# Overcoming the Technological Barriers in the Blockchain Supply Chain for Small Carriers
## 2 Related Work  
### Blockchain Technology  
Blockchain technology is not a single concept. It combines several concepts, such as cryptography, mathematics, networks, consensus principles, and algorithms [16]. The idea was first mentioned in the context of the cryptocurrency Bitcoin. [PERSON] [17] proposed the concept of a decentralised digital currency, Bitcoin, supported by a decentralised payment system. This concept allows peer-to-peer (P2P) transactions without a centralised authority. Bitcoin and all other current cryptocurrencies are based on blockchain technology. Blockchain is a fully distributed system for cryptographic recording and storing a consistent, immutable, linear record of transactions between network participants. Functionally, it resembles a distributed ledger, consensually managed, updated, verified, and validated by individual participants for all transactions executed [18]. [PERSON] et al. [19] consider blockchain a digital data storage concept. Where data can be, for example, a list of transactions, documents, or other valuable data that can be recorded, this data is stored in blocks. Blockchain is thus the concatenation of consecutive blocks of transactions. Further, the authors [20] defined blockchain as follows: a distributed database shared and agreed upon in a peer-to-peer network. It consists of a linked sequence of blocks that store time-stamped transactions encrypted with public-key cryptography and verified by the network community. Once a block is added to the blockchain, it cannot be changed, turning it into an immutable record of past activity. As mentioned above, the basis of blockchain technology is distributed ledger technology [21]. This provides a mechanism for verifying consensus through a network of computers. Such a network can also be referred to as a blockchain network. It is an interconnection of many computers, each with a copy of the ledger. A network formed in this way allows transactions to be carried out more easily and quickly without needing an intermediary or centralised authority [19]. Blockchain consists of blocks with a growing list of executed records (transactions). It is thus a continuously emerging chain of blocks. The blocks are linked using cryptography and hashing functions to prevent data tampering. Since all the blocks are decentralised and distributed, it is impossible to change any block without affecting all the others [22]. After successfully executing the data transactions, the valid transactions are encrypted and encoded into the Merkle tree in the block. New blocks are added to the chain so they do not overwrite the old ones already added but are appended to them [23]. The system works by distributing a copy of the database, or a partial copy, to each party. That party can then change the database according to mutually agreed-upon rules. The changes made by each party are collected and stored in the database in blocks at regular intervals [24]. If some participant wants to add a transaction to the ledger, the transaction must be shared on a peer-to-peer (P2P) blockchain network. All members keep a copy of the ledger. It is verified because participants sign transactions using public and private key cryptography before sharing them on the network. Therefore, only the owner of the private key can initiate them. Participants can be transparent while remaining anonymous because keys are not associated with real-world identities [25]. Blockchain technology presents the following advantages: anonymity--the blockchain is anonymous and can be freely connected, which means that individual parties can communicate freely. Data immutability--once data has been sent, it cannot be changed. At the same time, guarantees of integrity are not provided by a centralised party (authority, entity, etc.) but by the consensus of the entire network. Non-censorship--since the stored data cannot be changed, removed, or replaced, censorship (as in a centralised system) cannot be applied [26].