Blockchain technology related to Season’s Greetings Card NFTs

Mainnet, testnet, and private network

Ethereum mainnet is the primary public Ethereum blockchain, where
actual-value transactions occur. In addition to mainnet, there are public test networks which are networks used by Ethereum developers or smart contract developers to test both protocol upgrades as well as potential smart contracts in a production-like environment before deployment on the Mainnet. In contrast to the mainnet and testnets, a private network is one where nodes are running in an isolated environment detached from the public network.

Different networks are partitioned with different chainIDs; the chainID of the Ethereum mainnet is 1, the chainID of the Goerli testnet is 5, and our private network’s chainID is 703. Different networks have different native cryptocurrencies and tokens. Ethere (ETH) is the native cryptocurrency of the main Ethereum network, In our case, the network is different and it is called ‘UZH-Ethereum’ with the native cryptocurrency called ‘UZETHs’. Please note that UZETHs has no value on the Ethereum main network, therefore, there are no markets for trading it. You can create several addresses in your MetaMask wallet, and these addresses will work across different networks, but your balance and transaction history can just exist in one network. For instance, the UZETHs you got in our UZH Ethereum network (called UZHETHPoS) and the transactions you made here will just exist in this network, it will not exist when you switch to the mainnet.

The Private key, Public key, and Address

Private key

Ethereum is using public key cryptography to keep the security of your crypto assets and the privacy of your identity. These keys are based on mathematical functions that have a special property: it is easy to calculate them, but supper hard to calculate (guess) their inverse. Keys come in pairs consisting of a private key and a public key. The private key provides control over the account, and it must be kept private, otherwise, you will lose access to your funds if your private key is lost. You can think of a private key as a PIN to get access to your Ethereum account.

Public key

The public key is calculated from the private key using an elliptic curve multiplication, which is irreversible, you can freely share your public address with others.


Ethereum addresses are unique identifiers that are derived from public keys using start with “0x”, followed by 40 characters/numbers, for example, 0x147899f0856C60C23187a4bD3fB48DDDB7023905. Transactions in blockchain are used for transferring cryptocurrencies from one address to another, which can include transferring different token types or invoking smart contracts.

Transaction fees

Each transaction will pay the transaction fee, which is used to pay validators for the resources needed to verify transactions. The fees in Ethereum are charged in a virtual currency called gas, gas is the fee required to successfully conduct a transaction on the Ethereum blockchain. Users pay for the gas with ether, as part of the transaction. The transaction fee is calculated by the Gas. “Gas price” is the price per unit of work done and is priced in gwei (1 gwei=10-9 Ether). The lower the transaction fee, the longer time it takes for your transaction will be confirmed in the network.

Blockchain explorer

Blockchain explorer is a web page for visualizing blocks, transactions, and blockchain network metrics. Where you can see the entire transaction history of the blockchain and you can explore the transaction history of any address. We will use as our private blockchain explorer, which means you can view transactions in this explorer.