# Glossary

Due to the complexity of industry terminology, we have prepared technology and terms explainers for terms.

# e-Delivery

According to the Connecting Europe Facility (CEF), eDelivery is a network of nodes for digital communications. It is based on a distributed model where every participant becomes a node using standard transport protocols and security policies. eDelivery helps public administrations to exchange electronic data and documents with other public administrations, businesses, and citizens, in an interoperable, secure, reliable and trusted way. It is one of the building blocks of the Connecting Europe Facility (CEF). These building blocks are reusable specifications, software, and services that will form part of a wide variety of IT systems in different policy domains of the EU.

# Blockchain

Blockchain provides a decentralized and secure shared digital ledger, which gives participating parties a way of validating information related to a transaction. In doing so, it speeds up the process and cuts out intermediaries and costs. Blockchain is made from a trail of validated facts. These facts can be anything from money to information. As part of this digital system of record-keeping, each transaction and its details are validated and then recorded across a network of computers. Everyone who has access to the distributed ledger receives this information and the parties agree on the accuracy before the block is replicated, shared and synchronized among the entities. A Blockchain is virtually impossible to tamper with since each block of information references the block before it. In an age when trust is both elusive and held at a high premium, Blockchain presents a way to confirm, validate and authenticate both values and events.

# Smart Contracts

Smart contracts are codes or rules written into a digital program, which determines what happens when digital assets come in or when certain conditions are met.

# Blockchain e-Delivery

Blockchain eDelivery can be described as a network of nodes for digital communications and electronic data and document exchange. It is based on a decentralised model where the electronic data and document exchange process runs between blockchain wallets. Private and public cryptographic keys are used for transaction authentication. Due to decentralization, blockchain eDelivery has significant security advantages, compared to traditional eDelivery.

# Blockchain Wallet

A cryptocurrency wallet is a device, program or service which stores the public and/or private keys and can be used to track ownership, receive or spend cryptocurrencies. As all cryptocurrencies run on blockchains, cryptocurrency wallets can be referred to as blockchain wallets. Up to now, blockchain wallet was mostly used for cryptocurrency asset holding and exchange. The 4thTech wallet is a Google Chrome and Mozilla Firefox extension wallet that allows you to visit the distributed web of tomorrow in your browser today. It is one of 4thTech innovations, a first wallet system on the market capable of handling not only digital assets but also dMails and dChats.

# RSA & AES Encryption

RSA is one of the first public-key cryptosystems and is widely used for secure data transmission. In such a cryptosystem, the encryption key is public and distinct from the decryption key which is kept secret (private). In RSA, this asymmetry is based on the practical difficulty of factoring the product of two large prime numbers, the "factoring problem". FOURdx dMail Protocol uses the advanced encryption standard (i.e. AES), with a combination of RSA encryption algorithms. The dMail data files are first encrypted with a symmetric algorithm (i.e. AES). The asymmetric algorithm (i.e. RSA) is used to encrypt symmetric key and initialization vector (i.e. IV) with the public key of the receiver. This design does not allow an attacker to infer relationships between segments of the encrypted message.

# SHA-256

SHA-256 or Secure Hash Algorithm 256 is defined as one of the most secure ways to protect digital information. SHA-256 is a mathematical process that generates a 256 bit (64 characters long) random sequence of letters and numbers (hash) out of any input.

# Hash

Hash is a mathematical computer process that takes information and turns it into letters and numbers of a certain length. Hashing is used to make storing and finding information quicker because hashes are usually shorter and easier to find. Hashes also make information unreadable and so the original data can become confidential.

# Checksum

A checksum is to prevent accidental changes. If one byte changes, the checksum changes. It is pretty hard to create a file with a specific cryptographic hash.

# Docker

A Docker container image is a lightweight, standalone, executable package of software that includes everything needed to run an application: code, runtime, system tools, system libraries and settings (What Is a Container? | App Containerization | Docker, n.d.). Docker plays a vital role when developing blockchain applications and acts as an important tool; (1) when creating distributed applications locally, and; (2) providing automatization to reduce time spent on error-prone steps during deployment and testing (Docker Usage in Blockchain. Docker Is the Single Most Important… | by Johannes Bertens | Oneupcompany | Medium, n.d.). During the 4thtech research testing, Docker and Kubernetes performed without any issues on the same server. In the Docker case, conflicts can appear in the case of the same port usage if running multiple containers on the same machine. When dealing with blockchain and different container software interoperability, numerous use-cases have proven the interoperability between blockchain and Docker container software, but the blockchain interoperability with different container software remains an open issue.