Signing with PDAs

PDAs sign CPIs through seed slices passed to CpiContext::new_with_signer. The seeds must match the PDA constraints used at initialization.

Recipe

let seeds = &[b"vault".as_ref(), &[ctx.bumps.vault]];
let signer = &[&seeds[..]];
 
token::transfer(
    CpiContext::new_with_signer(
        ctx.accounts.token_program.to_account_info(),
        accounts,
        signer,
    ),
    amount,
)?;

When to reach for this: A PDA is authority over token accounts or owns SOL being transferred.

Working Example

pub fn vault_withdraw(ctx: Context<VaultWithdraw>, amount: u64) -> Result<()> {
    let bump = ctx.bumps.vault;
    let authority_key = ctx.accounts.vault.authority;
    let seeds: &[&[u8]] = &[b"vault", authority_key.as_ref(), &[bump]];
    let signer_seeds = &[seeds];
 
    token::transfer(
        CpiContext::new_with_signer(
            ctx.accounts.token_program.to_account_info(),
            token::Transfer {
                from: ctx.accounts.vault_ata.to_account_info(),
                to: ctx.accounts.user_ata.to_account_info(),
                authority: ctx.accounts.vault.to_account_info(),
            },
            signer_seeds,
        ),
        amount,
    )?;
    Ok(())
}

What this demonstrates:

• Signer seeds are nested slices &[&[&[u8]]]
• Bump must be canonical
• PDA account info is the authority meta
• Use ctx.bumps when seeds match field name

Deep Dive

invoke_signed vs Anchor CPI

Anchor CPI helpers accept with_signer for the same semantics as native invoke_signed.

Multi-seed PDAs

Include every seed element in the same order used in #[account(seeds = [...])].

Gotchas

• Wrong bump in signer array - CPI signature fails.. Fix: Use stored bump or ctx.bumps.
• Missing seed component - Derived address mismatch.. Fix: Copy seeds from constraint exactly.
• Authority meta not PDA account - Token program rejects.. Fix: Pass vault PDA as authority.
• Reusing seed buffer incorrectly - Lifetime/ borrow issues.. Fix: Build seeds array per CPI call.
• PDA signs without constraint on account - Attacker substitutes PDA.. Fix: Validate seeds on-chain.

Alternatives

FAQs

Related

• Signed CPIs - CPI patterns
• PDA Authorities - mints and vaults
• Storing Bumps - canonical bump

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.