Cryptographer David Chaum first proposed a blockchain-like protocol in his 1982 dissertation "Computer Systems Established, Maintained, and Trusted by Mutually Suspicious Groups".[12] In 1991, Stuart Haber and W. Scott Stornetta described further work on a cryptographically secure blockchain. and they wanted to implement a system where document timestamps could not be manipulated. In 1992, Haber, Stornetta, and Dave Bayer incorporated Merkle trees into the design, improving its efficiency by allowing multiple document certificates to be assembled into a single block.[13]​[14]​ Under their company Surety, their document certificate hashes have been published in The New York Times every week since 1995.[15]​.

The first blockchain was conceptualized by a person (or group of people) known as Satoshi Nakamoto in 2008. Nakamoto improved the design significantly by using a Hashcash-like method of time-stamping blocks without requiring them to be signed by a trusted party and introducing a difficulty parameter to stabilize the rate at which blocks are added to the chain.[13] The design was implemented the following year by Nakamoto as a core component of cryptocurrency. bitcoin, where it serves as the public ledger for all transactions on the network.[9]​.

In August 2014, the file size of the bitcoin blockchain, which contains records of all transactions that have occurred on the network, reached 20 GB (gigabytes).[16] By January 2015, the size had grown to almost 30 GB, and from January 2016 to January 2017, the bitcoin blockchain grew from 50 GB to 100 GB in size. The size had exceeded 200 GB by early 2020.[17]​.

According to Accenture, an application of the theory of diffusion of innovations suggests that blockchains reached an adoption rate of 13.5% within financial services in 2016, thus reaching the early adoption phase. Industry trade groups came together to create the Global Blockchain Forum in 2016, an initiative of the Chamber of Digital Commerce.

The concept of blockchain is used in the following fields:.

Depending on data access

Blockchains can be classified based on access to the data stored therein:[11]​[27]​.

Both types of chains should be considered extreme cases and there may be intermediate cases.

According to permissions

Blockchains can be classified based on the permissions to generate blocks on it:[11]​.

Possible combinations of access and permissions

The possible combinations of both types of characteristics are:[27]​.

According to state change model

Blockchains can also be classified according to the state change model in the database in:[28]​.

Mining rigs are specialized computing equipment designed for the Proof-of-Work process. They have evolved from household GPUs to high-efficiency ASICs, reducing cost per hash and increasing power performance. Its massive implementation has generated debates about energy consumption and sustainability of the blockchain ecosystem.

Mining rigs are computing equipment specifically designed to execute the proof-of-work process. Its evolution has been key to the development of the blockchain ecosystem. The first miners used central processing units (CPU), but they were quickly replaced by graphical processing units (GPU), due to their greater ability to perform mathematical operations in parallel.[32]​.

Later, FPGAs (Field Programmable Gate Arrays) emerged, which offered better energy performance. However, the greatest transformation occurred with the appearance of ASICs (Application-Specific Integrated Circuits), integrated circuits designed exclusively for mining, capable of providing much higher hash rates with considerably lower energy consumption per operation.[33]​.

The evolution of rigs has given rise to debates about sustainability, due to the increase in global energy consumption associated with intensive mining. This growth has driven the development of more efficient technologies, as well as initiatives aimed at the use of renewable energy in large-scale mining operations.[34]​.

A sidechain, in English sidechain, is a blockchain that validates data from another blockchain which is called the main one. Its main use is to be able to provide new functionalities, which may be in a testing period, relying on the trust offered by the main blockchain.[35]​[36]​ Side chains work in a similar way to how traditional currencies did with the gold standard.[37]​.

An example of a blockchain that uses sidechains is Lisk").[38]​ Due to the popularity of Bitcoin and the enormous strength of its network to provide trust through its proof-of-work consensus algorithm "Proof of Work (distributed consensus algorithm)"), we want to take advantage of it as the main blockchain and build linked sidechains that rely on it. A linked sidechain is a sidechain whose assets can be imported to and from the other chain. This type of chains can be obtained from two forms:[36]​.

The use of a blockchain in practice has made it possible to solve two problems related to the exchange of assets without a trusted certifying entity:.

Furthermore, trust is another of the intrinsic characteristics of the system. From a legal point of view, bitcoin would be a patrimonial, private, incorporeal, digital asset, in the form of a unit of account, created through a computer system and used as a common measure of value by agreement of the users of the system. It is a movable, fungible, identifiable and unrepeatable but divisible asset. But it is not money, it is not electronic money nor does it have movable value, it would be "patrimonial assets that are taken as a common measure of value in closed, cooperative and decentralized economic exchange systems, foreign to state fiduciary money, and based on the trust and agreement of the users of the system." For González Granado, unregulated bitcoin will not become a general currency as a means of payment.[40]​[41]​.

Security and trust

The ethics of blockchain technology focuses on its ability to provide security and trust to users,[42]​ thanks to its transparency and its impossibility of modifying data once it has been recorded in the blockchain.

First of all, the transparency of blockchain technology is due to the fact that all transactions and operations carried out on the network are public and visible to any user. This implies that the data is accessible and verifiable by anyone, which increases user confidence in the integrity of the system and transparency in transactions.[43]​.

Additionally, blockchain technology is immutable, meaning that data once recorded on the blockchain cannot be altered or deleted. This ensures that the information stored in the blockchain is reliable and accurate, and that there is no data manipulation by third parties.[44]​.

Blockchain technology can be considered ethical since it protects the privacy and integrity of user data, preventing fraud and theft of information, which fosters trust in the network and in the operations carried out on it.

Fight against counterfeiting

Blockchain, a distributed ledger technology (DLT),[45]​ has established itself as a valuable tool to combat counterfeiting and fraud. One of the key features of blockchain is its data immutability, meaning that once a transaction is recorded on the blockchain, it cannot be altered or deleted. This ensures that data and transactions are authentic and reliable, which in turn leads to greater efficiency and security in negotiation processes and in the business supply chain.[46]​.

In the fight against counterfeiting and fraud, blockchain has also proven useful in protecting copyrights such as works of art and medicines. By recording the information of these products on the blockchain, their authenticity can be guaranteed and consumers protected from possible fraud.[47]​.

Blockchain could be said to offer an ethical solution to address counterfeiting and fraud by ensuring the authenticity and reliability of data and transactions. This has a positive impact on society by providing greater security and protection to consumers and businesses.

Accountability and governance

Governance in blockchain refers to the way decisions are made and conflicts are resolved within the network. In general, it must be fair, transparent and democratic, to guarantee the equitable participation of users and decision-making for the benefit of the common good.[48]​.

There are different governance models in blockchain.[49]​ One of the most common is the decentralized model"), in which decisions are made collectively by network users. Each user has one vote and decisions are made by majority, which promotes democratic participation and equality for all users.

Another model is delegated, in which a group of users is elected to make decisions on behalf of the community. Users elect delegates by vote and they have the responsibility of making decisions for the benefit of the common good. Transparency in decision-making is essential to ensure that delegates act for the benefit of the community and not their own interests.[50]​.

In some cases, governance in blockchain can be automated through the use of smart contracts. These programs run automatically on the network and follow certain rules to make decisions. For example, they can be used to distribute rewards to nodes that perform specific tasks. This model promotes transparency and impartiality in decision making.

Environmental impact

Blockchain environmental ethics focuses on the environmental effects of blockchain technology on information management and sharing. Blockchain can reduce environmental impact by efficiently managing renewable energy.[51]​ However, cryptocurrency mining involves high energy consumption,[52][53]​ which raises ethical and environmental concerns. Additionally, the production and disposal of equipment used for mining is also problematic.[54]​ More sustainable solutions are needed to address the environmental impact of blockchain and the ethical implications should be considered when using the technology for other purposes.

Future ethical challenges

As a technology that is constantly evolving and expanding, it faces significant ethical challenges that must be addressed to ensure its responsible and sustainable use in the future. One of the biggest ethical challenges is the risk of creating monopolies. Participants with greater computing power and resources may dominate transaction validation and block creation, which could limit participation and decentralization on the network.

Another important ethical challenge is the management of personal data and privacy. In particular, in applications involving sensitive information, such as health and finance, this technology must find ways to ensure the privacy and protection of personal data while maintaining the transparency and integrity of the information.[56]​.

Furthermore, as mentioned in the previous section, the environmental impact of blockchain is also an important ethical issue. Due to the high energy consumption of mining and transaction validation operations,[57]​[58]​ it is necessary to find sustainable solutions for energy use and to mitigate the environmental impact of blockchain.

It is important that blockchain developers, users and regulators work together to address these ethical challenges. This will ensure that blockchain technology can be used responsibly and sustainably in the future, and that its impact on society is positive and beneficial for everyone involved.

Cryptographer David Chaum first proposed a blockchain-like protocol in his 1982 dissertation "Computer Systems Established, Maintained, and Trusted by Mutually Suspicious Groups".[12] In 1991, Stuart Haber and W. Scott Stornetta described further work on a cryptographically secure blockchain. and they wanted to implement a system where document timestamps could not be manipulated. In 1992, Haber, Stornetta, and Dave Bayer incorporated Merkle trees into the design, improving its efficiency by allowing multiple document certificates to be assembled into a single block.[13]​[14]​ Under their company Surety, their document certificate hashes have been published in The New York Times every week since 1995.[15]​.

The first blockchain was conceptualized by a person (or group of people) known as Satoshi Nakamoto in 2008. Nakamoto improved the design significantly by using a Hashcash-like method of time-stamping blocks without requiring them to be signed by a trusted party and introducing a difficulty parameter to stabilize the rate at which blocks are added to the chain.[13] The design was implemented the following year by Nakamoto as a core component of cryptocurrency. bitcoin, where it serves as the public ledger for all transactions on the network.[9]​.

In August 2014, the file size of the bitcoin blockchain, which contains records of all transactions that have occurred on the network, reached 20 GB (gigabytes).[16] By January 2015, the size had grown to almost 30 GB, and from January 2016 to January 2017, the bitcoin blockchain grew from 50 GB to 100 GB in size. The size had exceeded 200 GB by early 2020.[17]​.

According to Accenture, an application of the theory of diffusion of innovations suggests that blockchains reached an adoption rate of 13.5% within financial services in 2016, thus reaching the early adoption phase. Industry trade groups came together to create the Global Blockchain Forum in 2016, an initiative of the Chamber of Digital Commerce.

The concept of blockchain is used in the following fields:.

Depending on data access

Blockchains can be classified based on access to the data stored therein:[11]​[27]​.

Both types of chains should be considered extreme cases and there may be intermediate cases.

According to permissions

Blockchains can be classified based on the permissions to generate blocks on it:[11]​.

Possible combinations of access and permissions

The possible combinations of both types of characteristics are:[27]​.

According to state change model

Blockchains can also be classified according to the state change model in the database in:[28]​.

Mining rigs are specialized computing equipment designed for the Proof-of-Work process. They have evolved from household GPUs to high-efficiency ASICs, reducing cost per hash and increasing power performance. Its massive implementation has generated debates about energy consumption and sustainability of the blockchain ecosystem.

Mining rigs are computing equipment specifically designed to execute the proof-of-work process. Its evolution has been key to the development of the blockchain ecosystem. The first miners used central processing units (CPU), but they were quickly replaced by graphical processing units (GPU), due to their greater ability to perform mathematical operations in parallel.[32]​.

Later, FPGAs (Field Programmable Gate Arrays) emerged, which offered better energy performance. However, the greatest transformation occurred with the appearance of ASICs (Application-Specific Integrated Circuits), integrated circuits designed exclusively for mining, capable of providing much higher hash rates with considerably lower energy consumption per operation.[33]​.

The evolution of rigs has given rise to debates about sustainability, due to the increase in global energy consumption associated with intensive mining. This growth has driven the development of more efficient technologies, as well as initiatives aimed at the use of renewable energy in large-scale mining operations.[34]​.

A sidechain, in English sidechain, is a blockchain that validates data from another blockchain which is called the main one. Its main use is to be able to provide new functionalities, which may be in a testing period, relying on the trust offered by the main blockchain.[35]​[36]​ Side chains work in a similar way to how traditional currencies did with the gold standard.[37]​.

An example of a blockchain that uses sidechains is Lisk").[38]​ Due to the popularity of Bitcoin and the enormous strength of its network to provide trust through its proof-of-work consensus algorithm "Proof of Work (distributed consensus algorithm)"), we want to take advantage of it as the main blockchain and build linked sidechains that rely on it. A linked sidechain is a sidechain whose assets can be imported to and from the other chain. This type of chains can be obtained from two forms:[36]​.

The use of a blockchain in practice has made it possible to solve two problems related to the exchange of assets without a trusted certifying entity:.

Furthermore, trust is another of the intrinsic characteristics of the system. From a legal point of view, bitcoin would be a patrimonial, private, incorporeal, digital asset, in the form of a unit of account, created through a computer system and used as a common measure of value by agreement of the users of the system. It is a movable, fungible, identifiable and unrepeatable but divisible asset. But it is not money, it is not electronic money nor does it have movable value, it would be "patrimonial assets that are taken as a common measure of value in closed, cooperative and decentralized economic exchange systems, foreign to state fiduciary money, and based on the trust and agreement of the users of the system." For González Granado, unregulated bitcoin will not become a general currency as a means of payment.[40]​[41]​.

Security and trust

The ethics of blockchain technology focuses on its ability to provide security and trust to users,[42]​ thanks to its transparency and its impossibility of modifying data once it has been recorded in the blockchain.

First of all, the transparency of blockchain technology is due to the fact that all transactions and operations carried out on the network are public and visible to any user. This implies that the data is accessible and verifiable by anyone, which increases user confidence in the integrity of the system and transparency in transactions.[43]​.

Additionally, blockchain technology is immutable, meaning that data once recorded on the blockchain cannot be altered or deleted. This ensures that the information stored in the blockchain is reliable and accurate, and that there is no data manipulation by third parties.[44]​.

Blockchain technology can be considered ethical since it protects the privacy and integrity of user data, preventing fraud and theft of information, which fosters trust in the network and in the operations carried out on it.

Fight against counterfeiting

Blockchain, a distributed ledger technology (DLT),[45]​ has established itself as a valuable tool to combat counterfeiting and fraud. One of the key features of blockchain is its data immutability, meaning that once a transaction is recorded on the blockchain, it cannot be altered or deleted. This ensures that data and transactions are authentic and reliable, which in turn leads to greater efficiency and security in negotiation processes and in the business supply chain.[46]​.

In the fight against counterfeiting and fraud, blockchain has also proven useful in protecting copyrights such as works of art and medicines. By recording the information of these products on the blockchain, their authenticity can be guaranteed and consumers protected from possible fraud.[47]​.

Blockchain could be said to offer an ethical solution to address counterfeiting and fraud by ensuring the authenticity and reliability of data and transactions. This has a positive impact on society by providing greater security and protection to consumers and businesses.

Accountability and governance

Governance in blockchain refers to the way decisions are made and conflicts are resolved within the network. In general, it must be fair, transparent and democratic, to guarantee the equitable participation of users and decision-making for the benefit of the common good.[48]​.

There are different governance models in blockchain.[49]​ One of the most common is the decentralized model"), in which decisions are made collectively by network users. Each user has one vote and decisions are made by majority, which promotes democratic participation and equality for all users.

Another model is delegated, in which a group of users is elected to make decisions on behalf of the community. Users elect delegates by vote and they have the responsibility of making decisions for the benefit of the common good. Transparency in decision-making is essential to ensure that delegates act for the benefit of the community and not their own interests.[50]​.

In some cases, governance in blockchain can be automated through the use of smart contracts. These programs run automatically on the network and follow certain rules to make decisions. For example, they can be used to distribute rewards to nodes that perform specific tasks. This model promotes transparency and impartiality in decision making.

Environmental impact

Blockchain environmental ethics focuses on the environmental effects of blockchain technology on information management and sharing. Blockchain can reduce environmental impact by efficiently managing renewable energy.[51]​ However, cryptocurrency mining involves high energy consumption,[52][53]​ which raises ethical and environmental concerns. Additionally, the production and disposal of equipment used for mining is also problematic.[54]​ More sustainable solutions are needed to address the environmental impact of blockchain and the ethical implications should be considered when using the technology for other purposes.

Future ethical challenges

As a technology that is constantly evolving and expanding, it faces significant ethical challenges that must be addressed to ensure its responsible and sustainable use in the future. One of the biggest ethical challenges is the risk of creating monopolies. Participants with greater computing power and resources may dominate transaction validation and block creation, which could limit participation and decentralization on the network.

Another important ethical challenge is the management of personal data and privacy. In particular, in applications involving sensitive information, such as health and finance, this technology must find ways to ensure the privacy and protection of personal data while maintaining the transparency and integrity of the information.[56]​.

Furthermore, as mentioned in the previous section, the environmental impact of blockchain is also an important ethical issue. Due to the high energy consumption of mining and transaction validation operations,[57]​[58]​ it is necessary to find sustainable solutions for energy use and to mitigate the environmental impact of blockchain.

It is important that blockchain developers, users and regulators work together to address these ethical challenges. This will ensure that blockchain technology can be used responsibly and sustainably in the future, and that its impact on society is positive and beneficial for everyone involved.