Are there any risks with the PDA account generate with the hash function?

Question

I currently have a PDA account with the following structure:

#[derive(AnchorSerialize, AnchorDeserialize)]
pub struct NewFoo {
    pub foo_id: String,
}

#[derive(Accounts)]
#[instruction(new_foo: NewFoo)]
pub struct CreateFoo<'info> {
    #[account(
      init,
      space = 8 + Foo::INIT_SPACE,
      payer = sender,
      seeds = [
        FOO_SEED.as_bytes(),
        new_foo.foo_id.as_bytes(),
      ],
      bump,
    )]
    pub foo: Account<'info, Foo>,

With this setup, the compiled IDL structure of the PDA account looks like this:

  {
    "name": "foo",
    "writable": true,
    "pda": {
      "seeds": [
        {
          "kind": "const",
          "value": [
            83,
            116,
            97,
            116,
            101,
            109,
            101,
            110,
            116
          ]
        },
        {
          "kind": "arg",
          "path": "new_foo.foo_id"
        }
      ]
    }
  }

However, I modified the CreateFoo structure to use a hash function to generate one of the seeds. The updated structure is as follows:

use anchor_lang::{prelude::*, solana_program::hash::hash};

#[derive(Accounts)]
#[instruction(new_foo: NewFoo)]
pub struct CreateFoo<'info> {
    #[account(
      init,
      space = 8 + Foo::INIT_SPACE,
      payer = sender,
      seeds = [
        FOO_SEED.as_bytes(),
        &hash(&new_foo.foo_id.as_bytes()).to_bytes()[..], // changed this line
      ],
      bump,
    )]
    pub foo: Account<'info, Foo>,

After this change, I noticed that the compiled IDL structure no longer represents a PDA account. Instead, it appears as a regular account:

{
    "name": "foo",
    "writable": true,
}

My questions are:

1. Is it correct for a PDA account generated using a hash function to compile like this? Are there any risks with this approach?
2. Can a hash function be used to generate a seed for a PDA account? If yes, is this a common practice?

I appreciate any insights or guidance you can provide on this. Thank you in advance for your help and time!

Answer 1

1. I'm not sure what Anchor does exactly to extract the IDL, but it seems suspicious that it doesn't give more info. I imagine something is going wrong during IDL extraction.
2. You can use a hash function if you want, but I wouldn't encourage it. The PDA generation code itself is already hashing together all of the seeds, so that adds an additional hash step, which is compute-intensive when executed on-chain.

You can read more about PDA generation at https://solana.com/developers/courses/native-onchain-development/program-derived-addresses#3-create-program-address