and two receivers: an ordinary receiver and a robust receiver. The channel to the ordinary receiver is a given (known) discrete memoryless channel, whereas the channel to the robust receiver is an arbitrarily varying channel. Both receivers are required to decode the common message (the better-protected message), whereas only the ordinary receiver is required to decode the private message (the less-protected message). As in the single-user case, under the appropriate compactness and convexity conditions, the capacity region is either empty or else the intersection of the capacity regions of the broadcast channels that the various states induce.

Implementation of QR Code for Sharing Files.

QR code is a quick response code which is used to store information. In QR code, the information is stored in encoded form. To access information present in QR code , we need to decode information with the help of scanner. The information which is present in QR code is accessible to anybody. Private data is not safe in such scenario. This paper presents a visual secret sharing scheme to encode a secret QR code into distinct shares. Visual secret sharing scheme is a method of distributing secrete amongst a group of participants. The secret message is recovered by XOR-ing the shares. Secret message can be generated only when enough number of shares are combined. This provides security for private message using visual secret sharing scheme. Proposed system provides higher security to messages and it also provides more flexible access structure. Computational cost of proposed scheme is low.

Multicast Communication using Different Group Key Managements

The most appropriate communication mechanism for transfer of packets from one source to another is multicast IPv6 communication. Nowadays, multicast communication plays a major role in a large number of communication applications. In this multicast communication, the message privacy attains a highest position. The members of multicast are dynamic so they permit the host members to enter and depart the cluster without the permission of remaining group members and, it can't provide any transfer without the interference of host, this may reduce the performance. For security enhancement in multicast communication Group Key Management (GKM) was introduced. There are three different approaches in GKM and they were mainly involved to overcome the issues of host mobility in multicast communication. The challenges that are encountered by these GKM approaches their requirements and challenges was also discussed in this paper. Finally, some questions and their explanations were provided along with it. These GKM approaches will improve the privacy of multicast communication. So, the packets can deliver to the group members without any interference.

Design, Dissemination, and Disinformation in Viral Maps

Design, Dissemination, and Disinformation in Viral Maps

A QR Code Secret Hiding Scheme against Contrast Analysis Attack for the Internet of Things

Due to the advantages of larger content and error correction capability, quick response (QR) code is commonly used as a tagging technology for the Internet of Things (IoT) recently. However, the cover message of QR code can be easily decoded by a QR code reader, which causes the security and privacy of the cover message to raise the important issues. In this paper we present a new secret hiding scheme based on QR code. The proposed scheme has low computational complexity and is suitable for low-power devices in IoT systems because of utilizing the error correction property of QR code to hide secret information. The proposed scheme hides the secret information without changing the cover message of QR code and the user can get the cover message by using a general scanner, which contributes to reducing attacker’s curiosity. The hidden secret information can be read by a special scanner with the help of the user key. One thing which is better than other known schemes is that the proposed scheme can resist contrast analysis attack. In addition, experimental results show the proposed scheme has feasibility, low computational complexity, and high hiding payload.

Using Models to Persuade

We present a framework where “model persuaders” influence receivers’ beliefs by proposing models that organize past data to make predictions. Receivers are assumed to find models more compelling when they better explain the data, fixing receivers’ prior beliefs. Model persuaders face a trade-off: better-fitting models induce less movement in receivers’ beliefs. Consequently, a receiver exposed to the true model can be most misled by persuasion when that model fits poorly, competition between persuaders tends to neutralize the data by pushing toward better-fitting models, and a persuader facing multiple receivers is more effective when he can send tailored, private messages. (JEL C50, D82, D83)

Exact Error and Erasure Exponents for the Asymmetric Broadcast Channel

Consider the asymmetric broadcast channel with a random superposition codebook, which may be comprised of constant composition or i.i.d. codewords. By applying Forney’s optimal decoder for individual messages and the message pair for the receiver that decodes both messages, exact (ensemble-tight) error and erasure exponents are derived. It is shown that the optimal decoder designed to decode the pair of messages achieves the optimal trade-off between the total and undetected exponents associated with the optimal decoder for the private message. Convex optimization-based procedures to evaluate the exponents efficiently are proposed. Finally, numerical examples are presented to illustrate the results.

MIMO Gaussian Broadcast Channels With Common, Private, and Confidential Messages

The two-user multiple-input multiple-output Gaussian broadcast channel with common, private, and confidential messages is considered. The transmitter sends a common message to both users, a confidential message to the User 1 and a private (non-confidential) message to the User 2. The secrecy-capacity region is characterized by showing that certain inner and outer bounds coincide and that the boundary points are achieved by Gaussian inputs, which enables the development of a tight converse. The proof relies on the factorization of upper concave envelopes and a variant of dirty-paper coding (DPC). It is shown that the entire region is exhausted by using DPC to cancel out the signal of the non-confidential message at Receiver 1, thus making DPC against the signal of the confidential message unnecessary. A numerical example illustrates the secrecy-capacity results.

Facebook Use, Personality Characteristics and Academic Performance

The present article examines the relationship between student personality, use of social media and their academic performance and engagement. Specifically, this article examines the relationship of students' Facebook (FB) use and personality characteristics using the Big Five Personality Test. This is focused on (a) student engagement; (b) time spent preparing for class; (c) time spent in co-curricular activities; and (d) academic performance. 204 higher education students participated in the study. Results illustrate that FB time was significantly positively correlated to student engagement and time spent preparing for class. Sharing links activity was positively correlated with student engagement and playing FB games with time spent preparing for class. However, sending private messages and status updates were significantly negatively correlated with student engagement and time spent preparing for class. Also, viewing videos was negatively correlated with time spent in co-curricular activities. Chatting on FB and viewing photos found to be the most popular activities. Moreover, students' extraversion, conscientiousness, openness to experience were positively correlated to student engagement. In addition, extraversion had a positive relationship with time spent in co-curricular activities, although agreeableness had a negative relationship. Implications of the study for the instructors and the students are also discussed.

A scheme of flexible and reversible information-hiding in SMVQ mechanism

Information hiding refers to concealing data into cover media to prevent the private message from being stolen in peer-to-peer networks, mobile communication, and the cloud environment. Vector quantization (VQ) provides one means for this purpose; a distortion is created between the raw media and VQ compressed media. In this study, we proposed a flexible side-match vector quantization (SMVQ) information-hiding method. By using this method, the private message can be embedded into the distortion, and the visual quality of the stego media is improved. The proposed method achieves an improvement of about 13.13% (i.e., +3.73 dB) in the peak signal-to-noise ratio of the stego image and an improvement of about 59,355 bits of embedding capacity on average compared with Wang et al.’s method. The experiment results verify the significant contributions of this study to the field of SMVQ-based information hiding, especially with regard to the image quality of the stego image and the embedding capacity.

Privacy preserving with adaptive link selection for hybrid radio-frequency and free space optical networks.

In order to improve the secrecy performance, we propose a secure hybrid radio frequency/free space optical (RF/FSO) transmission scheme that takes advantage of both the RF and FSO channels to protect the privacy messages. In the proposed scheme, Alice adaptively selects RF link or FSO link for information transmission according to the secrecy performance of each link. Considering the priority of the FSO link, we propose two secure transmission policies: the FSO dominant secure (FDS) policy and the secrecy rate optimal (SRO) policy. In the FDS policy, we assign high priority to the FSO link due to its high secrecy performance. Therefore, in this policy, Alice transmits the privacy information through the FSO link when the FSO link is reliable. When the FSO link cannot provide successful transmission, Alice will consider the RF secure transmission. In the SRO policy, Alice optimally selects FSO link or RF link according to the secrecy rates of both the FSO and RF links in each time slot. For both FDS and SRO policies, we analyze the secrecy performances and derive closed-form expressions for the average secrecy rate. Numerical results demonstrate the performance improvement of the proposed policies when compared with the current RF or FSO secure schemes in terms of the average secrecy rate.

Interference Mitigation via Rate-Splitting and Common Message Decoding in Cloud Radio Access Networks

Cloud-radio access networks (C-RAN) help in overcoming the scarcity of radio resources by enabling dense deployment of base-stations (BSs) and connecting them to a central-processor (CP). This paper considers the downlink of a C-RAN, where the cloud is connected to the BSs via limited-capacity backhaul links. We propose and optimize a C-RAN transmission scheme that combines rate splitting, common message decoding, and beamforming vectors design and clustering. To this end, this paper optimizes a transmission scheme that combines rate splitting (RS), common message decoding (CMD), and clustering and coordinated beamforming. In this paper, we focus on maximizing the weighted sum-rate subject to per-BS backhaul capacity and transmit power constraints, so as to jointly determine the RS-CMD mode of transmission, the cluster of BSs serving private and common messages of each user, and the associated beamforming vectors of each user private and common messages. This paper proposes solving such a complicated non-convex optimization problem using $l_{0}$ -norm relaxation techniques, followed by inner-convex approximations (ICA), so as to achieve stationary solutions to the relaxed non-convex problem. The numerical results show that the proposed method provides significant performance gain as compared to conventional interference mitigation techniques in C-RAN which simply treat interference as noise (TIN).

A cryptosystem based on chaotic maps and factoring problems

A cryptosystem allows a sender to send any confidential or private message using a receiver's public key and the receiver next confirms the integrity and validity of the received message using his own secret key. Cryptosystem algorithms can be categorised based on the type of security suppositions, for example discrete logarithm, factorisation, and elliptic curve hard problems, which are all currently believed to be unsolvable in a reasonable time of period. Recently, cryptosystems based on chaotic maps have been proposed. Due to some subtle and close relationship between the properties of traditional cryptosystems and chaotic-based systems, the idea of using chaotic in cryptography has received a great deal of attention from many cryptography's researchers. Therefore, to enhance system security, we explore the implementation of a cryptosystem algorithm based on both cryptographic and chaotic system characteristics. We also provide security against known cryptographic attacks and discuss the performance analysis of the developed system.

A controlled multi-party quantum dialogue protocol in the network

A controlled multi-party quantum dialogue scheme in the network based on high dimensional multi-qudit entangled GHZ states is proposed. In our scheme, a semi-honest third party (TP) is introduced to assist the implementation of the scheme. Each user can be thought of as one node in the network and is connected by classical links and quantum links. In the network, multiple users can exchange their private messages with each other simultaneously under the control of TP. With the aid of secure classical channels and quantum channels, the proposed protocol can be ensured with unconditionally security. In addition, our protocol requires single-qudit measurements only which weakens the hardware requirements of network nodes. Compared with previous quantum dialogue protocols, our scheme demonstrates a large operating flexibility.

A cryptosystem based on chaotic maps and factoring problems

A cryptosystem allows a sender to send any confidential or private message using a receiver's public key and the receiver next confirms the integrity and validity of the received message using his own secret key. Cryptosystem algorithms can be categorised based on the type of security suppositions, for example discrete logarithm, factorisation, and elliptic curve hard problems, which are all currently believed to be unsolvable in a reasonable time of period. Recently, cryptosystems based on chaotic maps have been proposed. Due to some subtle and close relationship between the properties of traditional cryptosystems and chaotic-based systems, the idea of using chaotic in cryptography has received a great deal of attention from many cryptography's researchers. Therefore, to enhance system security, we explore the implementation of a cryptosystem algorithm based on both cryptographic and chaotic system characteristics. We also provide security against known cryptographic attacks and discuss the performance analysis of the developed system.

Cooperative Secondary Encryption for Primary Privacy Preserving in Cognitive Radio Networks

Aiming at protecting primary privacy messages and supporting secondary quality-of-service (QoS), we propose a secondary encrypted secure strategy for cognitive radio networks. In this scheme, a primary system directly transmits privacy messages or employs pre-transmitted secure secondary messages to encrypt the primary privacy information, and the secondary system acquires a fraction of the interference-free licensed spectrum. Following this idea, we consider two secure communication scenarios: the non-buffer scenario and the buffer-aided scenario. For the non-buffer scenario, the primary system first evaluates the channel quality of the direct transmission link. Then, the primary transmitter adaptively chooses to directly transmit the privacy messages or employ the encryption of the secure secondary messages according to the evaluation results. For this scenario, we investigate the primary ergodic secrecy performance and the secondary average performance. For the buffer-aided scenario, the secure secondary messages can be stored in the buffers at both the primary transmitter and receivers. According to the buffer states and channel quality, the primary system adaptively chooses to directly transmit the primary privacy information, permit the secondary secure transmission, or utilize the encryption of the stored secure secondary information. For this scenario, we also investigate the performances of both the primary and secondary systems, and derive the closed-form expression of the primary information delay. Numerical results are given to prove that the proposed scheme can provide privacy preserving for the primary information and acquire high secondary average transmission rate.

Multiparty Quantum Private Comparison of Size Relation Based on Single-Particle States

In order to reduce resource consumption and improve transmission efficiency, in this paper, using single-particle states, a multiparty quantum privacy comparison size relationship (QPCSR) protocol is proposed. Without leaking the compared private message, the blinded secret integer is encoded into the relative phase of single-particle by performing unitary operation. After each of the transformed quantum states has been measured, respectively, the comparison result of n participants' secret integers is obtained. Security analysis shows that this protocol not only resists outside attack and participant attack, but also resists the semi-honest third-party (TP) attack. Compared with the other similar quantum privacy comparison equal relationship (QPCER) protocols, the proposed protocol has better flexibility and universality; compared with the other similar QPCSR protocols, it has lower resource consumption and higher communication efficiency.