How to set contract ATA's authority to my program

Question

I know how ATA and PDA works. I know that an ATA is a PDA, and so the account which the PDA was derived from is the one that can sign transactions for this PDA. So, I assume that a contract's ATA's authority is the contract itself.

How can I specify this in an Anchor Instruction ?

Here is the code I'm trying to fix:

    pub token_mint: Account<'info, Mint>,

    #[account(
        mut,
        associated_token::mint = token_mint,
        associated_token::authority = ????,
    )]
    pub program_token_account: Box<Account<'info, TokenAccount>>,

Answer 1

You could create a PDA authority and use this instead as the authority of the ATA.

    #[account(
        mut,
        associated_token::mint = token_mint,
        associated_token::authority = vault_Account,
    )]
    pub program_token_account: Box<Account<'info, TokenAccount>>,

    #[account(mut)]
    pub vault_Account: Account<'info, VaultAccount>,

Using the program as the authority would mean that you'd need to use the Program Keypair to sign for transactions which I don't think is safe and practical.

Check out how we did it on soundwork with our market contracts