Which seeds does the `getAssociatedTokenAddress` function use to determine the associated token account public key?

Question

The @solana/spl-token package contains the getAssociatedTokenAddress function which can be used to obtain the address (public key) of an associated token account. Here's an example:

const programATAPublicKey = await getAssociatedTokenAddress(
  mintPublicKey,
  programPDAPublicKey,
  true,
  program.programId
);

I am trying to achieve the same result using the findProgramAddress function from the @project-serum/anchor package. My problem is that I can't figure out which seeds are used inside getAssociatedTokenAddress. For example, I expected the following code to return the associated token account public key:

const [programATAPublicKey] =
      await anchor.web3.PublicKey.findProgramAddress(
        [mintPublicKey.toBuffer(), programPDAPublicKey.toBuffer()],
        program.programId
      );

The result is, however, different. Which seed combination would yield an identical result to whatever is returned from getAssociatedTokenAddress?

Answer 1

The Associated Token Account uses the following structure:

[
    walletAddress.toBuffer(),
    TOKEN_PROGRAM_ID.toBuffer(),
    tokenMintAddress.toBuffer(),
],
SPL_ASSOCIATED_TOKEN_ACCOUNT_PROGRAM_ID

Where TOKEN_PROGRAM_ID = "TokenkegQfeZyiNwAJbNbGKPFXCWuBvf9Ss623VQ5DA" and SPL_ASSOCIATED_TOKEN_ACCOUNT_PROGRAM_ID = "ATokenGPvbdGVxr1b2hvZbsiqW5xWH25efTNsLJA8knL".

Answer 2

The best is to use the source! Here's the exact code that generates the associated token account address:

export async function getAssociatedTokenAddress(
    mint: PublicKey,
    owner: PublicKey,
    allowOwnerOffCurve = false,
    programId = TOKEN_PROGRAM_ID,
    associatedTokenProgramId = ASSOCIATED_TOKEN_PROGRAM_ID
): Promise<PublicKey> {
    if (!allowOwnerOffCurve && !PublicKey.isOnCurve(owner.toBuffer())) throw new TokenOwnerOffCurveError();

    const [address] = await PublicKey.findProgramAddress(
        [owner.toBuffer(), programId.toBuffer(), mint.toBuffer()],
        associatedTokenProgramId
    );

    return address;
}

where ASSOCIATED_TOKEN_PROGRAM_ID is "ATokenGPvbdGVxr1b2hvZbsiqW5xWH25efTNsLJA8knL".

Taken from https://github.com/solana-labs/solana-program-library/blob/ad97543192e05e6ecba88fff3b1da08ca523a5b6/token/js/src/state/mint.ts#L156