_ Git - rust-lightning/blob - lightning/src/util/chacha20poly1305rfc.rs

   1 // ring has a garbage API so its use is avoided, but rust-crypto doesn't have RFC-variant poly1305
   2 // Instead, we steal rust-crypto's implementation and tweak it to match the RFC.
   3 //
   4 // This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
   5 // or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   6 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
   7 // You may not use this file except in accordance with one or both of these
   8 // licenses.
   9 //
  10 // This is a port of Andrew Moons poly1305-donna
  11 // https://github.com/floodyberry/poly1305-donna
  12
  13 use ln::msgs::DecodeError;
  14 use util::ser::{FixedLengthReader, LengthRead, LengthReadableArgs, Readable, Writeable, Writer};
  15 use io::{self, Read, Write};
  16
  17 #[cfg(not(fuzzing))]
  18 mod real_chachapoly {
  19         use util::chacha20::ChaCha20;
  20         use util::poly1305::Poly1305;
  21         use bitcoin::hashes::cmp::fixed_time_eq;
  22
  23         #[derive(Clone, Copy)]
  24         pub struct ChaCha20Poly1305RFC {
  25                 cipher: ChaCha20,
  26                 mac: Poly1305,
  27                 finished: bool,
  28                 data_len: usize,
  29                 aad_len: u64,
  30         }
  31
  32         impl ChaCha20Poly1305RFC {
  33                 #[inline]
  34                 fn pad_mac_16(mac: &mut Poly1305, len: usize) {
  35                         if len % 16 != 0 {
  36                                 mac.input(&[0; 16][0..16 - (len % 16)]);
  37                         }
  38                 }
  39                 pub fn new(key: &[u8], nonce: &[u8], aad: &[u8]) -> ChaCha20Poly1305RFC {
  40                         assert!(key.len() == 16 || key.len() == 32);
  41                         assert!(nonce.len() == 12);
  42
  43                         // Ehh, I'm too lazy to *also* tweak ChaCha20 to make it RFC-compliant
  44                         assert!(nonce[0] == 0 && nonce[1] == 0 && nonce[2] == 0 && nonce[3] == 0);
  45
  46                         let mut cipher = ChaCha20::new(key, &nonce[4..]);
  47                         let mut mac_key = [0u8; 64];
  48                         let zero_key = [0u8; 64];
  49                         cipher.process(&zero_key, &mut mac_key);
  50
  51                         let mut mac = Poly1305::new(&mac_key[..32]);
  52                         mac.input(aad);
  53                         ChaCha20Poly1305RFC::pad_mac_16(&mut mac, aad.len());
  54
  55                         ChaCha20Poly1305RFC {
  56                                 cipher,
  57                                 mac,
  58                                 finished: false,
  59                                 data_len: 0,
  60                                 aad_len: aad.len() as u64,
  61                         }
  62                 }
  63
  64                 pub fn encrypt(&mut self, input: &[u8], output: &mut [u8], out_tag: &mut [u8]) {
  65                         assert!(input.len() == output.len());
  66                         assert!(self.finished == false);
  67                         self.cipher.process(input, output);
  68                         self.data_len += input.len();
  69                         self.mac.input(output);
  70                         ChaCha20Poly1305RFC::pad_mac_16(&mut self.mac, self.data_len);
  71                         self.finished = true;
  72                         self.mac.input(&self.aad_len.to_le_bytes());
  73                         self.mac.input(&(self.data_len as u64).to_le_bytes());
  74                         self.mac.raw_result(out_tag);
  75                 }
  76
  77                 pub fn encrypt_full_message_in_place(&mut self, input_output: &mut [u8], out_tag: &mut [u8]) {
  78                         self.encrypt_in_place(input_output);
  79                         self.finish_and_get_tag(out_tag);
  80                 }
  81
  82                 // Encrypt `input_output` in-place. To finish and calculate the tag, use `finish_and_get_tag`
  83                 // below.
  84                 pub(super) fn encrypt_in_place(&mut self, input_output: &mut [u8]) {
  85                         debug_assert!(self.finished == false);
  86                         self.cipher.process_in_place(input_output);
  87                         self.data_len += input_output.len();
  88                         self.mac.input(input_output);
  89                 }
  90
  91                 // If we were previously encrypting with `encrypt_in_place`, this method can be used to finish
  92                 // encrypting and calculate the tag.
  93                 pub(super) fn finish_and_get_tag(&mut self, out_tag: &mut [u8]) {
  94                         debug_assert!(self.finished == false);
  95                         ChaCha20Poly1305RFC::pad_mac_16(&mut self.mac, self.data_len);
  96                         self.finished = true;
  97                         self.mac.input(&self.aad_len.to_le_bytes());
  98                         self.mac.input(&(self.data_len as u64).to_le_bytes());
  99                         self.mac.raw_result(out_tag);
 100                 }
 101
 102                 pub fn decrypt(&mut self, input: &[u8], output: &mut [u8], tag: &[u8]) -> bool {
 103                         assert!(input.len() == output.len());
 104                         assert!(self.finished == false);
 105
 106                         self.finished = true;
 107
 108                         self.mac.input(input);
 109
 110                         self.data_len += input.len();
 111                         ChaCha20Poly1305RFC::pad_mac_16(&mut self.mac, self.data_len);
 112                         self.mac.input(&self.aad_len.to_le_bytes());
 113                         self.mac.input(&(self.data_len as u64).to_le_bytes());
 114
 115                         let mut calc_tag =  [0u8; 16];
 116                         self.mac.raw_result(&mut calc_tag);
 117                         if fixed_time_eq(&calc_tag, tag) {
 118                                 self.cipher.process(input, output);
 119                                 true
 120                         } else {
 121                                 false
 122                         }
 123                 }
 124
 125                 // Decrypt in place, without checking the tag. Use `finish_and_check_tag` to check it
 126                 // later when decryption finishes.
 127                 //
 128                 // Should never be `pub` because the public API should always enforce tag checking.
 129                 pub(super) fn decrypt_in_place(&mut self, input_output: &mut [u8]) {
 130                         debug_assert!(self.finished == false);
 131                         self.mac.input(input_output);
 132                         self.data_len += input_output.len();
 133                         self.cipher.process_in_place(input_output);
 134                 }
 135
 136                 // If we were previously decrypting with `decrypt_in_place`, this method must be used to finish
 137                 // decrypting and check the tag. Returns whether or not the tag is valid.
 138                 pub(super) fn finish_and_check_tag(&mut self, tag: &[u8]) -> bool {
 139                         debug_assert!(self.finished == false);
 140                         self.finished = true;
 141                         ChaCha20Poly1305RFC::pad_mac_16(&mut self.mac, self.data_len);
 142                         self.mac.input(&self.aad_len.to_le_bytes());
 143                         self.mac.input(&(self.data_len as u64).to_le_bytes());
 144
 145                         let mut calc_tag =  [0u8; 16];
 146                         self.mac.raw_result(&mut calc_tag);
 147                         if fixed_time_eq(&calc_tag, tag) {
 148                                 true
 149                         } else {
 150                                 false
 151                         }
 152                 }
 153         }
 154 }
 155 #[cfg(not(fuzzing))]
 156 pub use self::real_chachapoly::ChaCha20Poly1305RFC;
 157
 158 /// Enables simultaneously reading and decrypting a ChaCha20Poly1305RFC stream from a std::io::Read.
 159 struct ChaChaPolyReader<'a, R: Read> {
 160         pub chacha: &'a mut ChaCha20Poly1305RFC,
 161         pub read: R,
 162 }
 163
 164 impl<'a, R: Read> Read for ChaChaPolyReader<'a, R> {
 165         // Decrypt bytes from Self::read into `dest`.
 166         // `ChaCha20Poly1305RFC::finish_and_check_tag` must be called to check the tag after all reads
 167         // complete.
 168         fn read(&mut self, dest: &mut [u8]) -> Result<usize, io::Error> {
 169                 let res = self.read.read(dest)?;
 170                 if res > 0 {
 171                         self.chacha.decrypt_in_place(&mut dest[0..res]);
 172                 }
 173                 Ok(res)
 174         }
 175 }
 176
 177 /// Enables simultaneously writing and encrypting a byte stream into a Writer.
 178 struct ChaChaPolyWriter<'a, W: Writer> {
 179         pub chacha: &'a mut ChaCha20Poly1305RFC,
 180         pub write: &'a mut W,
 181 }
 182
 183 impl<'a, W: Writer> Writer for ChaChaPolyWriter<'a, W> {
 184         // Encrypt then write bytes from `src` into Self::write.
 185         // `ChaCha20Poly1305RFC::finish_and_get_tag` can be called to retrieve the tag after all writes
 186         // complete.
 187         fn write_all(&mut self, src: &[u8]) -> Result<(), io::Error> {
 188                 let mut src_idx = 0;
 189                 while src_idx < src.len() {
 190                         let mut write_buffer = [0; 8192];
 191                         let bytes_written = (&mut write_buffer[..]).write(&src[src_idx..]).expect("In-memory writes can't fail");
 192                         self.chacha.encrypt_in_place(&mut write_buffer[..bytes_written]);
 193                         self.write.write_all(&write_buffer[..bytes_written])?;
 194                         src_idx += bytes_written;
 195                 }
 196                 Ok(())
 197         }
 198 }
 199
 200 /// Enables the use of the serialization macros for objects that need to be simultaneously encrypted and
 201 /// serialized. This allows us to avoid an intermediate Vec allocation.
 202 pub(crate) struct ChaChaPolyWriteAdapter<'a, W: Writeable> {
 203         pub rho: [u8; 32],
 204         pub writeable: &'a W,
 205 }
 206
 207 impl<'a, W: Writeable> ChaChaPolyWriteAdapter<'a, W> {
 208         #[allow(unused)] // This will be used for onion messages soon
 209         pub fn new(rho: [u8; 32], writeable: &'a W) -> ChaChaPolyWriteAdapter<'a, W> {
 210                 Self { rho, writeable }
 211         }
 212 }
 213
 214 impl<'a, T: Writeable> Writeable for ChaChaPolyWriteAdapter<'a, T> {
 215         // Simultaneously write and encrypt Self::writeable.
 216         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 217                 let mut chacha = ChaCha20Poly1305RFC::new(&self.rho, &[0; 12], &[]);
 218                 let mut chacha_stream = ChaChaPolyWriter { chacha: &mut chacha, write: w };
 219                 self.writeable.write(&mut chacha_stream)?;
 220                 let mut tag = [0 as u8; 16];
 221                 chacha.finish_and_get_tag(&mut tag);
 222                 tag.write(w)?;
 223
 224                 Ok(())
 225         }
 226 }
 227
 228 /// Enables the use of the serialization macros for objects that need to be simultaneously decrypted and
 229 /// deserialized. This allows us to avoid an intermediate Vec allocation.
 230 pub(crate) struct ChaChaPolyReadAdapter<R: Readable> {
 231         #[allow(unused)] // This will be used soon for onion messages
 232         pub readable: R,
 233 }
 234
 235 impl<T: Readable> LengthReadableArgs<[u8; 32]> for ChaChaPolyReadAdapter<T> {
 236         // Simultaneously read and decrypt an object from a LengthRead, storing it in Self::readable.
 237         // LengthRead must be used instead of std::io::Read because we need the total length to separate
 238         // out the tag at the end.
 239         fn read<R: LengthRead>(mut r: &mut R, secret: [u8; 32]) -> Result<Self, DecodeError> {
 240                 if r.total_bytes() < 16 { return Err(DecodeError::InvalidValue) }
 241
 242                 let mut chacha = ChaCha20Poly1305RFC::new(&secret, &[0; 12], &[]);
 243                 let decrypted_len = r.total_bytes() - 16;
 244                 let s = FixedLengthReader::new(&mut r, decrypted_len);
 245                 let mut chacha_stream = ChaChaPolyReader { chacha: &mut chacha, read: s };
 246                 let readable: T = Readable::read(&mut chacha_stream)?;
 247                 chacha_stream.read.eat_remaining()?;
 248
 249                 let mut tag = [0 as u8; 16];
 250                 r.read_exact(&mut tag)?;
 251                 if !chacha.finish_and_check_tag(&tag) {
 252                         return Err(DecodeError::InvalidValue)
 253                 }
 254
 255                 Ok(Self { readable })
 256         }
 257 }
 258
 259 #[cfg(fuzzing)]
 260 mod fuzzy_chachapoly {
 261         #[derive(Clone, Copy)]
 262         pub struct ChaCha20Poly1305RFC {
 263                 tag: [u8; 16],
 264                 finished: bool,
 265         }
 266         impl ChaCha20Poly1305RFC {
 267                 pub fn new(key: &[u8], nonce: &[u8], _aad: &[u8]) -> ChaCha20Poly1305RFC {
 268                         assert!(key.len() == 16 || key.len() == 32);
 269                         assert!(nonce.len() == 12);
 270
 271                         // Ehh, I'm too lazy to *also* tweak ChaCha20 to make it RFC-compliant
 272                         assert!(nonce[0] == 0 && nonce[1] == 0 && nonce[2] == 0 && nonce[3] == 0);
 273
 274                         let mut tag = [0; 16];
 275                         tag.copy_from_slice(&key[0..16]);
 276
 277                         ChaCha20Poly1305RFC {
 278                                 tag,
 279                                 finished: false,
 280                         }
 281                 }
 282
 283                 pub fn encrypt(&mut self, input: &[u8], output: &mut [u8], out_tag: &mut [u8]) {
 284                         assert!(input.len() == output.len());
 285                         assert!(self.finished == false);
 286
 287                         output.copy_from_slice(&input);
 288                         out_tag.copy_from_slice(&self.tag);
 289                         self.finished = true;
 290                 }
 291
 292                 pub fn encrypt_full_message_in_place(&mut self, input_output: &mut [u8], out_tag: &mut [u8]) {
 293                         self.encrypt_in_place(input_output);
 294                         self.finish_and_get_tag(out_tag);
 295                 }
 296
 297                 pub(super) fn encrypt_in_place(&mut self, _input_output: &mut [u8]) {
 298                         assert!(self.finished == false);
 299                 }
 300
 301                 pub(super) fn finish_and_get_tag(&mut self, out_tag: &mut [u8]) {
 302                         assert!(self.finished == false);
 303                         out_tag.copy_from_slice(&self.tag);
 304                         self.finished = true;
 305                 }
 306
 307                 pub fn decrypt(&mut self, input: &[u8], output: &mut [u8], tag: &[u8]) -> bool {
 308                         assert!(input.len() == output.len());
 309                         assert!(self.finished == false);
 310
 311                         if tag[..] != self.tag[..] { return false; }
 312                         output.copy_from_slice(input);
 313                         self.finished = true;
 314                         true
 315                 }
 316
 317                 pub(super) fn decrypt_in_place(&mut self, _input: &mut [u8]) {
 318                         assert!(self.finished == false);
 319                 }
 320
 321                 pub(super) fn finish_and_check_tag(&mut self, tag: &[u8]) -> bool {
 322                         if tag[..] != self.tag[..] { return false; }
 323                         self.finished = true;
 324                         true
 325                 }
 326         }
 327 }
 328 #[cfg(fuzzing)]
 329 pub use self::fuzzy_chachapoly::ChaCha20Poly1305RFC;
 330
 331 #[cfg(test)]
 332 mod tests {
 333         use ln::msgs::DecodeError;
 334         use super::{ChaChaPolyReadAdapter, ChaChaPolyWriteAdapter};
 335         use util::ser::{self, FixedLengthReader, LengthReadableArgs, Writeable};
 336
 337         // Used for for testing various lengths of serialization.
 338         #[derive(Debug, PartialEq)]
 339         struct TestWriteable {
 340                 field1: Vec<u8>,
 341                 field2: Vec<u8>,
 342                 field3: Vec<u8>,
 343         }
 344         impl_writeable_tlv_based!(TestWriteable, {
 345                 (1, field1, vec_type),
 346                 (2, field2, vec_type),
 347                 (3, field3, vec_type),
 348         });
 349
 350         #[test]
 351         fn test_chacha_stream_adapters() {
 352                 // Check that ChaChaPolyReadAdapter and ChaChaPolyWriteAdapter correctly encode and decode an
 353                 // encrypted object.
 354                 macro_rules! check_object_read_write {
 355                         ($obj: expr) => {
 356                                 // First, serialize the object, encrypted with ChaCha20Poly1305.
 357                                 let rho = [42; 32];
 358                                 let writeable_len = $obj.serialized_length() as u64 + 16;
 359                                 let write_adapter = ChaChaPolyWriteAdapter::new(rho, &$obj);
 360                                 let encrypted_writeable_bytes = write_adapter.encode();
 361                                 let encrypted_writeable = &encrypted_writeable_bytes[..];
 362
 363                                 // Now deserialize the object back and make sure it matches the original.
 364                                 let mut rd = FixedLengthReader::new(encrypted_writeable, writeable_len);
 365                                 let read_adapter = <ChaChaPolyReadAdapter<TestWriteable>>::read(&mut rd, rho).unwrap();
 366                                 assert_eq!($obj, read_adapter.readable);
 367                         };
 368                 }
 369
 370                 // Try a big object that will require multiple write buffers.
 371                 let big_writeable = TestWriteable {
 372                         field1: vec![43],
 373                         field2: vec![44; 4192],
 374                         field3: vec![45; 4192 + 1],
 375                 };
 376                 check_object_read_write!(big_writeable);
 377
 378                 // Try a small object that fits into one write buffer.
 379                 let small_writeable = TestWriteable {
 380                         field1: vec![43],
 381                         field2: vec![44],
 382                         field3: vec![45],
 383                 };
 384                 check_object_read_write!(small_writeable);
 385         }
 386
 387         fn do_chacha_stream_adapters_ser_macros() -> Result<(), DecodeError> {
 388                 let writeable = TestWriteable {
 389                         field1: vec![43],
 390                         field2: vec![44; 4192],
 391                         field3: vec![45; 4192 + 1],
 392                 };
 393
 394                 // First, serialize the object into a TLV stream, encrypted with ChaCha20Poly1305.
 395                 let rho = [42; 32];
 396                 let write_adapter = ChaChaPolyWriteAdapter::new(rho, &writeable);
 397                 let mut writer = ser::VecWriter(Vec::new());
 398                 encode_tlv_stream!(&mut writer, {
 399                         (1, write_adapter, required),
 400                 });
 401
 402                 // Now deserialize the object back and make sure it matches the original.
 403                 let mut read_adapter: Option<ChaChaPolyReadAdapter<TestWriteable>> = None;
 404                 decode_tlv_stream!(&writer.0[..], {
 405                         (1, read_adapter, (option: LengthReadableArgs, rho)),
 406                 });
 407                 assert_eq!(writeable, read_adapter.unwrap().readable);
 408
 409                 Ok(())
 410         }
 411
 412         #[test]
 413         fn chacha_stream_adapters_ser_macros() {
 414                 // Test that our stream adapters work as expected with the TLV macros.
 415                 // This also serves to test the `option: $trait` variant of the `decode_tlv` ser macro.
 416                 do_chacha_stream_adapters_ser_macros().unwrap()
 417         }
 418 }