Key Generation Protocol Research Articles

이동성과 프라이버시를 제공하는 모바일 회의 인증 기법

Abstract The demand for messenger service goes on growing rapidly with widespread use of smartphones. Generally, the smartphone messenger provides group communication functions in which users can make the group and communicate with each other. In the mobile meeting, the attendees can participate in the meeting with use of smartphone messengers wherever they are. To make the mobile meeting put to practical use, the mobility and privacy should be ensured to attendees. To satisfy the mobility requirement, the user which is not belong to the group members should not be able to participate in the meeting. To ensure the privacy requirement, the attendees should have not to repudiate the meeting results. In this study, the mobile meeting authentication scheme is proposed which provides mobility and privacy. The proposed scheme consists of meeting group creation, group key generation, group signature and verification protocols. All attendees should have to participate in the signature verification because it is based on the challenge-response type protocol. Thus, it's not possible to collude with malicious attendees to change the meeting results.

SmokeGrenade: An Efficient Key Generation Protocol With Artificial Interference

Leveraging a wireless multipath channel as the source of common randomness, many key generation methods have been proposed according to the information-theory security. However, existing schemes suffer a low generation rate and a low entropy, and mainly rely on nodes' mobility. To overcome this limitation, we present a key generation protocol with known artificial interference, named SmokeGrenade, a new physical-layer approach for secret key generation in a narrowband fading channel. Our scheme utilizes artificial interference to contribute to the change of measured values on channel states. Our theoretical analysis shows that the key generation rate increases with the increment of the interference power. Particularly, the achievable key rate of SmokeGrenade gains three times better than that of the traditional key generation schemes when the average interference power is normalized to 1. Simulation results also demonstrate that SmokeGrenade achieves a higher generation rate and entropy compared with some state-of-the-art approaches.

Fine-Grained Lower Limit of Entropic Uncertainty in the Presence of Quantum Memory

The limitation on obtaining precise outcomes of measurements performed on two noncommuting observables of a particle as set by the uncertainty principle in its entropic form can be reduced in the presence of quantum memory. We derive a new entropic uncertainty relation based on fine graining, which leads to an ultimate limit on the precision achievable in measurements performed on two incompatible observables in the presence of quantum memory. We show that our derived uncertainty relation tightens the lower bound set by entropic uncertainty for members of the class of two-qubit states with maximally mixed marginals, while accounting for the recent experimental results using maximally entangled pure states and mixed Bell-diagonal states. An implication of our uncertainty relation on the security of quantum key generation protocols is pointed out.

A Secure Key Transfer Protocol for Group Communication

Providing security for messages in group communication is more essential and critical nowadays. In group oriented applications such as Video conferencing and entertainment applications, it is necessary to secure the confidential data in such a way that intruders are not able to modify or transmit the data. Key transfer protocols fully rely on trusted Key Generation Center (KGC) to compute group key and to transport the group keys to all communication parties in a secured and secret manner. In this paper, an efficient key generation and key transfer protocol has been proposed where KGC can broadcast group key information to all group members in a secure way. Hence, only authorized group members will be able to retrieve the secret key and unauthorized members cannot retrieve the secret key. Hence, inorder to maintain the forward and backward secrecy, the group keys are updated whenever a new member joins or leaves the communication group. The proposed algorithm is more efficient and relies on NP class. In addition, the keys are distributed to the group users in a safe and secure way. Moreover, the key generated is also very strong since it uses cryptographic techniques which provide efficient computation.

Cooperative Secret Key Generation from Phase Estimation in Narrowband Fading Channels

By exploiting multipath fading channels as a source of common randomness, physical layer (PHY) based key generation protocols allow two terminals with correlated observations to generate secret keys with information-theoretical security. The state of the art, however, still suffers from major limitations,e.g., low key generation rate, lower entropy of key bits and a high reliance on node mobility. In this paper, a novel cooperative key generation protocol is developed to facilitate high-rate key generation in narrowband fading channels, where two keying nodes extract the phase randomness of the fading channel with the aid of relay node(s). For the first time, we explicitly consider the effect of estimation methods on the extraction of secret key bits from the underlying fading channels and focus on a popular statistical method - maximum likelihood estimation (MLE). The performance of the cooperative key generation scheme is extensively evaluated theoretically. We successfully establish both a theoretical upper bound on the maximum secret key rate from mutual information of correlated random sources and a more practical upper bound from Cramer-Rao bound (CRB) in estimation theory. Numerical examples and simulation studies are also presented to demonstrate the performance of the cooperative key generation system. The results show that the key rate can be improved by a couple of orders of magnitude compared to the existing approaches.

Cooperative Key Generation in Wireless Networks

The impact of relay nodes on the secret key generation via the physical layer resources is investigated. A novel relay-assisted strategy is proposed to improve the generated secret key rate. The main idea is to exploit the random channels associated with relay nodes in the network as additional random sources for the key generation. This approach is particularly useful when the channels between legitimate nodes change slowly. Four increasingly sophisticated yet more practical scenarios are studied, for which relay-assisted key generation protocols are proposed and are shown to be optimal or order-optimal in terms of the key rate. It is also shown that the multiplexing gain in the key rate scales linearly with the number of relays, which demonstrates that relay-assisted schemes substantially increase the key rate. This is in sharp contrast to scenarios with relays helping information transmission, in which the multiplexing gain does not scale with the number of relays. Furthermore, a cooperative scheme is also proposed in which relays help key generation but the generated keys are kept secure from these relays.

Random Photon Key Pasting (RPKP) for Secure Optical Data Transport in Quantum Key Distribution

In this paper we proposed a new mutually authenticated method, ie Random Photon Key Pasting (RPKP) for secure data transmission which is already running under Quantum key distribution. RPKP is method which is trying to paste randomly generated number to the private key as log form and invoked from a trusted third party. The random numb will be completely based on the System level and it is highly depending on the time of the transmission, properties of the Source and destination and also the priority level. We are proposing separate protocol for Priority level key generation and property level communication establishment. The Time module is controlling the key pasting strategy. Quantum cryptography capitalizes on the inherent random polarization state of single photons, which are associated with binary logic values. Because the polarization state of a photon is not reproducible by an eavesdropper between the source and the destination, polarized photons are used with an intelligent algorithm to disseminate the cryptographic key with high security from he source to the destination, a process known as quantum key distribution. However, although the polarization state of a photon remains intact in free-space propagation, it does not remain so in dielectric medium and thus quantum cryptography is not problem-free. KeywordsQuantum key distribution; Entanglement swapping; Authentication; Bell-basis measurement

Secret Key Establishment Using Temporally and Spatially Correlated Wireless Channel Coefficients

When implementing data encryption and decryption in a symmetric cryptosystem, secure distribution of the secret key to legitimate nodes can be a challenge. In this paper, we consider establishing secret keys using the common wireless channel, with particular emphasis on the spatial and temporal correlations of the channel coefficients. Specifically, we investigate the influence of channel correlation on the bound of the key size generated from the common channel using a simple single-input single-output channel model, and we verify the existence of a sampling approach able to generate a key using the minimum possible sampling window. We also explore decorrelation of the channel coefficients in a multiple-input multiple-output channel, and we use a statistical independence test to demonstrate that this process cannot be separated into spatial and temporal decorrelation processes. The insights gained from these studies assist in the development of a practical key generation protocol based on a published channel coefficient quantization method and incorporating flexible quantization levels, transmission of the correlation eigenvector matrix, and LDPC coding to improve key agreement in an authenticated public channel. Finally, we present simulations with real channel measurements that solidify the fundamental conclusions.

Information-Theoretically Secret Key Generation for Fading Wireless Channels

The multipath-rich wireless environment associated with typical wireless usage scenarios is characterized by a fading channel response that is time-varying, location-sensitive, and uniquely shared by a given transmitter-receiver pair. The complexity associated with a richly scattering environment implies that the short-term fading process is inherently hard to predict and best modeled stochastically, with rapid decorrelation properties in space, time, and frequency. In this paper, we demonstrate how the channel state between a wireless transmitter and receiver can be used as the basis for building practical secret key generation protocols between two entities. We begin by presenting a scheme based on level crossings of the fading process, which is well-suited for the Rayleigh and Rician fading models associated with a richly scattering environment. Our level crossing algorithm is simple, and incorporates a self-authenticating mechanism to prevent adversarial manipulation of message exchanges during the protocol. Since the level crossing algorithm is best suited for fading processes that exhibit symmetry in their underlying distribution, we present a second and more powerful approach that is suited for more general channel state distributions. This second approach is motivated by observations from quantizing jointly Gaussian processes, but exploits empirical measurements to set quantization boundaries and a heuristic log likelihood ratio estimate to achieve an improved secret key generation rate. We validate both proposed protocols through experimentations using a customized 802.11a platform, and show for the typical WiFi channel that reliable secret key establishment can be accomplished at rates on the order of 10 b/s.

Secure Key Generation in Sensor Networks Based on Frequency-Selective Channels

Key management in wireless sensor networks faces several new challenges. The scale, resource limitations, and new threats such as node capture necessitate the use of an on-line key generation by the nodes themselves. However, the cost of such schemes is high since their secrecy is based on computational complexity. Recently, several research contributions justified that the wireless channel itself can be used to generate information-theoretic secure keys. By exchanging sampling messages during movement, a bit string can be derived that is only known to the involved entities. Yet, movement is not the only possibility to generate randomness. The channel response is also strongly dependent on the frequency of the transmitted signal. In our work, we introduce a protocol for key generation based on the frequency-selectivity of channel fading. The practical advantage of this approach is that we do not require node movement. Thus, the frequent case of a sensor network with static motes is supported. Furthermore, the error correction property of the protocol mitigates the effects of measurement errors and other temporal effects, giving rise to an agreement rate of over 97%. We show the applicability of our protocol by implementing it on MICAz motes, and evaluate its robustness and secrecy through experiments and analysis.

Secure threshold multi authority attribute based encryption without a central authority

An attribute based encryption scheme (ABE) is a cryptographic primitive in which every user is identified by a set of attributes, and some function of these attributes is used to determine the ability to decrypt each ciphertext. Chase proposed the first multi authority ABE scheme which requires a fully trusted central authority who has the ability to decrypt each ciphertext in the system. This central authority would endanger the whole system if it is corrupted. This paper provides a threshold multi authority fuzzy identity based encryption (MA-FIBE) scheme without a central authority for the first time. An encrypter can encrypt a message such that a user could only decrypt if he has at least d k of the given attributes about the message for at least t + 1 , t ⩽ n / 2 honest authorities of all the n attribute authorities in the proposed scheme. This paper considers a stronger adversary model in the sense that the corrupted authorities are allowed to distribute incorrect secret keys to the users. The security proof is based on the secrecy of the underlying distributed key generation protocol and joint zero secret sharing protocol and the standard decisional bilinear Diffie–Hellman assumption. The proposed MA-FIBE could be extended to the threshold multi authority attribute based encryption (MA-ABE) scheme, and both key policy based and ciphertext policy based MA-ABE schemes without a central authority are presented in this paper. Moreover, several other extensions, such as a proactive large universe MA-ABE scheme, are also provided in this paper.

Adaptively Secure Threshold Signature Scheme in the Standard Model

We propose a distributed key generation protocol for pairing-based cryptosystems which is adaptively secure in the erasure-free and secure channel model, and at the same time completely avoids the use of interactive zero-knowledge proofs. Utilizing it as the threshold key generation protocol, we present a secure (t,n) threshold signature scheme based on the Waters' signature scheme. We prove that our scheme is unforgeable and robust against any adaptive adversary who can choose players for corruption at any time during the run of the protocols and make adaptive chosen-message attacks. And the security proof of ours is in the standard model (without random oracles). In addition our scheme achieves optimal resilience, that is, the adversary can corrupt any t<n/2 players.

One-Round ID-Based Threshold Signature Scheme from Bilinear Pairings

In this paper, we propose a new ID-based threshold signature scheme from the bilinear pairings, which is provably secure in the random oracle model under the bilinear Diffie-Hellman assumption. Our scheme adopts the approach that the private key associated with an identity rather than the master key of PKG is shared. Comparing to the-state-of-art work by Baek and Zheng, our scheme has the following advantages. (1) The round-complexity of the threshold signing protocol is optimal. Namely, during the signing procedure, each party broadcasts only one message. (2) The communication channel is optimal. Namely, during the threshold signing procedure, the broadcast channel among signers is enough. No private channel between any two signing parties is needed. (3) Our scheme is much more efficient than the Baek and Zheng scheme in term of computation, since we try our best to avoid using bilinear pairings. Indeed, the private key of an identity is indirectly distributed by sharing a number x ID∈ $$\mathbb{Z}^{*}_{q}$$, which is much more efficient than directly sharing the element in the bilinear group. And the major computationally expensive operation called distributed key generation protocol based on the bilinear map is avoided. (4) At last, the proactive security can be easily added to our scheme.

A privacy problem on Hu–Huang's proxy key generation protocol

A proxy signature scheme enables an original signer to delegate his signing capability to a proxy signer and then the proxy signer can sign a message on behalf of the original signer. Recently, several ID-based proxy signature schemes have been proposed. ID-based Cryptosystems (ID-Cs) are advantageous than the traditional Public Key Cryptosystems (PKCs), as the key distribution is not required. But, an inherent problem of ID-Cs is the key escrow. Hu and Huang also proposed an ID-based proxy signature scheme with proxy key generation protocol. In Hu–Huang's scheme, whenever the original signer requests the Public Key Generation Center (PKG) to generate a proxy derivation key for a designated proxy signer, it generates a proxy key using the proxy signer's private key without his agreement. Thus, the PKG gets to infringe general privacy laws and regulations. Also, this is an example of PKG's misuse of the user's private key due to ID-C's key escrow problem. To solve these problems we propose an improvement of Hu–Huang's scheme.

Secure Distributed Key Generation for Discrete-Log Based Cryptosystems

A Distributed Key Generation (DKG) protocol is an essential component of threshold cryptosystems required to initialize the cryptosystem securely and generate its private and public keys. In the case of discrete-log-based (dlog-based) threshold signature schemes (ElGamal and its derivatives), the DKG protocol is further used in the distributed signature generation phase to generate one-time signature randomizers (r = gk). In this paper we show that a widely used dlog-based DKG protocol suggested by Pedersen does not guarantee a uniformly random distribution of generated keys: we describe an efficient active attacker controlling a small number of parties which successfully biases the values of the generated keys away from uniform. We then present a new DKG protocol for the setting of dlog-based cryptosystems which we prove to satisfy the security requirements from DKG protocols and, in particular, it ensures a uniform distribution of the generated keys. The new protocol can be used as a secure replacement for the many applications of Pedersen's protocol. Motivated by the fact that the new DKG protocol incurs additional communication cost relative to Pedersen's original protocol, we investigate whether the latter can be used in specific applications which require relaxed security properties from the DKG protocol. We answer this question affirmatively by showing that Pedersen's protocol suffices for the secure implementation of certain threshold cryptosystems whose security can be reduced to the hardness of the discrete logarithm problem. In particular, we show Pedersen's DKG to be sufficient for the construction of a threshold Schnorr signature scheme. Finally, we observe an interesting trade-off between security (reductions), computation, and communication that arises when comparing Pedersen's DKG protocol with ours.

A novel proxy key generation protocol and its application

Proxy signature is an important technology in secure e-commerce. Short signature and fast verification are of paramount importance for its practical application. In this paper, we propose a proxy signature key generation protocol in which the warrant is the proxy public key for the first time. This protocol can be combined with ID-based signature scheme from bilinear pairing to construct an ID-based proxy signature scheme. Furthermore, compared with all previous proxy signature schemes, the scheme constructed has two virtues: (1) the proxy signature is shorter because it does not include any parameters for rebuilding the proxy public key; (2) the verification of the proxy signature is faster because the public proxy key does not have to be computed. Also we give such a proxy signature scheme.

Practical quantum key distribution with polarization entangled photons

We present an entangled-state quantum cryptography system that operated for the first time in a real-world application scenario. The full key generation protocol was performed in real-time between two distributed embedded hardware devices, which were connected by 1.45 km of optical fiber, installed for this experiment in the Vienna sewage system. The generated quantum key was immediately handed over and used by a secure communication application.

A fair certification protocol

In this paper a 'fair' key generation and certification protocol for Diffie-Hellman keys is proposed, which is intended for use in cases where neither User nor CA are trusted to choose the User's key on their own. This protocol also ensures that key agreement mechanism 1 in ISO/IEC 11770-3 [2] provides 'fair key agreement' [4].