Blockchain Meets Secured Microservice Architecture: A Trustworthy
Consensus Algorithm
Mohiuddin Ahmed
1 a
, A. F. M. Suaib Akhter
2 b
, A. N. M. Bazlur Rashid
1 c
, Mahdi Fahmideh
3 d
,
Al-Sakib Khan Pathan
4 e
and Adnan Anwar
5 f
1
School of Science, Edith Cowan University, Perth, Australia
2
Computer Engineering Department, Sakarya University of Applied Science, Sakarya, Turkey
3
School of Business, University of Southern Queensland, Queensland, Australia
4
Department of Computer Science and Engineering, United International University, Dhaka, Bangladesh
5
School of IT, Deakin University, Geelong, Australia
Keywords:
Blockchain, Microservices, Consensus Algorithm, False Data Injection Attacks, Internet of Everything.
Abstract:
Microservices are becoming an integral component in the architecture design and development of Internet-
based distributed systems, such as the Internet of Things. A critical ongoing challenge in microservice ar-
chitecture design is to ensure the integrity and availability of data. Blockchain technology offers the solution
to these challenges in the distributed microservice architecture. Blockchains use consensus algorithms for
validating their transactions and also providing extra security. Taming the advantages of consensus algorithms
in blockchain-based architecture models, this paper proposes a trustworthy consensus algorithm to tackle data
integrity challenges in microservice architectures. The results of the evaluation highlight the efficacy of the
proposed algorithm in real-world scenarios of microservice architecture endeavour. Lessons learned in apply-
ing the algorithms, and future research directions are also discussed.
1 INTRODUCTION
IoT deployments are not flexible, reliable, efficient,
and easy to build despite these solutions (Lu et al.,
2017). To overcome the limitations for IoT deploy-
ment, many solutions have been proposed in the lit-
erature. One of the interesting solutions is based on
service-oriented approach. In this approach, any IoT
node can be considered a smart object that provides a
number of services over the network. Therefore, the
developers can focus on the level of services and data
instead of the devices and communication network.
Accordingly, the microservice-based approach pro-
posed in the literature to tackle the IoT system deploy-
ment challenges (Lu et al., 2017). A microservice-
based deployment allows the IoT systems to construct
a
https://orcid.org/0000-0002-4559-4768
b
https://orcid.org/0000-0002-2675-1684
c
https://orcid.org/0000-0002-8672-5023
d
https://orcid.org/0000-0001-7196-7217
e
https://orcid.org/0000-0001-6572-3451
f
https://orcid.org/0000-0003-3916-1381
the fine-grained and self-contained independently de-
veloped microservices. Microservice architecture is
composed of microservices connected and deployed
via composition techniques. The microservice archi-
tecture allows the decomposition of larger services
into several small, loosely-coupled, self-contained,
and focused services. Because microservices can be
distributed over the network, there can be the prob-
lem of data sharing between nodes in a trustable
way. Blockchain technology is fundamentally a dis-
tributed database of records, which can be executed
and shared between the associated nodes (Khan et al.,
2020). There are five basic principles of blockchain.
These include a distributed database, irreversibility
of records, transparency with pseudonymity, compu-
tational logic, and peer-to-peer transmission. These
principles ensure access to the new information when
available over the network. These also ensure not
to update or erase the data (Khan and Byun, 2020).
Blockchain technology can solve microservices’ data
sharing problem by providing a stable and distributed
base. A distributed service that can be trusted by all
Ahmed, M., Akhter, A., Rashid, A., Fahmideh, M., Pathan, A. and Anwar, A.
Blockchain Meets Secured Microservice Architecture: A Trustworthy Consensus Algorithm.
DOI: 10.5220/0011290400003286
In Proceedings of the 19th International Conference on Wireless Networks and Mobile Systems (WINSYS 2022), pages 53-60
ISBN: 978-989-758-592-0; ISSN: 2184-948X
Copyright
c
2022 by SCITEPRESS Science and Technology Publications, Lda. All rights reserved
53
its participating nodes and can guaranty the data im-
mutability may provide trustworthiness in microser-
vice architecture data integrity. Blockchain uses a
consensus algorithm to validate all of its transactions
and ensure the data have not been tampered with since
the first definition (Reyna et al., 2018; Zhang et al.,
2021; Nartey et al., 2021). Therefore, with the com-
bination of microservice and blockchain technology,
the independently developed and deployed microser-
vices can be created as a secured and robust system
(Sousa et al., 2020).
However, because of the Internet-connected de-
vices in the IoT system, the deployed microservice-
based architecture can have cyber security issues. Cy-
ber security is an absolute necessity in today’s Inter-
net connected world, a.k.a. Internet of Everything
(IoE). Cyber criminals have the capability to launch
sophisticated attacks which can have deadly conse-
quences, e.g., shutting down the power gird for a
complete blackout. It is also found that the hack-
ers have the power to tamper with the election re-
sults(Ahmed and Pathan, 2020a). In recent times, due
to cyber attacks in a hospital facility in Germany, a
patient died(Goodin, 2020). Although embracing In-
ternet has impacted the security and privacy aspects in
our daily life, at the same time, it has become impos-
sible to deny the advantages it has introduced, such
as microservices(Eismann et al., 2020). Blockchains
use consensus algorithms to validate their transactions
and add extra security, integrity, trustability, etc. To
attack a blockchain, the attacker has to overcome the
security services provided by the consensus. Follow-
ing the popular consensus algorithms and their weak-
nesses, a trustworthy consensus algorithm (TCA) has
been proposed in this paper. The proposed TCA can
ensure the data integrity and different cyber attacks in
blockchain, such as 51% attack, selfish attack, miner
bribe, and N confirmation. The efficiency of TCA
has been evaluated based on different false data in-
jection attacks. Hence, TCA is a more robust and
trusted system for the microservice architecture using
blockchain technology.
Rest of the paper is organized as follows. Sec-
tion 2 presents the microservice architecture. Sec-
tion 3 discusses the false data injection attacks in
the context of blockchain. Section 4 contains the
critical analysis of the consensus algorithms, which
are the key reasons for false data injection attacks in
blockchain-supported microservice architecture. Sec-
tion 5 presents the proposed TCA (Trustworthy Con-
sensus Algorithm) and Section 6 includes the perfor-
mance analysis. The paper is concluded in Section
7.
2 MICROSERVICE
ARCHITECTURE
Figure 1: A simple microservices architecture, adapted
from Microsoft.
Microservice architecture is generally used for large
software projects as an architectural style. The funda-
mental objective of microservices is providing short-
release cycles and flexible on-demand scalability to
the target venue. This microservice architecture de-
composes an application into several independent
components, which are called microservices. Each
microservice runs on its individual process (Koschel
et al., 2017). Microservices are used by the devel-
opers who find it convenient as function-specific so-
lution. The corporations such as Amazon, Netflix
are taking full advantage of the microservice archi-
tecture. Microservice architecture benefits the com-
plete independence and developers can revise an ex-
isting service without rebuilding and redeploying the
entire application. The microservice architecture has
key advantages, including independent development
and deployment, decentralized data management and
governance, small and focused teams (Jamil et al.,
2020). Because microservices can be independently
scaled, they can also efficiently allocate computing
resources and enable flexible horizontal scaling in the
cloud (Khan et al., 2020). Such architecture contains
a collection of small, autonomous services and these
services are self-contained (as shown in Figure 1 - in
the figure, API stands for Application Programming
Interface). However, the main challenge with mi-
croservices is to coordinate various small parts. This
is deemed as the loophole or vulnerability of the mi-
croservice architecture. Hence, microservices are not
as effective as it seems to be in terms of cyber safety
and its trustworthiness.
3 FALSE DATA INJECTION
ATTACKS on BLOCKCHAIN
The strength and uniqueness of blockchain is its con-
sensus algorithms. Trusted security and integrity are
ensured by blockchains by applying consensus algo-
rithms. However, recent studied have proved that
WINSYS 2022 - 19th International Conference on Wireless Networks and Mobile Systems
54
popular consensus algorithms, such as PoW (Proof-
of-Work), PoS (Proof-of-Stake), DPoS (Delegated
Proof-of-Stake) are vulnerable to several types of
attacks like DDoS (Distributed Denial-of-Service),
Sybil, and 51% attacks. An overview of the possible
attacks in the blockchain are discussed in this section
as problem statement and potential motivation for this
work.
51% Attack: Blockchain technologies are at-
tracting users from different areas for their strong
security services but still the top blockchain based
cryptocurrencies lost huge amount of money be-
cause of 51% attacks. Whenever a single entity or
a group of entities acquires more that 51% of the
hashing power, it is possible to include block or
chain of blocks by winning the consensus every-
time (Ahmed and Pathan, 2020b). In that case, the
miner can perform double spending attack any-
time which is the biggest threat for the cryptocur-
rencies (Zhang and Lee, 2019). However, it is also
possible to perform similar kind of attack while
the the hashing power is less than 51%, but with
less probability to get a success.
Selfish Mining: When two or more miners
are trying to add their mined blocks into the
blockchain, the chain that consists of maximum
number of blocks will be accepted for the main
chain. This is called the longest chain rule
(Nakamoto, 2019). Thus to win the race, min-
ers mine blocks secretly and submit long chain to
win the race. Miners with relatively higher hash
power can dominate the race and by mining longer
chain, win the race, whereas the miners with com-
paratively lower hash power remain behind and
face losses as their contributions become wasted
because of this rule. This process is called self-
ish mining. It is easy to perform selfish mining
if someone has more than 25% of the network’s
hashing power. It will allow the selfish miners to
mine too many blocks within a short amount of
time to win the chain and earn more profit. In
contrast, others would continuously lose the race
as they are not able to generate that many blocks
within the short time.
Miner Bribe: Because of consensus, it requires
some time to complete a transaction. Attackers try
to generate a second transaction just after the first
one and offer high transaction fees for the second
one to attract miners to perform mining for the
second transaction quickly. Target of this brib-
ing process is to use the same coin to perform the
transactions. If it is possible to complete the sec-
ond transaction before the first one is confirmed,
Table 1: Vulnerabilities of the popular consensus algo-
rithms.
Consensus algorithms
Attacks PoW PoS DPoS
51% Attack ×
Selfish mining
Miner bribe × ×
Zero confirmation × ×
One confirmation × ×
the success rate of double spending is 100% (Sun
et al., 2020).
Zero Confirmation: The Zero confirmation is
another attacking technique to perform double
spending. Attackers show a fake output of a real
transaction and convince them (the victims) to
provide the service before the transaction is been
confirmed. If the merchant agrees to provide the
service before the transaction is confirmed, at-
tacker withdraws the transaction and replaces it
by another one (Nicolas et al., 2019).
One Confirmation: Similar to the zero confirma-
tion, one confirmation is an attack where the at-
tacker’s transaction is confirmed in the block and
shows the output to the merchant so that the mer-
chant can provide the product or service. How-
ever, when the attacker’s block is sent for re-
mining by losing the race to another miner be-
cause of the longest chain rule, the attacker gets
the opportunity to remove the transaction and gets
refunded (Judmayer et al., 2017).
4 CRITICAL ANALYSIS OF THE
CONSENSUS ALGORITHMS
Consensus algorithms are used by blockchains to val-
idate their transactions and to add extra level of secu-
rity, integrity, trustability, etc. To attack a blockchain,
the attacker has to overcome the security services pro-
vided by the consensus. In this section, weaknesses
of the popular consensus algorithms are described in
brief. In Table 1, vulnerabilities of the popular con-
sensus algorithms are summarized.
Proof-of-Work (PoW): PoW is a consensus al-
gorithm initiated by bitcoin where miners are re-
sponsible to generate transactions requested by
nodes. To generate blocks from one or multiple
transactions, it requires to solve complex equa-
tion to generate hash for the next block. Nodes
of the blockchain verify the blocks before it gets
accepted to be added into the blockchain. PoW
Blockchain Meets Secured Microservice Architecture: A Trustworthy Consensus Algorithm
55
is vulnerable if any of the miners gets more than
50% of the hashing power because in that case,
it will be easy for the miner to perform most of
the attacks, such as double-spending, 51% attack,
and P+Epsilon attack (Wang, 2017). By generat-
ing large number of fake nodes, it is possible to
perform Sybil attack.
Proof-of-Stake (PoS): PoS is a consensus algo-
rithm where the transactions are mined and vali-
dated by the nodes selected by a voting system.
Nodes with higher stake will get priority to be se-
lected as miner and rather than calculating com-
plex hash value, a single miner can perform the
mining to minimize the computation cost. As it
is nearly impossible to achieve more than 51%
stake value, PoS is considered as secured com-
pared to 51% attack. However, it is vulnera-
ble to P+Epsilon (Wang, 2017), long-range attack
(Sharma, 2018) and it is possible to minimize the
performance by using DDoS and Sybil attack.
Delegated Proof-of-Stake (DPoS): To make the
mining process faster and to reduce the wastage
of energy, DPoS proposed where witnesses are
selected to perform mining. A voting process is
used to select the witness where higher stake hold-
ers have the opportunity to cast more than one
vote. A penalization model is used where the min-
ers, i.e., the witnesses win coins for successful
block generation while receive penalties for fail-
ure. Although, DPoS performs better than PoW in
terms of energy consumption and mining speed.
However, the system is not fully decentralized.
In addition, if a single or a group of stakeholders
gains more than 51% of voting power, the system
will become vulnerable to 51% attack. Further-
more, likewise other consensus methods, DPoS
also suffers from balance attack, long-range at-
tack, P+Epsilon attack, Sybil attack and DDoS at-
tack.
4.1 Existing Works and Their
Limitations
A time penalty based system proposed by Horizen
(Garoffolo et al., 2018) where the gap between trans-
action received and block creating was calculated.
When the delay crosses a threshold time, the miner
received a punishment. During the punishment time,
the miner is not be able to perform any sort of ac-
tion in the blockchain. With the amount of delay
and frequency of similar action, the punishment pe-
riod increases. The proposed method can mitigate
the attack up to a certain level. However, a miner
with high hashing capacity does not face any pun-
ishment because it does not require much time for
that miner to generate large number of blocks. To
minimize the double-spending attacks, a consensus
technique called delayed proof of work (dPoW) pro-
posed (ChainZilla, 2019). Firstly, dPoW removes the
longest chain rule from the PoW to minimize the self-
ish mining and 51% attack. Additionally, it elects a
number of nodes to create a checkpoint to monitor
all the transactions of bitcoin targeted to stop dou-
ble spending attacks. dPoW provides comparatively
stronger security but checking every transaction in-
creases the time consumption. Because of monitor-
ing nodes, the system is not fully decentralized and
by attacking the supervisor nodes, it is possible to
perform those attacks. Another centralized algorithm
called PirlGuard proposed by Rado Minchev to mit-
igate the 51% attack (Minchev, 2018). In this pro-
posal, masternode operates notary contracts on mul-
tiple blockchains and monitoring system. If the no-
tary nodes find someone who has mined blocks pri-
vately to win the longest chain race, they would assign
penalty that means the miner will be suspended from
mining to a certain number of blocks. The penalty in-
creases with the number of secret mining nodes. Sim-
ilar to (Garoffolo et al., 2018), Pirlguard is able to
mitigate the 51% attack up to a certain level and a
miner with high computational power can (still) avoid
punishment easily. However, presence of masternode
brings the drawbacks of centralization.
A consensus algorithm, ChainLocks, proposed in
2018 to mitigate the 51% attack (Block, 2018). In the
proposed method, it requires positive response from
60% nodes to get acceptance as a block. After the
block generation, P2P messages are generated to in-
form all the nodes about the block generation. Addi-
tionally, the method does not support reverse transac-
tion after the transaction is signed. A master node is
there to manage the algorithm which brings the lim-
itations of centralized system. However, by gaining
much hashing power, it is still possible to perform at-
tacks.
From the literature review of related works on
consensus algorithms for blockchain technology, it
can be observed that the proposed algorithms suffer
from a number of drawbacks, including 51% attack,
selfish mining, miner bribe, and zero or one confirma-
tion attacks. Therefore, there is a need to study a new
or trustworthy consensus algorithm that can be used
by blockchain technology to offer a secured microser-
vice architecture. The proposed trustworthy consen-
sus algorithm has been discussed in the next section.
WINSYS 2022 - 19th International Conference on Wireless Networks and Mobile Systems
56
Figure 2: TCA: Trustworthy Consensus Algorithm.
5 PROPOSED TRUSTWORTHY
CONSENSUS ALGORITHM
To enhance the efficiency of the consensus techniques
used by blockchains, a novel consensus algorithm
(Algorithm 1) is proposed in this paper, named TCA
(Trustworthy Consensus Algorithm). The aim of the
proposed consensus algorithm is to protect the mi-
croservice architecture from the above mentioned at-
tacks. The flow chart in Figure 2 illustrates the pro-
posed technique and it can be summarized as follows.
After every successful mining, there is a min-
ing Entry Period (EP) where miners competes to get
chance and perform the verification/validation pro-
cess. Miner continues mining and tries to get chance
in the next time slot. Only one block is allowed per
miner to enter into the Validation Period (VP). This
removes the longest chain rule problem to mitigate
51% attack. During the validation period, no miners
are allowed to submit blocks. Instead, they wait for
the next slot. Multiple blocks can enter into the VP
and after collecting the votes from the nodes, Trust
Value (TV) of each of the miner is calculated and the
block with the highest TV is selected for the chain to
be added. The rate of positive responses from the par-
Algorithm 1: Trustworthy Consensus Algorithm
(TCA).
Begin
Step 1: Entry Period (EP) open to all miners;
Step 2: Check the requested block numbers;
if requested block number > 1 then
Reject;
end
if EP is avialable then
Go to Step 1;
else
Suspend block submission until next EP;
end
end
Step 3: Enter into Validation Period (VP);
Step 4: Receive validation message;
Step 5: Check VP status;
if VP is not available then
Await validation message;
else
Calculate TV (Eq. 1);
end
end
Step 6: Add the block with maximum TV;
Step 7: Go to Step 1.
End
ticipating nodes is multiplied by the block size i.e.,
size of the transactions added in the block to get the
TV (Eq. 1). Block Size (BS) is added so that blocks
with more number of transactions gets advantage. In
Eq. 1, PR is Positive Responses and TR is Total Re-
sponse.
TV =
PR
T R
BS (1)
Figure 3: Blocks in the validation period (VP) and their trust
value (TV) calculation.
Blockchain Meets Secured Microservice Architecture: A Trustworthy Consensus Algorithm
57
Figure 4: Mitigation technique from the 51% attack.
For example, in Figure 3, blocks are illustrated
who get chance in the VP and after validation and
TV calculation, block C is selected to be the next
block. Delay calculation and punishment, negative
reputation value assignment etc. are not required
to perform likewise the previously proposed meth-
ods, which can minimize the additional computa-
tional costs performed by the server. Miner with more
than 51% computational power would not be able to
get benefits by wining the longest chain rule as only
one block is allowed from each miner.
6 PERFORMANCE EVALUATION
OF TCA
Table 2 presents the efficiency of TCA under several
false data injection attacks. It is evident that the state-
of-the-art consensus mechanisms are not suitable to
address the false data injection attacks, which are se-
rious threats to the microservice architecture. It is
important to provide trustworthiness to any technol-
ogy; however, due to the vulnerabilities in the con-
sensus algorithms, the blockchain ecosystem is still
in jeopardy. The proposed TCA is a more robust and
trusted system for microservice architecture within
blockchain framework.
A miner with more than 51% hashing power can
generate a long chain to perform 51% attack. How-
ever, in the proposed consensus algorithm (TCA),
only one block is selected to enter in the evaluation
period. Thus, it is not possible to add more than one
block in the blockchain. When any miner comes with
multiple blocks and applies to get a chance in the EP
with a block height, which is more than the expected
height would get rejected before the validation pe-
riod. For instance, a miner comes with a block height
10347, where the EP is expecting a block to be se-
lected for a block of height 10344, the mined block
by the miner will be rejected. In Figure 4, the sce-
nario has been explained graphically. During VP, a
block from miner B is rejected because it is applied
for block number 10348, while the system is pro-
cessed to add block number 10344.
PoW is vulnerable to zero and one confirmation
attacks and other similar type of attack including
miner bribe attacks. All these attacks take the ad-
vantage of the transaction confirmation delay of the
bitcoin as it requires 6 blocks confirmation to vali-
date a single transaction. That means, a transaction
mined in block number 1024 can be confirmed after
block number 1030. When it is required around 10
minutes to generate one block, the waiting time for
confirmation is almost one hour. Within this delay
period, the attackers could find opportunities to per-
form any of the above mentioned attacks. To mitigate
this kind of problem, in the proposed method, each
block is being confirmed immediately after the block
verification. Thus, the waiting times for the transac-
tions are very little. Because each and every block is
validated separately, it is not possible to perform the
above mentioned attacks, i.e., zero confirmation, one
confirmation, miner bribe, and other attacks.
Referring to the discussion in Section 3, the self-
ish mining is the process where a miner or a group of
miners with higher computational strength can per-
form fast mining to generate longer chain of blocks to
get chance in the main blockchain. Because of faster
mining capacity, they can add more blocks than other
miners, which make the miner with normal computa-
tion power unable to receive award of mining. It has
been found that a group that consists of 6 miners are
able to generate more than 67% of the total blocks
generated by bitcoin in a single day and as a set of
selfish miners, they are able to perform conjugative
block generation (Sayeed and Marco-Gisbert, 2019).
To remove this alarming attack, the proposed method
(TCA) accepts only one block per miner in the EP.
Thus, a miner with high mining capacity cannot get
entry there with multiple blocks. Instead, they have to
wait for the next slot. Additionally, mining power is
not able to affect the proposed algorithm because the
system does not accept multiple blocks from a miner.
To generate longer chain, transactions had to face
delay because miners need a large number of trans-
actions to generate a high number of blocks for win-
ning the longest chain race in the PoW consensus al-
gorithm. However, in the proposed TCA, there is no
benefit in creating longer chain (because a miner can
WINSYS 2022 - 19th International Conference on Wireless Networks and Mobile Systems
58
Table 2: Efficiency of TCA.
Comparison with State-of-the-art
Attacks PoW (Garoffolo
et al., 2018)
(ChainZilla,
2019)
(Minchev,
2018)
(Block,
2018)
TCA
51% Attack × × × ×
Selfish mining × × × × ×
Miner bribe × × × ×
Zero confirmation × × × ×
One confirmation × × × ×
Figure 5: Computational cost vs Cryptographic Complex-
ity.
submit only one block in the EP). Thus, miners can
mine single block rather than keeping transactions
waiting. Then, they can try to get chance in the EP.
For bitcoin, average block generation time is 10 min-
utes. It requires generating 6 blocks to get confirma-
tion for a transaction, which is a good amount of time.
In the proposed algorithm, this waiting time can be re-
moved because all transactions will get confirmation
just after the block verification and selection process.
6.1 Hashing
Hashing is one of the integral parts of blockchain
technology. There are different types of hashing algo-
rithms available and each algorithm has different out-
puts. It is important to keep in confederation, which
hashing technique is optimal for the proposed con-
sensus algorithm in this paper. It is also important
to note that, the proof of work requires to solve a
predefined mathematical puzzle, which is both com-
putationally and energy intensive task regardless of
hashing process. Therefore, the combination of SHA-
224 with TCA will be an optimal solution for ensur-
ing data integrity and availability. However, there is
a trade-off between the cryptographic complexity or
the length of hash values and the computational cost
or time required. In Figure 5, it can be shown that the
optimal solution is the diagonal line and only SHA-
384 seemed to be very close to that. Meaning, the
SHA-384 hashing is more balanced and can be useful
for integrating with the proposed consensus algorithm
(TCA) in this paper.
7 CONCLUSIONS
Internet of Things (IoT) offers distributed connectiv-
ity of networked items, and microservice architecture
is becoming an essential part of IoT in designing the
system. Furthermore, blockchain can ensure the data
integrity for the microservices architecture by using a
consensus algorithm. However, to tackle the cyber se-
curity issues, a trustworthy consensus algorithm can
help to mitigate the security issues. In this paper, a
robust and trustworthy consensus mechanism, called
TCA has been proposed for use in a blockchain-based
microservice architecture. The key objective of this
algorithm is to address the data integrity and avail-
ability attacks in blockchain, i.e., 51% attack, selfish
mining, miner bribe and N confirmation. Although
data availability is well studied, data integrity attacks,
e.g., false data injection attacks (similar to the man-
in-the-middle), are less explored, which can benefit
from the proposed framework. It is crucial to iden-
tify the need to address availability and integrity at-
tacks in the blockchain ecosystem used for secure
and dependable microservice architecture. Hence,
it is necessary to devise critical components of the
blockchain, i.e., the consensus mechanism, in a trust-
worthy way to enhance the reliability and immutabil-
ity of the blockchain-based microservices. The TCA
will be studied using a real-case scenario as a future
study.
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