This work shows how a secure Internet can be implemented through a fast key distribution system that uses physical noise to protect the transmitted information. Starting from a shared random sequence
K0 between two (or more) users, longsequences
R of random bits can be shared. The signals sent over the Internet are deterministic but have a built-in Nature-made uncertainty that protects the shared sequences. After privacy amplification the shared
R random bits --encrypted by noise-- are subsequently utilized in one-time-pad data ciphering.
Cryptographic protocols can be classified by the type of security against eavesdropping which they provide. There exist mathematically secure schemes whose security relies on mathematical proofs (like the Vernam cipher discussed below) or conjectures (like public key RSA encryption) about the complexity of deciphering the message without possessing the correct key. The majority of current secure public Internet connections rely on such schemes. Alternatively, a cryptographic setup may provide a physically secure method for communicating. In these setups the security is provided by the physical laws governing the communication protocol. Here we first discuss a provably secure classical communication protocol and then quantum methods for distributing the necessary keys. The BB84 protocol relies on the impossibility of perfectly distinguishing non-orthogonal quantum states from one copy of the quantum system. The scheme was invented in 1984 and is the first of its kind. In contrast, the Ekert91 protocol makes use of Bell correlations between entangled pairs of photons. These correlations are destroyed when Eve attempts to make a measurement on one of the particles but also when imperfections, such as decoherence processes, affect the scheme. As long as no such “elements of reality” are introduced, and Bell correlations violating local realism can be generated by Alice and Bob, no eavesdropper can be present. One-time pads and the Vernam cipher The Vernam cipher is a cryptographic protocol which allows the encryption and decryption protocol to be publicly known. The security of the protocol relies entirely on the key which is private and not publicly known. Alice and Bob share identical n -bit secret key strings (one-time pad).
One-time pad encrypted files can be sent through Internet channels using current Internet protocols. However, the need for renewing shared secret keys make this method unpractical. This work shows how users can use a fast physical random generator based on fluctuations of a light field and the Internet channel to directly boost key renewals. The transmitted signals are deterministic but carries imprinted noise that cannot be eliminated by the attacker. Thus, a one-time pad for Internet can be made practical. Security is achieved without third parties and not relying on the difficulty of factoring numbers in primes. An informational fragility to be avoided is discussed. Information-theoretic analysis is presented and bounds for secure operation are determined.
Current key sharing techniques rely on the hardness of solving a solvable, but complex, mathematical problem. This entails, in Information Theoretical sense, the encryption key is not secret, it can be found by solving the underlying mathemat-ical problem. Sensitive data we encrypt today using traditional techniques can be recorded by malicious parties and be deciphered in the future whenever improved hacking techniques and supporting computing technology permit. Information Theory proves the existence of methods for sharing of encryption keys that are unconditionally secure, but does not show how to bring such theoretical results to practical use. One of the central information theoretical approaches to key sharing is based on exploiting common randomness. This theoretical result states that if two dependent random variables,
Aand B, are available at Alice and Bob, then, by communicating through a public channel between
Aand B, it is possible to securely share a key of size I(A;B). To bridge the gap between theory and practice, one needs a method to generate two sets of dependent random variables, one at Alice‘s side and the other one at the Bob’ side, as well as a method to extract two identical keys from these dependent random variables. This article presents a novel technique to achieve this goal over the Internet. Dependent random variables are generated by measuring packet travel times between Alice and Bob, and error-free key extraction from dependent random variables is realized by using a randomized Low Density Parity Check Code (LDPC). Through looping of packets between Alice and Bob, the mutual information between random variables is increased. Finally, methods are presented to measure the likelihood values required in decoding the underlying LDPC. It is shown that the key rate is approximately equal to
0.5log9(4L2/(4L−1))≈0.5log2(L)where
Lis the number of round trips (loops). Test results (based on measurements between distant nodes over the Internet) are presented, demonstrating the feasibility of the proposed technique. The proposed method is implemented entirely in software (through high-level programming, e.g., using C-language, at the application layer). This operation does not require modifying the underlying network.
With the Kish‐Sethuraman (KS) cipher an attempt was made, by using special operators and communication, to reach absolutely secure classical communication. First the message is bounced back with additional encryption by the Receiver and then the original encryption is removed and the message is resent by the Sender. The mechanical analogy of this operation is using two padlocks; one by the Sender and one by the Receiver. Klappenecker has pointed out that finding an efficient software realization of the operators is equivalent of proving the P ≠ NP problem. Various open problems are discussed.
This work shows how a secure Internet for users A and B can be implemented through a fast key distribution system that uses physical noise to encrypt information transmitted in deterministic form. Starting from a shared secret random sequence between them, long sequences of fresh random bits can be shared in a secure way and not involving a third party. The shared decrypted random bits -encrypted by noise at the source- are subsequently utilized for one-time-pad data encryption. The physical generated protection is not susceptible to advances in computation or mathematics. In particular, it does not depend on the difficulty of factoring numbers in primes. Also, there is no use of Linear Feed Back Shift Registers. The attacker has free access to the communication channels and may acquire arbitrary number of copies of the transmitted signal without lowering the security level. No intrusion detection method is needed.