vs-storage

Persistent storage abstraction for configuration and key material.

Overview

This crate defines a StorageProvider trait for key-value storage that can be backed by RAM, flash, EEPROM, or filesystem depending on the target platform. All implementations are fixed-size and heap-free, suitable for #![no_std] embedded use. A RamStorageProvider is included for testing, and a FileStorageProvider is available behind the std feature flag.

Key Types

• StorageProvider — trait for key-value read/write/delete/contains operations
• RamStorageProvider — in-memory implementation for testing and prototyping
• FileStorageProvider — filesystem-backed implementation (requires std feature)

Usage

use vs_storage::{StorageProvider, RamStorageProvider};
use vs_types::VsError;

fn example() -> Result<(), VsError> {
    let mut store = RamStorageProvider::new();
    store.write(b"config.key", b"value")?;
    let mut buf = [0u8; 64];
    let _len = store.read(b"config.key", &mut buf)?;
    Ok(())
}

Encrypted storage (requires encrypted feature)

Wrap any StorageProvider with EncryptedStorageProvider to transparently encrypt all values at rest using AES-GCM. Available when the encrypted feature is enabled (pulls in vs-crypto):

// Cargo.toml: vs-storage = { version = "0.7", features = ["encrypted"] }
use vs_storage::{EncryptedStorageProvider, RamStorageProvider, StorageProvider};
use vs_crypto::{KeyId, RustCryptoProvider};

let mut crypto = RustCryptoProvider::default();
// AES-256-GCM requires a 32-byte key. The real `RustCryptoProvider`
// rejects any other length with `VsError::InvalidInput`.
crypto.set_key(KeyId(0), &[0x42u8; 32])?;

let inner = RamStorageProvider::new();
// `new_persistent` stores the AES-GCM nonce counter inside `inner` under a
// reserved key, so it is reloaded automatically on the next boot and a nonce
// can never be reused. Prefer it over `new(.., nonce_start)`.
let mut enc = EncryptedStorageProvider::new_persistent(inner, &crypto, KeyId(0))?;
enc.write(b"secret.key", b"plaintext-value")?;

Feature Flags

See feature-flags.md for the full workspace feature reference.

License

Apache-2.0. See LICENSE.