71 lines
1.8 KiB
Rust
71 lines
1.8 KiB
Rust
use crate::encrypted_data::EncryptedData;
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use crate::error::{Error, Result};
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use aes_gcm::aead::{Aead, KeyInit, Payload};
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use aes_gcm::{Aes128Gcm, Key, Nonce};
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pub(crate) const AES128_KEY_SIZE: usize = 128;
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// 96 bits (12 bytes)
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// Reason: NIST Special Publication 800-38D
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// https://doi.org/10.6028/NIST.SP.800-38D
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// Section 5.2.1.1 recommends that implementations restrict support to 96 bit.
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// Section 8.2 states that nonces of 96 bits and higher may be randomly generated.
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const NONCE_SIZE: usize = 12;
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pub(crate) fn aes128gcm_gen_nonce() -> Result<Vec<u8>> {
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let mut nonce: [u8; NONCE_SIZE] = [0; NONCE_SIZE];
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getrandom::getrandom(&mut nonce)?;
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Ok(nonce.to_vec())
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}
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pub(crate) fn aes128gcm_encrypt(
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key: &[u8],
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nonce: &[u8],
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data: &[u8],
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aad: &str,
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) -> Result<EncryptedData> {
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// Adapt the key and nonce
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let key = Key::<Aes128Gcm>::from_slice(key);
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let nonce = Nonce::from_slice(&nonce[0..NONCE_SIZE]);
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// Prepare the payload
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let payload = Payload {
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msg: data,
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aad: aad.as_bytes(),
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};
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// Encrypt the payload
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let cipher = Aes128Gcm::new(key);
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let ciphertext = cipher.encrypt(nonce, payload)?;
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// Return the result
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Ok(EncryptedData {
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nonce: nonce.to_vec(),
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ciphertext,
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})
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}
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pub(crate) fn aes128gcm_decrypt(
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key: &[u8],
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encrypted_data: &EncryptedData,
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aad: &str,
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) -> Result<Vec<u8>> {
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// Adapt the key and nonce
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let key = Key::<Aes128Gcm>::from_slice(key);
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if encrypted_data.nonce.len() != NONCE_SIZE {
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return Err(Error::InvalidNonceSize(
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NONCE_SIZE,
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encrypted_data.nonce.len(),
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));
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}
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let nonce = Nonce::from_slice(&encrypted_data.nonce[0..NONCE_SIZE]);
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// Prepare the payload
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let payload = Payload {
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msg: &encrypted_data.ciphertext,
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aad: aad.as_bytes(),
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};
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// Decrypt the payload and return
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let cipher = Aes128Gcm::new(key);
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Ok(cipher.decrypt(nonce, payload)?)
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}
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