Deriving PDAs

PDAs are derived from seeds and a program id. find_program_address returns the canonical off-curve address and bump seed required for invoke_signed.

Recipe

let (pda, bump) = Pubkey::find_program_address(
    &[b"metadata", mint.key.as_ref()],
    program_id,
);

When to reach for this:

• Computing addresses in clients before submitting transactions.
• Verifying client-supplied PDAs on-chain.
• Designing multi-tenant seed schemes.

Working Example

pub fn verify_config(config: &AccountInfo, authority: &Pubkey, program_id: &Pubkey, stored_bump: u8) -> ProgramResult {
    let (expected, bump) = Pubkey::find_program_address(&[b"config", authority.as_ref()], program_id);
    if expected != *config.key || bump != stored_bump {
        return Err(ProgramError::InvalidSeeds);
    }
    Ok(())
}

What this demonstrates:

• Includes authority pubkey in seeds for per-user configs.
• Compares derived key and bump to stored values.
• Returns InvalidSeeds on mismatch.

Deep Dive

Algorithm

• Hash seeds + program id + bump until off-curve point found.
• Canonical bump is highest valid (255 downward).

Seed Limits

Rust Notes

let bump_seed = [bump];
let signer_seeds: &[&[u8]] = &[b"vault", owner.as_ref(), &bump_seed];
 
// invoke_signed wants &[&[&[u8]]] - wrap the group once more:
invoke_signed(&ix, account_infos, &[signer_seeds])?;

Gotchas

• Wrong program id in client - Derives different address. Fix: Pass program id from deployed key.
• Missing bump in seeds - invoke_signed fails. Fix: Append &[bump] slice.
• UTF-8 string seeds - Use .as_bytes() consistently. Fix: Document encoding.
• u64 in seeds - Use fixed-endian bytes: id.to_le_bytes(). Fix: Avoid ambiguous packing.
• Re-derive every time - Wastes CU on-chain. Fix: Store canonical bump.

Alternatives

FAQs

Related

• PDA Basics - Intro
• Canonical Bumps - Store bump
• Signing with PDAs - invoke_signed

Stack versions: This page was written for Agave 4.1.1, Solana CLI 3.0.10, Anchor 0.32.1, anchor-lang 0.32.1, Rust 1.91.1, @solana/kit 7.0.0, Surfpool 0.12.0, and LiteSVM 0.6.x. 3730363230327c3638336f6967637c6f692e73656469756765646f63