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Blockchain Technology for Smartphones and Constrained IoT Devices: A Future Perspective and Implementation

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The blockchain technology is currently penetrating different sides of modern ICT community. Most of the devices involved in blockchain-related processes are specially designed targeting only the mining aspect. At the same time, the use of wearable and mobile devices may also become a part of blockchain operation, especially during the charging time. The paper considers the possibility of using a large number of constrained devices supporting the operation of the blockchain. The utilization of such devices is expected to improve the efficiency of the system and also to attract a more substantial number of users. Authors propose a novel consensus algorithm based on a combination of Proof-of-Work (PoW), Proof-of-Activity (PoA), and Proof-of-Stake (PoS). The paper first overviews the existing strategies and further describes the developed cryptographic primitives used to build a blockchain involving mobile devices. A brief numerical evaluation of the designed system is also provided in the paper.
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Blockchain Technology for Smartphones
and Constrained IoT Devices:
A Future Perspective and Implementation
Konstantin Zhidanov, Sergey Bezzateev, Alexandra Afanasyeva, Mikhail Sayfullin, Sergey
Vanurin, Yulia Bardinova, Aleksandr Ometov
Email: ceo@enecuum.com
Abstract—The blockchain technology is currently penetrating
different sides of modern IT community. Most of the devices
involved in blockchain-related processes are specially designed
targeting only the mining aspect. At the same time, the use
of wearable and mobile devices may also become a part of
blockchain operation, especially during the charging time. The
paper considers the possibility of using a large number of con-
strained devices supporting the operation of the blockchain. The
utilization of such devices is expected to improve the efficiency
of the system and also to attract a more substantial number of
users. Authors propose a novel consensus algorithm based on
a combination of Proof-of-Work (PoW), Proof-of-Activity (PoA),
and Proof-of-Stake (PoS). The paper first overviews the existing
strategies and further describes the developed cryptographic
primitives used to build a blockchain involving mobile devices. A
brief numerical evaluation of the designed system is also provided
in the paper.
Keywordsblockchain, distributed systems, networks, applica-
tions, future perspective
I. INT ROD UC TI ON A ND MOTIVATIO N
The introduction of Bitcoin by Satoshi Nakamoto in 2008
had a significant impact on digital society [1]. As a first step,
Bitcoin-like cryptocurrencies seemed an extremely innovative
alternative financial paradigm. However, underpinning it lies a
fascinating technological breakthrough: blockchain technology.
The applications that could previously work only through
trusted centralized entities can now operate without any con-
stant connection to the authority while maintaining the same
security and improving the overall system functionality [2].
This distinguishing feature has extended the implementation
of blockchain beyond conventional cryptocurrency area [3].
The main idea behind blockchain itself lies in the concept
of trust [4]. This idea is based on the fact that parties
interacting in the system do not necessarily know or trust each
other but still have an opportunity to transact securely. The
use of blockchain eliminates the need for the involvement and
continuous maintenance by the centralized ‘trusted’ authority,
thus, enabling the network to operate in a distributed manner.
True to its name, the records of transactions between nodes
in a blockchain network are organized in a data structure
known as “blocks”. A series of blocks are arranged in a strictly
increasing-time order by a linked-list like data style known
as the chain of blocks, i.e., “blockchain”. The blockchain is
maintained as appending only local replicas of itself by the
nodes participating in the replicated consensus process. Due to
the blockchain property of immutability, it can be abstracted as
a transactional system that enables a consensus to form within
its participants [5]. The consensus holds unique probabilistic
properties and can thus be leveraged as a fundamental building
block for adaptive middleware that offers both deterministic
and probabilistic consensus.
Most of the blockchain operation is based on specially
designed devices – miners, i.e., nodes attempting to add a block
to the chain. They try to solve the computational puzzles, i.e.,
to reach the Proof-of-Work (PoW) [6] for new block creating,
and profit from the monetary compensation associated with
it. Briefly speaking, a block contains ‘nonces’ that a miner
must set in such a way that the hash of the entire block
is smaller than a known target, which is typically a very
small number. The difficulty of mining should be adjusted
dynamically throughout the lifetime of the system [7].
The possibility to customize and style them along with
technological enhancements towards small-scale electronics
and modern applications make handheld and wearable devices
a strong contender in the Internet of Things (IoT) technological
race [8]. Almost one billion wearable devices are expected to
join the IoT family by 2021 [9]. Said fascinating development
is a driving force behind the convergence of the physical and
digital worlds that promises to create an unprecedented IoT
market of 19 trillion USD over the next decade, and it is
expected that a significant percentage of those devices will
be smartphones.
There are currently about 2.71 billion smartphones in the
world1and the average one can process 2 billion floating
point operations per second (FLOPS)2, thus, leaving us with
1See “Number of smartphone users worldwide from 2014 to 2020
(in billions)” by Statista, 2019: https://www.statista.com/statistics/274774/
forecast-of- mobile-phone- users-worldwide/
2See “Processing power compared” by Experts Exchange, 2019: https://
pages.experts-exchange.com/processing-power-compared
constantly underused 5 EFLOPS. This power can be used
in the transaction publication and validation processes, smart
contracts, or distributed storage [10]. Based on the above,
almost any modern smartphone already has this power to be
a part of Proof of Activity (PoA) [11] and execute related
cryptographic primitives [12].
PoA node
PoW node
PoS node
Fig. 1. Smartphones as part of blockchain ecosystem.
However, deploying blockchain applications to mobile net-
works acting as actual miners faces many critical challenges.
It is mainly due to the mining process habits, i.e., solving the
PoW that requires not only computing power but also energy
from the interacting mobile devices. To address this challenge,
the edge computing paradigm was introduced by the research
community for cases of mobile blockchain networks [13].
However, it requires the use of more computational- and
power-independent nodes to take block generation actions
instead of actual smartphones. There are, however, a number of
miner implementations of blockchain applications for smart-
phones but it has been shown that the income of a single device
acting as a miner in the blockchain network is nonprofitable3.
Worth noting, the use of constrained devices is generally
underestimated concerning the blockchain. The mining feature
is ultimately not the most efficient utilization of this class due
to the computational and power limitations, but the concept
known as Proof-of-Stake (PoS) provided the first opportunity
for such constrained devices utilization [14]. Here, PoS nodes
do not act as miners to solve complex tasks. With PoS,
stakeholders are used to confirming transactions and blocks
based on their “stake” in the system and the use of the
resource-constrained device, for this reason, is a natural step
forward. The role of smartphones is to pay only the transaction
fees of the network without involvement in actual mining. The
probability of being selected to take part in the next block
generation to the chain directly depends on the number of
coins or tokens held by the relevant node.
The most interesting from smartphone perspective concept,
proposed in [11], is indeed PoA. The authors envision a new
protocol for a cryptocurrency constructed upon Bitcoin by
combining the PoW component with a PoS type of system.
PoA recommended itself as more secure against known prac-
tical attacks with relatively low utilization of both commu-
nications and storage resources. In PoA, mining is usually
executed in a traditional PoW manner. However, the mined
3See “Is Mobile Mining Profitable?”, by COINCENTRAL, 2018: https:
//coincentral.com/is-mobile- mining-profitable/
block does not contain transactions, i.e., the block is composed
of the header and the rewards address. After the mining
process, the system operation changes to PoS mode. Several
stakeholders (smartphones, in our case) are randomly selected
to sign (verify) the newly generated block. After everyone in
the group signs the block, it is added to the blockchain. If
some of the ‘validators’ have not participated in the validation
process, the block is discarded, and the next PoW-based one
is used, and the procedure is repeated. The reward is then split
between active PoS validators and PoW miners.
The main contribution of this work is a protocol suite
titled ‘Trinity’. It allows utilizing an intelligent combination
of PoA, PoS, and PoW aiming at the involvement of mobile
devices for blockchain operation. The underlying concepts
used in Trinity are as follows. The first one is ID-based
cryptography initially proposed in [15] during the times when
blockchain itself was brought to the research community’s
attention. After 20 years, the first realization of this strategy
took place in work [16] by C. Cocks et al. They proposed a
novel approach on obtaining the public key of the recipient
for the signed message transmission employing Public Key
Generator (PKG) and unique IDs of the participants. However,
there is a number of challenges related to PKG utilization:
(i) PKG can sign and decrypt all the messages; (ii) key
revoking is not implemented; (iii) safe channel is required
for the key dissemination; and (iv) encryption and decryption
mechanisms are computationally different. Most of those could
be mitigated by utilizing Shamir Secret Sharing [17] allowing
for the secret key dissemination and reconstruction based on
only a portion of previously distributed shares.
The rest of the paper is organized as follows. Section II
provides the main primitives and constructs used to construct
the Trinity. Next, Section III provides a detailed description
of the developed cryptographic protocols. Section V provides
a quantitative performance evaluation of the developed sys-
tem. The last section concludes the paper and lists future
research directions.
II. MAIN SYSTEM COMPONENTS
This section provides a brief overview of the main system
components used during Trinity development. To start with, the
block creation process begins when there are enough pending
transactions to start assembling a block. Analyzing specified
parameters of each transaction, miners determine its value for
the system and add it into a corresponding block. Minimum-
size blocks can be created to reach the minimum delay in speed
per operation while possible, and as the load on the network
increases, the block size grows. In circumstances where a
user needs a block size larger than 4 MB, the system also
supports combining any number of blocks (microblocks) into
a macroblock, thereby allowing the storage of large volumes
of data on the blockchain.
Bitcoin-NG protocol is selected to handle macroblocks [18]
to reduce the latency between the creation of blocks so that
each microblock inside a macroblock is created in real time
and adds transactions to the blockchain immediately upon their
arrival. So, there is no need to wait until an entire macroblock
is completed, its hash is found, and it is synced between all
nodes on the network – small microblocks can be generated
concurrently inside it. The main reason behind the utilization
of this protocol lies in its possibility to increase the mining
speed in the system, i.e., to increase the number of blocks
generated by the system within selected time frame. The
fundamental limit here is the distribution time of the newly
generated block between all the nodes in the system. In case
the generation time is smaller, the probability of forking in
two distant sections of the network may arise tremendously.
Direct Acyclic Graph (DAG) [19] allows the addition of new
blocks in different network segments handling the forking.
The goal of DAG is to deterministically rearrange the k-
blocks for the ledger recalculation based on the following set
of requirements:
Graph construction and graph walk procedures are
developed minding the consensus between the nodes,
i.e., there is a need for defining the minimal number
of nodes to guarantee the validity of current system
state at any time of execution;
New k-block is validated (added to consensus) during
a specific time frame;
New k-block should be inserted in the chain according
to its publishing time;
Addition of a new k-block should not require the
traversal of the entire graph;
Long-time forks should be avoided.
A. Proposed utilization of DAG
First, the graph walk procedure is defined, starting with
inverting the DAG. Next, the Queue-based topological order
algorithm is applied to the graph as by iterative removing of
the nodes and storing the logs of this process, see [19]. We
assume that there exists the deterministic algorithm allowing
to calculate the difficulty for each k-block during the graph
traversal. Thus, every new k-block is considered valid if its’
hash is equal to its’ difficulty. We also assume the deterministic
algorithm allowing to calculate the value branch max during
the graph traversal based on the k-block number,brunch
(0< branch < branchmax ). Each k-block shas two links to
previous and next k-blocks t1and t2such that t1.branch ==
s.branch and t1.branch ! = s.branch despite the case when
branchmax = 1.
New k-block generation procedure is described as follows.
First k-block has branch = 0, number = 0. It is valid if:
1) {number, branch}pair is unique;
2) k-block has links to t1and t2,t1.branch ==
s.branch,t1.branch ! = s.branch,s.number >
t1.number. In case there are more than one s, the
one with higher t2.number will be accepted;
3) k-block’s hash is equal to diff iculty.
B. Ledger operation
The following parameters are considered during the ledger
calculation: k-block mining; a reward for microblock publish-
ing; and transaction fee. The rewards are dynamic and based
on the blockchain operation history. The transactions inside the
microblock are stored in a sorted array. Therefore, all k-blocks,
microblocks, and transactions could also be arranged for any
DAG size. As a result, the entire history of events could be
linearly retrieved, thus allowing to calculate the states of the
account balance.
At the beginning of the execution, the ledger is empty.
During the block rewarding process, the balance of the existing
account will be changed, or a new record will be found. The
states of nodes are updated during the transactions accordingly.
The transaction is treated as invalid if there is no information
about the account in the ledger or it has not enough coins in
the wallet. Invalid transactions are discarded.
C. Rewarding and Difficulty Estimation Policies
The estimation of the reward is based on the deterministic
algorithm for each system state based on history and the
current block. The estimation of rewards depends on the
emission curve and current emission distribution. Initially, the
distributions are as follows: PoW – 10%; PoS – 25%; and PoA
– 65% of the emission. The emission distribution balance is
a dynamic system property and could be used as a tool to
mitigate malicious activity between different nodes based on a
specifically selected emission curve. Generally, the values of
rewards are estimated in such a way that it is inexpedient to
run PoA emulators on the hardware suitable for PoW or PoS.
Authors have designed a reward and difficulty assignment
system, Neuro, based on the recurrent neural network. Neuro
uses historical blockchain data to predict the required rewards
and difficulties for each new cycle. As soon as a cycle is
completed, the statistics of that cycle are used to improve
the network’s next predictions. To make these predictions, we
make use of a variation on a type of neural network that has
a selective long-term memory: a recurrent neural network. For
the non-recurrent neural network, each forward cycle starts
with a clean state, and neurons have values that originate only
from weighed connections to neurons in the previous layers (or
inputs). A recurrent neural network is a network where the
result of a neuron activation, the state, affects the next forward
cycle of the network.
D. Trinity consensus
The following subsection describes the interaction between
nodes during the blockchain construction.
The system is based on three types of users:
(i) solver (PoW); (ii) holder (PoS); and (iii) publisher (PoA).
None of those could take the role of another, which is
achieved by cryptographic and technical methods. The
following describes how the blockchain operation is divided
by those nodes. Note, none of the types can form the
blockchain independently.
PoW solver is responsible for the generation of new k-
blocks. The main requirements for this type of nodes are
(i) reliable access to the Internet; (ii) storage (required to store
the blockchain structure); and (iii) computational power for
hashing. The solver is recursively calculating nonces for new
k-block generation according to the set of predefined rules –
difficulty, batch number, hash links validity. Each k-block is
distributed through the network in a broadcast way after its
generation. Each node is checking its validity based on locally
stored data and add it to local blockchain storage if valid.
Widely known Nakamoto protocol [1] is used for the
blockchain construction. The solver’s main aim is to generate
the block and obtain the resulting award for the computa-
tional expenses. k-block contains its solver’s public key. The
selection of the hashing function does not affect the overall
system operation directly. Presently, we utilize SHA-256 for
performance evaluation, but this choice is temporal since
modern ASICs can easily calculate it.
The PoS holder is a node holding a significant amount of
coins. The node can prove the eligibility to become a holder,
as described in subsection III-A. Key SKHK is a shared
key distributed between a set of holders based on the La-
grange interpolation formula [20]. The corresponding P KHK
is known to any node. The Resident node is responsible for
SKH K generation, and a group of holders forms a Private Key
Generator (PKG).
Holders are systematically executing the protocol described
in subsection III-B to verify who has the right to distribute
the publication keys during this system operation state. The
corresponding time interval is set to 100 k-blocks in the
simulation environment. The Leading PoS (LPoS) selection
result is then stored as statistic blocks and may be verified by
any node.
Next, all PoSs are generating the publication secret key
for LPoS after the k-block retrieval. The publication public
key is calculated based on the k-block ID (hash sum) and
LPoS ID. The secret key and the corresponding shares are
calculated based on the protocol described in subsection III-C.
The intermediate execution results are stored in the static block
and could be verified later on. The holder gets a reward for
participation in the voting and PKG-related procedures.
PoA publishers are involved in the microblock publish-
ing process. A coalition of grouped PoA publishers should
generate each microblock. In order to retrieve a new k-block,
a group of PoA generates the microblock payload (array of
transactions) and forwards it to the LPoS. After the LPoS
verifies each microblock, it puts the signature by using the
current publication secret key. Therefore, the microblock data
becomes validated by PoA node and LPoS node in the system,
and their participation may be verified later. The PoA rewards
are based on participation in the verification procedure.
The resident is one of the PoS holders of the system being
controlled by the blockchain itself. The resident node is active
only during some period of the initial system operation, and
its function may be automatically distributed between the other
PoSs in the network.
The Resident’s functions are: (i) to store SKHK ; (ii) to
distribute it to other PoSs; and (iii) to estimate the Lagrange
polynomial properties. After the resident is stopped, the key
shares will be distributed to PoS according to protocols de-
scribed in subsection III-H and III-I. The Lagrange polynomial
characteristics would not be possible after the resident leaves
the system and, thus, they should be adjusted after the initial
period of the system operation.
III. DEV EL OP ED C RYP TOGRA PH IC P ROT OCOLS
This section provides a brief overview of the devel-
oped protocols. More details on the implementation could
be found in [21], more recent versions of protocols (if any
changes) would also be available via the link.
Each k-block has its unique IDkestimated according to
correct execution of function f()as
IDk=f(blockk),(1)
where fis the desired hashing function.
A. Stakes verification protocol
This protocol represents the phase while any participant is
proving his actual stake to another one. The main requirements
set during the protocol development are the possibility of
verification and resistance against forgery.
B. Protocol of the “leading” PoS miner selection during the
session (voting)
The main requirements of the protocol are resistance
against the repetitive selection of the same miner during a
series of sessions, i.e., improved randomization; and protocol
should be executed either by a group of PoS miners or the
entire available set but the selection rule is different for each
execution.
To exclude the possibility of restarting elections by dis-
gruntled PoS miners, the result should be pseudo-random but
rigidly deterministic current k-block and list of voters. A series
of assumptions are thus introduced:
1) All PoS miners in the state of the Ledger stored by
them can compile a list of all PoSs. In this case,
all sets of identifiers will be obtained identically and
ordered lexicographically.
2) In the course of the routing procedures, each PoS
miner compiles a list of currently active PoS. At
the same time, the lists of participants differ by no
more than 10%. The list is stored as a binary vector:
VP oS = (0,1,1,1,0,...,1), where the number of
positions coincides with the size of the list from
item 1, “0” means that the participant with the given
identifier is inactive, and “1” that he is active.
With this list and its associated vector, each node can vote.
Stage A: After the list is constructed, each participant (PoS
miner) calculates the hashing function
r=Hash(IDk|P oS1|. . . P oSN)
Hashmax
(0,1),(2)
where Hashmax =maxHash(I Dk|P oS1|. . . |P oSN).
Therefore, the voting is further based on rand on com-
paring it to a newly generated discrete random variable in the
same bound. Thus, each P oSireceives a probabilistic value
based on his public rating. The sum of all PoS probabilities
should be equal to 1. After that, the probabilities are logically
interpreted into intervals on the section from 0to 1, and the
tagged PoS node is selected if ris located in its interval.
Stage B: After the tagged PoS was selected (LPoS status),
the voter calculates corresponding publication public key and
transmits the secret key share to selected LPoS. After one PoS
receives at least kof shares (basically, those have the same
list on their side), the secret key is generated as described in
protocol III-C.
Stage C: LPoS forms an entry to the static block after the
session key is received. The entry is formed from the k-block
number and voting list signed with the session key. Thus, it be-
comes possible to validate LPoS rights and distribute rewards.
C. Leading PoS miner key generation
The main requirements set to the protocol are: keys could
only be used once; keys should be distributed securely; any
user could not generate keys; and keys do not contain any
information related to PoS miner secret keys.
The protocol execution could be done in case the leading
miner is selected by LP oS =P oSiaccording to the described
protocol. Each PoS has its pair of keys P KP oSi, SKP oSi
directly related to his wallet.
Next, the session key P KLPoS is generated for leading
PoS. It will be further utilized for the microblocks signature
and, thus, would be split into shares and distributed between
PoAs. P KLP oS is defined by kblock present in current session
and IDLP oS .IDLP oS is selected as P KLP oS or a function
of this key. P KLP oS and SKLP oS would be thus selected as
P KLP oS =f(blockk||I DLP oS ),(3)
SKLP oS =newSKLP oS .(4)
SKLP oS is generated by PoS miners according to the
distributed ID-based cryptographic PKG method [22] by kof
nschema. Which considers the collision resolution for cases
when more that one leader is selected.
Algorithm 1 Initialization of ID-based schema with distributed
PKG
1: Define groups:
2: Define G1as a cyclic group of order q(group of
points on elliptic curve);
3: Define multiplicative group G2;
4: Define functions:
5: H1 : (0,1)∗ → G1;
6: H2 : G2(0,1);
7: H3 : (0,1)∗ → Zq;
8: e:G1×G1G2(bilinear mapping);
9: Define Master Secret Key (MSK) as sZq;
10: Define P: generator of G1;
11: Define Public Master Public Key (MPK) as sP.
Algorithm 2 PKG (k, n) Master Secret Key splitting
1: Generate random polynomial in residue field q:
deg(φ(x)) = k1;
2: Each participant (PoS miner)receives its key share of
Master Secret Key ssi=φ(IDi)mod q.
Algorithm 3 Session key SKLP oS generation for LP oS
1: Each of kparticipants calculates P KLP oS =
f(blockk||IDLP oS )according to equation (3).
2: Transmits its ssi·P KLPoS and IDito LPoS.
Algorithm 4 Secret key recovery
1: LPoS is calculating SLLP oS based on the received from
algorithm III-C data as
2: SKLP oS =Pk
i=1 λ(IDi,0)ssiP KLP oS , where
λ(IDi,0) is a Lagrange coefficient generated per coalition
for each user IDiand 0.
D. Protocol of the PoA applicability for microblock generation
procedure
The coalition of PoA miners is selected after new k-
block is published. It is selected based on constant NP oA per
node and the corresponding ID so that Hash(P oAI D ) =
Hash(kblock||i), i = 1, . . . , NP oA. Therefore, each node
has an opportunity to verify if his ID is in the group fast,
while brute-force attack on the ID is a computationally
complex task.
E. Generation of microblock by PoA for current k-block
The main requirements for the protocol are simultaneous
and independent execution of the coalition members; data
exchange minimization; in-block additional data minimization;
and confirmation of the participation in the verification process.
Each PoA miner verifies if it is applicable for new mi-
croblock generation III-D after new k-block is published. In
case applicable, it forms a new microblock Mbased on the
selected transaction with a predefined size. After Mis formed,
PoA adds the following data to it: P oAID , k-block number.
Next, it is signed by its’ SKP oA and immediately published.
F. LPoS microblock assurance protocol
After protocol III-B is executed and the new session key is
generated III-C, LPoS starts to assure the microblocks. Stage
A: After PoAs have published the corresponding microblocks,
LPoS is collecting those from the network. LPoS is verifying
the k-block number and verifies if PoAs are in the coalition
of this block.
Stage B: LPoS verifies the validity of transactions in
the microblock based on the ledger. Stage C: In case the
verification succeeds, each microblock is signed with SKLP oS
from protocol III-C according to Algorithm 5.
Algorithm 5 Microblock signature protocol
1: LPoS generates rfrom Zq;
2: Calculates R=rP and
S=SKLP oS +rf (I DLP oS , M ) =
=sQ +rf (IDLP oS , M ),(5)
where Mis the entire microblock;
3: Adds (R, S)to the microblock.
Next, PoW miner is in standby mode until the required
number of transactions is collected, and generates new k-block
for all the obtained microblocks.
G. Cryptographic microblock verification protocol
The main goal of the protocol is to check the created
microblock at any time, and the requirements are: it should
be executable at any node; it should be based only on
publicly available information. Two signatures verify each
microblock: the first one is the signature of PoA miner
generating microblock, and the second one is the signature
of LPoS miner. The verification procedure is made according
to algorithm III-G.
Algorithm 6 Cryptographic microblock verification protocol
1: At first the verifiers checks the k-block number, and then
that the PoA-miner is a member of the group of publishers
for this session and his signature.
2: Then it calculates P KLP oS =f(blockk||IDLP oS )ac-
cording to equation 3.
3: Then the verify node check the signature of the microblock
Rand Sby
e(P, S) = (6)
=e(M P K, P KLP oS =Q)·e(R, f (IDLP oS , M )),
where Pis a generator of G1, M P K is a Master Public
Key and Mis a microblock.
The microblock is assumed as verified if both signatures
are verified successfully.
H. Distributed PKG secret update protocol
This protocol is executed either whenever the PoS miners
set is changes, or during the ledger recalculation when any
of the PoS nodes loses the PoS status. The resident node
distributes new key shares. It is also responsible for the (k, n)
relations during the initial system operation stage. After the
system operation is stable, its role is distributed between PoSs.
I. Distributed PKG new secret share transmission protocol
When a new node arrives (reaching the border or if some
other condition is met), the new node requests its share of
PKG master secret key. If it has the right, the Resident node
responds. Keys to new participants are built and given out
by the resident node, while the system developer acts in his
role. When the parameters are settled, the resident role can be
dissolved in PoS miners. For a new participant, his polynomial
point is calculated from the PKG creation protocol:
ssi=φ(IDnew)mod q, (7)
where qis the order of the group of points G1.
By efficient integration of the previously developed proto-
cols, it would become possible to involve a high number of
recourse-constrained devices in the blockchain operation.
IV. SIMULATION ENVIRONMENT DESCRIPTION
For the performance evaluation campaign, we selected
project p2psim mainly because it has native support for Chord
emulation, which is essentially our graph topology. Moreover,
it has a set of real packet propagation measurements between
thousands of nodes, collected in kingdata package. Next, we
analyze many simultaneous TCP sockets between the nodes if
the link allows it. By this means, the delay may be significantly
decreased. We detail the system model in the following.
In this paper, we provide an example of the system opera-
tion evaluation from communication (signaling) perspective.
The main focus is given to ‘tagged’ LPoS and the packet
transmission time between related nodes and the corresponding
packet processing and storing (interaction with the database)
metrics. The PoS nodes (acting as PoW) are generating new
blocks while PoA nodes are adding those to the blockchain.
Generally, packet exchange is present between (i) Chord
nodes, i.e., PoSs based on TCP; or (ii) PoA to PoS nodes. The
communication in the second scenario is organized directly
from PoA to first PoS node and further through the Chord (ex-
ecuting the Chord routing). PoA nodes could be classified as
“data” stored in Chord. The details of the Chord consistency
are omitted in this document but could be checked in [23].
The broadcast procedure is balanced according to [24].
The message sizes utilized in this campaign are microblock
– 100kb (˜
650 transactions); others – 144 bytes (˜
1 transaction).
Table I provides an overview of the main message types and
relative load. Therefore, additional Chord Chord messages
can provide a significant load on the LPoS. Precisely, this may
happen while receiving replies from PoA LPoS.
Next, we will focus on the packet propagation time faced
by our system. The use of TCP for our system generally
increases the Round Trip Time (RTT)/delay in a trade-off
to reliability. The approximations used in this campaign are
based on the public data4,5. Note, potential higher delays faced
by the cellular network users are not expected to affect our
system operation. The locations of PoW and PoS nodes are
hard to predict while PoAs are expected to be mobile nodes.
Thus, the system analysis should also consider the delays
between the main operator’s gateways. The detailed data on
the measurements could be found in [21].
V. SELECTED NUMERICAL RESULTS
In the following, nis the number of network nodes, kis
an average number of PoA nodes per PoS, latais the average
delay between PoS PoA, latch in the average delay between
Chord’s nodes, bwch in the node processing speed in Mbps,
diskspeed is LPoSs’ average database interaction speed, kblsize
is the k-block size, mblsize is the microblock size, msigsize
is signed microblock from PoA.
We aim at finding the limitations of the LPoS (regarding
maximization of k) varying the number of PoAs in terms of
operational delay and Based on the above, we have quantita-
tively analyzed the number of signaling messages required for
different messages dissemination, and the simplified results are
shown in Table II.
Note, that real life timings may be less optimistic due to
our simplification and averaging of latch. The results of a
more realistic system operation estimates are also presented
in Table II in the last column. Based on the results, the
4See “Global Ping Statistics: Ping times between WonderNetwork servers”,
2018: https://wondernetwork.com/pings
5See “Ookla Speedtest, and Speedtest Intelligence”, 2018: http://www.
speedtest.net
TABLE I. APPR OXIM ATE NE TWO RK L OAD B Y DIFF ER ENT M ES SAGE T YP E
Type Source Destination Other Chord nodes Other Chord nodes average # Example: n=
300
AS1 1 - - -
SA1 1 - - -
Chord Chord 1 1 < log(n) ((log((n))/22))/((n2)) 0.0084/0.0084
Broadcast Chord Chord 2 1 Each node receives one and transmits
either zero or two
1/1 1/1
Broadcast Chord PoA 2 1 PoW like in Chord Chord and
each PoS transmits the related to his
PoA messages
1/... 1/...
TABLE II. DESCRIPTION AND THE NUMBER OF MESSAGES REQUIRED FOR BLOCKS DISSEMINATION
Time LPoS Chord’s nodes PoAs Optimistic action Pessimistic action
0 PoW’s k-block transmission -
4latch k-block received k-block received
by 50%
Started to re-
ceive k-block
kkblsize /bwch required to deliver
k-block to PoAs
kkblsize /bwch required to deliver
k-block to PoAs. For example, 0.05
klatch.
5latch shadowrequest
transmitted
13 latch Received
shadowresponse
k-block received k-block
received by
the majority
LPoS is ready to send leaderbeacon If k400 – k-blocks are delivered
to PoAs.
23 latch The remaining
ones are
transmitting
leaderbeacon to
PoAs
Receiving
leaderbeacon
LPoS’s disk utilization increases.
mblocksign arrival begins
If k600 – k-blocks are already
delivered to PoA
33 latch Majority received LPoS disk load is still present knmsigsize/diskspeed equals
kn/180000 seconds
45 latch Last mblocksign
received
LPoS starts to broadcast mblock via
Chord.
Either the disk utilization is finished,
or k-block distribution is finished.
54 latch mblock received The procedure is over. Total time is
around 8 seconds.
0
50
100
100
200
150
Distribution time, slots
300 2600
200
2400
400 2200
500
250
2000
600 1800
Number of PoS
700 1600
Number of PoA
800 1400
1200
900 1000
1000 800
1100 600
1200 400
200
100
Fig. 2. System operation time varying number of PoSs and PoAs
pessimistic estimation of the time required for the new k-
block creation is max(53 + kn/18000,30 + 0.05 k). Next,
we provide a graph with the effects of kand nrelation,
see Fig. 2. Note, latch = 0.150 seconds, so that 30 seconds
equals 200 timeslots. It could be concluded that the variation
of the PoS nodes number does not have a significant impact
on the communications delay due to highly predictable packet
propagation time through the Chord nodes. On the other hand,
increasing the number of PoA nodes has a more significant
impact due to the need to communicate through the more
complex network infrastructure.
VI. CONCLUSION
The penetration of blockchain technology in our daily lives
could not be stopped, therefore, we have proposed a ‘Trinity’
concept coupling together Proof-of-Work, Proof-of-Stake, and
Proof-of-Activity blockchain strategies motivated to involve
mobile devices in the new block generation process since the
computational resources of said devices are underused today.
Currently, we are in the final phase of the developed primitives
implementation in our custom simulation environment, and
some quantitative numerical results are already presented in
the paper. At the moment of the paper submission, authors
already implemented the testnet involving more than 500
accounts in 22 countries6.
6See “Development Report May 2019 #2”, by ENQ
Enecuum Blockchain, 2019: https://medium.com/@ENQBlockchain/
development-report-may- 2019-1- 2b7f1f92322e
As for the future work, we aim at evaluating the effects of
network parameters (throughput, latency, propagation delays,
etc.) of the system operation, detailed study on a variety of
security and privacy threads of the developed system, and
actual benefits on the developed system utilization for the
end users.
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