envelopers 0.8.2

A very simple envelope encryption library using aes-gcm
Documentation 
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//! Trait for a KeyProvider

use aes_gcm::{Key, KeySizeUser};
use async_trait::async_trait;
use zeroize::{Zeroize, ZeroizeOnDrop};

use crate::errors::{KeyDecryptionError, KeyGenerationError};

#[derive(Debug, Clone, Zeroize, ZeroizeOnDrop)]
pub struct DataKey<S: KeySizeUser> {
    pub key: Key<S>,
    // TODO: Maybe make a type for EncryptedKey
    pub encrypted_key: Vec<u8>,
    pub key_id: String,
}

#[async_trait]
pub trait KeyProvider: Send + Sync {
    type Cipher: KeySizeUser;

    /// Generate a [`DataKey`] to encrypt a specific number of bytes
    ///
    /// # Arguments
    ///
    /// * `bytes_to_encrypt` - The number of bytes that this key will be used to encrypt
    ///
    async fn generate_data_key(
        &self,
        bytes_to_encrypt: usize,
        aad: Option<&str>,
    ) -> Result<DataKey<Self::Cipher>, KeyGenerationError>;

    /// Decrypt an encrypted key and return the plaintext key
    async fn decrypt_data_key(
        &self,
        encrypted_key: &[u8],
        aad: Option<&str>,
    ) -> Result<Key<Self::Cipher>, KeyDecryptionError>;
}

#[async_trait]
impl<S: KeySizeUser> KeyProvider for Box<dyn KeyProvider<Cipher = S>> {
    type Cipher = S;

    async fn generate_data_key(
        &self,
        bytes_to_encrypt: usize,
        aad: Option<&str>,
    ) -> Result<DataKey<S>, KeyGenerationError> {
        (**self).generate_data_key(bytes_to_encrypt, aad).await
    }

    async fn decrypt_data_key(
        &self,
        encrypted_key: &[u8],
        aad: Option<&str>,
    ) -> Result<Key<S>, KeyDecryptionError> {
        (**self).decrypt_data_key(encrypted_key, aad).await
    }
}