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Diffstat (limited to 'rand/rand_isaac/src/isaac.rs')
| -rw-r--r-- | rand/rand_isaac/src/isaac.rs | 476 |
1 files changed, 0 insertions, 476 deletions
diff --git a/rand/rand_isaac/src/isaac.rs b/rand/rand_isaac/src/isaac.rs deleted file mode 100644 index 2caf61a..0000000 --- a/rand/rand_isaac/src/isaac.rs +++ /dev/null @@ -1,476 +0,0 @@ -// Copyright 2018 Developers of the Rand project. -// Copyright 2013-2018 The Rust Project Developers. -// -// 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 ISAAC random number generator. - -use core::{fmt, slice}; -use core::num::Wrapping as w; -#[cfg(feature="serde1")] use serde::{Serialize, Deserialize}; -use rand_core::{RngCore, SeedableRng, Error, le}; -use rand_core::block::{BlockRngCore, BlockRng}; -use crate::isaac_array::IsaacArray; - -#[allow(non_camel_case_types)] -type w32 = w<u32>; - -const RAND_SIZE_LEN: usize = 8; -const RAND_SIZE: usize = 1 << RAND_SIZE_LEN; - -/// A random number generator that uses the ISAAC algorithm. -/// -/// ISAAC stands for "Indirection, Shift, Accumulate, Add, and Count" which are -/// the principal bitwise operations employed. It is the most advanced of a -/// series of array based random number generator designed by Robert Jenkins -/// in 1996[^1][^2]. -/// -/// ISAAC is notably fast and produces excellent quality random numbers for -/// non-cryptographic applications. -/// -/// In spite of being designed with cryptographic security in mind, ISAAC hasn't -/// been stringently cryptanalyzed and thus cryptographers do not not -/// consensually trust it to be secure. When looking for a secure RNG, prefer -/// `Hc128Rng` from the [`rand_hc`] crate instead, which, like ISAAC, is an -/// array-based RNG and one of the stream-ciphers selected the by eSTREAM -/// -/// In 2006 an improvement to ISAAC was suggested by Jean-Philippe Aumasson, -/// named ISAAC+[^3]. But because the specification is not complete, because -/// there is no good implementation, and because the suggested bias may not -/// exist, it is not implemented here. -/// -/// ## Overview of the ISAAC algorithm: -/// (in pseudo-code) -/// -/// ```text -/// Input: a, b, c, s[256] // state -/// Output: r[256] // results -/// -/// mix(a,i) = a ^ a << 13 if i = 0 mod 4 -/// a ^ a >> 6 if i = 1 mod 4 -/// a ^ a << 2 if i = 2 mod 4 -/// a ^ a >> 16 if i = 3 mod 4 -/// -/// c = c + 1 -/// b = b + c -/// -/// for i in 0..256 { -/// x = s_[i] -/// a = f(a,i) + s[i+128 mod 256] -/// y = a + b + s[x>>2 mod 256] -/// s[i] = y -/// b = x + s[y>>10 mod 256] -/// r[i] = b -/// } -/// ``` -/// -/// Numbers are generated in blocks of 256. This means the function above only -/// runs once every 256 times you ask for a next random number. In all other -/// circumstances the last element of the results array is returned. -/// -/// ISAAC therefore needs a lot of memory, relative to other non-crypto RNGs. -/// 2 * 256 * 4 = 2 kb to hold the state and results. -/// -/// This implementation uses [`BlockRng`] to implement the [`RngCore`] methods. -/// -/// ## References -/// [^1]: Bob Jenkins, [*ISAAC: A fast cryptographic random number generator*]( -/// http://burtleburtle.net/bob/rand/isaacafa.html) -/// -/// [^2]: Bob Jenkins, [*ISAAC and RC4*]( -/// http://burtleburtle.net/bob/rand/isaac.html) -/// -/// [^3]: Jean-Philippe Aumasson, [*On the pseudo-random generator ISAAC*]( -/// https://eprint.iacr.org/2006/438) -/// -/// [`rand_hc`]: https://docs.rs/rand_hc -#[derive(Clone, Debug)] -#[cfg_attr(feature="serde1", derive(Serialize, Deserialize))] -pub struct IsaacRng(BlockRng<IsaacCore>); - -impl RngCore for IsaacRng { - #[inline] - fn next_u32(&mut self) -> u32 { - self.0.next_u32() - } - - #[inline] - fn next_u64(&mut self) -> u64 { - self.0.next_u64() - } - - #[inline] - fn fill_bytes(&mut self, dest: &mut [u8]) { - self.0.fill_bytes(dest) - } - - #[inline] - fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), Error> { - self.0.try_fill_bytes(dest) - } -} - -impl SeedableRng for IsaacRng { - type Seed = <IsaacCore as SeedableRng>::Seed; - - #[inline] - fn from_seed(seed: Self::Seed) -> Self { - IsaacRng(BlockRng::<IsaacCore>::from_seed(seed)) - } - - /// Create an ISAAC random number generator using an `u64` as seed. - /// If `seed == 0` this will produce the same stream of random numbers as - /// the reference implementation when used unseeded. - #[inline] - fn seed_from_u64(seed: u64) -> Self { - IsaacRng(BlockRng::<IsaacCore>::seed_from_u64(seed)) - } - - #[inline] - fn from_rng<S: RngCore>(rng: S) -> Result<Self, Error> { - BlockRng::<IsaacCore>::from_rng(rng).map(|rng| IsaacRng(rng)) - } -} - -/// The core of [`IsaacRng`], used with [`BlockRng`]. -#[derive(Clone)] -#[cfg_attr(feature="serde1", derive(Serialize, Deserialize))] -pub struct IsaacCore { - #[cfg_attr(feature="serde1",serde(with="super::isaac_array::isaac_array_serde"))] - mem: [w32; RAND_SIZE], - a: w32, - b: w32, - c: w32, -} - -// Custom Debug implementation that does not expose the internal state -impl fmt::Debug for IsaacCore { - fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { - write!(f, "IsaacCore {{}}") - } -} - -impl BlockRngCore for IsaacCore { - type Item = u32; - type Results = IsaacArray<Self::Item>; - - /// Refills the output buffer, `results`. See also the pseudocode desciption - /// of the algorithm in the `IsaacRng` documentation. - /// - /// Optimisations used (similar to the reference implementation): - /// - /// - The loop is unrolled 4 times, once for every constant of mix(). - /// - The contents of the main loop are moved to a function `rngstep`, to - /// reduce code duplication. - /// - We use local variables for a and b, which helps with optimisations. - /// - We split the main loop in two, one that operates over 0..128 and one - /// over 128..256. This way we can optimise out the addition and modulus - /// from `s[i+128 mod 256]`. - /// - We maintain one index `i` and add `m` or `m2` as base (m2 for the - /// `s[i+128 mod 256]`), relying on the optimizer to turn it into pointer - /// arithmetic. - /// - We fill `results` backwards. The reference implementation reads values - /// from `results` in reverse. We read them in the normal direction, to - /// make `fill_bytes` a memcopy. To maintain compatibility we fill in - /// reverse. - fn generate(&mut self, results: &mut IsaacArray<Self::Item>) { - self.c += w(1); - // abbreviations - let mut a = self.a; - let mut b = self.b + self.c; - const MIDPOINT: usize = RAND_SIZE / 2; - - #[inline] - fn ind(mem:&[w32; RAND_SIZE], v: w32, amount: usize) -> w32 { - let index = (v >> amount).0 as usize % RAND_SIZE; - mem[index] - } - - #[inline] - fn rngstep(mem: &mut [w32; RAND_SIZE], - results: &mut [u32; RAND_SIZE], - mix: w32, - a: &mut w32, - b: &mut w32, - base: usize, - m: usize, - m2: usize) { - let x = mem[base + m]; - *a = mix + mem[base + m2]; - let y = *a + *b + ind(&mem, x, 2); - mem[base + m] = y; - *b = x + ind(&mem, y, 2 + RAND_SIZE_LEN); - results[RAND_SIZE - 1 - base - m] = (*b).0; - } - - let mut m = 0; - let mut m2 = MIDPOINT; - for i in (0..MIDPOINT/4).map(|i| i * 4) { - rngstep(&mut self.mem, results, a ^ (a << 13), &mut a, &mut b, i + 0, m, m2); - rngstep(&mut self.mem, results, a ^ (a >> 6 ), &mut a, &mut b, i + 1, m, m2); - rngstep(&mut self.mem, results, a ^ (a << 2 ), &mut a, &mut b, i + 2, m, m2); - rngstep(&mut self.mem, results, a ^ (a >> 16), &mut a, &mut b, i + 3, m, m2); - } - - m = MIDPOINT; - m2 = 0; - for i in (0..MIDPOINT/4).map(|i| i * 4) { - rngstep(&mut self.mem, results, a ^ (a << 13), &mut a, &mut b, i + 0, m, m2); - rngstep(&mut self.mem, results, a ^ (a >> 6 ), &mut a, &mut b, i + 1, m, m2); - rngstep(&mut self.mem, results, a ^ (a << 2 ), &mut a, &mut b, i + 2, m, m2); - rngstep(&mut self.mem, results, a ^ (a >> 16), &mut a, &mut b, i + 3, m, m2); - } - - self.a = a; - self.b = b; - } -} - -impl IsaacCore { - /// Create a new ISAAC random number generator. - /// - /// The author Bob Jenkins describes how to best initialize ISAAC here: - /// <https://rt.cpan.org/Public/Bug/Display.html?id=64324> - /// The answer is included here just in case: - /// - /// "No, you don't need a full 8192 bits of seed data. Normal key sizes will - /// do fine, and they should have their expected strength (eg a 40-bit key - /// will take as much time to brute force as 40-bit keys usually will). You - /// could fill the remainder with 0, but set the last array element to the - /// length of the key provided (to distinguish keys that differ only by - /// different amounts of 0 padding). You do still need to call `randinit()` - /// to make sure the initial state isn't uniform-looking." - /// "After publishing ISAAC, I wanted to limit the key to half the size of - /// `r[]`, and repeat it twice. That would have made it hard to provide a - /// key that sets the whole internal state to anything convenient. But I'd - /// already published it." - /// - /// And his answer to the question "For my code, would repeating the key - /// over and over to fill 256 integers be a better solution than - /// zero-filling, or would they essentially be the same?": - /// "If the seed is under 32 bytes, they're essentially the same, otherwise - /// repeating the seed would be stronger. randinit() takes a chunk of 32 - /// bytes, mixes it, and combines that with the next 32 bytes, et cetera. - /// Then loops over all the elements the same way a second time." - #[inline] - fn init(mut mem: [w32; RAND_SIZE], rounds: u32) -> Self { - fn mix(a: &mut w32, b: &mut w32, c: &mut w32, d: &mut w32, - e: &mut w32, f: &mut w32, g: &mut w32, h: &mut w32) { - *a ^= *b << 11; *d += *a; *b += *c; - *b ^= *c >> 2; *e += *b; *c += *d; - *c ^= *d << 8; *f += *c; *d += *e; - *d ^= *e >> 16; *g += *d; *e += *f; - *e ^= *f << 10; *h += *e; *f += *g; - *f ^= *g >> 4; *a += *f; *g += *h; - *g ^= *h << 8; *b += *g; *h += *a; - *h ^= *a >> 9; *c += *h; *a += *b; - } - - // These numbers are the result of initializing a...h with the - // fractional part of the golden ratio in binary (0x9e3779b9) - // and applying mix() 4 times. - let mut a = w(0x1367df5a); - let mut b = w(0x95d90059); - let mut c = w(0xc3163e4b); - let mut d = w(0x0f421ad8); - let mut e = w(0xd92a4a78); - let mut f = w(0xa51a3c49); - let mut g = w(0xc4efea1b); - let mut h = w(0x30609119); - - // Normally this should do two passes, to make all of the seed effect - // all of `mem` - for _ in 0..rounds { - for i in (0..RAND_SIZE/8).map(|i| i * 8) { - a += mem[i ]; b += mem[i+1]; - c += mem[i+2]; d += mem[i+3]; - e += mem[i+4]; f += mem[i+5]; - g += mem[i+6]; h += mem[i+7]; - mix(&mut a, &mut b, &mut c, &mut d, - &mut e, &mut f, &mut g, &mut h); - mem[i ] = a; mem[i+1] = b; - mem[i+2] = c; mem[i+3] = d; - mem[i+4] = e; mem[i+5] = f; - mem[i+6] = g; mem[i+7] = h; - } - } - - Self { mem, a: w(0), b: w(0), c: w(0) } - } -} - -impl SeedableRng for IsaacCore { - type Seed = [u8; 32]; - - fn from_seed(seed: Self::Seed) -> Self { - let mut seed_u32 = [0u32; 8]; - le::read_u32_into(&seed, &mut seed_u32); - // Convert the seed to `Wrapping<u32>` and zero-extend to `RAND_SIZE`. - let mut seed_extended = [w(0); RAND_SIZE]; - for (x, y) in seed_extended.iter_mut().zip(seed_u32.iter()) { - *x = w(*y); - } - Self::init(seed_extended, 2) - } - - /// Create an ISAAC random number generator using an `u64` as seed. - /// If `seed == 0` this will produce the same stream of random numbers as - /// the reference implementation when used unseeded. - fn seed_from_u64(seed: u64) -> Self { - let mut key = [w(0); RAND_SIZE]; - key[0] = w(seed as u32); - key[1] = w((seed >> 32) as u32); - // Initialize with only one pass. - // A second pass does not improve the quality here, because all of the - // seed was already available in the first round. - // Not doing the second pass has the small advantage that if - // `seed == 0` this method produces exactly the same state as the - // reference implementation when used unseeded. - Self::init(key, 1) - } - - fn from_rng<R: RngCore>(mut rng: R) -> Result<Self, Error> { - // Custom `from_rng` implementation that fills a seed with the same size - // as the entire state. - let mut seed = [w(0u32); RAND_SIZE]; - unsafe { - let ptr = seed.as_mut_ptr() as *mut u8; - - let slice = slice::from_raw_parts_mut(ptr, RAND_SIZE * 4); - rng.try_fill_bytes(slice)?; - } - for i in seed.iter_mut() { - *i = w(i.0.to_le()); - } - - Ok(Self::init(seed, 2)) - } -} - -#[cfg(test)] -mod test { - use rand_core::{RngCore, SeedableRng}; - use super::IsaacRng; - - #[test] - fn test_isaac_construction() { - // Test that various construction techniques produce a working RNG. - let seed = [1,0,0,0, 23,0,0,0, 200,1,0,0, 210,30,0,0, - 0,0,0,0, 0,0,0,0, 0,0,0,0, 0,0,0,0]; - let mut rng1 = IsaacRng::from_seed(seed); - assert_eq!(rng1.next_u32(), 2869442790); - - let mut rng2 = IsaacRng::from_rng(rng1).unwrap(); - assert_eq!(rng2.next_u32(), 3094074039); - } - - #[test] - fn test_isaac_true_values_32() { - let seed = [1,0,0,0, 23,0,0,0, 200,1,0,0, 210,30,0,0, - 57,48,0,0, 0,0,0,0, 0,0,0,0, 0,0,0,0]; - let mut rng1 = IsaacRng::from_seed(seed); - let mut results = [0u32; 10]; - for i in results.iter_mut() { *i = rng1.next_u32(); } - let expected = [ - 2558573138, 873787463, 263499565, 2103644246, 3595684709, - 4203127393, 264982119, 2765226902, 2737944514, 3900253796]; - assert_eq!(results, expected); - - let seed = [57,48,0,0, 50,9,1,0, 49,212,0,0, 148,38,0,0, - 0,0,0,0, 0,0,0,0, 0,0,0,0, 0,0,0,0]; - let mut rng2 = IsaacRng::from_seed(seed); - // skip forward to the 10000th number - for _ in 0..10000 { rng2.next_u32(); } - - for i in results.iter_mut() { *i = rng2.next_u32(); } - let expected = [ - 3676831399, 3183332890, 2834741178, 3854698763, 2717568474, - 1576568959, 3507990155, 179069555, 141456972, 2478885421]; - assert_eq!(results, expected); - } - - #[test] - fn test_isaac_true_values_64() { - // As above, using little-endian versions of above values - let seed = [1,0,0,0, 23,0,0,0, 200,1,0,0, 210,30,0,0, - 57,48,0,0, 0,0,0,0, 0,0,0,0, 0,0,0,0]; - let mut rng = IsaacRng::from_seed(seed); - let mut results = [0u64; 5]; - for i in results.iter_mut() { *i = rng.next_u64(); } - let expected = [ - 3752888579798383186, 9035083239252078381,18052294697452424037, - 11876559110374379111, 16751462502657800130]; - assert_eq!(results, expected); - } - - #[test] - fn test_isaac_true_bytes() { - let seed = [1,0,0,0, 23,0,0,0, 200,1,0,0, 210,30,0,0, - 57,48,0,0, 0,0,0,0, 0,0,0,0, 0,0,0,0]; - let mut rng = IsaacRng::from_seed(seed); - let mut results = [0u8; 32]; - rng.fill_bytes(&mut results); - // Same as first values in test_isaac_true_values as bytes in LE order - let expected = [82, 186, 128, 152, 71, 240, 20, 52, - 45, 175, 180, 15, 86, 16, 99, 125, - 101, 203, 81, 214, 97, 162, 134, 250, - 103, 78, 203, 15, 150, 3, 210, 164]; - assert_eq!(results, expected); - } - - #[test] - fn test_isaac_new_uninitialized() { - // Compare the results from initializing `IsaacRng` with - // `seed_from_u64(0)`, to make sure it is the same as the reference - // implementation when used uninitialized. - // Note: We only test the first 16 integers, not the full 256 of the - // first block. - let mut rng = IsaacRng::seed_from_u64(0); - let mut results = [0u32; 16]; - for i in results.iter_mut() { *i = rng.next_u32(); } - let expected: [u32; 16] = [ - 0x71D71FD2, 0xB54ADAE7, 0xD4788559, 0xC36129FA, - 0x21DC1EA9, 0x3CB879CA, 0xD83B237F, 0xFA3CE5BD, - 0x8D048509, 0xD82E9489, 0xDB452848, 0xCA20E846, - 0x500F972E, 0x0EEFF940, 0x00D6B993, 0xBC12C17F]; - assert_eq!(results, expected); - } - - #[test] - fn test_isaac_clone() { - let seed = [1,0,0,0, 23,0,0,0, 200,1,0,0, 210,30,0,0, - 57,48,0,0, 0,0,0,0, 0,0,0,0, 0,0,0,0]; - let mut rng1 = IsaacRng::from_seed(seed); - let mut rng2 = rng1.clone(); - for _ in 0..16 { - assert_eq!(rng1.next_u32(), rng2.next_u32()); - } - } - - #[test] - #[cfg(feature="serde1")] - fn test_isaac_serde() { - use bincode; - use std::io::{BufWriter, BufReader}; - - let seed = [1,0,0,0, 23,0,0,0, 200,1,0,0, 210,30,0,0, - 57,48,0,0, 0,0,0,0, 0,0,0,0, 0,0,0,0]; - let mut rng = IsaacRng::from_seed(seed); - - let buf: Vec<u8> = Vec::new(); - let mut buf = BufWriter::new(buf); - bincode::serialize_into(&mut buf, &rng).expect("Could not serialize"); - - let buf = buf.into_inner().unwrap(); - let mut read = BufReader::new(&buf[..]); - let mut deserialized: IsaacRng = bincode::deserialize_from(&mut read).expect("Could not deserialize"); - - for _ in 0..300 { // more than the 256 buffered results - assert_eq!(rng.next_u32(), deserialized.next_u32()); - } - } -} |