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ssh-cipher: refactor
ChaCha20Poly1305 to use aead API
Changes the `ChaCha20Poly1305` type to impl the standard AEAD APIs exported by the `aead` crate.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,11 +1,21 @@ | ||
| //! OpenSSH variant of ChaCha20Poly1305. | ||
|
|
||
| use crate::{Error, Nonce, Result, Tag}; | ||
| use chacha20::{ChaCha20, Key}; | ||
| use cipher::{KeyInit, KeyIvInit, StreamCipher, StreamCipherSeek}; | ||
| use crate::Tag; | ||
| use aead::{ | ||
| array::typenum::{U0, U16, U32, U8}, | ||
| AeadCore, AeadInPlace, Error, KeyInit, KeySizeUser, Result, | ||
| }; | ||
| use chacha20::ChaCha20Legacy as ChaCha20; | ||
| use cipher::{KeyIvInit, StreamCipher, StreamCipherSeek}; | ||
| use poly1305::Poly1305; | ||
| use subtle::ConstantTimeEq; | ||
|
|
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| /// Key for `[email protected]`. | ||
| pub type ChaChaKey = chacha20::Key; | ||
|
|
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| /// Nonce for `[email protected]`. | ||
| pub type ChaChaNonce = chacha20::LegacyNonce; | ||
|
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| /// OpenSSH variant of ChaCha20Poly1305: `[email protected]` | ||
| /// as described in [PROTOCOL.chacha20poly1305]. | ||
| /// | ||
|
|
@@ -16,19 +26,60 @@ use subtle::ConstantTimeEq; | |
| /// | ||
| /// [PROTOCOL.chacha20poly1305]: https://cvsweb.openbsd.org/src/usr.bin/ssh/PROTOCOL.chacha20poly1305?annotate=HEAD | ||
| /// [RFC8439]: https://datatracker.ietf.org/doc/html/rfc8439 | ||
| #[derive(Clone)] | ||
| pub struct ChaCha20Poly1305 { | ||
| // TODO(tarcieri): zeroize on drop | ||
| key: ChaChaKey, | ||
| } | ||
|
|
||
| impl KeySizeUser for ChaCha20Poly1305 { | ||
| type KeySize = U32; | ||
| } | ||
|
|
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| impl KeyInit for ChaCha20Poly1305 { | ||
| #[inline] | ||
| fn new(key: &ChaChaKey) -> Self { | ||
| Self { key: *key } | ||
| } | ||
| } | ||
|
|
||
| impl AeadCore for ChaCha20Poly1305 { | ||
| type NonceSize = U8; | ||
| type TagSize = U16; | ||
| type CiphertextOverhead = U0; | ||
| } | ||
|
|
||
| impl AeadInPlace for ChaCha20Poly1305 { | ||
| fn encrypt_in_place_detached( | ||
| &self, | ||
| nonce: &ChaChaNonce, | ||
| associated_data: &[u8], | ||
| buffer: &mut [u8], | ||
| ) -> Result<Tag> { | ||
| Cipher::new(&self.key, nonce).encrypt(associated_data, buffer) | ||
| } | ||
|
|
||
| fn decrypt_in_place_detached( | ||
| &self, | ||
| nonce: &ChaChaNonce, | ||
| associated_data: &[u8], | ||
| buffer: &mut [u8], | ||
| tag: &Tag, | ||
| ) -> Result<()> { | ||
| Cipher::new(&self.key, nonce).decrypt(associated_data, buffer, *tag) | ||
| } | ||
| } | ||
|
|
||
| /// Internal type representing a cipher instance. | ||
| struct Cipher { | ||
| cipher: ChaCha20, | ||
| mac: Poly1305, | ||
| } | ||
|
|
||
| impl ChaCha20Poly1305 { | ||
| /// Create a new [`ChaCha20Poly1305`] instance with a 32-byte key. | ||
| /// | ||
| /// [PROTOCOL.chacha20poly1305]: https://cvsweb.openbsd.org/src/usr.bin/ssh/PROTOCOL.chacha20poly1305?annotate=HEAD | ||
| pub fn new(key: &[u8], nonce: &[u8]) -> Result<Self> { | ||
| let key = Key::try_from(key).map_err(|_| Error::KeySize)?; | ||
| let nonce = Nonce::try_from(nonce).map_err(|_| Error::IvSize)?; | ||
| let mut cipher = ChaCha20::new(&key, &nonce.into()); | ||
| impl Cipher { | ||
| /// Create a new cipher instance. | ||
| pub fn new(key: &ChaChaKey, nonce: &ChaChaNonce) -> Self { | ||
| let mut cipher = ChaCha20::new(&key, nonce.into()); | ||
| let mut poly1305_key = poly1305::Key::default(); | ||
| cipher.apply_keystream(&mut poly1305_key); | ||
|
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||
|
|
@@ -37,14 +88,19 @@ impl ChaCha20Poly1305 { | |
| // Seek to block 1 | ||
| cipher.seek(64); | ||
|
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||
| Ok(Self { cipher, mac }) | ||
| Self { cipher, mac } | ||
| } | ||
|
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||
| /// Encrypt the provided `buffer` in-place, returning the Poly1305 authentication tag. | ||
| #[inline] | ||
| pub fn encrypt(mut self, buffer: &mut [u8]) -> Tag { | ||
| pub fn encrypt(mut self, associated_data: &[u8], buffer: &mut [u8]) -> Result<Tag> { | ||
| // TODO(tarcieri): support associated data (RustCrypto/SSH#279) | ||
| if !associated_data.is_empty() { | ||
| return Err(Error); | ||
| } | ||
|
|
||
| self.cipher.apply_keystream(buffer); | ||
| self.mac.compute_unpadded(buffer).into() | ||
| Ok(self.mac.compute_unpadded(buffer).into()) | ||
| } | ||
|
|
||
| /// Decrypt the provided `buffer` in-place, verifying it against the provided Poly1305 | ||
|
|
@@ -55,14 +111,19 @@ impl ChaCha20Poly1305 { | |
| /// | ||
| /// Upon success, `Ok(())` is returned and `buffer` is rewritten with the decrypted plaintext. | ||
| #[inline] | ||
| pub fn decrypt(mut self, buffer: &mut [u8], tag: Tag) -> Result<()> { | ||
| pub fn decrypt(mut self, associated_data: &[u8], buffer: &mut [u8], tag: Tag) -> Result<()> { | ||
| // TODO(tarcieri): support associated data (RustCrypto/SSH#279) | ||
| if !associated_data.is_empty() { | ||
| return Err(Error); | ||
| } | ||
|
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| let expected_tag = self.mac.compute_unpadded(buffer); | ||
|
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| if expected_tag.ct_eq(&tag).into() { | ||
| self.cipher.apply_keystream(buffer); | ||
| Ok(()) | ||
| } else { | ||
| Err(Error::Crypto) | ||
| Err(Error) | ||
| } | ||
| } | ||
| } | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
|
|
@@ -35,20 +35,24 @@ mod encryptor; | |
|
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| pub use crate::error::{Error, Result}; | ||
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| #[cfg(feature = "chacha20poly1305")] | ||
| pub use crate::chacha20poly1305::ChaCha20Poly1305; | ||
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| #[cfg(any(feature = "aes-cbc", feature = "aes-ctr", feature = "tdes"))] | ||
| pub use crate::{decryptor::Decryptor, encryptor::Encryptor}; | ||
|
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| #[cfg(feature = "chacha20poly1305")] | ||
| pub use crate::chacha20poly1305::{ChaCha20Poly1305, ChaChaKey, ChaChaNonce}; | ||
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| use cipher::array::{typenum::U16, Array}; | ||
| use core::{fmt, str}; | ||
| use encoding::{Label, LabelError}; | ||
|
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| #[cfg(feature = "aes-gcm")] | ||
| use aes_gcm::{aead::AeadInPlace, Aes128Gcm, Aes256Gcm}; | ||
| use { | ||
| aead::array::typenum::U12, | ||
| aes_gcm::{Aes128Gcm, Aes256Gcm}, | ||
| }; | ||
|
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| #[cfg(feature = "aes-gcm")] | ||
| use cipher::KeyInit; | ||
| #[cfg(any(feature = "aes-gcm", feature = "chacha20poly1305"))] | ||
| use aead::{AeadInPlace, KeyInit}; | ||
|
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| /// AES-128 in block chaining (CBC) mode | ||
| const AES128_CBC: &str = "aes128-cbc"; | ||
|
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@@ -80,17 +84,15 @@ const CHACHA20_POLY1305: &str = "[email protected]"; | |
| /// Triple-DES in block chaining (CBC) mode | ||
| const TDES_CBC: &str = "3des-cbc"; | ||
|
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| /// Nonce for AEAD modes. | ||
| /// | ||
| /// This is used by e.g. `[email protected]`/`[email protected]` and | ||
| /// `[email protected]`. | ||
| pub type Nonce = [u8; 12]; | ||
| /// Nonce for `[email protected]`/`[email protected]`. | ||
| #[cfg(feature = "aes-gcm")] | ||
| pub type AesGcmNonce = Array<u8, U12>; | ||
|
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| /// Authentication tag for ciphertext data. | ||
| /// | ||
| /// This is used by e.g. `[email protected]`/`[email protected]` and | ||
| /// `[email protected]`. | ||
| pub type Tag = [u8; 16]; | ||
| pub type Tag = Array<u8, U16>; | ||
|
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| /// Counter mode with a 128-bit big endian counter. | ||
| #[cfg(feature = "aes-ctr")] | ||
|
|
@@ -172,7 +174,7 @@ impl Cipher { | |
| Self::Aes256Ctr => Some((32, 16)), | ||
| Self::Aes128Gcm => Some((16, 12)), | ||
| Self::Aes256Gcm => Some((32, 12)), | ||
| Self::ChaCha20Poly1305 => Some((32, 12)), | ||
| Self::ChaCha20Poly1305 => Some((32, 8)), | ||
| Self::TDesCbc => Some((24, 8)), | ||
| } | ||
| } | ||
|
|
@@ -233,7 +235,7 @@ impl Cipher { | |
| #[cfg(feature = "aes-gcm")] | ||
| Self::Aes128Gcm => { | ||
| let cipher = Aes128Gcm::new_from_slice(key).map_err(|_| Error::KeySize)?; | ||
| let nonce = Nonce::try_from(iv).map_err(|_| Error::IvSize)?; | ||
| let nonce = AesGcmNonce::try_from(iv).map_err(|_| Error::IvSize)?; | ||
| let tag = tag.ok_or(Error::TagSize)?; | ||
| cipher | ||
| .decrypt_in_place_detached(&nonce.into(), &[], buffer, &tag.into()) | ||
|
|
@@ -244,7 +246,7 @@ impl Cipher { | |
| #[cfg(feature = "aes-gcm")] | ||
| Self::Aes256Gcm => { | ||
| let cipher = Aes256Gcm::new_from_slice(key).map_err(|_| Error::KeySize)?; | ||
| let nonce = Nonce::try_from(iv).map_err(|_| Error::IvSize)?; | ||
| let nonce = AesGcmNonce::try_from(iv).map_err(|_| Error::IvSize)?; | ||
| let tag = tag.ok_or(Error::TagSize)?; | ||
| cipher | ||
| .decrypt_in_place_detached(&nonce.into(), &[], buffer, &tag.into()) | ||
|
|
@@ -254,8 +256,12 @@ impl Cipher { | |
| } | ||
| #[cfg(feature = "chacha20poly1305")] | ||
| Self::ChaCha20Poly1305 => { | ||
| let key = key.try_into().map_err(|_| Error::KeySize)?; | ||
| let nonce = iv.try_into().map_err(|_| Error::IvSize)?; | ||
| let tag = tag.ok_or(Error::TagSize)?; | ||
| ChaCha20Poly1305::new(key, iv)?.decrypt(buffer, tag) | ||
| ChaCha20Poly1305::new(key) | ||
| .decrypt_in_place_detached(nonce, b"", buffer, &tag) | ||
| .map_err(|_| Error::Crypto) | ||
| } | ||
| // Use `Decryptor` for non-AEAD modes | ||
| #[cfg(any(feature = "aes-cbc", feature = "aes-ctr", feature = "tdes"))] | ||
|
|
@@ -294,7 +300,7 @@ impl Cipher { | |
| #[cfg(feature = "aes-gcm")] | ||
| Self::Aes128Gcm => { | ||
| let cipher = Aes128Gcm::new_from_slice(key).map_err(|_| Error::KeySize)?; | ||
| let nonce = Nonce::try_from(iv).map_err(|_| Error::IvSize)?; | ||
| let nonce = AesGcmNonce::try_from(iv).map_err(|_| Error::IvSize)?; | ||
| let tag = cipher | ||
| .encrypt_in_place_detached(&nonce.into(), &[], buffer) | ||
| .map_err(|_| Error::Crypto)?; | ||
|
|
@@ -304,7 +310,7 @@ impl Cipher { | |
| #[cfg(feature = "aes-gcm")] | ||
| Self::Aes256Gcm => { | ||
| let cipher = Aes256Gcm::new_from_slice(key).map_err(|_| Error::KeySize)?; | ||
| let nonce = Nonce::try_from(iv).map_err(|_| Error::IvSize)?; | ||
| let nonce = AesGcmNonce::try_from(iv).map_err(|_| Error::IvSize)?; | ||
| let tag = cipher | ||
| .encrypt_in_place_detached(&nonce.into(), &[], buffer) | ||
| .map_err(|_| Error::Crypto)?; | ||
|
|
@@ -313,7 +319,11 @@ impl Cipher { | |
| } | ||
| #[cfg(feature = "chacha20poly1305")] | ||
| Self::ChaCha20Poly1305 => { | ||
| let tag = ChaCha20Poly1305::new(key, iv)?.encrypt(buffer); | ||
| let key = key.try_into().map_err(|_| Error::KeySize)?; | ||
| let nonce = iv.try_into().map_err(|_| Error::IvSize)?; | ||
| let tag = ChaCha20Poly1305::new(key) | ||
| .encrypt_in_place_detached(nonce, b"", buffer) | ||
| .map_err(|_| Error::Crypto)?; | ||
| Ok(Some(tag)) | ||
| } | ||
| // Use `Encryptor` for non-AEAD modes | ||
|
|
||
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