03 - PDA Metadata Leak

Analysis

Program Derived Addresses (PDAs) are derived using a collection of seeds. If sensitive information (like a user's Social Security Number, phone number, or real-world ID) is used directly as a seed, that information is leaked onto the public blockchain.

Even if the account data is encrypted, the seeds are public. Anyone scanning the blockchain can see the seeds used to derive every account.

Exploit (Insecure)

Using raw PII (Personally Identifiable Information) as a seed:

pub struct InitializeInsecure<'info> {
    #[account(
        init,
        seeds = [b"profile", sensitive_id.as_bytes()], //  Plaintext leak
        bump
    )]
    pub profile: Account<'info, UserProfile>,
    // ...
}

Fix (Secure)

To protect privacy, sensitive seeds should be hashed before being passed to the PDA derivation logic. This allows the program to maintain a unique mapping for the user without revealing their actual ID.

pub struct InitializeSecure<'info> {
    #[account(
        init,
        //  Only the hash of the ID is visible publicly.
        seeds = [b"profile", hash(sensitive_id.as_bytes()).to_bytes().as_ref()],
        bump
    )]
    pub profile: Account<'info, UserProfile>,
    // ...
}