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What is the main way to guarantee the security of blockchain
Publish: 2021-05-05 20:26:30
1. Chongqing jinwowo analysis: the information security advantages of blockchain technology are as follows:
first, through the application in the field of digital currency, blockchain provides a solution for the flow of capital flow (or capital flow) information on the Internet
secondly, blockchain solves the problem of right confirmation in the transaction process through encryption and reference of distributed ledger
thirdly, blockchain determines the exchange of digital assets through the technology of consensus mechanism.
first, through the application in the field of digital currency, blockchain provides a solution for the flow of capital flow (or capital flow) information on the Internet
secondly, blockchain solves the problem of right confirmation in the transaction process through encryption and reference of distributed ledger
thirdly, blockchain determines the exchange of digital assets through the technology of consensus mechanism.
2. Private key~
3.
One of the characteristics of blockchain projects (especially public chains) is open source. Through open source code, to improve the credibility of the project, so that more people can participate. But the open source code also makes it easier for attackers to attack blockchain system. In the past two years, there have been a number of hacker attacks. Recently, the anonymous currency verge (xvg) was attacked again. The attacker locked a vulnerability in the xvg code, which allowed malicious miners to add false timestamps on the block, and then quickly dig out new blocks. In a few hours, the attacker obtained nearly $1.75 million worth of digital currency. Although the subsequent attack was successfully stopped, no one can guarantee whether the attacker will attack again in the future
of course, blockchain developers can also take some measures
one is to use professional code audit services,
the other is to understand the security coding specifications and take preventive measures
the security of cryptographic algorithm
with the development of quantum computer, it will bring a major security threat to the current cryptosystem. Blockchain mainly relies on elliptic curve public key encryption algorithm to generate digital signature for secure transactions. Currently, the most commonly used ECDSA, RSA, DSA, etc. can not withstand quantum attacks in theory, and there will be greater risks. More and more researchers begin to pay attention to cryptographic algorithms that can resist quantum attacks
of course, in addition to changing the algorithm, there is another way to improve the security:
refer to bitcoin's treatment of public key address to rece the potential risk of public key disclosure. As users, especially bitcoin users, the balance after each transaction is stored in a new address to ensure that the public key of the address where bitcoin funds are stored is not leaked
security of consensus mechanism
the current consensus mechanisms include proof of work (POW), proof of stake (POS), delegated proof of stake (dpos), practical Byzantine fault tolerance (pbft), etc
POW faces 51% attack. Because POW depends on computing power, when the attacker has the advantage of computing power, the probability of finding a new block will be greater than that of other nodes. At this time, the attacker has the ability to cancel the existing transaction. It should be noted that even in this case, the attacker can only modify his own transaction, but not the transaction of other users (the attacker does not have the private key of other users)
in POS, attackers can attack successfully only when they hold more than 51% token, which is more difficult than 51% computing power in pow
in pbft, when the malicious nodes are less than 1 / 3 of the total nodes, the system is secure. Generally speaking, any consensus mechanism has its own conditions. As an attacker, we also need to consider that once the attack is successful, the value of the system will return to zero. At this time, the attacker does not get any other valuable return except destruction
for the designers of blockchain projects, they should understand the advantages and disadvantages of each consensus mechanism, so as to select an appropriate consensus mechanism or design a new consensus mechanism according to the needs of the scene
security of smart contract
smart contract has the advantages of low operation cost and low risk of human intervention, but if there are problems in the design of smart contract, it may bring greater losses. In June 2016, the Dao, the most popular funding project of Ethereum, was attacked. The hacker obtained more than 3.5 million Ethereum coins, which later led to the bifurcation of Ethereum into Eth and etc
there are two aspects of the proposed measures:
one is to audit the security of smart contract, and the other is to follow the principle of smart contract security development
the security development principles of smart contract are: to be prepared for possible errors, to ensure that the code can correctly handle the bugs and vulnerabilities; Release smart contracts carefully, do well in function test and security test, and fully consider the boundary; Keep smart contracts simple; Pay attention to the threat intelligence of blockchain and check and update in time; Be clear about the characteristics of blockchain, such as calling external contracts carefully
security of digital wallet
there are three main security risks in digital wallet: first, design defects. At the end of 2014, a user lost hundreds of digital assets e to a serious random number problem (repeated r value). Second, the digital wallet contains malicious code. Third, the loss of assets caused by the loss or damage of computers and mobile phones
there are four main countermeasures:
one is to ensure the randomness of the private key
The second is to check the hash value before installing the software to ensure that the digital wallet software has not been tampered with The third is to use cold wallet The fourth is to back up the private key4. Blockchain is a technology, but it is not a single technology, but the result of the integration of a variety of technologies, including cryptography, mathematics, economics, network science and so on. You can think of it as a distributed shared accounting technology, or as a database, but the database is jointly maintained by all nodes in the chain, and each node has an account book. Because the account books of all nodes are consistent, different nodes can trust each other, and there is no doubt about the data, so we all say that the blockchain has realized trust technically. For detailed professional technology, you can consult some professional technology companies, such as Jinbo technology, which focuses on the development of blockchain related procts, professional R & D team and perfect after-sales service, and you can consult by telephone.
5. Blockchain itself solves the problem of large-scale cooperation between strangers, that is, strangers can cooperate with each other without mutual trust. So how to ensure the trust between strangers to achieve mutual consensus mechanism? The centralized system uses trusted third-party endorsements, such as banks. In the eyes of the common people, banks are reliable and trustworthy institutions. The common people can trust banks to solve real disputes. But how does a decentralized blockchain guarantee trust
in fact, blockchain uses the basic principles of modern cryptography to ensure its security mechanism. The knowledge system involved in the field of cryptography and security is very complicated. Here, I only introce the basic knowledge of cryptography related to blockchain, including hash algorithm, encryption algorithm, information digest and digital signature, zero knowledge proof, quantum cryptography, etc. Through this lesson, you can learn how to ensure the confidentiality, integrity, authentication and non repudiation of the blockchain using cryptography technology
basic course lesson 7 basic knowledge of blockchain security
1. Hash algorithm (hash algorithm)
hash function (hash), also known as hash function. Hash function: hash (original information) = summary information. Hash function can map any length of binary plaintext string to a shorter (generally fixed length) binary string (hash value)
a good hash algorithm has the following four characteristics:
1. One to one correspondence: the same plaintext input and hash algorithm can always get the same summary information output
2. Input sensitivity: even if the plaintext input changes slightly, the newly generated summary information will change greatly, which is greatly different from the original output
3. Easy to verify: plaintext input and hash algorithm are public, anyone can calculate by themselves, and whether the output hash value is correct
4. Irreversibility: if there is only the output hash value, the hash algorithm can never dece the plaintext
5. Conflict avoidance: it is difficult to find two plaintexts with different contents, but their hash values are the same (collision)
for example:
hash (Zhang San lent Li Si 100000 yuan for 6 months) = 123456789012
such a record as 123456789012 is recorded in the account book
it can be seen that hash function has four functions:
simplify information
it is easy to understand, and the information after hashing becomes shorter
identification information
you can use 123456789012 to identify the original information, and summary information is also called the ID of the original information
hidden information
the account book is a record like 123456789012, and the original information is hidden
verification information
if Li Si cheated that Zhang San only lent Li Si 50000 when repaying, both parties can verify the original information with the hash value of 123456789012 recorded before
hash (Zhang San lent Li Si 50000 for 6 months) = 987654321098
987654321098 is completely different from 123456789012, which proves that Li Si lied, Then the information can't be tampered
common hash algorithms include MD4, MD5 and Sha series algorithms, and Sha series algorithms are basically used in mainstream fields. Sha (secure hash algorithm) is not an algorithm, but a group of hash algorithms. At first, it was SHA-1 series, and now the mainstream applications are sha-224, SHA-256, sha-384 and sha-512 algorithms (commonly known as SHA-2). Recently, Sha-3 related algorithms have been proposed, such as keccak-256 used by Ethereum
MD5 is a very classic hash algorithm, but unfortunately, both it and SHA-1 algorithm have been cracked. It is considered by the instry that its security is not enough to be used in business scenarios. Generally, sha2-256 or more secure algorithm is recommended
hash algorithm is widely used in blockchain. For example, in blocks, the latter block will contain the hash value of the previous block, and the content of the later block + the hash value of the previous block will jointly calculate the hash value of the later block, which ensures the continuity and non tamperability of the chain< Encryption and decryption algorithm is the core technology of cryptography, which can be divided into two basic types: symmetric encryption algorithm and asymmetric encryption algorithm. According to whether the key used in the encryption and decryption process is the same or not, the two modes are suitable for different needs, just forming a complementary relationship, and sometimes can be combined to form a hybrid encryption mechanism
symmetric cryptography (also known as common key cryptography) has the advantages of high computational efficiency and high encryption strength; Its disadvantage is that it needs to share the key in advance, which is easy to leak and lose the key. The common algorithms are des, 3DES, AES and so on
asymmetric cryptography (also known as public key cryptography) is different from the encryption and decryption key, and its advantage is that it does not need to share the key in advance; Its disadvantage is that it has low computational efficiency and can only encrypt short content. Common algorithms include RSA, SM2, ElGamal and elliptic curve series. Symmetric encryption algorithm is suitable for the encryption and decryption process of a large number of data; It can't be used in signature scenario: and it often needs to distribute the key in advance. Asymmetric encryption algorithm is generally suitable for signature scenario or key agreement, but it is not suitable for large amount of data encryption and decryption< Third, information digest and digital signature
as the name suggests, information digest is to hash the information content to obtain a unique digest value to replace the original and complete information content. Information digest is the most important use of hash algorithm. Using the anti-collision feature of hash function, information digest can solve the problem that the content has not been tampered
digital signature is similar to signing on paper contract to confirm contract content and prove identity. Digital signature is based on asymmetric encryption, which can be used to prove the integrity of a digital content and confirm the source (or non repudiation)
we have two requirements for digital signature to make it consistent with our expectation for handwritten signature. First, only you can make your own signature, but anyone who sees it can verify its validity; Second, we want the signature to be only related to a specific file and not support other files. These can be achieved by our asymmetric encryption algorithm above
in practice, we usually sign the hash value of information instead of the information itself, which is determined by the efficiency of asymmetric encryption algorithm. Corresponding to the blockchain, it is to sign the hash pointer. In this way, the front is the whole structure, not just the hash pointer itself< Zero knowledge proof means that the verifier can make the verifier believe that a certain conclusion is correct without providing any additional information to the verifier
zero knowledge proof generally meets three conditions:
1. Completeness: authentic proof can make the verifier successfully verify
2. Soundness: false proof can not make the verifier pass the verification
3. Zero knowledge: if you get proof, you can't get any information other than the proof information from the proof process< With more and more attention paid to the research of quantum computing and quantum communication, quantum cryptography will have a huge impact on the information security of cryptography in the future
the core principle of quantum computing is that qubits can be in multiple coherent superposition states at the same time. Theoretically, a large amount of information can be expressed by a small number of qubits and processed at the same time, which greatly improves the computing speed
in this way, a large number of current encryption algorithms are theoretically unreliable and can be cracked, so the encryption algorithm has to be upgraded, otherwise it will be broken by quantum computing
as we all know, quantum computing is still in the theoretical stage, which is far from large-scale commercial use. However, the new generation of encryption algorithms should consider the possibility of this situation.
in fact, blockchain uses the basic principles of modern cryptography to ensure its security mechanism. The knowledge system involved in the field of cryptography and security is very complicated. Here, I only introce the basic knowledge of cryptography related to blockchain, including hash algorithm, encryption algorithm, information digest and digital signature, zero knowledge proof, quantum cryptography, etc. Through this lesson, you can learn how to ensure the confidentiality, integrity, authentication and non repudiation of the blockchain using cryptography technology
basic course lesson 7 basic knowledge of blockchain security
1. Hash algorithm (hash algorithm)
hash function (hash), also known as hash function. Hash function: hash (original information) = summary information. Hash function can map any length of binary plaintext string to a shorter (generally fixed length) binary string (hash value)
a good hash algorithm has the following four characteristics:
1. One to one correspondence: the same plaintext input and hash algorithm can always get the same summary information output
2. Input sensitivity: even if the plaintext input changes slightly, the newly generated summary information will change greatly, which is greatly different from the original output
3. Easy to verify: plaintext input and hash algorithm are public, anyone can calculate by themselves, and whether the output hash value is correct
4. Irreversibility: if there is only the output hash value, the hash algorithm can never dece the plaintext
5. Conflict avoidance: it is difficult to find two plaintexts with different contents, but their hash values are the same (collision)
for example:
hash (Zhang San lent Li Si 100000 yuan for 6 months) = 123456789012
such a record as 123456789012 is recorded in the account book
it can be seen that hash function has four functions:
simplify information
it is easy to understand, and the information after hashing becomes shorter
identification information
you can use 123456789012 to identify the original information, and summary information is also called the ID of the original information
hidden information
the account book is a record like 123456789012, and the original information is hidden
verification information
if Li Si cheated that Zhang San only lent Li Si 50000 when repaying, both parties can verify the original information with the hash value of 123456789012 recorded before
hash (Zhang San lent Li Si 50000 for 6 months) = 987654321098
987654321098 is completely different from 123456789012, which proves that Li Si lied, Then the information can't be tampered
common hash algorithms include MD4, MD5 and Sha series algorithms, and Sha series algorithms are basically used in mainstream fields. Sha (secure hash algorithm) is not an algorithm, but a group of hash algorithms. At first, it was SHA-1 series, and now the mainstream applications are sha-224, SHA-256, sha-384 and sha-512 algorithms (commonly known as SHA-2). Recently, Sha-3 related algorithms have been proposed, such as keccak-256 used by Ethereum
MD5 is a very classic hash algorithm, but unfortunately, both it and SHA-1 algorithm have been cracked. It is considered by the instry that its security is not enough to be used in business scenarios. Generally, sha2-256 or more secure algorithm is recommended
hash algorithm is widely used in blockchain. For example, in blocks, the latter block will contain the hash value of the previous block, and the content of the later block + the hash value of the previous block will jointly calculate the hash value of the later block, which ensures the continuity and non tamperability of the chain< Encryption and decryption algorithm is the core technology of cryptography, which can be divided into two basic types: symmetric encryption algorithm and asymmetric encryption algorithm. According to whether the key used in the encryption and decryption process is the same or not, the two modes are suitable for different needs, just forming a complementary relationship, and sometimes can be combined to form a hybrid encryption mechanism
symmetric cryptography (also known as common key cryptography) has the advantages of high computational efficiency and high encryption strength; Its disadvantage is that it needs to share the key in advance, which is easy to leak and lose the key. The common algorithms are des, 3DES, AES and so on
asymmetric cryptography (also known as public key cryptography) is different from the encryption and decryption key, and its advantage is that it does not need to share the key in advance; Its disadvantage is that it has low computational efficiency and can only encrypt short content. Common algorithms include RSA, SM2, ElGamal and elliptic curve series. Symmetric encryption algorithm is suitable for the encryption and decryption process of a large number of data; It can't be used in signature scenario: and it often needs to distribute the key in advance. Asymmetric encryption algorithm is generally suitable for signature scenario or key agreement, but it is not suitable for large amount of data encryption and decryption< Third, information digest and digital signature
as the name suggests, information digest is to hash the information content to obtain a unique digest value to replace the original and complete information content. Information digest is the most important use of hash algorithm. Using the anti-collision feature of hash function, information digest can solve the problem that the content has not been tampered
digital signature is similar to signing on paper contract to confirm contract content and prove identity. Digital signature is based on asymmetric encryption, which can be used to prove the integrity of a digital content and confirm the source (or non repudiation)
we have two requirements for digital signature to make it consistent with our expectation for handwritten signature. First, only you can make your own signature, but anyone who sees it can verify its validity; Second, we want the signature to be only related to a specific file and not support other files. These can be achieved by our asymmetric encryption algorithm above
in practice, we usually sign the hash value of information instead of the information itself, which is determined by the efficiency of asymmetric encryption algorithm. Corresponding to the blockchain, it is to sign the hash pointer. In this way, the front is the whole structure, not just the hash pointer itself< Zero knowledge proof means that the verifier can make the verifier believe that a certain conclusion is correct without providing any additional information to the verifier
zero knowledge proof generally meets three conditions:
1. Completeness: authentic proof can make the verifier successfully verify
2. Soundness: false proof can not make the verifier pass the verification
3. Zero knowledge: if you get proof, you can't get any information other than the proof information from the proof process< With more and more attention paid to the research of quantum computing and quantum communication, quantum cryptography will have a huge impact on the information security of cryptography in the future
the core principle of quantum computing is that qubits can be in multiple coherent superposition states at the same time. Theoretically, a large amount of information can be expressed by a small number of qubits and processed at the same time, which greatly improves the computing speed
in this way, a large number of current encryption algorithms are theoretically unreliable and can be cracked, so the encryption algorithm has to be upgraded, otherwise it will be broken by quantum computing
as we all know, quantum computing is still in the theoretical stage, which is far from large-scale commercial use. However, the new generation of encryption algorithms should consider the possibility of this situation.
6. One of the characteristics of blockchain projects (especially public chains) is open source. Through open source code, to improve the credibility of the project, so that more people can participate. But the open source code also makes it easier for attackers to attack blockchain system. In the past two years, there have been a number of hacker attacks. Recently, the anonymous currency verge (xvg) was attacked again. The attacker locked a vulnerability in the xvg code, which allowed malicious miners to add false timestamps on the block, and then quickly dig out new blocks. In a few hours, the attacker obtained nearly $1.75 million worth of digital currency. Although the subsequent attack was successfully stopped, no one can guarantee whether the attacker will attack again in the future
of course, blockchain developers can also take some measures
one is to use professional code audit services,
the other is to understand the security coding specifications and take preventive measures
the security of cryptographic algorithm
with the development of quantum computer, it will bring great security threat to the current cryptosystem. Blockchain mainly relies on elliptic curve public key encryption algorithm to generate digital signature for secure transactions. Currently, the most commonly used ECDSA, RSA, DSA, etc. can not withstand quantum attacks in theory, and there will be greater risks. More and more researchers begin to pay attention to cryptographic algorithms that can resist quantum attacks
of course, in addition to changing the algorithm, there is another way to improve the security:
refer to bitcoin's treatment of public key address to rece the potential risk of public key disclosure. As users, especially bitcoin users, the balance after each transaction is stored in a new address to ensure that the public key of the address where bitcoin funds are stored is not leaked
security of consensus mechanism
the current consensus mechanisms include proof of work (POW), proof of stake (POS), delegated proof of stake (dpos), practical Byzantine fault tolerance (pbft), etc
POW faces 51% attack. Because POW depends on computing power, when the attacker has the advantage of computing power, the probability of finding a new block will be greater than that of other nodes. At this time, the attacker has the ability to cancel the existing transaction. It should be noted that even in this case, the attacker can only modify his own transaction, but not the transaction of other users (the attacker does not have the private key of other users)
in POS, attackers can only attack successfully when they hold more than 51% of the token, which is more difficult than 51% of the computing power in pow
in pbft, when the malicious nodes are less than 1 / 3 of the total nodes, the system is secure. Generally speaking, any consensus mechanism has its own conditions. As an attacker, we also need to consider that once the attack is successful, the value of the system will return to zero. At this time, the attacker does not get any other valuable return except destruction
for the designers of blockchain projects, they should understand the advantages and disadvantages of each consensus mechanism, so as to select an appropriate consensus mechanism or design a new consensus mechanism according to the needs of the scene
security of smart contract
smart contract has the advantages of low operation cost and low risk of human intervention, but if there are problems in the design of smart contract, it may bring great losses. In June 2016, the Dao, the most popular funding project of Ethereum, was attacked. The hacker obtained more than 3.5 million Ethereum coins, which later led to the bifurcation of Ethereum into Eth and etc
there are two aspects of the proposed measures:
one is to audit the security of smart contracts, and the other is to follow the principles of smart contract security development
the security development principles of smart contract are: be prepared for possible errors to ensure that the code can correctly handle the bugs and vulnerabilities; Release smart contracts carefully, do well in function test and security test, and fully consider the boundary; Keep smart contracts simple; Pay attention to the threat intelligence of blockchain and check and update in time; Be clear about the characteristics of blockchain, such as calling external contracts carefully
security of digital wallet
there are three main security risks in digital wallet: first, design defects. At the end of 2014, a user lost hundreds of digital assets e to a serious random number problem (repeated r value). Second, the digital wallet contains malicious code. Third, the loss of assets caused by the loss or damage of computers and mobile phones
there are four main countermeasures:
one is to ensure the randomness of the private key
the second is to verify the hash value before software installation to ensure that the digital wallet software has not been tampered with
the third is to use cold wallets
the fourth is to back up the private key.
of course, blockchain developers can also take some measures
one is to use professional code audit services,
the other is to understand the security coding specifications and take preventive measures
the security of cryptographic algorithm
with the development of quantum computer, it will bring great security threat to the current cryptosystem. Blockchain mainly relies on elliptic curve public key encryption algorithm to generate digital signature for secure transactions. Currently, the most commonly used ECDSA, RSA, DSA, etc. can not withstand quantum attacks in theory, and there will be greater risks. More and more researchers begin to pay attention to cryptographic algorithms that can resist quantum attacks
of course, in addition to changing the algorithm, there is another way to improve the security:
refer to bitcoin's treatment of public key address to rece the potential risk of public key disclosure. As users, especially bitcoin users, the balance after each transaction is stored in a new address to ensure that the public key of the address where bitcoin funds are stored is not leaked
security of consensus mechanism
the current consensus mechanisms include proof of work (POW), proof of stake (POS), delegated proof of stake (dpos), practical Byzantine fault tolerance (pbft), etc
POW faces 51% attack. Because POW depends on computing power, when the attacker has the advantage of computing power, the probability of finding a new block will be greater than that of other nodes. At this time, the attacker has the ability to cancel the existing transaction. It should be noted that even in this case, the attacker can only modify his own transaction, but not the transaction of other users (the attacker does not have the private key of other users)
in POS, attackers can only attack successfully when they hold more than 51% of the token, which is more difficult than 51% of the computing power in pow
in pbft, when the malicious nodes are less than 1 / 3 of the total nodes, the system is secure. Generally speaking, any consensus mechanism has its own conditions. As an attacker, we also need to consider that once the attack is successful, the value of the system will return to zero. At this time, the attacker does not get any other valuable return except destruction
for the designers of blockchain projects, they should understand the advantages and disadvantages of each consensus mechanism, so as to select an appropriate consensus mechanism or design a new consensus mechanism according to the needs of the scene
security of smart contract
smart contract has the advantages of low operation cost and low risk of human intervention, but if there are problems in the design of smart contract, it may bring great losses. In June 2016, the Dao, the most popular funding project of Ethereum, was attacked. The hacker obtained more than 3.5 million Ethereum coins, which later led to the bifurcation of Ethereum into Eth and etc
there are two aspects of the proposed measures:
one is to audit the security of smart contracts, and the other is to follow the principles of smart contract security development
the security development principles of smart contract are: be prepared for possible errors to ensure that the code can correctly handle the bugs and vulnerabilities; Release smart contracts carefully, do well in function test and security test, and fully consider the boundary; Keep smart contracts simple; Pay attention to the threat intelligence of blockchain and check and update in time; Be clear about the characteristics of blockchain, such as calling external contracts carefully
security of digital wallet
there are three main security risks in digital wallet: first, design defects. At the end of 2014, a user lost hundreds of digital assets e to a serious random number problem (repeated r value). Second, the digital wallet contains malicious code. Third, the loss of assets caused by the loss or damage of computers and mobile phones
there are four main countermeasures:
one is to ensure the randomness of the private key
the second is to verify the hash value before software installation to ensure that the digital wallet software has not been tampered with
the third is to use cold wallets
the fourth is to back up the private key.
7. Jinwowo, Chongqing: artificial intelligence has the ability to analyze massive data at high speed. As the basis of artificial intelligence, data must be accurate and safe, and there must be no forged data
if the blockchain technology is used, the authenticity and security of data can be guaranteed
by combining the two, consciousness chain forms a data pool, creates an efficient data exchange center, and finally constructs a three-dimensional and multi-functional artificial intelligence ecosystem.
if the blockchain technology is used, the authenticity and security of data can be guaranteed
by combining the two, consciousness chain forms a data pool, creates an efficient data exchange center, and finally constructs a three-dimensional and multi-functional artificial intelligence ecosystem.
8. Dmtc mainly uses blockchain technology to integrate the resources of agricultural supply chain, combined with the support of soft and hard chain technology, so as to realize the whole process of agricultural organic food proction record, check, tamper proof and traceability, and thoroughly solve the practical problems of agricultural development. It includes data acquisition, data security and data sharing
in terms of data collection, through artificial intelligence and Internet of things technology, dmtc runs through the whole agricultural ecological chain. During agricultural proction, it automatically records the proction environment data, proction process data, transportation, sales and consumer behavior data of agricultural procts
in terms of data security, the existing traceability IT architecture is used to maintain the security of the system through network equipment and Agricultural Internet of things (IOA)
in terms of data sharing, the data collected in the whole process of dmtc can be conditionally shared with users in the whole supply chain of ecological agriculture, and the proction and transportation data can be shared with consumers, so as to trace the origin and development of procts, guide agricultural procers to adjust proction direction and improve proction efficiency.
in terms of data collection, through artificial intelligence and Internet of things technology, dmtc runs through the whole agricultural ecological chain. During agricultural proction, it automatically records the proction environment data, proction process data, transportation, sales and consumer behavior data of agricultural procts
in terms of data security, the existing traceability IT architecture is used to maintain the security of the system through network equipment and Agricultural Internet of things (IOA)
in terms of data sharing, the data collected in the whole process of dmtc can be conditionally shared with users in the whole supply chain of ecological agriculture, and the proction and transportation data can be shared with consumers, so as to trace the origin and development of procts, guide agricultural procers to adjust proction direction and improve proction efficiency.
9. Public chain: refers to the blockchain that anyone in the world can access to the system at any time to read data, send confirmatory transactions and compete for bookkeeping. For example: bitcoin, Ethereum
private chain: refers to the blockchain whose write permission is controlled by an organization and institution, and the qualification of participating nodes will be strictly limited
alliance chain: refers to a blockchain with several institutions participating in the management. Each institution runs one or more nodes. The data only allows different institutions in the system to read, write and send transactions, and record transaction data together
alliance chain is a relatively new way to apply blockchain technology to enterprises. The public chain is open to all, while the private chain usually only provides services for one enterprise. The alliance chain has more restrictions than the public chain, and usually provides services for the cooperation among multiple enterprises
the difference between alliance chain and public chain is that it requires prior permission. Therefore, not everyone with an Internet connection can access the alliance blockchain. Alliance chain can also be described as semi decentralized. The control of alliance chain is not granted to a single entity, but to multiple organizations or indivials
for alliance chain, consensus process may be different from public chain. The consensus participants of the alliance chain may be a group of pre approved nodes on the network, rather than anyone can participate in the process. Alliance chain allows more control over the network
when it comes to the advantages of alliance chain:
first of all, alliance chain is completely controlled by a specific group, but it is not monopoly. When each member agrees, this control can establish its own rules
secondly, it has greater privacy, because the information used to verify the block will not be disclosed to the public, and only alliance members can process the information. It creates greater trust and confidence for platform customers
finally, compared with the public blockchain, the alliance chain has no transaction costs and is more flexible. A large number of verifiers in public blockchain lead to the trouble of synchronization and mutual protocol. Usually this divergence will lead to bifurcation, but the alliance chain will not
alliance chain technology can be used to optimize the business process of most traditional information systems, especially for business scenarios without strong center, multi-party cooperation and controllable risk. The shared ledger mechanism of alliance chain can greatly rece the reconciliation cost, improve the efficiency of data acquisition, increase the fault tolerance, consolidate the trust foundation, and avoid malicious fraud
with the continuous development of blockchain technology, more and more institutions and enterprises begin to increase the research and application of blockchain. Compared with the public chain, the alliance chain has better landing, and has been supported by many enterprises and the government
alliance chain can be understood as a kind of distributed ledger established by internal institutions to meet the needs of specific instries. This account book is open and transparent to internal institutions. However, if there are relevant business needs and the data of this account book is modified, it is still necessary to join the smart contract
smart contract is a kind of computer protocol which aims to disseminate, verify or execute contracts in an information way. Smart contracts allow trusted transactions without a third party, which are traceable and irreversible
generally speaking, the current mainstream architecture of alliance chain intelligent contract is: system contract + business contract
system contract: the configuration is completed before the node is started. It is generally used for system management (such as bcos precompiled contract (permission management, naming management, etc.), and it is written by the project side, with high security
Business Contract: it is written according to the actual business and needs to be deployed. It is similar to the public chain smart contract. It is written by the general internal organization participants and needs to comply with certain requirements. The security is general< However, there are still security risks in the following aspects:
(1) code language security features
one is to continue to use the main stream public chain programming language and improve on it (such as: the solidness used by bcos), The other is to specify the corresponding smart contract mole (such as fabric's go / Java / node. JS) based on the general programming language. No matter what language is used to program the smart contract, there are security problems in its corresponding language and related contract standards< (2) integer overflow caused by contract execution: no matter which virtual machine is used to execute the contract, all kinds of integer types have corresponding storage width. When trying to save data beyond this range, the signed number will overflow
stack overflow: when there are too many method parameters and local variables defined and the bytes are too large, the program may have errors
denial of service attack: it mainly involves the alliance chain that consumes resources to execute the contract, and the corresponding transaction cannot be completed e to the exhaustion of resources
(3) contract security problems caused by system mechanism
here mainly refers to the alliance chain of Multi Chain Architecture:
if the generation of contract variables depends on uncertain factors (such as the time stamp of this node) or a variable that is not persistent in the ledger, the transaction verification may fail because the reading and writing sets of the variable of each node are different
global variables are not stored in the database, but in a single node. Therefore, if this kind of node fails or restarts, it may cause the global variable value to be no longer consistent with other nodes, and affect node transactions. Therefore, data read, written or returned from the database should not depend on global state variables
when calling the contract of the external chain in the multi chain structure, only the return result of the called chain code function may be obtained, and no transaction will be submitted in any form in the external channel
when a contract accesses external resources, it may expose unexpected security risks of the contract and affect the chain code business logic
(4) business security issues
the smart contract of alliance chain is to complete a business requirement and execute a business, so there may still be security risks in business logic and business implementation, such as function permission mismatch, unreasonable input parameters, and improper exception handling
our suggestions on alliance chain security are as follows:
(1) simplify the design of smart contract to achieve the balance between function and security
(2) strictly implement smart contract code audit (self-evaluation / project team review / tripartite audit)
(3) strengthen the security training for smart contract developers
(4) implement the application of blockchain, It needs to be promoted step by step, from simple to complex. In this process, we should constantly comb the contract and platform related functions / security attributes
(5) consider the idea of devsecops (development + Security + operations)
chain platform security includes: transaction security, consensus security, account security, compliance, RPC security, endpoint security, P2P security, etc
hackers attack alliance chain by means of internal threats, DNS attacks, MSP attacks, 51% attacks, etc
take MSP attack as an example: MSP is the abbreviation of membership service provider in fabric alliance chain. It is a component that provides an abstract member operation framework. MSP abstracts all cryptographic mechanisms and protocols behind the issuance and verification of certificates and user authentication. An MSP can define its own identity, as well as identity management (authentication) and authentication (generation and verification of signatures) rules< Generally speaking, attacks against MSP may exist in the following aspects:
(1) internal threats: a) the current version of MSP allows single certificate control, that is, if an insider holds a certificate that can manage MSP, he can configure the fabric network, such as adding or revoking access rights, Adding identity to CRL (essentially blacklisted identity), too centralized management may lead to security risks. b) If there are sensors and other Internet of things devices connected to the alliance chain, it may spread false information to the chain, and because the sensor itself may not support perfect security protection, it may lead to further attacks
(2) private key leakage, the certificate file of node or sensor is generally stored locally, which may lead to private key leakage, and then lead to witch attack, man in the cloud attack, etc.
(3) DNS attack: when creating a new participant's identity and adding it to MSP, DNS attack may occur in any case. The process of creating certificates to blockchain members may be attacked in many places, such as man in the middle attack, cache poisoning, DDoS. An attacker can convert a simple DNS query into a larger payload, causing DDoS attacks. Similar to Ca attacks, this attack results in certificate tampering and / or theft, such as the permissions and access rights that some blockchain members will have. Sensor networks are particularly vulnerable to DDoS attacks. Smart city is not only faced with the weakness of sensor networks against DDoS attacks, but also the challenge of blockchain system< (4) Ca attack: digital certificate and identity are very important to the operation of MSP. Hyperledger fabric allows users to choose how to run a certification authority and generate encrypted materials. Options include fabric Ca, process built by hyperledger fabric, cryptogen contributors, and own / third party ca. The implementation of these CAS has its own defects. Cryptogen generates all the private keys in a centralized location, which are then fully and securely copied by the user to the appropriate host and container. This facilitates private key disclosure attacks by providing all private keys in one place. In addition to the weakness of the implementation, the whole MSP and the membership of the blockchain run on the Ca, and have the ability to trust that the certificate is valid, and the certificate owner is what they call the identity. If the attack on well-known third-party CA is executed successfully, the security of MSP may be damaged, resulting in forged identity. Another weakness of Ca in hyperledger fabric is how they are implemented in MSP. MSP needs at least one root Ca, and can support as root Ca and intermediate CA as needed. If the root CA certificate is attacked, all certificates issued by the root certificate will be affected
Cheng chain security has launched the alliance chain security solution. With the development of alliance chain ecology, in 2020, Cheng chain security has cooperated with multi provincial network information office to conct multi-level security audit on the alliance chain system of local government, enterprises and institutions from the bottom of the chain to the application layer, and found the loopholes and weaknesses of the alliance chain system with multiple scenarios, multiple applications and multiple forms and its supporting systems
in addition, Cheng Lianan has cooperated with ant blockchain to join the open alliance chain as the first batch of nodes selected by ant blockchain. We will give full play to security technology, service and market
private chain: refers to the blockchain whose write permission is controlled by an organization and institution, and the qualification of participating nodes will be strictly limited
alliance chain: refers to a blockchain with several institutions participating in the management. Each institution runs one or more nodes. The data only allows different institutions in the system to read, write and send transactions, and record transaction data together
alliance chain is a relatively new way to apply blockchain technology to enterprises. The public chain is open to all, while the private chain usually only provides services for one enterprise. The alliance chain has more restrictions than the public chain, and usually provides services for the cooperation among multiple enterprises
the difference between alliance chain and public chain is that it requires prior permission. Therefore, not everyone with an Internet connection can access the alliance blockchain. Alliance chain can also be described as semi decentralized. The control of alliance chain is not granted to a single entity, but to multiple organizations or indivials
for alliance chain, consensus process may be different from public chain. The consensus participants of the alliance chain may be a group of pre approved nodes on the network, rather than anyone can participate in the process. Alliance chain allows more control over the network
when it comes to the advantages of alliance chain:
first of all, alliance chain is completely controlled by a specific group, but it is not monopoly. When each member agrees, this control can establish its own rules
secondly, it has greater privacy, because the information used to verify the block will not be disclosed to the public, and only alliance members can process the information. It creates greater trust and confidence for platform customers
finally, compared with the public blockchain, the alliance chain has no transaction costs and is more flexible. A large number of verifiers in public blockchain lead to the trouble of synchronization and mutual protocol. Usually this divergence will lead to bifurcation, but the alliance chain will not
alliance chain technology can be used to optimize the business process of most traditional information systems, especially for business scenarios without strong center, multi-party cooperation and controllable risk. The shared ledger mechanism of alliance chain can greatly rece the reconciliation cost, improve the efficiency of data acquisition, increase the fault tolerance, consolidate the trust foundation, and avoid malicious fraud
with the continuous development of blockchain technology, more and more institutions and enterprises begin to increase the research and application of blockchain. Compared with the public chain, the alliance chain has better landing, and has been supported by many enterprises and the government
alliance chain can be understood as a kind of distributed ledger established by internal institutions to meet the needs of specific instries. This account book is open and transparent to internal institutions. However, if there are relevant business needs and the data of this account book is modified, it is still necessary to join the smart contract
smart contract is a kind of computer protocol which aims to disseminate, verify or execute contracts in an information way. Smart contracts allow trusted transactions without a third party, which are traceable and irreversible
generally speaking, the current mainstream architecture of alliance chain intelligent contract is: system contract + business contract
system contract: the configuration is completed before the node is started. It is generally used for system management (such as bcos precompiled contract (permission management, naming management, etc.), and it is written by the project side, with high security
Business Contract: it is written according to the actual business and needs to be deployed. It is similar to the public chain smart contract. It is written by the general internal organization participants and needs to comply with certain requirements. The security is general< However, there are still security risks in the following aspects:
(1) code language security features
one is to continue to use the main stream public chain programming language and improve on it (such as: the solidness used by bcos), The other is to specify the corresponding smart contract mole (such as fabric's go / Java / node. JS) based on the general programming language. No matter what language is used to program the smart contract, there are security problems in its corresponding language and related contract standards< (2) integer overflow caused by contract execution: no matter which virtual machine is used to execute the contract, all kinds of integer types have corresponding storage width. When trying to save data beyond this range, the signed number will overflow
stack overflow: when there are too many method parameters and local variables defined and the bytes are too large, the program may have errors
denial of service attack: it mainly involves the alliance chain that consumes resources to execute the contract, and the corresponding transaction cannot be completed e to the exhaustion of resources
(3) contract security problems caused by system mechanism
here mainly refers to the alliance chain of Multi Chain Architecture:
if the generation of contract variables depends on uncertain factors (such as the time stamp of this node) or a variable that is not persistent in the ledger, the transaction verification may fail because the reading and writing sets of the variable of each node are different
global variables are not stored in the database, but in a single node. Therefore, if this kind of node fails or restarts, it may cause the global variable value to be no longer consistent with other nodes, and affect node transactions. Therefore, data read, written or returned from the database should not depend on global state variables
when calling the contract of the external chain in the multi chain structure, only the return result of the called chain code function may be obtained, and no transaction will be submitted in any form in the external channel
when a contract accesses external resources, it may expose unexpected security risks of the contract and affect the chain code business logic
(4) business security issues
the smart contract of alliance chain is to complete a business requirement and execute a business, so there may still be security risks in business logic and business implementation, such as function permission mismatch, unreasonable input parameters, and improper exception handling
our suggestions on alliance chain security are as follows:
(1) simplify the design of smart contract to achieve the balance between function and security
(2) strictly implement smart contract code audit (self-evaluation / project team review / tripartite audit)
(3) strengthen the security training for smart contract developers
(4) implement the application of blockchain, It needs to be promoted step by step, from simple to complex. In this process, we should constantly comb the contract and platform related functions / security attributes
(5) consider the idea of devsecops (development + Security + operations)
chain platform security includes: transaction security, consensus security, account security, compliance, RPC security, endpoint security, P2P security, etc
hackers attack alliance chain by means of internal threats, DNS attacks, MSP attacks, 51% attacks, etc
take MSP attack as an example: MSP is the abbreviation of membership service provider in fabric alliance chain. It is a component that provides an abstract member operation framework. MSP abstracts all cryptographic mechanisms and protocols behind the issuance and verification of certificates and user authentication. An MSP can define its own identity, as well as identity management (authentication) and authentication (generation and verification of signatures) rules< Generally speaking, attacks against MSP may exist in the following aspects:
(1) internal threats: a) the current version of MSP allows single certificate control, that is, if an insider holds a certificate that can manage MSP, he can configure the fabric network, such as adding or revoking access rights, Adding identity to CRL (essentially blacklisted identity), too centralized management may lead to security risks. b) If there are sensors and other Internet of things devices connected to the alliance chain, it may spread false information to the chain, and because the sensor itself may not support perfect security protection, it may lead to further attacks
(2) private key leakage, the certificate file of node or sensor is generally stored locally, which may lead to private key leakage, and then lead to witch attack, man in the cloud attack, etc.
(3) DNS attack: when creating a new participant's identity and adding it to MSP, DNS attack may occur in any case. The process of creating certificates to blockchain members may be attacked in many places, such as man in the middle attack, cache poisoning, DDoS. An attacker can convert a simple DNS query into a larger payload, causing DDoS attacks. Similar to Ca attacks, this attack results in certificate tampering and / or theft, such as the permissions and access rights that some blockchain members will have. Sensor networks are particularly vulnerable to DDoS attacks. Smart city is not only faced with the weakness of sensor networks against DDoS attacks, but also the challenge of blockchain system< (4) Ca attack: digital certificate and identity are very important to the operation of MSP. Hyperledger fabric allows users to choose how to run a certification authority and generate encrypted materials. Options include fabric Ca, process built by hyperledger fabric, cryptogen contributors, and own / third party ca. The implementation of these CAS has its own defects. Cryptogen generates all the private keys in a centralized location, which are then fully and securely copied by the user to the appropriate host and container. This facilitates private key disclosure attacks by providing all private keys in one place. In addition to the weakness of the implementation, the whole MSP and the membership of the blockchain run on the Ca, and have the ability to trust that the certificate is valid, and the certificate owner is what they call the identity. If the attack on well-known third-party CA is executed successfully, the security of MSP may be damaged, resulting in forged identity. Another weakness of Ca in hyperledger fabric is how they are implemented in MSP. MSP needs at least one root Ca, and can support as root Ca and intermediate CA as needed. If the root CA certificate is attacked, all certificates issued by the root certificate will be affected
Cheng chain security has launched the alliance chain security solution. With the development of alliance chain ecology, in 2020, Cheng chain security has cooperated with multi provincial network information office to conct multi-level security audit on the alliance chain system of local government, enterprises and institutions from the bottom of the chain to the application layer, and found the loopholes and weaknesses of the alliance chain system with multiple scenarios, multiple applications and multiple forms and its supporting systems
in addition, Cheng Lianan has cooperated with ant blockchain to join the open alliance chain as the first batch of nodes selected by ant blockchain. We will give full play to security technology, service and market
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