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Diffstat (limited to 'rand/rand_chacha/src/chacha.rs')
| -rw-r--r-- | rand/rand_chacha/src/chacha.rs | 452 |
1 files changed, 0 insertions, 452 deletions
diff --git a/rand/rand_chacha/src/chacha.rs b/rand/rand_chacha/src/chacha.rs deleted file mode 100644 index b1b89e0..0000000 --- a/rand/rand_chacha/src/chacha.rs +++ /dev/null @@ -1,452 +0,0 @@ -// Copyright 2018 Developers of the Rand project. -// -// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or -// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license -// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your -// option. This file may not be copied, modified, or distributed -// except according to those terms. - -//! The ChaCha random number generator. - -#[cfg(feature = "std")] -use std as core; -#[cfg(not(feature = "std"))] -use core; - -use c2_chacha::guts::ChaCha; -use self::core::fmt; -use rand_core::block::{BlockRng, BlockRngCore}; -use rand_core::{CryptoRng, Error, RngCore, SeedableRng}; - -const STREAM_PARAM_NONCE: u32 = 1; -const STREAM_PARAM_BLOCK: u32 = 0; - -pub struct Array64<T>([T; 64]); -impl<T> Default for Array64<T> where T: Default { - fn default() -> Self { - Self([T::default(), T::default(), T::default(), T::default(), T::default(), T::default(), T::default(), T::default(), - T::default(), T::default(), T::default(), T::default(), T::default(), T::default(), T::default(), T::default(), - T::default(), T::default(), T::default(), T::default(), T::default(), T::default(), T::default(), T::default(), - T::default(), T::default(), T::default(), T::default(), T::default(), T::default(), T::default(), T::default(), - T::default(), T::default(), T::default(), T::default(), T::default(), T::default(), T::default(), T::default(), - T::default(), T::default(), T::default(), T::default(), T::default(), T::default(), T::default(), T::default(), - T::default(), T::default(), T::default(), T::default(), T::default(), T::default(), T::default(), T::default(), - T::default(), T::default(), T::default(), T::default(), T::default(), T::default(), T::default(), T::default()]) - } -} -impl<T> AsRef<[T]> for Array64<T> { - fn as_ref(&self) -> &[T] { - &self.0 - } -} -impl<T> AsMut<[T]> for Array64<T> { - fn as_mut(&mut self) -> &mut [T] { - &mut self.0 - } -} -impl<T> Clone for Array64<T> where T: Copy + Default { - fn clone(&self) -> Self { - let mut new = Self::default(); - new.0.copy_from_slice(&self.0); - new - } -} -impl<T> fmt::Debug for Array64<T> { - fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { - write!(f, "Array64 {{}}") - } -} - -macro_rules! chacha_impl { - ($ChaChaXCore:ident, $ChaChaXRng:ident, $rounds:expr, $doc:expr) => { - #[doc=$doc] - #[derive(Clone)] - pub struct $ChaChaXCore { - state: ChaCha, - } - - // Custom Debug implementation that does not expose the internal state - impl fmt::Debug for $ChaChaXCore { - fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { - write!(f, "ChaChaXCore {{}}") - } - } - - impl BlockRngCore for $ChaChaXCore { - type Item = u32; - type Results = Array64<u32>; - #[inline] - fn generate(&mut self, r: &mut Self::Results) { - // Fill slice of words by writing to equivalent slice of bytes, then fixing endianness. - self.state.refill4($rounds, unsafe { - &mut *(&mut *r as *mut Array64<u32> as *mut [u8; 256]) - }); - for x in r.as_mut() { - *x = x.to_le(); - } - } - } - - impl SeedableRng for $ChaChaXCore { - type Seed = [u8; 32]; - #[inline] - fn from_seed(seed: Self::Seed) -> Self { - $ChaChaXCore { state: ChaCha::new(&seed, &[0u8; 8]) } - } - } - - /// A cryptographically secure random number generator that uses the ChaCha algorithm. - /// - /// ChaCha is a stream cipher designed by Daniel J. Bernstein[^1], that we use as an RNG. It is - /// an improved variant of the Salsa20 cipher family, which was selected as one of the "stream - /// ciphers suitable for widespread adoption" by eSTREAM[^2]. - /// - /// ChaCha uses add-rotate-xor (ARX) operations as its basis. These are safe against timing - /// attacks, although that is mostly a concern for ciphers and not for RNGs. We provide a SIMD - /// implementation to support high throughput on a variety of common hardware platforms. - /// - /// With the ChaCha algorithm it is possible to choose the number of rounds the core algorithm - /// should run. The number of rounds is a tradeoff between performance and security, where 8 - /// rounds is the minimum potentially secure configuration, and 20 rounds is widely used as a - /// conservative choice. - /// - /// We use a 64-bit counter and 64-bit stream identifier as in Bernstein's implementation[^1] - /// except that we use a stream identifier in place of a nonce. A 64-bit counter over 64-byte - /// (16 word) blocks allows 1 ZiB of output before cycling, and the stream identifier allows - /// 2<sup>64</sup> unique streams of output per seed. Both counter and stream are initialized - /// to zero but may be set via the `set_word_pos` and `set_stream` methods. - /// - /// The word layout is: - /// - /// ```text - /// constant constant constant constant - /// seed seed seed seed - /// seed seed seed seed - /// counter counter stream_id stream_id - /// ``` - /// - /// This implementation uses an output buffer of sixteen `u32` words, and uses - /// [`BlockRng`] to implement the [`RngCore`] methods. - /// - /// [^1]: D. J. Bernstein, [*ChaCha, a variant of Salsa20*]( - /// https://cr.yp.to/chacha.html) - /// - /// [^2]: [eSTREAM: the ECRYPT Stream Cipher Project]( - /// http://www.ecrypt.eu.org/stream/) - #[derive(Clone, Debug)] - pub struct $ChaChaXRng { - rng: BlockRng<$ChaChaXCore>, - } - - impl SeedableRng for $ChaChaXRng { - type Seed = [u8; 32]; - #[inline] - fn from_seed(seed: Self::Seed) -> Self { - let core = $ChaChaXCore::from_seed(seed); - Self { - rng: BlockRng::new(core), - } - } - } - - impl RngCore for $ChaChaXRng { - #[inline] - fn next_u32(&mut self) -> u32 { - self.rng.next_u32() - } - #[inline] - fn next_u64(&mut self) -> u64 { - self.rng.next_u64() - } - #[inline] - fn fill_bytes(&mut self, bytes: &mut [u8]) { - self.rng.fill_bytes(bytes) - } - #[inline] - fn try_fill_bytes(&mut self, bytes: &mut [u8]) -> Result<(), Error> { - self.rng.try_fill_bytes(bytes) - } - } - - impl $ChaChaXRng { - // The buffer is a 4-block window, i.e. it is always at a block-aligned position in the - // stream but if the stream has been seeked it may not be self-aligned. - - /// Get the offset from the start of the stream, in 32-bit words. - /// - /// Since the generated blocks are 16 words (2<sup>4</sup>) long and the - /// counter is 64-bits, the offset is a 68-bit number. Sub-word offsets are - /// not supported, hence the result can simply be multiplied by 4 to get a - /// byte-offset. - #[inline] - pub fn get_word_pos(&self) -> u128 { - let mut block = u128::from(self.rng.core.state.get_stream_param(STREAM_PARAM_BLOCK)); - // counter is incremented *after* filling buffer - block -= 4; - (block << 4) + self.rng.index() as u128 - } - - /// Set the offset from the start of the stream, in 32-bit words. - /// - /// As with `get_word_pos`, we use a 68-bit number. Since the generator - /// simply cycles at the end of its period (1 ZiB), we ignore the upper - /// 60 bits. - #[inline] - pub fn set_word_pos(&mut self, word_offset: u128) { - let block = (word_offset >> 4) as u64; - self.rng - .core - .state - .set_stream_param(STREAM_PARAM_BLOCK, block); - self.rng.generate_and_set((word_offset & 15) as usize); - } - - /// Set the stream number. - /// - /// This is initialized to zero; 2<sup>64</sup> unique streams of output - /// are available per seed/key. - /// - /// Note that in order to reproduce ChaCha output with a specific 64-bit - /// nonce, one can convert that nonce to a `u64` in little-endian fashion - /// and pass to this function. In theory a 96-bit nonce can be used by - /// passing the last 64-bits to this function and using the first 32-bits as - /// the most significant half of the 64-bit counter (which may be set - /// indirectly via `set_word_pos`), but this is not directly supported. - #[inline] - pub fn set_stream(&mut self, stream: u64) { - self.rng - .core - .state - .set_stream_param(STREAM_PARAM_NONCE, stream); - if self.rng.index() != 64 { - let wp = self.get_word_pos(); - self.set_word_pos(wp); - } - } - } - - impl CryptoRng for $ChaChaXRng {} - - impl From<$ChaChaXCore> for $ChaChaXRng { - fn from(core: $ChaChaXCore) -> Self { - $ChaChaXRng { - rng: BlockRng::new(core), - } - } - } - } -} - -chacha_impl!(ChaCha20Core, ChaCha20Rng, 10, "ChaCha with 20 rounds"); -chacha_impl!(ChaCha12Core, ChaCha12Rng, 6, "ChaCha with 12 rounds"); -chacha_impl!(ChaCha8Core, ChaCha8Rng, 4, "ChaCha with 8 rounds"); - -#[cfg(test)] -mod test { - use rand_core::{RngCore, SeedableRng}; - - type ChaChaRng = super::ChaCha20Rng; - - #[test] - fn test_chacha_construction() { - let seed = [ - 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 3, 0, 0, 0, 0, - 0, 0, 0, - ]; - let mut rng1 = ChaChaRng::from_seed(seed); - assert_eq!(rng1.next_u32(), 137206642); - - let mut rng2 = ChaChaRng::from_rng(rng1).unwrap(); - assert_eq!(rng2.next_u32(), 1325750369); - } - - #[test] - fn test_chacha_true_values_a() { - // Test vectors 1 and 2 from - // https://tools.ietf.org/html/draft-nir-cfrg-chacha20-poly1305-04 - let seed = [0u8; 32]; - let mut rng = ChaChaRng::from_seed(seed); - - let mut results = [0u32; 16]; - for i in results.iter_mut() { - *i = rng.next_u32(); - } - let expected = [ - 0xade0b876, 0x903df1a0, 0xe56a5d40, 0x28bd8653, 0xb819d2bd, 0x1aed8da0, 0xccef36a8, - 0xc70d778b, 0x7c5941da, 0x8d485751, 0x3fe02477, 0x374ad8b8, 0xf4b8436a, 0x1ca11815, - 0x69b687c3, 0x8665eeb2, - ]; - assert_eq!(results, expected); - - for i in results.iter_mut() { - *i = rng.next_u32(); - } - let expected = [ - 0xbee7079f, 0x7a385155, 0x7c97ba98, 0x0d082d73, 0xa0290fcb, 0x6965e348, 0x3e53c612, - 0xed7aee32, 0x7621b729, 0x434ee69c, 0xb03371d5, 0xd539d874, 0x281fed31, 0x45fb0a51, - 0x1f0ae1ac, 0x6f4d794b, - ]; - assert_eq!(results, expected); - } - - #[test] - fn test_chacha_true_values_b() { - // Test vector 3 from - // https://tools.ietf.org/html/draft-nir-cfrg-chacha20-poly1305-04 - let seed = [ - 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, - 0, 0, 1, - ]; - let mut rng = ChaChaRng::from_seed(seed); - - // Skip block 0 - for _ in 0..16 { - rng.next_u32(); - } - - let mut results = [0u32; 16]; - for i in results.iter_mut() { - *i = rng.next_u32(); - } - let expected = [ - 0x2452eb3a, 0x9249f8ec, 0x8d829d9b, 0xddd4ceb1, 0xe8252083, 0x60818b01, 0xf38422b8, - 0x5aaa49c9, 0xbb00ca8e, 0xda3ba7b4, 0xc4b592d1, 0xfdf2732f, 0x4436274e, 0x2561b3c8, - 0xebdd4aa6, 0xa0136c00, - ]; - assert_eq!(results, expected); - } - - #[test] - fn test_chacha_true_values_c() { - // Test vector 4 from - // https://tools.ietf.org/html/draft-nir-cfrg-chacha20-poly1305-04 - let seed = [ - 0, 0xff, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, - 0, 0, 0, 0, - ]; - let expected = [ - 0xfb4dd572, 0x4bc42ef1, 0xdf922636, 0x327f1394, 0xa78dea8f, 0x5e269039, 0xa1bebbc1, - 0xcaf09aae, 0xa25ab213, 0x48a6b46c, 0x1b9d9bcb, 0x092c5be6, 0x546ca624, 0x1bec45d5, - 0x87f47473, 0x96f0992e, - ]; - let expected_end = 3 * 16; - let mut results = [0u32; 16]; - - // Test block 2 by skipping block 0 and 1 - let mut rng1 = ChaChaRng::from_seed(seed); - for _ in 0..32 { - rng1.next_u32(); - } - for i in results.iter_mut() { - *i = rng1.next_u32(); - } - assert_eq!(results, expected); - assert_eq!(rng1.get_word_pos(), expected_end); - - // Test block 2 by using `set_word_pos` - let mut rng2 = ChaChaRng::from_seed(seed); - rng2.set_word_pos(2 * 16); - for i in results.iter_mut() { - *i = rng2.next_u32(); - } - assert_eq!(results, expected); - assert_eq!(rng2.get_word_pos(), expected_end); - - // Test skipping behaviour with other types - let mut buf = [0u8; 32]; - rng2.fill_bytes(&mut buf[..]); - assert_eq!(rng2.get_word_pos(), expected_end + 8); - rng2.fill_bytes(&mut buf[0..25]); - assert_eq!(rng2.get_word_pos(), expected_end + 15); - rng2.next_u64(); - assert_eq!(rng2.get_word_pos(), expected_end + 17); - rng2.next_u32(); - rng2.next_u64(); - assert_eq!(rng2.get_word_pos(), expected_end + 20); - rng2.fill_bytes(&mut buf[0..1]); - assert_eq!(rng2.get_word_pos(), expected_end + 21); - } - - #[test] - fn test_chacha_multiple_blocks() { - let seed = [ - 0, 0, 0, 0, 1, 0, 0, 0, 2, 0, 0, 0, 3, 0, 0, 0, 4, 0, 0, 0, 5, 0, 0, 0, 6, 0, 0, 0, 7, - 0, 0, 0, - ]; - let mut rng = ChaChaRng::from_seed(seed); - - // Store the 17*i-th 32-bit word, - // i.e., the i-th word of the i-th 16-word block - let mut results = [0u32; 16]; - for i in results.iter_mut() { - *i = rng.next_u32(); - for _ in 0..16 { - rng.next_u32(); - } - } - let expected = [ - 0xf225c81a, 0x6ab1be57, 0x04d42951, 0x70858036, 0x49884684, 0x64efec72, 0x4be2d186, - 0x3615b384, 0x11cfa18e, 0xd3c50049, 0x75c775f6, 0x434c6530, 0x2c5bad8f, 0x898881dc, - 0x5f1c86d9, 0xc1f8e7f4, - ]; - assert_eq!(results, expected); - } - - #[test] - fn test_chacha_true_bytes() { - let seed = [0u8; 32]; - let mut rng = ChaChaRng::from_seed(seed); - let mut results = [0u8; 32]; - rng.fill_bytes(&mut results); - let expected = [ - 118, 184, 224, 173, 160, 241, 61, 144, 64, 93, 106, 229, 83, 134, 189, 40, 189, 210, - 25, 184, 160, 141, 237, 26, 168, 54, 239, 204, 139, 119, 13, 199, - ]; - assert_eq!(results, expected); - } - - #[test] - fn test_chacha_nonce() { - // Test vector 5 from - // https://tools.ietf.org/html/draft-nir-cfrg-chacha20-poly1305-04 - // Although we do not support setting a nonce, we try it here anyway so - // we can use this test vector. - let seed = [0u8; 32]; - let mut rng = ChaChaRng::from_seed(seed); - // 96-bit nonce in LE order is: 0,0,0,0, 0,0,0,0, 0,0,0,2 - rng.set_stream(2u64 << (24 + 32)); - - let mut results = [0u32; 16]; - for i in results.iter_mut() { - *i = rng.next_u32(); - } - let expected = [ - 0x374dc6c2, 0x3736d58c, 0xb904e24a, 0xcd3f93ef, 0x88228b1a, 0x96a4dfb3, 0x5b76ab72, - 0xc727ee54, 0x0e0e978a, 0xf3145c95, 0x1b748ea8, 0xf786c297, 0x99c28f5f, 0x628314e8, - 0x398a19fa, 0x6ded1b53, - ]; - assert_eq!(results, expected); - } - - #[test] - fn test_chacha_clone_streams() { - let seed = [ - 0, 0, 0, 0, 1, 0, 0, 0, 2, 0, 0, 0, 3, 0, 0, 0, 4, 0, 0, 0, 5, 0, 0, 0, 6, 0, 0, 0, 7, - 0, 0, 0, - ]; - let mut rng = ChaChaRng::from_seed(seed); - let mut clone = rng.clone(); - for _ in 0..16 { - assert_eq!(rng.next_u64(), clone.next_u64()); - } - - rng.set_stream(51); - for _ in 0..7 { - assert!(rng.next_u32() != clone.next_u32()); - } - clone.set_stream(51); // switch part way through block - for _ in 7..16 { - assert_eq!(rng.next_u32(), clone.next_u32()); - } - } -} |