PDAs & Account Storage

Every tag registered on TIP is stored as an individual account on the Solana blockchain owned by the tip_registry program.

Seed Derivation Scheme

Tag accounts are Program Derived Addresses (PDAs). Because PDAs are derived deterministically without a private key, tag uniqueness is enforced directly by Solana runtime account initialization.

The PDA for any handle is derived using two seed byte arrays:

import { PublicKey } from "@solana/web3.js";

const [pda, bump] = PublicKey.findProgramAddressSync(
  [
    Buffer.from("tag", "utf-8"),
    Buffer.from(normalizedTag, "utf-8"), // e.g. "alice"
  ],
  PROGRAM_ID
);

On-Chain Account Layout

Each tag account stores a binary struct with the following layout:

// Rust Account Struct (programs/tip-registry/src/state.rs)
pub struct TagAccount {
    pub discriminator: [u8; 8],  // Anchor/Borsh 8-byte discriminator
    pub tag: String,             // Max 32 UTF-8 bytes (stored with 4-byte length prefix)
    pub owner: Pubkey,           // 32-byte Solana Public Key (Tag Owner)
    pub wallet: Pubkey,          // 32-byte Solana Public Key (Payment Destination)
    pub bump: u8,                // 1-byte PDA canonical bump
}

Field Definitions

1. discriminator ([u8; 8]): First 8 bytes of the SHA-256 hash of account:TagAccount. Ensures the account type cannot be confused with other program accounts.
2. tag (String): The canonical normalized handle (e.g., "alice").
3. owner (Pubkey): The wallet that registered the tag. Only this pubkey can sign transactions to update wallet.
4. wallet (Pubkey): The target address where funds should be delivered when sending tokens or SOL to @alice. Defaults to owner at registration.
5. bump (u8): The canonical bump seed that places the derived address off the ed25519 elliptic curve.

Rent Exemption

Registering a tag deposits a small amount of SOL (approx. 0.0016 SOL) to cover the account's rent-exempt storage fee. This SOL remains stored in the tag's PDA account on-chain.

By default the owner's wallet pays this deposit. The register_tag instruction accepts a separate payer account, decoupled from owner, so a sponsor can cover it on the owner's behalf instead; owner is still recorded as the tag's controller regardless of who paid. See Registering a Tag for the sponsored flow.