​​Basic information

Namecoin is a distributed name index and cryptocurrency, based on and secured by Bitcoin's open-source blockchain technology. The codebase and all consensus rules are defined by the Namecoin Core wallet, which is used for currency- and name-transactions as well as for mining blocks and data queries on the blockchain.

Namecoin is primarily designed as an alternative Domain Name System (DNS). As a decentral and censorship-resistant key/value store, it allows any record on the blockchain, such as blockchain domains, Non-Fungible Tokens (NFTs) and whatever data up to a size of 255 bytes for the key (255 characters, e.g. the domain name) and additional 520 bytes for the value (520 characters, e.g. the DNS configuration of a domain).

In total a key/value pair can contain 775 bytes or 775 characters (see record with TxID b5a1d922cb66299ced3856b8b112201f798b81dee31a4483e935f43866bb5554 as an example). Every record on the blockchain is cryptographically secured. With the private key of the specific record the owner can generate a signature for electronic data such as text documents or login tokens. With his signature, the ownership and identity can be verified by everyone through the Namecoin software wallet, e.g. for granting access or just for verifying the data integrity of documents such as e-mails.

In April 17, 2021 at 00:30:02 (GMT/UTC) we mined block 554960. So including the Genesis block, we got 554,961 confirmations of block 0. During these 10 years, a total of 5,584,201 TxIDs (transactions) were written to the blockchain, including the so-called Coinbase transactions for newly mined blocks that credit the miner's wallet with the reward. Subtracting the Coinbase transactions, 5,029,240 TxIDs were issued, so 5 million transactions for transferring coins and creating and updating names. On average, these are 10 TxIDs per block including the Coinbase transactions (or 9 TxIDs per block excluding the Coinbase transactions) and 152 blocks per day over the last 10 years.

While a normal centralized database on a local server is built with tables, the blockchain is a kind of database built from blocks, with a maximum size around 1 MB for Bitcoin and Namecoin. For data integrity, a hash is calculated from each block, which is then the basis for the next block header. Thus, all blocks are chained immutable one after the other. Manipulating a single bit in the chain would cause the following blocks to become invalid.

For more details, please refer to section Data structure and integrity.

More interesting facts

• For normal name transactions we have in general two inputs (coming from previous TxIDs) and two outputs for the next transactions (each time one for the name operation and one for the remaining funds of the wallet).

• We have 2 historical TxIDs with the maximum of each 863 inputs (such as TxID 3780a5ea5e5b269c073c335c0d186a5d3df621fe2582998eeb939398b29b045a at block 389,582)

• SegWit (Segregated Witness), a method of handling the signatures of the transactions, has been implemented with Namecoin Core version 0.18, coming along with the new Bech32 address format (see the discussion in the GitHub repository in May 2019). This original Bitcoin soft fork had been proposed in December 2015 in BIP 141, with the goal to increase the possible number of transactions per block and to ensure the transaction malleability. Although the size of a Namecoin block has never been too small to capture all the transactions of the miners' mem-pool (pending transaction queue), the Namecoin code is up to date with the Bitcoin code. In the historical records there have been just 18 TxIDs with a total of 2650 outputs, such as TxID 5875a0009b158f594d14a164e4b035355372c7a5c70c0acb2654c3eb1f92c61c at block 99,489 seen in March 2013.

• At block 19,200 in October 2011 merged mining was introduced, as originally proposed by Satoshi Nakamoto, the inventor of Bitcoin.​This enabled parallel mining along with SHA-256 encoded currencies such as Bitcoin. Namecoin is being mined for free in parallel mode at this point, it took a few month, until the last miners were configured for combined mining. Due to merged mining the hashing rate is almost equal to BTC and thus unreached by any other SHA-256 encoded coin. In September 2021 the hashrates (given in Exahash per second, 1 EH = 1.000.000 TH) are 93 EH/s for Namecoin and 121 EH/s for Bitcoin.

• Due to inadequate coinbase data we have 52 historical double/multiple TxIDs, which aren't indexed in the known blockchain explorers. The latest double TxID appeared in June 2013. This issue was then resolved with BIP 30 and BIP 34. See the affected TxIDs below:

The worst example was TxID 69e18202f4f3f7db607db9109d8be04712ea6bad191ecc68afe0f52a930eee1f with address NBoJMzHJ8QXe3qUUBZDH8518bbPB4qZMpt and 30 duplicates:

Blockchain security

Bitcoin and Namecoin are secured by the well-known Proof-of-Work (PoW) consensus mechanism that miners have to meet before the block hash is accepted by the network. For resolving the proof-of-work and completing the current block with the block hash, the miner or mining farm that solved the block receives newly issued coins. This is why the process is called mining, because this is how the digital coins are created. The process of generating the block hashes is performed by so-called ASICs, which are Application-Specific Integrated Circuits designed specifically to execute the crypto hash algorithms. The proof-of-work consensus mechanism was defined under the assumption that the majority of the mining community, which verifies transactions in an honest way without manipulating the transaction history, has the higher hashing power than potential fraudsters. On April 12, 2009, Satoshi Nakamoto wrote to Mike Hearn, one of the original code contributors:

...the value that could be stolen should always be smaller than the amount of effort required to steal it.

In addition to the proof-of-work consensus mechanism, a target block time of 10 minutes was defined by Bitcoin's creator Satoshi Nakamoto as a measure against inflation, otherwise all 21 million Bitcoins would have been mined all at once. To keep the blocktime at the target of 10 minutes on average the difficulty of the proof-of-work is adjusted automatically by the Bitcoin network, according to the available total hashing power. This blocktime varies at the Namecoin blockchain between 1 minute and 1 hour, dependent from the computing power of the connected mining pools.

The difficulty to generate a blockhash is defined by the specification of appearance of the blockhash. While a usual hash of a 1 MB block is being calculated within nano seconds, it is defined, that the block (in merged mining only the parent block e.g. of the Bitcoin blockchain) has to start with a defined number of leading zeros. Therefore the block gets a separate data field for random data called the “nonce”, where a 4 Byte random string has to be inserted until the blockhash gets the demanded number of leading zeros. The task of this proof-of-work is to find this nonce until the hash meets the actual difficulty. With each additional leading zero the difficulty gets doubled. The Bitcoin consensus rules define the difficulty each 2016 blocks, requiring one more leading zero for the blockhash for increasing the difficulty or one zero less for the decrease of the difficulty. In September 2021 a Bitcoin hash has 19 leading zeros.

Namecoin is still capable of solo mining and has implemented the same difficulty adjustment mechanism. However, since the Namecoin blockchain is only built via merged mining nowadays, the block time is dependent on the parent chain like Bitcoin or Bitcoin Cash.

As another mechanism to avoid inflation, “bitcoin halving” is automatically performed every 210,000 blocks, where the miner's reward for completing a block is halved, which is independent of the difficulty adjustment mechanism:

Since Namecoin uses Bitcoin's source code, its halvings are performed at the same switching points every four years: