Efficient and reliable block propagation on the Bitcoin network is vital for ensuring the scalability of this peer-to-peer network. To this end, several schemes have been proposed over the last few years to speed up the block propagation, most notably the compact block protocol (BIP 152). Despite this, we show experimental evidence that nodes that have recently joined the network may need about ten days until this protocol becomes 90 effective. This problem is endemic for nodes that do not have persistent network connectivity. We propose to mitigate this ineffectiveness by maintaining mempool synchronization among Bitcoin nodes. For this purpose, we design and implement into Bitcoin a new prioritized data synchronization protocol, called FalafelSync. Our experiments show that FalafelSync helps intermittently connected nodes to maintain better consistency with more stable nodes, thereby showing promise for improving block propagation in the broader network. In the process, we have also developed an effective logging mechanism for bitcoin nodes we release for public use.
As the network grows, communication complexity plans an increasingly significant role. In an effort to minimize communication, Ozisik have developed the Graphene protocol @cite_19 , a new block protocol that couples an Invertible Bloom Lookup Table (IBLT) @cite_15 with a Bloom filter in order to send transaction hashes in a smaller package. Rather than sending each transaction's hash individually, as is done in compact blocks, the Graphene protocol inserts all the transactions hashes into a Bloom filter and an IBLT which are then sent to peers. When a Graphene block is received, it is subtracted from the mempool's IBLT and the rest of the transactions hashes are decoded from the remaining IBLT. According to the authors in @cite_19 , a Graphene block is capable of being around a fifth of the size of a compact block, and they provide simulations (but not an actual implementation) demonstrating their system.
@cite_19 @cite_15
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We devise a novel method of interactive set reconciliation for efficient block distribution. Our approach, called Graphene, couples a Bloom filter with an IBLT. We evaluate performance analytically and show that Graphene blocks are always smaller. For example, while a 17.5 KB Xtreme Thinblock can be encoded in 10 KB with Compact Blocks, the same information can be encoded in 2.6 KB with Graphene. We show in simulation that Graphene reduces traffic overhead by reducing block overhead. In this paper we propose a new approach to privately compute the set-union cardinality and the set-intersection cardinality among multiple honest-but-curious parties. Our approach is inspired by a proposal of Ashok and Mukkamala (DBSec’14) which deploys Bloom filters to approximate the size tightly. One advantage of their solution is that it avoids ample public-key cryptography. Unfortunately, we show here that their protocol is vulnerable to actual attacks. We therefore propose a new Bloom filter based protocol, also forgoing heavy cryptography, and prove its security. Smart metering application has received a lot of attention from the research community lately. Usually, LLN based network runs on RPL protocol which constructs a DAG structure for its normal operation. In this paper, we devise a wormhole attack scenario in such a network. Furthermore, we propose a Merkle tree based authentication protocol which runs on the notion of constructing a tree of hashed security information. We evaluated the approach by formulating the wormhole problem as graph theoretic problem and have shown the effectiveness of the proposed Merkle tree based approach for authenticating communications. Furthermore, we perform simulations in NS 2 to observe the network performance by adopting Merkle tree based to prevent from disrupting the links and observed boost in throughput, reduction in jitter and end to end delay. In the end, we have taken the step towards optimizing the performance of the algorithm by proposing an effective tree traversal algorithm which works on the notion of electing nodes as root in a large scale network from where a Merkle tree will be originated this will assist in managing the authentication in a huge sized network broken down into many trees avoiding wormhole attacks in the network. We propose a more efficient privacy preserving set intersection protocol which improves the previously known result by a factor of O(N) in both the computation and communication complexities (N is the number of parties in the protocol). Our protocol is obtained in the malicious model, in which we assume a probabilistic polynomial-time bounded adversary actively controls a fixed set of t (t < N 2) parties. We use a (t + 1,N)-threshold version of the Boneh-Goh-Nissim (BGN) cryptosystem whose underlying group supports bilinear maps. The BGN cryptosystem is generally used in applications where the plaintext space should be small, because there is still a Discrete Logarithm (DL) problem after the decryption. In our protocol the plaintext space can be as large as bounded by the security parameter τ, and the intractability of DL problem is utilized to protect the private datasets. Based on the bilinear map, we also construct some efficient non-interactive proofs. The security of our protocol can be reduced to the common intractable problems including the random oracle, subgroup decision and discrete logarithm problems. The computation complexity of our protocol is O(NS2τ3) (S is the cardinality of each party's dataset), and the communication complexity is O(NS2τ) bits. A similar work by (2006) needs O(N2S2τ3) computation complexity and O(N2S2τ) communication complexity for the same level of correctness as ours.