rok commented on code in PR #7111:
URL: https://github.com/apache/arrow-rs/pull/7111#discussion_r2004521719
##########
parquet/src/encryption/ciphers.rs:
##########
@@ -61,3 +64,118 @@ impl BlockDecryptor for RingGcmBlockDecryptor {
Ok(result)
}
}
+
+pub trait BlockEncryptor: Debug + Send + Sync {
+ fn encrypt(&mut self, plaintext: &[u8], aad: &[u8]) -> Result<Vec<u8>>;
+}
+
+#[derive(Debug, Clone)]
+struct CounterNonce {
+ start: u128,
+ counter: u128,
+}
+
+impl CounterNonce {
+ pub fn new(rng: &SystemRandom) -> Result<Self> {
+ let mut buf = [0; 16];
+ rng.fill(&mut buf)?;
+
+ // Since this is a random seed value, endianness doesn't matter at all,
+ // and we can use whatever is platform-native.
+ let start = u128::from_ne_bytes(buf) & RIGHT_TWELVE;
+ let counter = start.wrapping_add(1);
+
+ Ok(Self { start, counter })
+ }
+
+ /// One accessor for the nonce bytes to avoid potentially flipping
endianness
+ #[inline]
+ pub fn get_bytes(&self) -> [u8; NONCE_LEN] {
+ self.counter.to_le_bytes()[0..NONCE_LEN].try_into().unwrap()
+ }
+}
+
+impl NonceSequence for CounterNonce {
+ fn advance(&mut self) -> Result<ring::aead::Nonce,
ring::error::Unspecified> {
+ // If we've wrapped around, we've exhausted this nonce sequence
+ if (self.counter & RIGHT_TWELVE) == (self.start & RIGHT_TWELVE) {
+ Err(ring::error::Unspecified)
+ } else {
+ // Otherwise, just advance and return the new value
+ let buf: [u8; NONCE_LEN] = self.get_bytes();
+ self.counter = self.counter.wrapping_add(1);
+ Ok(ring::aead::Nonce::assume_unique_for_key(buf))
+ }
+ }
+}
+
+#[derive(Debug, Clone)]
+pub(crate) struct RingGcmBlockEncryptor {
+ key: LessSafeKey,
+ nonce_sequence: CounterNonce,
+}
+
+impl RingGcmBlockEncryptor {
+ /// Create a new `RingGcmBlockEncryptor` with a given key and random nonce.
+ /// The nonce will advance appropriately with each block encryption and
+ /// return an error if it wraps around.
+ pub(crate) fn new(key_bytes: &[u8]) -> Result<Self> {
+ let rng = SystemRandom::new();
+
+ // todo support other key sizes
+ let key = UnboundKey::new(&AES_128_GCM, key_bytes)
+ .map_err(|e| general_err!("Error creating AES key: {}", e))?;
+ let nonce = CounterNonce::new(&rng)?;
+
+ Ok(Self {
+ key: LessSafeKey::new(key),
+ nonce_sequence: nonce,
+ })
+ }
+}
+
+impl BlockEncryptor for RingGcmBlockEncryptor {
+ fn encrypt(&mut self, plaintext: &[u8], aad: &[u8]) -> Result<Vec<u8>> {
+ // Create encrypted buffer.
+ // Format is: [ciphertext size, nonce, ciphertext, authentication tag]
+ let ciphertext_length = NONCE_LEN + plaintext.len() + TAG_LEN;
+ let mut ciphertext = Vec::with_capacity(SIZE_LEN + ciphertext_length);
+ ciphertext.extend((ciphertext_length as u32).to_le_bytes());
Review Comment:
Fair point! I've changed this to:
```rust
let ciphertext_length : u32 = (NONCE_LEN + plaintext.len() +
TAG_LEN).try_into()
.map_err(|err|
General(format!("Plaintext data too long. {:?}", err)))?;
// Not checking for overflow here because we've already checked for
it with ciphertext_length
let mut ciphertext = Vec::with_capacity(SIZE_LEN + ciphertext_length
as usize);
ciphertext.extend((ciphertext_length).to_le_bytes());
```
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