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Have you ever wondered why ERC20 addresses are universal across multiple chains?

Especially when you ask your good brother what chain to withdraw funds from, what's going on? Let me explain it to you.

Generation of Address

1. Generation of Mnemonic

Let's first take a look,

  1. First, generate a series of 0s and 1s (a total of 128 bits, known as entropy in cryptography, meaning 'random data') through a random number generator. We know that humans cannot remember this kind of data, but computers can.

  2. Add a checksum to this 128 random number (which is actually done using SHA-256 for hashing, adding the first four calculated digits to the end of this 128 bits, resulting in 132 bits).

  3. Then divide this 132 bits into groups of 11 bits, resulting in 12 groups. Can we determine the range of integers from 0 to 2047? Why 11 bits? Because BIP39 mnemonic words consist of a fixed 2048 words.

  4. By looking up the above 12 arrays in the BIP39 mnemonic word dictionary, we can correspond the words one by one to form the familiar mnemonic, making it easier to remember.

The above image is simplified for understanding. We directly illustrated how the private key is generated from the mnemonic. In fact, there are many details inside, such as first generating a 512-bit seed using mnemonic + password (optional) through 2048 iterations of PBKDF2-HMAC-SHA512, then deriving the master private key, public key, etc., but we won't elaborate on this here.

The above image is a part that we have omitted, so we won't elaborate here, but directly show the image for everyone to reference:

  1. First, using the BIP32 standard, we can derive a 'key tree' from the seed.

  2. The root of the tree is the 'master private key'

  3. This tree can infinitely derive child private keys, grandchild private keys...

This way, we can generate countless addresses from a single mnemonic, which is the mechanism currently used by hardware wallets and HD wallets.

2. How to find the Ethereum private key on this tree?

The base is generated according to the standard derivation path (BIP44), and then the corresponding private key is found based on different paths for each chain, for example, the rule for Ethereum is: m / 44' / 60' / 0' / 0 / 0

These parameters are defined in BIP44, and through the above path, we generated our first Ethereum address. We can also derive different addresses using different paths.

3. Public Key, Address, Irreversible

Once we obtain the private key, we can quickly derive the public key and address, for example, the encryption algorithm used by Ethereum is secp256k1 elliptic curve encryption, which is also used by Bitcoin. This involves performing elliptic curve multiplication on the private key → resulting in a 64-byte public key.


So how does the public key obtain the address?

1. Remove the prefix from the public key (keep only 64 bytes)

2. Perform keccak-256 hashing on it (not SHA)

3. Take the last 20 bytes (40 hex characters)

4. Add '0x' → 0xAbC...456

4. Overall Process


Mnemonic

↓ (BIP39)

Seed

↓ (BIP32/BIP44)

Private Key (256 bits)

↓ (secp256k1)

Public Key (64 bytes)

↓ (Keccak-256 Hash)

Address (take the last 20 bytes and add the 0x prefix)



Why can an address be universal across multiple chains?

✅ Root Cause: Multiple chains use the same key algorithm and address format, private key → public key → address. This process is completed through cryptographic algorithms. Chains compatible with EVM (Ethereum Virtual Machine) almost all use the following combination:


📌 Therefore: As long as you are using the same private key, no matter which EVM chain you are on (Ethereum, Polygon, BNB Chain, Arbitrum, Optimism, Base...), the address you get will be the same. It's like using the same ID card to open an account in different provinces; the account number is the same, but each bank's ledger is independent.

Mnemonic / Private Key

|

↓ (Algorithm)

secp256k1 (EVM Chain)

|

0x123...abc ← Universal across multiple chains

/ | \

ETH BSC Polygon Arbitrum ...

vs

Ed25519 (Non-EVM Chain)

↓

Solana Address ≠ Sui Address ≠ Aptos Address