Hey Meet, great questions—let's unpack crypto wallet logic from the ground up, since understanding keys, verification, and multi-coin management all tie together. I'll break this down into clear, actionable sections so you can wrap your head around it.

1. Private Key vs Public Key: The Core of Your Wallet #

Let's start with the basics, because everything else builds on this:

• Private Key: This is a randomly generated 256-bit string (or a mnemonic phrase that maps to it) that's your only proof of ownership over your crypto. Think of it as a super-secret password that you must never share or lose—if you do, you'll lose access to your funds forever.
• Public Key: Derived directly from your private key using an asymmetric encryption algorithm (most commonly ECDSA for Bitcoin/Ethereum). It's completely safe to share publicly—this is what others use to send you crypto.
• Public Address: A shorter, user-friendly version of your public key, created by hashing the public key (e.g., SHA-256 followed by RIPEMD-160 for Bitcoin). Addresses have built-in checksums to prevent typos, which we'll cover next.

2. How Wallets Verify Public Addresses and "Users" #

Crypto doesn't have traditional "user accounts"—it's all about cryptographic proof. Here's how verification works:

Verifying a Public Address's Validity #

When you enter a recipient's address into a wallet, it runs two quick checks:

• Format Check: Every cryptocurrency has a unique address format (e.g., Bitcoin starts with 1, 3, or bc1; Ethereum starts with 0x). The wallet first confirms the address matches the expected format for the coin you're sending.
• Checksum Verification: Most addresses include a small checksum (a few bytes derived from the public key hash). The wallet decodes the address, recalculates the checksum, and compares it to the one in the address. If they match, the address was generated correctly (no typos or tampering).

Verifying "Other Users" (Cryptographic Proof of Ownership) #

If someone claims to own a specific address, the only way to verify this is via a digital signature:

1. Ask them to sign a unique, random message (e.g., "I confirm ownership of address XYZ on 2024-05-20") using their private key.
2. Your wallet takes the message, the signature, and the public address, then uses the corresponding public key to verify the signature.
3. If the signature is valid, it proves beyond doubt that the person holds the private key for that address—since only the private key can generate a signature that the public key can validate.

For transactions, this logic is automated: when you send crypto, your wallet signs the transaction with your private key. The blockchain network (or your wallet, when previewing) uses your public key to confirm the signature is valid, ensuring no one else could have initiated that transaction.

3. How Coinomi Manages Multiple Cryptocurrencies #

Coinomi is a non-custodial multi-coin wallet, meaning it never holds your keys—it just manages them locally on your device. Here's its core workflow for multi-coin support:

Master Seed & Hierarchical Key Derivation #

• Mnemonic Phrase: When you set up Coinomi, you create a 12/18/24-word mnemonic phrase (following BIP-39 standards). This phrase is your master seed—all your keys for every coin are derived from it.
• Hierarchical Structure: Using BIP-32 and BIP-44 (or variants like BIP-49 for segwit addresses), Coinomi creates a tree of keys:

  m / purpose' / coin_type' / account' / change / address_index
  

  Each cryptocurrency gets its own unique coin_type' value (e.g., Bitcoin = 0, Ethereum = 60, Solana = 501). This means your single mnemonic phrase generates unique, isolated key pairs for every coin you use—no need to back up separate keys for each.

Local Storage & Network Integration #

• Key Storage: All keys are stored locally on your device (encrypted with a password you set). Coinomi never sends your mnemonic or private keys to its servers.
• Blockchain Sync: For each coin, Coinomi connects to the relevant blockchain's nodes (either its own infrastructure or public nodes) to fetch your balance, transaction history, and broadcast outgoing transactions. Each coin's data is tracked independently, since blockchains are separate networks.

Token Support (e.g., ERC-20, BEP-20) #

For tokens built on top of a blockchain (like ERC-20 tokens on Ethereum), Coinomi uses the same key pair as the underlying blockchain. Since tokens live on their parent chain, you don't need new keys—your Ethereum key pair gives you access to all ERC-20 tokens you hold.

4. Full Wallet Workflow Recap #

To tie it all together, here's how a wallet like Coinomi works end-to-end:

1. Setup: You create a mnemonic phrase, which generates a master seed.
2. Key Generation: The wallet derives a master private key, then uses BIP standards to create unique key pairs for every supported coin.
3. Receiving Crypto: You share your public address; senders initiate transactions to it. The wallet syncs with the blockchain to detect incoming funds.
4. Sending Crypto: You enter a verified recipient address, input an amount, and the wallet signs the transaction with your private key. It then broadcasts the signed transaction to the blockchain.
5. Verification: At every step, the wallet uses cryptographic checks to confirm address validity, signature authenticity, and transaction integrity.

内容的提问来源于stack exchange，提问作者Meet Patel