1 // Copyright 2013 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 //! The ISAAC random number generator.
13 #![allow(non_camel_case_types)]
16 use core::iter::repeat;
17 use core::num::Wrapping as w;
19 use {Rng, SeedableRng, Rand};
24 const RAND_SIZE_LEN: usize = 8;
25 const RAND_SIZE: u32 = 1 << RAND_SIZE_LEN;
26 const RAND_SIZE_USIZE: usize = 1 << RAND_SIZE_LEN;
28 /// A random number generator that uses the ISAAC algorithm[1].
30 /// The ISAAC algorithm is generally accepted as suitable for
31 /// cryptographic purposes, but this implementation has not be
32 /// verified as such. Prefer a generator like `OsRng` that defers to
33 /// the operating system for cases that need high security.
35 /// [1]: Bob Jenkins, [*ISAAC: A fast cryptographic random number
36 /// generator*](http://www.burtleburtle.net/bob/rand/isaacafa.html)
40 rsl: [w32; RAND_SIZE_USIZE],
41 mem: [w32; RAND_SIZE_USIZE],
47 static EMPTY: IsaacRng = IsaacRng {
49 rsl: [w(0); RAND_SIZE_USIZE],
50 mem: [w(0); RAND_SIZE_USIZE],
58 /// Create an ISAAC random number generator using the default
60 pub fn new_unseeded() -> IsaacRng {
66 /// Initialises `self`. If `use_rsl` is true, then use the current value
67 /// of `rsl` as a seed, otherwise construct one algorithmically (not
69 fn init(&mut self, use_rsl: bool) {
70 let mut a = w(0x9e3779b9);
81 a=a^(b<<11); d=d+a; b=b+c;
82 b=b^(c>>2); e=e+b; c=c+d;
83 c=c^(d<<8); f=f+c; d=d+e;
84 d=d^(e>>16); g=g+d; e=e+f;
85 e=e^(f<<10); h=h+e; f=f+g;
86 f=f^(g>>4); a=a+f; g=g+h;
87 g=g^(h<<8); b=b+g; h=h+a;
88 h=h^(a>>9); c=c+h; a=a+b;
97 macro_rules! memloop {
99 for i in (0..RAND_SIZE_USIZE).step_by(8) {
124 for i in (0..RAND_SIZE_USIZE).step_by(8) {
140 /// Refills the output buffer (`self.rsl`)
142 fn isaac(&mut self) {
143 self.c = self.c + w(1);
146 let mut b = self.b + self.c;
148 const MIDPOINT: usize = RAND_SIZE_USIZE / 2;
151 ($x:expr) => (self.mem[($x >> 2).0 as usize & (RAND_SIZE_USIZE - 1)] )
154 let r = [(0, MIDPOINT), (MIDPOINT, 0)];
155 for &(mr_offset, m2_offset) in &r {
157 macro_rules! rngstepp {
158 ($j:expr, $shift:expr) => {{
160 let mix = a << $shift;
162 let x = self.mem[base + mr_offset];
163 a = (a ^ mix) + self.mem[base + m2_offset];
164 let y = ind!(x) + a + b;
165 self.mem[base + mr_offset] = y;
167 b = ind!(y >> RAND_SIZE_LEN) + x;
168 self.rsl[base + mr_offset] = b;
172 macro_rules! rngstepn {
173 ($j:expr, $shift:expr) => {{
175 let mix = a >> $shift;
177 let x = self.mem[base + mr_offset];
178 a = (a ^ mix) + self.mem[base + m2_offset];
179 let y = ind!(x) + a + b;
180 self.mem[base + mr_offset] = y;
182 b = ind!(y >> RAND_SIZE_LEN) + x;
183 self.rsl[base + mr_offset] = b;
187 for i in (0..MIDPOINT).step_by(4) {
188 rngstepp!(i + 0, 13);
191 rngstepn!(i + 3, 16);
197 self.cnt = RAND_SIZE;
201 // Cannot be derived because [u32; 256] does not implement Clone
202 impl Clone for IsaacRng {
203 fn clone(&self) -> IsaacRng {
208 impl Rng for IsaacRng {
210 fn next_u32(&mut self) -> u32 {
212 // make some more numbers
217 // self.cnt is at most RAND_SIZE, but that is before the
218 // subtraction above. We want to index without bounds
219 // checking, but this could lead to incorrect code if someone
220 // misrefactors, so we check, sometimes.
222 // (Changes here should be reflected in Isaac64Rng.next_u64.)
223 debug_assert!(self.cnt < RAND_SIZE);
225 // (the % is cheaply telling the optimiser that we're always
226 // in bounds, without unsafe. NB. this is a power of two, so
227 // it optimises to a bitwise mask).
228 self.rsl[(self.cnt % RAND_SIZE) as usize].0
232 impl<'a> SeedableRng<&'a [u32]> for IsaacRng {
233 fn reseed(&mut self, seed: &'a [u32]) {
234 // make the seed into [seed[0], seed[1], ..., seed[seed.len()
235 // - 1], 0, 0, ...], to fill rng.rsl.
236 let seed_iter = seed.iter().cloned().chain(repeat(0));
238 for (rsl_elem, seed_elem) in self.rsl.iter_mut().zip(seed_iter) {
239 *rsl_elem = w(seed_elem);
249 /// Create an ISAAC random number generator with a seed. This can
250 /// be any length, although the maximum number of elements used is
251 /// 256 and any more will be silently ignored. A generator
252 /// constructed with a given seed will generate the same sequence
253 /// of values as all other generators constructed with that seed.
254 fn from_seed(seed: &'a [u32]) -> IsaacRng {
261 impl Rand for IsaacRng {
262 fn rand<R: Rng>(other: &mut R) -> IsaacRng {
265 let ptr = ret.rsl.as_mut_ptr() as *mut u8;
267 let slice = slice::from_raw_parts_mut(ptr, RAND_SIZE_USIZE * 4);
268 other.fill_bytes(slice);
280 const RAND_SIZE_64_LEN: usize = 8;
281 const RAND_SIZE_64: usize = 1 << RAND_SIZE_64_LEN;
283 /// A random number generator that uses ISAAC-64[1], the 64-bit
284 /// variant of the ISAAC algorithm.
286 /// The ISAAC algorithm is generally accepted as suitable for
287 /// cryptographic purposes, but this implementation has not be
288 /// verified as such. Prefer a generator like `OsRng` that defers to
289 /// the operating system for cases that need high security.
291 /// [1]: Bob Jenkins, [*ISAAC: A fast cryptographic random number
292 /// generator*](http://www.burtleburtle.net/bob/rand/isaacafa.html)
294 pub struct Isaac64Rng {
296 rsl: [w64; RAND_SIZE_64],
297 mem: [w64; RAND_SIZE_64],
303 static EMPTY_64: Isaac64Rng = Isaac64Rng {
305 rsl: [w(0); RAND_SIZE_64],
306 mem: [w(0); RAND_SIZE_64],
313 /// Create a 64-bit ISAAC random number generator using the
314 /// default fixed seed.
315 pub fn new_unseeded() -> Isaac64Rng {
316 let mut rng = EMPTY_64;
321 /// Initialises `self`. If `use_rsl` is true, then use the current value
322 /// of `rsl` as a seed, otherwise construct one algorithmically (not
324 fn init(&mut self, use_rsl: bool) {
327 let mut $var = w(0x9e3779b97f4a7c13);
341 a=a-e; f=f^(h>>9); h=h+a;
342 b=b-f; g=g^(a<<9); a=a+b;
343 c=c-g; h=h^(b>>23); b=b+c;
344 d=d-h; a=a^(c<<15); c=c+d;
345 e=e-a; b=b^(d>>14); d=d+e;
346 f=f-b; c=c^(e<<20); e=e+f;
347 g=g-c; d=d^(f>>17); f=f+g;
348 h=h-d; e=e^(g<<14); g=g+h;
357 macro_rules! memloop {
359 for i in (0..RAND_SIZE_64 / 8).map(|i| i * 8) {
384 for i in (0..RAND_SIZE_64 / 8).map(|i| i * 8) {
400 /// Refills the output buffer (`self.rsl`)
401 fn isaac64(&mut self) {
402 self.c = self.c + w(1);
405 let mut b = self.b + self.c;
406 const MIDPOINT: usize = RAND_SIZE_64 / 2;
407 const MP_VEC: [(usize, usize); 2] = [(0, MIDPOINT), (MIDPOINT, 0)];
410 *self.mem.get_unchecked((($x >> 3).0 as usize) & (RAND_SIZE_64 - 1))
414 for &(mr_offset, m2_offset) in &MP_VEC {
415 for base in (0..MIDPOINT / 4).map(|i| i * 4) {
417 macro_rules! rngstepp {
418 ($j:expr, $shift:expr) => {{
419 let base = base + $j;
420 let mix = a ^ (a << $shift);
421 let mix = if $j == 0 {!mix} else {mix};
424 let x = *self.mem.get_unchecked(base + mr_offset);
425 a = mix + *self.mem.get_unchecked(base + m2_offset);
426 let y = ind!(x) + a + b;
427 *self.mem.get_unchecked_mut(base + mr_offset) = y;
429 b = ind!(y >> RAND_SIZE_64_LEN) + x;
430 *self.rsl.get_unchecked_mut(base + mr_offset) = b;
435 macro_rules! rngstepn {
436 ($j:expr, $shift:expr) => {{
437 let base = base + $j;
438 let mix = a ^ (a >> $shift);
439 let mix = if $j == 0 {!mix} else {mix};
442 let x = *self.mem.get_unchecked(base + mr_offset);
443 a = mix + *self.mem.get_unchecked(base + m2_offset);
444 let y = ind!(x) + a + b;
445 *self.mem.get_unchecked_mut(base + mr_offset) = y;
447 b = ind!(y >> RAND_SIZE_64_LEN) + x;
448 *self.rsl.get_unchecked_mut(base + mr_offset) = b;
462 self.cnt = RAND_SIZE_64;
466 // Cannot be derived because [u32; 256] does not implement Clone
467 impl Clone for Isaac64Rng {
468 fn clone(&self) -> Isaac64Rng {
473 impl Rng for Isaac64Rng {
474 // FIXME #7771: having next_u32 like this should be unnecessary
476 fn next_u32(&mut self) -> u32 {
477 self.next_u64() as u32
481 fn next_u64(&mut self) -> u64 {
483 // make some more numbers
488 // See corresponding location in IsaacRng.next_u32 for
490 debug_assert!(self.cnt < RAND_SIZE_64);
491 self.rsl[(self.cnt % RAND_SIZE_64) as usize].0
495 impl<'a> SeedableRng<&'a [u64]> for Isaac64Rng {
496 fn reseed(&mut self, seed: &'a [u64]) {
497 // make the seed into [seed[0], seed[1], ..., seed[seed.len()
498 // - 1], 0, 0, ...], to fill rng.rsl.
499 let seed_iter = seed.iter().cloned().chain(repeat(0));
501 for (rsl_elem, seed_elem) in self.rsl.iter_mut().zip(seed_iter) {
502 *rsl_elem = w(seed_elem);
512 /// Create an ISAAC random number generator with a seed. This can
513 /// be any length, although the maximum number of elements used is
514 /// 256 and any more will be silently ignored. A generator
515 /// constructed with a given seed will generate the same sequence
516 /// of values as all other generators constructed with that seed.
517 fn from_seed(seed: &'a [u64]) -> Isaac64Rng {
518 let mut rng = EMPTY_64;
524 impl Rand for Isaac64Rng {
525 fn rand<R: Rng>(other: &mut R) -> Isaac64Rng {
526 let mut ret = EMPTY_64;
528 let ptr = ret.rsl.as_mut_ptr() as *mut u8;
530 let slice = slice::from_raw_parts_mut(ptr, RAND_SIZE_64 * 8);
531 other.fill_bytes(slice);
546 use std::prelude::v1::*;
548 use core::iter::order;
549 use {Rng, SeedableRng};
550 use super::{IsaacRng, Isaac64Rng};
553 fn test_rng_32_rand_seeded() {
554 let s = ::test::rng().gen_iter::<u32>().take(256).collect::<Vec<u32>>();
555 let mut ra: IsaacRng = SeedableRng::from_seed(&s[..]);
556 let mut rb: IsaacRng = SeedableRng::from_seed(&s[..]);
557 assert!(order::equals(ra.gen_ascii_chars().take(100),
558 rb.gen_ascii_chars().take(100)));
561 fn test_rng_64_rand_seeded() {
562 let s = ::test::rng().gen_iter::<u64>().take(256).collect::<Vec<u64>>();
563 let mut ra: Isaac64Rng = SeedableRng::from_seed(&s[..]);
564 let mut rb: Isaac64Rng = SeedableRng::from_seed(&s[..]);
565 assert!(order::equals(ra.gen_ascii_chars().take(100),
566 rb.gen_ascii_chars().take(100)));
570 fn test_rng_32_seeded() {
571 let seed: &[_] = &[1, 23, 456, 7890, 12345];
572 let mut ra: IsaacRng = SeedableRng::from_seed(seed);
573 let mut rb: IsaacRng = SeedableRng::from_seed(seed);
574 assert!(order::equals(ra.gen_ascii_chars().take(100),
575 rb.gen_ascii_chars().take(100)));
578 fn test_rng_64_seeded() {
579 let seed: &[_] = &[1, 23, 456, 7890, 12345];
580 let mut ra: Isaac64Rng = SeedableRng::from_seed(seed);
581 let mut rb: Isaac64Rng = SeedableRng::from_seed(seed);
582 assert!(order::equals(ra.gen_ascii_chars().take(100),
583 rb.gen_ascii_chars().take(100)));
587 fn test_rng_32_reseed() {
588 let s = ::test::rng().gen_iter::<u32>().take(256).collect::<Vec<u32>>();
589 let mut r: IsaacRng = SeedableRng::from_seed(&s[..]);
590 let string1: String = r.gen_ascii_chars().take(100).collect();
594 let string2: String = r.gen_ascii_chars().take(100).collect();
595 assert_eq!(string1, string2);
598 fn test_rng_64_reseed() {
599 let s = ::test::rng().gen_iter::<u64>().take(256).collect::<Vec<u64>>();
600 let mut r: Isaac64Rng = SeedableRng::from_seed(&s[..]);
601 let string1: String = r.gen_ascii_chars().take(100).collect();
605 let string2: String = r.gen_ascii_chars().take(100).collect();
606 assert_eq!(string1, string2);
611 fn test_rng_32_true_values() {
612 let seed: &[_] = &[1, 23, 456, 7890, 12345];
613 let mut ra: IsaacRng = SeedableRng::from_seed(seed);
614 // Regression test that isaac is actually using the above vector
615 let v = (0..10).map(|_| ra.next_u32()).collect::<Vec<_>>();
617 vec!(2558573138, 873787463, 263499565, 2103644246, 3595684709,
618 4203127393, 264982119, 2765226902, 2737944514, 3900253796));
620 let seed: &[_] = &[12345, 67890, 54321, 9876];
621 let mut rb: IsaacRng = SeedableRng::from_seed(seed);
622 // skip forward to the 10000th number
627 let v = (0..10).map(|_| rb.next_u32()).collect::<Vec<_>>();
629 vec!(3676831399, 3183332890, 2834741178, 3854698763, 2717568474,
630 1576568959, 3507990155, 179069555, 141456972, 2478885421));
634 fn test_rng_64_true_values() {
635 let seed: &[_] = &[1, 23, 456, 7890, 12345];
636 let mut ra: Isaac64Rng = SeedableRng::from_seed(seed);
637 // Regression test that isaac is actually using the above vector
638 let v = (0..10).map(|_| ra.next_u64()).collect::<Vec<_>>();
640 vec!(547121783600835980, 14377643087320773276, 17351601304698403469,
641 1238879483818134882, 11952566807690396487, 13970131091560099343,
642 4469761996653280935, 15552757044682284409, 6860251611068737823,
643 13722198873481261842));
645 let seed: &[_] = &[12345, 67890, 54321, 9876];
646 let mut rb: Isaac64Rng = SeedableRng::from_seed(seed);
647 // skip forward to the 10000th number
652 let v = (0..10).map(|_| rb.next_u64()).collect::<Vec<_>>();
654 vec!(18143823860592706164, 8491801882678285927, 2699425367717515619,
655 17196852593171130876, 2606123525235546165, 15790932315217671084,
656 596345674630742204, 9947027391921273664, 11788097613744130851,
657 10391409374914919106));
662 fn test_rng_clone() {
663 let seed: &[_] = &[1, 23, 456, 7890, 12345];
664 let mut rng: Isaac64Rng = SeedableRng::from_seed(seed);
665 let mut clone = rng.clone();
667 assert_eq!(rng.next_u64(), clone.next_u64());