203 research outputs found
Group secret key agreement over state-dependent wireless broadcast channels
We consider a group of m trusted nodes that aim to create a shared secret key K, using a state-dependent wireless broadcast channel that exists from one of the honest nodes to the rest of the nodes including a passive eavesdropper Eve. All of the trusted nodes can also discuss over a cost-free and unlimited rate public channel which is also observed by Eve. For this setup, we develop an information-theoretically secure secret key agreement protocol. We show the optimality of this protocol for linear deterministic wireless broadcast channels as well as in the high-SNR regime for wireless channels with large dynamic range over channel states
Efficient One-Way Secret-Key Agreement and Private Channel Coding via Polarization
We introduce explicit schemes based on the polarization phenomenon for the
tasks of one-way secret key agreement from common randomness and private
channel coding. For the former task, we show how to use common randomness and
insecure one-way communication to obtain a strongly secure key such that the
key construction has a complexity essentially linear in the blocklength and the
rate at which the key is produced is optimal, i.e., equal to the one-way
secret-key rate. For the latter task, we present a private channel coding
scheme that achieves the secrecy capacity using the condition of strong secrecy
and whose encoding and decoding complexity are again essentially linear in the
blocklength.Comment: 18.1 pages, 2 figures, 2 table
Linking Classical and Quantum Key Agreement: Is There "Bound Information"?
After carrying out a protocol for quantum key agreement over a noisy quantum
channel, the parties Alice and Bob must process the raw key in order to end up
with identical keys about which the adversary has virtually no information. In
principle, both classical and quantum protocols can be used for this
processing. It is a natural question which type of protocols is more powerful.
We prove for general states but under the assumption of incoherent
eavesdropping that Alice and Bob share some so-called intrinsic information in
their classical random variables, resulting from optimal measurements, if and
only if the parties' quantum systems are entangled. In addition, we provide
evidence that the potentials of classical and of quantum protocols are equal in
every situation. Consequently, many techniques and results from quantum
information theory directly apply to problems in classical information theory,
and vice versa. For instance, it was previously believed that two parties can
carry out unconditionally secure key agreement as long as they share some
intrinsic information in the adversary's view. The analysis of this purely
classical problem from the quantum information-theoretic viewpoint shows that
this is true in the binary case, but false in general. More explicitly, bound
entanglement, i.e., entanglement that cannot be purified by any quantum
protocol, has a classical counterpart. This "bound intrinsic information"
cannot be distilled to a secret key by any classical protocol. As another
application we propose a measure for entanglement based on classical
information-theoretic quantities.Comment: Accepted for Crypto 2000. 17 page
Secret-key generation from wireless channels: Mind the reflections
Secret-key generation in a wireless environment exploiting the randomness and
reciprocity of the channel gains is considered. A new channel model is proposed
which takes into account the effect of reflections (or re-radiations) from
receive antenna elements, thus capturing an physical property of practical
antennas. It turns out that the reflections have a deteriorating effect on the
achievable secret-key rate between the legitimate nodes at high
signal-to-noise-power-ratio (SNR). The insights provide guidelines in the
design and operation of communication systems using the properties of the
wireless channel to prevent eavesdropping.Comment: 6 pages, 9 figure
Commitment and Oblivious Transfer in the Bounded Storage Model with Errors
The bounded storage model restricts the memory of an adversary in a
cryptographic protocol, rather than restricting its computational power, making
information theoretically secure protocols feasible. We present the first
protocols for commitment and oblivious transfer in the bounded storage model
with errors, i.e., the model where the public random sources available to the
two parties are not exactly the same, but instead are only required to have a
small Hamming distance between themselves. Commitment and oblivious transfer
protocols were known previously only for the error-free variant of the bounded
storage model, which is harder to realize
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