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],
57 /// Create an ISAAC random number generator using the default
59 pub fn new_unseeded() -> IsaacRng {
65 /// Initialises `self`. If `use_rsl` is true, then use the current value
66 /// of `rsl` as a seed, otherwise construct one algorithmically (not
68 fn init(&mut self, use_rsl: bool) {
69 let mut a = w(0x9e3779b9);
80 a=a^(b<<11); d=d+a; b=b+c;
81 b=b^(c>>2); e=e+b; c=c+d;
82 c=c^(d<<8); f=f+c; d=d+e;
83 d=d^(e>>16); g=g+d; e=e+f;
84 e=e^(f<<10); h=h+e; f=f+g;
85 f=f^(g>>4); a=a+f; g=g+h;
86 g=g^(h<<8); b=b+g; h=h+a;
87 h=h^(a>>9); c=c+h; a=a+b;
96 macro_rules! memloop {
98 for i in (0..RAND_SIZE_USIZE).step_by(8) {
123 for i in (0..RAND_SIZE_USIZE).step_by(8) {
139 /// Refills the output buffer (`self.rsl`)
141 fn isaac(&mut self) {
142 self.c = self.c + w(1);
145 let mut b = self.b + self.c;
147 const MIDPOINT: usize = RAND_SIZE_USIZE / 2;
150 ($x:expr) => (self.mem[($x >> 2).0 as usize & (RAND_SIZE_USIZE - 1)] )
153 let r = [(0, MIDPOINT), (MIDPOINT, 0)];
154 for &(mr_offset, m2_offset) in &r {
156 macro_rules! rngstepp {
157 ($j:expr, $shift:expr) => {{
159 let mix = a << $shift;
161 let x = self.mem[base + mr_offset];
162 a = (a ^ mix) + self.mem[base + m2_offset];
163 let y = ind!(x) + a + b;
164 self.mem[base + mr_offset] = y;
166 b = ind!(y >> RAND_SIZE_LEN) + x;
167 self.rsl[base + mr_offset] = b;
171 macro_rules! rngstepn {
172 ($j:expr, $shift:expr) => {{
174 let mix = a >> $shift;
176 let x = self.mem[base + mr_offset];
177 a = (a ^ mix) + self.mem[base + m2_offset];
178 let y = ind!(x) + a + b;
179 self.mem[base + mr_offset] = y;
181 b = ind!(y >> RAND_SIZE_LEN) + x;
182 self.rsl[base + mr_offset] = b;
186 for i in (0..MIDPOINT).step_by(4) {
187 rngstepp!(i + 0, 13);
190 rngstepn!(i + 3, 16);
196 self.cnt = RAND_SIZE;
200 // Cannot be derived because [u32; 256] does not implement Clone
201 impl Clone for IsaacRng {
202 fn clone(&self) -> IsaacRng {
207 impl Rng for IsaacRng {
209 fn next_u32(&mut self) -> u32 {
211 // make some more numbers
216 // self.cnt is at most RAND_SIZE, but that is before the
217 // subtraction above. We want to index without bounds
218 // checking, but this could lead to incorrect code if someone
219 // misrefactors, so we check, sometimes.
221 // (Changes here should be reflected in Isaac64Rng.next_u64.)
222 debug_assert!(self.cnt < RAND_SIZE);
224 // (the % is cheaply telling the optimiser that we're always
225 // in bounds, without unsafe. NB. this is a power of two, so
226 // it optimises to a bitwise mask).
227 self.rsl[(self.cnt % RAND_SIZE) as usize].0
231 impl<'a> SeedableRng<&'a [u32]> for IsaacRng {
232 fn reseed(&mut self, seed: &'a [u32]) {
233 // make the seed into [seed[0], seed[1], ..., seed[seed.len()
234 // - 1], 0, 0, ...], to fill rng.rsl.
235 let seed_iter = seed.iter().cloned().chain(repeat(0));
237 for (rsl_elem, seed_elem) in self.rsl.iter_mut().zip(seed_iter) {
238 *rsl_elem = w(seed_elem);
248 /// Create an ISAAC random number generator with a seed. This can
249 /// be any length, although the maximum number of elements used is
250 /// 256 and any more will be silently ignored. A generator
251 /// constructed with a given seed will generate the same sequence
252 /// of values as all other generators constructed with that seed.
253 fn from_seed(seed: &'a [u32]) -> IsaacRng {
260 impl Rand for IsaacRng {
261 fn rand<R: Rng>(other: &mut R) -> IsaacRng {
264 let ptr = ret.rsl.as_mut_ptr() as *mut u8;
266 let slice = slice::from_raw_parts_mut(ptr, RAND_SIZE_USIZE * 4);
267 other.fill_bytes(slice);
279 const RAND_SIZE_64_LEN: usize = 8;
280 const RAND_SIZE_64: usize = 1 << RAND_SIZE_64_LEN;
282 /// A random number generator that uses ISAAC-64[1], the 64-bit
283 /// variant of the ISAAC algorithm.
285 /// The ISAAC algorithm is generally accepted as suitable for
286 /// cryptographic purposes, but this implementation has not be
287 /// verified as such. Prefer a generator like `OsRng` that defers to
288 /// the operating system for cases that need high security.
290 /// [1]: Bob Jenkins, [*ISAAC: A fast cryptographic random number
291 /// generator*](http://www.burtleburtle.net/bob/rand/isaacafa.html)
293 pub struct Isaac64Rng {
295 rsl: [w64; RAND_SIZE_64],
296 mem: [w64; RAND_SIZE_64],
302 static EMPTY_64: Isaac64Rng = Isaac64Rng {
304 rsl: [w(0); RAND_SIZE_64],
305 mem: [w(0); RAND_SIZE_64],
312 /// Create a 64-bit ISAAC random number generator using the
313 /// default fixed seed.
314 pub fn new_unseeded() -> Isaac64Rng {
315 let mut rng = EMPTY_64;
320 /// Initialises `self`. If `use_rsl` is true, then use the current value
321 /// of `rsl` as a seed, otherwise construct one algorithmically (not
323 fn init(&mut self, use_rsl: bool) {
326 let mut $var = w(0x9e3779b97f4a7c13);
340 a=a-e; f=f^(h>>9); h=h+a;
341 b=b-f; g=g^(a<<9); a=a+b;
342 c=c-g; h=h^(b>>23); b=b+c;
343 d=d-h; a=a^(c<<15); c=c+d;
344 e=e-a; b=b^(d>>14); d=d+e;
345 f=f-b; c=c^(e<<20); e=e+f;
346 g=g-c; d=d^(f>>17); f=f+g;
347 h=h-d; e=e^(g<<14); g=g+h;
356 macro_rules! memloop {
358 for i in (0..RAND_SIZE_64 / 8).map(|i| i * 8) {
383 for i in (0..RAND_SIZE_64 / 8).map(|i| i * 8) {
399 /// Refills the output buffer (`self.rsl`)
400 fn isaac64(&mut self) {
401 self.c = self.c + w(1);
404 let mut b = self.b + self.c;
405 const MIDPOINT: usize = RAND_SIZE_64 / 2;
406 const MP_VEC: [(usize, usize); 2] = [(0, MIDPOINT), (MIDPOINT, 0)];
409 *self.mem.get_unchecked((($x >> 3).0 as usize) & (RAND_SIZE_64 - 1))
413 for &(mr_offset, m2_offset) in &MP_VEC {
414 for base in (0..MIDPOINT / 4).map(|i| i * 4) {
416 macro_rules! rngstepp {
417 ($j:expr, $shift:expr) => {{
418 let base = base + $j;
419 let mix = a ^ (a << $shift);
420 let mix = if $j == 0 {!mix} else {mix};
423 let x = *self.mem.get_unchecked(base + mr_offset);
424 a = mix + *self.mem.get_unchecked(base + m2_offset);
425 let y = ind!(x) + a + b;
426 *self.mem.get_unchecked_mut(base + mr_offset) = y;
428 b = ind!(y >> RAND_SIZE_64_LEN) + x;
429 *self.rsl.get_unchecked_mut(base + mr_offset) = b;
434 macro_rules! rngstepn {
435 ($j:expr, $shift:expr) => {{
436 let base = base + $j;
437 let mix = a ^ (a >> $shift);
438 let mix = if $j == 0 {!mix} else {mix};
441 let x = *self.mem.get_unchecked(base + mr_offset);
442 a = mix + *self.mem.get_unchecked(base + m2_offset);
443 let y = ind!(x) + a + b;
444 *self.mem.get_unchecked_mut(base + mr_offset) = y;
446 b = ind!(y >> RAND_SIZE_64_LEN) + x;
447 *self.rsl.get_unchecked_mut(base + mr_offset) = b;
461 self.cnt = RAND_SIZE_64;
465 // Cannot be derived because [u32; 256] does not implement Clone
466 impl Clone for Isaac64Rng {
467 fn clone(&self) -> Isaac64Rng {
472 impl Rng for Isaac64Rng {
473 // FIXME #7771: having next_u32 like this should be unnecessary
475 fn next_u32(&mut self) -> u32 {
476 self.next_u64() as u32
480 fn next_u64(&mut self) -> u64 {
482 // make some more numbers
487 // See corresponding location in IsaacRng.next_u32 for
489 debug_assert!(self.cnt < RAND_SIZE_64);
490 self.rsl[(self.cnt % RAND_SIZE_64) as usize].0
494 impl<'a> SeedableRng<&'a [u64]> for Isaac64Rng {
495 fn reseed(&mut self, seed: &'a [u64]) {
496 // make the seed into [seed[0], seed[1], ..., seed[seed.len()
497 // - 1], 0, 0, ...], to fill rng.rsl.
498 let seed_iter = seed.iter().cloned().chain(repeat(0));
500 for (rsl_elem, seed_elem) in self.rsl.iter_mut().zip(seed_iter) {
501 *rsl_elem = w(seed_elem);
511 /// Create an ISAAC random number generator with a seed. This can
512 /// be any length, although the maximum number of elements used is
513 /// 256 and any more will be silently ignored. A generator
514 /// constructed with a given seed will generate the same sequence
515 /// of values as all other generators constructed with that seed.
516 fn from_seed(seed: &'a [u64]) -> Isaac64Rng {
517 let mut rng = EMPTY_64;
523 impl Rand for Isaac64Rng {
524 fn rand<R: Rng>(other: &mut R) -> Isaac64Rng {
525 let mut ret = EMPTY_64;
527 let ptr = ret.rsl.as_mut_ptr() as *mut u8;
529 let slice = slice::from_raw_parts_mut(ptr, RAND_SIZE_64 * 8);
530 other.fill_bytes(slice);
545 use std::prelude::v1::*;
547 use core::iter::order;
548 use {Rng, SeedableRng};
549 use super::{IsaacRng, Isaac64Rng};
552 fn test_rng_32_rand_seeded() {
553 let s = ::test::rng().gen_iter::<u32>().take(256).collect::<Vec<u32>>();
554 let mut ra: IsaacRng = SeedableRng::from_seed(&s[..]);
555 let mut rb: IsaacRng = SeedableRng::from_seed(&s[..]);
556 assert!(order::equals(ra.gen_ascii_chars().take(100),
557 rb.gen_ascii_chars().take(100)));
560 fn test_rng_64_rand_seeded() {
561 let s = ::test::rng().gen_iter::<u64>().take(256).collect::<Vec<u64>>();
562 let mut ra: Isaac64Rng = SeedableRng::from_seed(&s[..]);
563 let mut rb: Isaac64Rng = SeedableRng::from_seed(&s[..]);
564 assert!(order::equals(ra.gen_ascii_chars().take(100),
565 rb.gen_ascii_chars().take(100)));
569 fn test_rng_32_seeded() {
570 let seed: &[_] = &[1, 23, 456, 7890, 12345];
571 let mut ra: IsaacRng = SeedableRng::from_seed(seed);
572 let mut rb: IsaacRng = SeedableRng::from_seed(seed);
573 assert!(order::equals(ra.gen_ascii_chars().take(100),
574 rb.gen_ascii_chars().take(100)));
577 fn test_rng_64_seeded() {
578 let seed: &[_] = &[1, 23, 456, 7890, 12345];
579 let mut ra: Isaac64Rng = SeedableRng::from_seed(seed);
580 let mut rb: Isaac64Rng = SeedableRng::from_seed(seed);
581 assert!(order::equals(ra.gen_ascii_chars().take(100),
582 rb.gen_ascii_chars().take(100)));
586 fn test_rng_32_reseed() {
587 let s = ::test::rng().gen_iter::<u32>().take(256).collect::<Vec<u32>>();
588 let mut r: IsaacRng = SeedableRng::from_seed(&s[..]);
589 let string1: String = r.gen_ascii_chars().take(100).collect();
593 let string2: String = r.gen_ascii_chars().take(100).collect();
594 assert_eq!(string1, string2);
597 fn test_rng_64_reseed() {
598 let s = ::test::rng().gen_iter::<u64>().take(256).collect::<Vec<u64>>();
599 let mut r: Isaac64Rng = SeedableRng::from_seed(&s[..]);
600 let string1: String = r.gen_ascii_chars().take(100).collect();
604 let string2: String = r.gen_ascii_chars().take(100).collect();
605 assert_eq!(string1, string2);
610 fn test_rng_32_true_values() {
611 let seed: &[_] = &[1, 23, 456, 7890, 12345];
612 let mut ra: IsaacRng = SeedableRng::from_seed(seed);
613 // Regression test that isaac is actually using the above vector
614 let v = (0..10).map(|_| ra.next_u32()).collect::<Vec<_>>();
616 vec!(2558573138, 873787463, 263499565, 2103644246, 3595684709,
617 4203127393, 264982119, 2765226902, 2737944514, 3900253796));
619 let seed: &[_] = &[12345, 67890, 54321, 9876];
620 let mut rb: IsaacRng = SeedableRng::from_seed(seed);
621 // skip forward to the 10000th number
626 let v = (0..10).map(|_| rb.next_u32()).collect::<Vec<_>>();
628 vec!(3676831399, 3183332890, 2834741178, 3854698763, 2717568474,
629 1576568959, 3507990155, 179069555, 141456972, 2478885421));
633 fn test_rng_64_true_values() {
634 let seed: &[_] = &[1, 23, 456, 7890, 12345];
635 let mut ra: Isaac64Rng = SeedableRng::from_seed(seed);
636 // Regression test that isaac is actually using the above vector
637 let v = (0..10).map(|_| ra.next_u64()).collect::<Vec<_>>();
639 vec!(547121783600835980, 14377643087320773276, 17351601304698403469,
640 1238879483818134882, 11952566807690396487, 13970131091560099343,
641 4469761996653280935, 15552757044682284409, 6860251611068737823,
642 13722198873481261842));
644 let seed: &[_] = &[12345, 67890, 54321, 9876];
645 let mut rb: Isaac64Rng = SeedableRng::from_seed(seed);
646 // skip forward to the 10000th number
651 let v = (0..10).map(|_| rb.next_u64()).collect::<Vec<_>>();
653 vec!(18143823860592706164, 8491801882678285927, 2699425367717515619,
654 17196852593171130876, 2606123525235546165, 15790932315217671084,
655 596345674630742204, 9947027391921273664, 11788097613744130851,
656 10391409374914919106));
661 fn test_rng_clone() {
662 let seed: &[_] = &[1, 23, 456, 7890, 12345];
663 let mut rng: Isaac64Rng = SeedableRng::from_seed(seed);
664 let mut clone = rng.clone();
666 assert_eq!(rng.next_u64(), clone.next_u64());