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