Important Notes

(1). Please use Firefox browser. You can download and install the enterprise version Firefox-ESR here. Firefox is open-source software, making it extremely difficult to contain backdoors.

(2). Always use Firefox's Private Window (launch by pressing Ctrl+Shift+P after starting Firefox). All browsing traces will be destroyed after closing the Private Window, ensuring your private keys remain absolutely secure.

(3). When generating wallets, recovering wallets, or signing transactions, always disconnect the browser from the internet (Press Alt key, then click "File" in the top-left corner, and select "Work Offline"). This guarantees your private keys cannot be leaked through network transmission.

(4). When copying and pasting private keys, use the three-segment method: First copy-paste one segment, then manually type the next few characters, and finally copy-paste the remaining characters. This prevents clipboard-monitoring spyware from stealing your complete private key. Reference example below:

1. Trading Introduction

Let's begin with a story. John saved some money after years of work but found no good investment opportunities domestically. "At the very least, I should preserve the value of my hard-earned money," John pondered, ultimately deciding to invest all his savings in cryptocurrency. Hearing that one Bitcoin could buy an apartment in a second-tier city within five years, he chose to purchase Bitcoin.

First, John needed a Bitcoin wallet. He registered an account on a cryptocurrency exchange, which automatically provided him with an online Bitcoin wallet (let's call it Wallet A), and later acquired an offline wallet (Wallet B). John bought Bitcoin through Wallet A and transferred his holdings to Wallet B once they reached a certain value (say, $30,000 equivalent), since Wallet A on a third-party platform was less secure than Wallet B which only he controlled. When selling Bitcoin, he would first transfer from Wallet B back to Wallet A before selling on the platform. Beyond online trading, peer-to-peer transactions were another option - like when John bought Bitcoin directly from acquaintance Jack via WeChat Pay, with Jack sending the coins straight to John's Wallet B.

Through this website, you can not only obtain Wallet B but also learn how to: send coins peer-to-peer, find where to get Wallet A, locate local cryptocurrency sellers, and more...

In China, investing in cryptocurrencies is one of the best ways for the poor to become rich. By late 2024, one Bitcoin was worth $100,000 - enough to buy an apartment in third-tier cities. We're confident that in five years it'll buy homes in second-tier cities, and in ten years, first-tier cities! Excited? If so, keep reading.

So how exactly do you trade cryptocurrency? Stay tuned for our next chapter... just kidding!

First, you'll need at least one cryptocurrency wallet with its unique address. When buying coins, you'd provide this address saying "Please send coins here!" The seller might cautiously reply "Triple-check this address - wrong transfers are your responsibility!" After repeatedly verifying, you'd confirm "Address is correct, don't worry bro!" After transfer, you can check receipt on blockchain explorers like https://blockchair.com/.

As you accumulate coins and watch prices soar daily, you'll calculate your growing wealth. Gradually escaping your underdog status, one day you'll finally make it - perhaps exclaiming: "Damn, I love this crazy world! Let's toast to our mortal lives!"

How to actually buy cryptocurrency? Patience... Imagine approaching a mysterious cabin on a dark, windy night... just kidding again!

Your wallet contains a private key. When selling coins, you'll initiate a transfer transaction signed with this private key, then broadcast the signed transaction to the network. Miners will include it in a block - usually completing within minutes. Higher transaction fees (paid in crypto, not actual dollars) grant priority. Currently miners care more about block rewards than fees. You set the fee (typically under $1 equivalent) - unrelated to transfer amount. I once paid just $0.40 equivalent (about 400 satoshis at 100,000 satoshi/$1) for a speedy transaction. Example transaction data: Recipient's address: xxxxx, Amount: 30,000,000 satoshis (0.3 BTC), Fee: 1,000 satoshis.

Addresses derive from private keys but cannot reverse-engineer them. Never share your private key - it's the sole access to spend your coins!

How to get a wallet? See "Wallet Management" below. How to initiate transactions? Click "Offline Signing" and "Broadcast Transaction".

2. Cryptocurrency Wallets

2.1 Private Keys

A private key IS your cryptocurrency wallet! Essentially, it's a 256-bit random binary number. Imagine flipping a coin where heads=1 and tails=0 - if you record 256 consecutive flips, you've created a valid private key, like this example:

I actually tested this coin-flip method myself, generating this binary sequence: 1100111101001101000100000011000011111110110011100001000001110001101101110011001001000110011110010011110100000110110100111101000010001110101011010011100001010100100000011110111000101000110010111111011110110010001010000101100101110111001001111001100011010001.

Since 256-bit binary is hard to remember, we convert it to hexadecimal. My coin-flip key becomes: cf4d1030fece1071b73246793d06d3d08ead385481ee28cbf7b22859772798d1. "Seriously? That's still impossible to memorize!" "Dude, just write it down!"

Written on paper, it's a paper wallet; memorized, it's a brain wallet; stored digitally, an electronic wallet. Both Bitcoin and Ethereum use 256-bit private keys, meaning one key could technically control both assets - but I strongly advise against this. If you lose the key, game over for all associated coins. If compromised, all assets are at risk.

Bitcoin experts recommend: Use a unique private key for every incoming transaction! Receive 3 BTC from John? Use key X. Get 5 BTC from Jack? Use key Y. Wang Er sending coins? Generate another new key. My practical advice: Follow this for large transactions, but use fewer keys for small amounts to avoid management headaches.

For easier wallet integration, Bitcoin converts hexadecimal keys to Base58-encoded WIF (Wallet Import Format). My coin-flip key in WIF becomes: L4AgDeoTPbdRd4S7X9UhXaNtyxZhDuj7EoUxPUndDYkvfmHjR8Cd. The binary, hexadecimal, and WIF formats are interchangeable. Ethereum only uses hexadecimal format. Important note: Hexadecimal is case-insensitive, but WIF is CASE-SENSITIVE!

NEVER share your private key - it should be known ONLY to you! (Well... maybe share with family as contingency planning, unless you want your crypto to die with you... just saying.)

In practice, we generate keys programmatically rather than coin-flipping. For deeper exploration of private keys, check out our new book The Definitive Guide to Cryptocurrency Secure Trading in Practice available on my personal site (https://www.veryopen.org).

2.2 Addresses

A wallet address is derived from a public key, which in turn is generated from a private key. However, it's impossible to reverse-engineer the public key from an address or deduce the private key from a public key. You can freely share your address with others to receive cryptocurrency, similar to providing your shipping address for online purchases. Different cryptocurrencies use different methods to derive addresses from private keys, resulting in distinct address formats. For example, Bitcoin and Ethereum addresses generated from the same private key will be completely different - a Bitcoin address cannot receive Ether, and vice versa. Sending coins to the wrong address type will result in permanent loss!

Even within the same cryptocurrency, multiple address types may emerge over time. Bitcoin currently has several address types in chronological order: P2PK, P2PKH, P2SH, P2WPKH, and P2TR (introduced in 2021). P2WPKH is currently the most popular due to smaller transaction data size and lower fees. P2SH and P2TR support multisignature transactions, ideal for organizational use cases requiring multiple approvals - for example, a company requiring signatures from the CEO, CFO, and accounting manager to authorize payments.

The same private key can generate all address types. For instance, I can derive all Bitcoin address formats from one private key. When transacting, I provide the most advanced address type the recipient's wallet supports. If John's wallet handles P2WPKH, P2SH, and P2PKH, I'll share my P2WPKH address. For Jack's wallet that only supports P2PKH and P2PK, I'd provide the P2PKH address instead. Older wallets may not support newer address types.

Example Bitcoin addresses derived from my earlier coin-flip private key (L4AgDeoTPbdRd4S7X9UhXaNtyxZhDuj7EoUxPUndDYkvfmHjR8Cd), generated using our open offline wallet's "Bitcoin > Wallet Management > Derive Public Key and Address" tool:

I've omitted P2PK addresses as they're obsolete. P2PKH and P2SH addresses use Base58 encoding with case-sensitive characters, while the last three types use Bech32 encoding (all lowercase).

Ethereum uses a single address format like 0x2e8681f8e38726D6C99009A4d724651Ff611fB27. Ethereum Name Service (ENS) - similar to DNS for websites - maps human-readable names (e.g., abc.eth) to Ethereum addresses. Instead of sharing complex addresses, you can provide your ENS domain (e.g., "Send to abc.eth"). Register your ENS domain at https://app.ens.domains/ (detailed instructions in my book The Definitive Guide to Cryptocurrency Secure Trading in Practice. As Ethereum becomes more widely adopted, short ENS domains may become valuable digital assets.

2.3 Wallet Balance

Ethereum has a concept of account balance, but Bitcoin doesn't maintain balances in the traditional sense. The "balance" shown in Bitcoin wallet apps is dynamically calculated - it's the sum of all unspent transaction outputs (UTXOs) you've received. To better understand how this works, let's examine an example:

Suppose your address has received two transactions: 1 BTC from John and 0.5 BTC from Jack, making your wallet balance 1.5 BTC. Now you want to send 0.7 BTC to Alice. This would require spending John's original 1 BTC transaction. You'd create a transaction with these details:

After signing this transaction with your private key and broadcasting it, John's original transaction is marked as spent. Your wallet now shows a new balance of 0.79999 BTC (Jack's 0.5 BTC plus your 0.29999 BTC change).

Could you have spent Jack's 0.5 BTC instead? No, because it's insufficient. However, you could combine both inputs (1.5 BTC total) and send the difference (0.79999 BTC) back to yourself (typically to a different address for fund consolidation).

In summary, a Bitcoin wallet balance is simply the sum of all unspent transaction outputs (UTXOs) associated with your addresses.

3. Offline Transaction Signing

All cryptocurrency transactions must be digitally signed before being broadcast to the network. Miners verify these signatures before including transactions in blocks - unsigned or invalid transactions are immediately rejected. To create a valid transaction, you must specify:

For Bitcoin:

For Ethereum (which uses account balances):

Since signing requires your private key, online signing methods (like exchange platforms or mobile wallets) risk private key exposure. Our open offline wallet allows secure signing in air-gapped environments, ensuring absolute private key protection!

4. Private Key Management

Given the critical importance of private keys, their secure management remains a paramount concern for all cryptocurrency users. A forgotten private key means permanent loss of assets, while a compromised private key equals stolen funds.

4.1 Private Key Encryption

To prevent theft, private keys can be encrypted - creating ciphertext private keys. Even if someone obtains the encrypted version, without the decryption password they cannot access the actual private key or initiate transactions (as miners reject all unsigned transactions). The encryption password (similar to online banking passwords) typically consists of 7-8 memorable characters. The encrypted private key can then be safely stored on paper, computers, USB drives, cloud storage, or email.

Warning: Simple passwords (like "123456") create significant risk, especially for cloud-stored keys. We recommend passwords with:

Our Open Offline Wallet's "Private Key Protection" tool handles encryption/decryption and supports direct signing with encrypted private keys (temporarily decrypting during signing).

4.2 HD Wallet

An HD wallet can generate a large number of private keys and is easy to remember and manage. It fulfills one of the recommendations in The Definitive Guide to Cryptocurrency Secure Trading in Practice: use a separate private key for each transaction. As the number of transactions increases, the number of private keys used also rises significantly. Encrypting each private key individually becomes time-consuming and labor-intensive, and this is where HD wallets come into play. An HD wallet, or Hierarchical Deterministic wallet, is based on the core idea of deriving a large number of wallets from a set of words (seed phrase) according to a wallet path, as illustrated below.

Once the random number is determined, the mnemonic phrase is fixed. The mnemonic phrase + password uniquely determines the seed, and the seed uniquely determines the root private key (m). From there, the wallet path determines each private key. Whether a password is used or not, and what password is used, the seed derived from the same mnemonic phrase will be entirely different. The path from the root (m) to the 5th level is referred to as the Bitcoin HD wallet path, with the following format:

Wallet paths exceeding 5 levels are non-standard and may not be supported by many wallet apps. However, our "Open Offline Wallet" supports non-standard paths. The standard wallet path format for Bitcoin's P2WPKH type is "m/84'/0'/i'/x/j," while Ethereum's HD wallet path format is "m/44'/60'/i'/x/j." Here, the values of i and j range from [0, 2147483647]. When x = 0, it represents the (j+1)th external wallet of the (i+1)th account; when x = 1, it represents the (j+1)th internal wallet of the (i+1)th account. External wallet addresses are public, allowing others to send coins to them, while internal wallet addresses are kept private and known only to the owner. For example, the Bitcoin wallet path "m/84'/0'/1'/0/3" refers to the 4th external wallet of the 2nd account, while "m/84'/0'/1'/1/3" refers to the 4th internal wallet of the 2nd account. Since cryptocurrencies currently exist in a legal gray area in almost all countries, many cryptocurrency investors prefer not to expose their privacy, even avoiding publicizing wallet addresses. A common practice is to publish an external wallet address and transfer accumulated coins to an internal wallet once a certain amount is reached, while keeping only a small amount in the external wallet. As previously mentioned, a private key is equivalent to a wallet. Now, we only need to remember a set of words, known as the mnemonic phrase. The number of words in a mnemonic phrase can be 12, 15, 18, 21, or 24. The more words there are, the harder it is for others to guess, making your HD wallet more secure. For example, "asset curve boss naive trade never sister evoke what lunch glory update course acquire first mistake solve bullet pipe practice husband round glow wing" is a 24-word mnemonic phrase. Mnemonic phrases cannot be manually specified by users because the last word contains a checksum of the preceding words. This open offline wallet provides a feature to customize mnemonic phrases (under "Tools > Custom Mnemonic"), but it is not advisable to specify too few words, as this makes it easier for others to guess. If you want to understand the mechanism behind mnemonic phrase generation, please refer to our book The Definitive Guide to Cryptocurrency Secure Trading in Practice When deriving an account from a mnemonic phrase, a password can be added, ensuring that even if someone obtains your mnemonic phrase, they cannot access your accounts without the password.

When generating an HD wallet, you need to specify the wallet path. To restore an HD wallet, you must input the mnemonic phrase and wallet path. If a password was set, it must also be provided. For example, two years ago, I used the mnemonic phrase "poem crater dove table knock moment raccoon scrub color raccoon figure stumble" with the password "A1b2C3&" to derive a wallet with the path "m/84'/0'/5'/0/2" and had Zhang San transfer 3 Bitcoins to it. At the time, I noted the following on paper: "poem crater dove table knock moment raccoon scrub color raccoon figure stumble | m/84'/0'/5'/0/2," while the password was one I frequently used and memorized.

Now, if you want to spend these funds, you must recover the private key from the mnemonic phrase. To do this, go to "Bitcoin > Wallet Management > Create/Restore Wallet" in the open offline wallet, enter the mnemonic phrase "poem crater dove table knock moment raccoon scrub color raccoon figure stumble," the password "A1b2C3&," and the wallet path "m/84'/0'/5'/0/2." Then click the "Restore Wallet" button to reveal the private key "KyPwsvn7cPoCoyujACRUz4m5SsH9tYaYv6JTm4YAu1XBMfH1fs17." Once you have the private key, you can initiate and sign transactions.

You might think, "Why not just memorize the private key instead of restoring it from the mnemonic phrase every time?" That's correct—if a wallet is used frequently, memorizing the private key separately is a good idea, as frequent use of the mnemonic phrase increases the risk of exposure. The mnemonic phrase is the lifeline of all your wallets. However, we recommend encrypting the private key before memorizing it.

5. Best Practices

These are purely our summarized experiences and do not represent the optimal or the only methods. They are provided for reference only.

(1) For ordinary users who only buy/sell cryptocurrencies with low transaction frequency (rarely exceeding 10 times a year) and whose crypto assets are below one million, we recommend using just one private key. Protect the private key with a password, then derive both a Bitcoin P2WPKH and P2PKH address from it, as well as an Ethereum address.

(2) For users with crypto assets between one million and ten million and low transaction frequency, we recommend using a single mnemonic phrase (containing 18 or more words) protected by a password. Use this mnemonic to derive a Bitcoin HD wallet with an external wallet path like "m/84'/0'/i'/0/j" (i.e., the (j+1)th wallet in the (i+1)th account). Only create 1-2 accounts, with 2-3 wallets per account, along with a few internal wallets. Additionally, set up a few Ethereum external wallets with paths like "m/44'/60'/i'/0/j" (where i and j have the same meaning as in Bitcoin) and a few Ethereum internal wallets with paths like "m/44'/60'/i'/1/j".

(3) For heavy cryptocurrency investors with assets exceeding tens of millions, hundreds of millions, or even billions, use a separate mnemonic phrase (containing 24 words) for each cryptocurrency. Protect each mnemonic with a strong password (at least 15 characters long, including uppercase/lowercase letters, numbers, and special symbols). Use 3-5 accounts per cryptocurrency, with multiple external and internal wallets in each. Plan account and wallet usage carefully—each large transaction (over ten million) should use a dedicated wallet for receiving funds. The private keys of these wallets must be encrypted, and signing transactions should be done using the encrypted private key and password (temporarily decrypting the private key for signing).