Eavesdropping Behavior Research Articles

Quantum secure direct communication scheme based on the mixture of single photon and Bell state with two way authentication

In response to the demand for identity authentication in quantum secure direct communication, this paper proposes a quantum secure direct communication scheme based on a mixture of single photon and Bell state, by combining the bidirectional identity authentication. Before communication begins, both parties share a series of secret information to prepare a series of single photon and Bell state particles. Encoding four single photons and four Bell states yields eight types of encoded information, followed by identity authentication. The first step in identity authentication is to use a single photon to verify the legitimacy of the receiver. If the error exceeds the given threshold, it indicates the presence of eavesdropping. Otherwise, the channel is safe. Then, Bell state particles are used to verify the legitimacy of the sender, and the threshold is also used to determine whether there is eavesdropping. The present method is the same as previous one. If the error rate is higher than the given threshold, it indicates the existence of third-party eavesdropping. Otherwise, it indicates that the channel is secure. As for the specific verification method, it will be explained in detail in the article. Afterwards, Bell state particles are mixed with a single photon as a transmission carrier, and eavesdropping detection particles are added whenever the quantum state is sent. However, once the eavesdropper intercepts the transmitted particles, owing to incomplete information obtained, the eavesdropper is unable to recover the original information, and the eavesdropping behavior will be immediately detected, thus terminating communication. In this scheme, single photon and Bell states are fully utilized, and hybrid communication can effectively improve transmission efficiency, encoding capability, and quantum bit utilization. Security analysis shows that this scheme can resist common external and internal attacks such as interception/measurement replay attacks, auxiliary particle attacks, and identity impersonation attacks. The analysis of efficiency and encoding capacity shows that the transmission efficiency of this scheme is 1, the encoding capacity is 3 bits per state, and the quantum bit utilization rate is 1. Compared with other schemes, this scheme has significant advantages because it uses different particles for bidirectional authentication, making it more difficult for attackers to crack, and thus it has higher security than traditional schemes.

Jamming and Eavesdropping Defense Scheme Based on Deep Reinforcement Learning in Autonomous Vehicle Networks

As a legacy from conventional wireless services, illegal eavesdropping is regarded as one of the critical security challenges in Connected and Autonomous Vehicles (CAVs) network. Our work considers the use of Distributed Kalman Filtering (DKF) and Deep Reinforcement Learning (DRL) techniques to improve anti-eavesdropping communication capacity and mitigate jamming interference. Aiming to improve the security performance against smart eavesdropper and jammer, we first develop a DKF algorithm that is capable of tracking the attacker more accurately by sharing state estimates among adjacent nodes. Then, a design problem for controlling transmission power and selecting communication channel is established while ensuring communication quality requirements of the authorized vehicular user. Since the eavesdropping and jamming model is uncertain and dynamic, a hierarchical Deep Q-Network (DQN)-based architecture is developed to design the anti-eavesdropping power control and possibly channel selection policy. Specifically, the optimal power control scheme without prior information of the eavesdropping behavior can be quickly achieved first. Based on the system secrecy rate assessment, the channel selection process is then performed when necessary. Simulation results confirm that our jamming and eavesdropping defense technique enhances the secrecy rate as well as achievable communication rate compared with currently available techniques.

Know your enemy: The dragonfly Erythrodiplax fusca (Libellulidae) uses eavesdropping to obtain information about potential rivals

Animals can eavesdrop on other competitors during territorial defense disputes to better choose rivals weaker than themselves and increase the chances of monopolizing resources. In dragonflies, males often compete for access to water bodies, which attract sexually receptive females to mate and lay eggs. During the breeding season, satellite males can observe fights between territory owners and intruders and, therefore, obtain information about potential rivals through visual cues. Consequently, weaker competitors may face more intense competition than stronger ones when defending a territory. In this study, we conducted field experiments with the dragonfly Erythrodiplax fusca to investigate whether eavesdropping on territorial disputes, using visual cues, affects the intensity of competition that territory owners face. We recorded the number of intruders that engage in disputes against males that recently occupied territories in two groups: the “eavesdropping” group (i.e., individuals with access to rivals’ prior information) and the control group (i.e., competitors with no access to prior information). The number of intruders was greater in the eavesdropping group compared to the control group. This effect depended on the interaction between the size of the territory owners and the presence of eavesdropping. The number of intruders decreased with increase in the size of the owners in the presence of eavesdropping, but this relationship did not occur in the control group. We discuss the implications of our findings for the male decision-making process to initiate agonistic disputes and how investigating eavesdropping behavior can improve current models of conflict resolution in animals.

Joint active and passive beamforming optimization for intelligent reflecting surface assisted proactive eavesdropping

This paper investigates a three-node proactive eavesdropping system with the aid of intelligent reflecting surface (IRS), where a monitor tries to wiretap information and transmit jamming signals simultaneously to interfere with the suspicious link. The IRS is deployed around the suspicious users to reconstruct propagation channel. Meanwhile, with large low-cost passive reflecting elements, it can provide more spatial degrees of freedom to moderate the link quality. In order to degrade exposure risk of eavesdropping behavior, the authors' objective is to minimize the jamming power by carefully designing jamming beamforming vectors and the phase shifts under the constraint of reliable intercepted information. The formulated problem is non-trivial to solve due to the coupling variables and unit-modulus constraints. Fortunately, by using alternating optimization and successive convex approximation techniques, the original problem is transformed into convex form and a sub-optimal solution is achieved. Numerical results show that the proposed scheme can effectively reduce the jamming power and the number of the jamming antennas over benchmark schemes, which is quite suitable for covertly overhearing signal.

Controlled quantum dialogue with authentication protocol on a basis of GHZ-like state

A controlled quantum dialogue with authentication protocol on a basis of GHZ-like state was proposed in this paper. To start with, three participants of the communication protocol generated a corresponding identity ID through quantum key distribution and it was kept secret. Controller Trent prepared the three-particle Greenberger–Home–Zeilinger-like (GHZ-like) state and shared with other two communication users Alice and Bob. Communication participants use the entangled particles in their respective hands which satisfy the nature of the classical XOR relationship for encryption, controlling and decryption of quantum messages and to verify the identities of communication users. Meanwhile, security of communication was assured by introducing decoy photons. According to analysis results, the proposed protocol can effectively not only prevent any form of eavesdropping behavior from external and internal eavesdroppers including the controller Trent, but also detect such activities. Finally, this protocol is proved to have high communication efficiency.

The Study of Security During Quantum Dense Coding in High-Dimensions

Here we analyze the security of quantum dense coding protocol in which the keys are encoded on d-dimensional Hilbert space. The incoherent attack is considered during the qubits transmission through practical quantum channels. To show the performance of the protocol, the mutual information is numerically calculated under the potential eavesdropping behavior by applying a cloning-based individual attack, along with an upper bound on the error rate that ensures unconditional security against incoherent attacks.

Deterministic Secure Four-qubit GHZ States Three-step Protocol for Quantum Communication

A deterministic secret quantum communication (DSQC) protocol is proposed with four-qubit GHZ states. It has some outstanding advantages. Firstly, it has a high communication capacity as each four-qubit GHZ state can carry three bits of secret messages. Secondly, as all of the quantum resource is useful, the intrinsic efficiency of the communication approaches the maximum value 100%. Besides, its total efficiency of the present protocol is 60%, more higher than most of the current existing DSQC protocols. The decoy photon detection technique guarantees that Eve’s any eavesdropping behavior can be detected on site, and the three-step transmitting strategy ensures no information will be leaked in the communication process. Moreover, the present protocol is feasible with the present day technique.

Predator Eavesdropping in a Mixed-Species Environment: How Prey Species May Use Grouping, Confusion, and the Cocktail Party Effect to Reduce Predator Detection

The field of predator eavesdropping concentrates on the detection by a predator or parasite of signals that prey direct at conspecifics, and the subsequent evolution by prey to avoid or lessen such detection. Here, we first point out that signaling prey species are often found in mixed-species moving groups or stationary aggregations, and ask the question of how simultaneous signaling, by members of one species or more, might affect predator eavesdropping behavior and the composition of the groups themselves. The detection risk of prey species will be affected by the other species they associate with, and prey should generally avoid joining a group with more detectable species. Yet prey may select to join other species that are preferred by predators, diluting their own risk of attack, as long as that does not lead to substantially greater detection and thereby increased predation. We next review the evidence that prey grouping and collective responses when attacked can confuse predators, leading to lower capture rates. Evidence for this confusion effect mostly involves visually orienting predators. We then ask if a similar phenomenon could occur when animals in a group simultaneously send acoustic signals, and find relevant evidence for predator confusion under such situations in the literature associated with the “cocktail party effect”. As confusion is heightened by similarities among mixed-species group members, this provides a force at ecological or evolutionary timescales to make species that associate in groups, and their signals, more similar to each other. However, heterogeneous mixed-species groups may be favored if species are differentially preferred as prey. We suggest experiments to examine whether the success rates of acoustically orienting predators depend on the group size of their mixed-species prey. More observations on the relative positions of conspecifics and heterospecifics in space, and the temporal association of their signals, will also increase our understanding of the relationship between mixed-species grouping and predator eavesdropping.

Controlled quantum secure direct communication with authentication protocol based on five-particle cluster state and classical XOR operation

A controlled quantum secure direct communication with authentication protocol based on the five-particle cluster state and the classical XOR operation is proposed in this paper. To begin with, three participants of the communication protocol generated a corresponding identity ID through quantum key distribution and kept it secret. The five-particle cluster state had two particles for the information frame, two for the identity and security check frame, and one for the control frame. According to a certain rule, the identity and security check was completed by using the z-base or x-base single-particle measurement. The sender Alice encoded the information by performing a unitary operation on the information particle sequence. With the controller’s help (Cindy), Bob decoded the information that Alice had sent by measuring the particle sequence and using the classical XOR operation according to certain rules. An analysis of the security of this protocol revealed that this protocol could effectively prevent eavesdroppers from acquiring useful information and was able to detect the eavesdropping behavior.

Soundscape of an Indo-Pacific humpback dolphin (Sousa chinensis) hotspot before windfarm construction in the Pearl River Estuary, China: Do dolphin engage in noise avoidance and passive eavesdropping behavior?

Soundscapes are vital to acoustically specialized animals. Using passive acoustic monitoring data, the temporal and spectral variations in the soundscape of a Chinese white dolphin hotspot were analyzed. By cluster analysis, the 1/3 octave band power spectrum can be grouped into three bands with median overall contribution rates of 35.24, 14.14 and 30.61%. Significant diel and tidal soundscape variations were observed with a generalized linear model. Temporal patterns and frequency ranges of middle frequency band sound matched well with those of fish vocalization, indicating that fish might serve as a signal source. Dolphin sounds were mainly detected in periods involving low levels of ambient sound and without fish vocalization, which could reflect noise avoidance and passive eavesdropping behaviors engaged in by the predator. Pre-construction data can be used to assess the effects of offshore windfarms on acoustic environments and aquatic animals by comparing them with the soundscape of postconstruction and/or postmitigation.

Eavesdropping and countermeasures for backflash side channel in fiber polarization-coded quantum key distribution

Nowadays, the practical security of quantum key distribution (QKD) is the biggest challenge. In practical implementation, the security of a practical system strongly depends on its device implementation, and device defects will create security holes. The information leakage from a receiving unit due to secondary photon emission (backflash) is caused by a single-photon detector in the avalanche process. Now studies have shown that the backflash will leak the information about time and polarization and the eavesdropping behavior will not generate additional error rate in the communication process. An eavesdropping scheme obtaining time information by using backflash is proposed. Targeting this security hole for backflash leaking polarization information, an eavesdropping scheme for obtaining polarization information by using backflash is proposed in free-space QKD; however, it has not been reported in fiber QKD. In this study, the eavesdropping scheme and countermeasures for obtaining information by using backflash in fiber polarization-coded QKD is proposed. Since the polarization state of the fiber polarization-coded QKD system is easy to change, the scheme is proposed based on the time-division multiplexing polarization compensation fiber polarization-coded QKD system. In theory, the eavesdropper in this scheme obtaining the key information by using the backflash is theoretically deduced, and corrects the polarization change of the backflash by time-division multiplexing polarization compensation method, thus obtaining the accurate polarization information. The probability of backflash in the fiber polarization-coded QKD is measured to be 0.05, and the information leakage in the proposed eavesdropping scheme is quantified. The lower limit of the information obtained by the eavesdropper is 2.5 × 10<sup>–4</sup>. Due to the fact that the polarization compensation process increases invalid information in actual operation, the information obtained by the eavesdropper will be further reduced, thus obtaining the lower limit of information leakage. The results show that the backflash leaks a small amount of key information in a time-multiplexed polarization-compensated fiber polarization-coded QKD system. The wavelength characteristics of the backflash can be utilized to take corresponding defense methods. Backflash has a wide spectral range, and the count of backflash has a peak wavelength. So, tunable filters and isolators can be used to reduce backflash leakage, thereby reducing the information leakage.

No evidence of eavesdropping on heterospecific alarm calls by captive zebra finches recently descended from wild birds

Alarm calls are vocalisations animals give in response to predators which mainly function to alert conspecifics of danger. Studies show that numerous species eavesdrop on heterospecific calls to gain information about predator presence. Responding to heterospecific calls may be a learned or innate response, determined by whether the response occurs with or without prior exposure to the call. In this study, we investigated the presence of eavesdropping behaviour in zebra finchesTaeniopygia guttata. This species is not known to possess a distinct alarm call to warn adult conspecifics of a threat, and could be relying on alarm calls of nearby heterospecifics for predator information. We used a playback experiment to expose captive zebra finches to three heterospecific sounds: an unfamiliar alarm call (from the chestnut‐rumped thornbillAcanthiza uropygialis), a familiar alarm call, and a familiar control (both from the noisy minerManorina melanocephala). These calls were chosen to test if the birds had learnt to distinguish between the function of the two familiar calls, and if the acoustic properties of the unfamiliar alarm indicated presence of a threat to the finches. Our results showed that in response to the thornbill alarm, the birds reduced the rate of production of short calls. However, this decrease was also seen when considering both short and distance calls in response to the control sound. An increase in latency to call was also seen after the control stimulus when compared to the miner alarm. The time spent scanning increased in response to all three stimuli, but this did not differ between stimuli. There were no significant differences when considering the stimulus by time interaction for any of the three vigilance measures. Overall, no strong evidence was found to indicate that the captive zebra finches were responding to the heterospecific alarm stimuli with anti‐predator behaviour.

Prevention Measures of the Eavesdropping Behavior by Various Advanced Systems

첨단 스마트기기의 개발과 보급에 따라 개인, 기관 및 산업체에서 비밀이나 사생활에 대한 보 호 활동이 증가되고 있으며 이를 탐지하려는 불법적인 도청 행위가 점차 첨단 과학화, 소형화되어가고 있다. 특히, 녹음, 영상촬영, 감시 등의 활동이 증가하면서 불법 도청이 사회적 불안과 공포적인 환경 이 조성됨에 따라 사생활 보장에 침해와 제한을 받고, 기업정보 유출로 인한 기업의 도산을 초래하여 국가 경제에 큰 타격을 주고 있다. 또한, 현실적으로 정치, 경제 및 사회 등 제반 분야에 침습되어 있는 불법적인 도청 행위가 과감성마저 나타나고 있다. 이에 대한 대응책으로 다양한 도청 탐지 장비의 개발 및 보급과 불법 행위자에 처벌을 위한 강화된 법규 정비 등의 예방대책과 정책적인 검토사항을 제시 하였다.With the development and dissemination of advanced smart devices, activities to protect confidentiality and privacy have been increasing in individuals, organizations and industries, and illegal eavesdropping activities to detect them are gradually becoming advanced science and miniaturization. Especially, as activities such as recording, video shooting and surveillance are increased, illegal eavesdropping is infringed and restricted by privacy guarantee due to social anxiety and fearful environment, which is caused corporate bankruptc that caused by the leakage of corporate information, it has been hurting the national economy. In addition, illegal eavesdropping practices that are invasive in various fields such as politics, economy and society are appearing boldly. As a countermeasure for this, we need to develop and supplement various eavesdropping detection devices and strengthened regulations for punishing illegal actors.

Heterospecific eavesdropping in ant-following birds of the Neotropics is a learned behaviour.

Animals eavesdrop on other species to obtain information about their environments. Heterospecific eavesdropping can yield tangible fitness benefits by providing valuable information about food resources and predator presence. The ability to eavesdrop may therefore be under strong selection, although extensive research on alarm-calling in avian mixed-species flocks has found only limited evidence that close association with another species could select for innate signal recognition. Nevertheless, very little is known about the evolution of eavesdropping behaviour and the mechanism of heterospecific signal recognition, particularly in other ecological contexts, such as foraging. To understand whether heterospecific eavesdropping was an innate or learned behaviour in a foraging context, we studied heterospecific signal recognition in ant-following birds of the Neotropics, which eavesdrop on vocalizations of obligate ant-following species to locate and recruit to swarms of the army ant Eciton burchellii, a profitable food resource. We used a playback experiment to compare recruitment of ant-following birds to vocalizations of two obligate species at a mainland site (where both species are present) and a nearby island site (where one species remains whereas the other went extinct approx. 40 years ago). We found that ant-following birds recruited strongly to playbacks of the obligate species present at both island and mainland sites, but the island birds did not recruit to playbacks of the absent obligate species. Our results strongly suggest that (i) ant-following birds learn to recognize heterospecific vocalizations from ecological experience and (ii) island birds no longer recognize the locally extinct obligate species after eight generations of absence from the island. Although learning appears to be the mechanism of heterospecific signal recognition in ant-following birds, more experimental tests are needed to fully understand the evolution of eavesdropping behaviour.

Breaking the cipher: ant eavesdropping on the variational trail pheromone of its termite prey.

Predators may eavesdrop on their prey using innate signals of varying nature. In regards to social prey, most of the prey signals are derived from social communication and may therefore be highly complex. The most efficient predators select signals that provide the highest benefits. Here, we showed the use of eusocial prey signals by the termite-raiding ant Odontoponera transversaO. transversa selected the trail pheromone of termites as kairomone in several species of fungus-growing termites (Termitidae: Macrotermitinae: Odontotermes yunnanensis, Macrotermes yunnanensis, Ancistrotermes dimorphus). The most commonly predated termite, O. yunnanensis, was able to regulate the trail pheromone component ratios during its foraging activity. The ratio of the two trail pheromone compounds was correlated with the number of termites in the foraging party. (3Z)-Dodec-3-en-1-ol (DOE) was the dominant trail pheromone component in the initial foraging stages when fewer termites were present. Once a trail was established, (3Z,6Z)-dodeca-3,6-dien-1-ol (DDE) became the major recruitment component in the trail pheromone and enabled mass recruitment of nest-mates to the food source. Although the ants could perceive both components, they revealed stronger behavioural responses to the recruitment component, DDE, than to the common major component, DOE. In other words, the ants use the trail pheromone information as an indication of suitable prey abundance, and regulate their behavioural responses based on the changing trail pheromone component. The eavesdropping behaviour in ants therefore leads to an arms race between predator and prey where the species specific production of trail pheromones in termites is targeted by predatory ant species.

Interspecific information use by army-ant–following birds

ABSTRACT Many animals use cues from other species to gather information about foraging opportunities, but engaging in such behavior requires balancing the potential benefits with the risks of increased competition. Neotropical birds that follow army ants are an appropriate system within which to study such eavesdropping behavior. Mixed-species groups of these understory birds congregate around ant swarms, where they forage on insects flushed by the ants. Obligate ant-followers have specialized behaviors to track ant swarms and may serve as information sources for facultative ant-followers. Owing to strong dominance hierarchies among species, however, the value of the information likely depends on the competitive relationship between the information provider and the eavesdropper. I investigated whether ant-following birds preferentially followed the songs of some antbird species over others, testing the prediction that the vocalizations of small (subordinate) ant-following species would attract more indivi...

Security analysis of BB84 protocol in the collective-rotation noise channel

Most of quantum cryptography protocols are designed under the ideal conditions without considering the impact of noise in actual communication; thus they may result in that the confidential information cannot be transmitted to the receiver accurately or eavesdroppers can steal the confidential information by mixing in noise. Therefore, analyzing the security of quantum cryptography protocols under noise conditions is of great significance. For the purpose of analyzing the security of quantum BB84 protocol in collective-rotation noise, firstly this paper introduces the quantum BB84 protocol, and considers the influence of environmental noise on it. An explanation should be stated that in a noise environment, the effects of noise and eavesdropping cannot be distinguished between each other. So the mechanism for which the error bit is simply used as the criterion to judge whether there exists eavesdropping in the BB84 protocol, cannot be used in the noise environment. The mechanism to judge whether there exists eavesdropping in quantum noise channel needs to be modified and improved for protecting the information. An initial qubit error rate can be set according to the noisy quantum channel. If the qubit error rate of the quantum communication channel is larger than that, it can be determined that the quantum channel is not secure and exists eavesdropping, no matter what the reason is. And on this basis, the collective-rotation noise model will be established in quantum channel by using the particle deflection model and distinguish the noise from the eavesdropping in quantum channel quantitatively, and the relationship of the amount of information that eavesdroppers can steal, the quantum bits error rate and the noise level will be analyzed by using the von Neumann entropy. Finally, the noise critical point will be calculated by using the collective noise model and the relationship between the amount of information that eavesdroppers can steal, at the quantum bits error rate, and the noise level. Through the analysis, we can know that in the existing noise level, the most of the eavesdropping can steal 25% of the key from the communication. However, the Eve's eavesdropping behavior will be detected, so that Alice and Bob will give up the current consultation key, and restart the key negotiation. This result shows that the quantum BB84 protocol is safe and secure in the collective-rotation noise channel. The research results of this paper will enrich the theory of quantum cryptography, and the innovation of security detection methods in quantum cryptographic protocols will help promote the process of practical quantum cryptography.

The role of social experience in eavesdropping by male wolf spiders (Lycosidae)

When reproductive success is limited by mate search costs, males can reduce costs by eavesdropping and initiating displays if conspecific courtship is detected. Here, we examine eavesdropping by male Schizocosa ocreata wolf spiders, with field studies, laboratory studies using video playback and live exposure studies. In field enclosure experiments, introduced males responded with increased courtship signalling behaviour in the presence of a courting male. In the laboratory, field-collected males spent more time engaged in interaction behaviours and performed more bouts of courtship activity in response to a courting video male stimulus than did laboratory-reared males, suggesting that eavesdropping might arise as a consequence of field experience. To explore this further, we conducted associative learning studies on naïve, laboratory-reared males, pairing video playback of male courtship with sensory cues indicating female presence. Results showed that males with no prior exposure learned to associate courtship of other males with cues indicating the presence of females. In subsequent video playback experiments, field-collected males recognized differences in male behaviour, responding with courtship more often and for longer periods to video stimuli of courting male spiders than to walking males or an empty leaf litter background (no spider). Additional studies showed that males spent significantly more time in courtship displays when presented with two to three live or video male stimuli simultaneously. Together, these findings confirm that male wolf spiders meet assumptions of eavesdropping behaviour, and suggest that social experience arising from exposure to courtship interactions of conspecifics may impact male eavesdropping and subsequent courtship behaviour. • We examined eavesdropping by male Schizocosa ocreata wolf spiders in the field and laboratory. • In the field, males showed more courtship signalling behaviour in the presence of a courting male. • Field-collected males were more responsive to videos of courting males than lab-reared males. • Naïve lab-reared males learned to associate courtship of other males with female presence. • Males courted longer when two to three live or video males were presented simultaneously.

Species-specific communication bars interspecific mating between syntopic species ofZwickniastoneflies (Plecoptera: Capniidae)

Most Northern Hemisphere stoneflies have species-specific mating signals that are generally thought to constitute a barrier against interspecific mating. We tested this hypothesis in two species of the genus Zwicknia that have only very recently been recognised as distinct species, and that were found to occur together in a stream in Lower Saxony, Germany. Analyses of molecular markers COI and 28S in combination with wing length (distinguishing males of both species) and mating signals revealed no instance of hybridisation among 23 studied specimens. In addition, eleven further males identified on the basis of morphology alone all produced the expected species-specific signal. Females and males of both species were presented with played back conspecific and heterospecific signals and duetting sequences, and responded only to conspecific stimuli. This lends support to the hypothesis that the intersexual communication system functions as an important pre-mating barrier against gene flow, although post-mating isolation cannot be excluded. Interspecific mating did occur when a mixed pair was confined together in a small container. Males of both species were found to call in response to played back duetting sequences with stereotypic latencies that are clearly longer than the latencies in male-female duets. We interpret this as an indication of eavesdropping behaviour coupled with attempts to take over the perceived duet. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 113, 969–980.

Selective Eavesdropping Behaviour in Three Neotropical Bat Species

AbstractKnowledge of interspecies information transfer in mammals is scarce compared with other taxa. We investigated whether eavesdropping on echolocation calls of bats may be used by sympatric bats with similar feeding ecology. We performed playback experiments with three free‐ranging neotropical bat species, broadcasting search phase calls or feeding buzzes of conspecifics and heterospecifics belonging either to the same or to another bat family. Both the greater fishing batNoctilio leporinusand the lesser bulldog batNoctilio albiventris(Noctilionidae) reacted with repeated approaches in response to playbacks of search phase calls and feeding buzzes from conspecifics and also to congeneric feeding buzzes.Noctilio leporinusalso were attracted by search phase calls from its sister speciesN. albiventris. In contrast, the sac‐winged batSaccopteryx bilineata(Emballonuridae) did not react to any playback sequences presented. Our results support the existence of eavesdropping behaviour for both species ofNoctilio. We suggest that information transfer via eavesdropping may depend mainly on species‐specific traits, including foraging style and social behaviour (territoriality, group foraging), and on distribution and density of prey. Call design had only a minor influence on the reaction.