Zeroize: The Tiny and Memory-Safe Rust Crate

#programming #rust #cybersecurity #security

Sensitive Data in Memory: A Hidden Threat

In a secure environment, one of the most overlooked threats is the presence of sensitive data in memory, such as passwords, tokens, cryptographic keys, or card numbers.

Even when using Rust, where we emphasize ownership and thread safety, there's another crucial question to consider:

What remains in the heap or stack after we no longer need it?

Why Memory Zeroing Matters

Zeroize helps us address this. It’s a lightweight but powerful crate that allows us to zero out memory securely and efficiently.

Imagine this scenario:

Your program reads a password from user input
It uses it for authentication or to decrypt a file
The variable goes out of scope and Rust "cleans it up"... right?

Not quite. Rust does not guarantee that memory will be overwritten.

So your password might remain in memory, in plain text, until it's overwritten by something else. In the case of a memory dump or cold boot attack, it could be exposed.

What Can You Do About It?

That’s where Zeroize comes in. It lets you explicitly clear memory when you're done using sensitive data.

Instead of relying on the runtime or assuming safety, you take control.

It provides a trait Zeroize which can be derive or implemented manually for your types.

Using it is literally one line:

use zeroize::Zeroize;
fn main() {
    let mut password = String::from("hunter2");
    // Use it for authentication or anything else

     // now clean memory
    password.zeroize();
}

The last line will overwrite the contents of the string with zero. If you use other types like Vec<u8> it will work in the same way

Automate the process

If you want to automate everything, you can wrap your data with Zeroizing, which will automatically reset it when it goes out of scope:

use zeroize::Zeroizing;

fn main() {
    let password = Zeroizing::new(String::from("hunter2"));
    // No need to call zeroize, auto-zero on drop
}

Easy, elegant, secure. It adds almost no overhead to your final binary

When should you use it?

Every time you handle:

Password
Auth token (eg. JWT, OAuth)
Encryption keys (AES, ChaCha20, etc)
Any data that shouldn't live in RAM longer than necessary

In synthesis

Zeroize is not magic.But it's a good habit. It won't protect you from every attack, but it does make your code more resilient, especially in environments where security ≠ optional (embedded, mobile, backend auth, etc.)

💡 Do you know any other crate that you'd like to explore? Let me know