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],
51 a: w(0), b: w(0), c: w(0),
56 /// Create an ISAAC random number generator using the default
58 pub fn new_unseeded() -> IsaacRng {
64 /// Initialises `self`. If `use_rsl` is true, then use the current value
65 /// of `rsl` as a seed, otherwise construct one algorithmically (not
67 fn init(&mut self, use_rsl: bool) {
68 let mut a = w(0x9e3779b9);
79 a=a^(b<<11); d=d+a; b=b+c;
80 b=b^(c>>2); e=e+b; c=c+d;
81 c=c^(d<<8); f=f+c; d=d+e;
82 d=d^(e>>16); g=g+d; e=e+f;
83 e=e^(f<<10); h=h+e; f=f+g;
84 f=f^(g>>4); a=a+f; g=g+h;
85 g=g^(h<<8); b=b+g; h=h+a;
86 h=h^(a>>9); c=c+h; a=a+b;
95 macro_rules! memloop {
97 for i in (0..RAND_SIZE_USIZE).step_by(8) {
98 a=a+$arr[i ]; b=b+$arr[i+1];
99 c=c+$arr[i+2]; d=d+$arr[i+3];
100 e=e+$arr[i+4]; f=f+$arr[i+5];
101 g=g+$arr[i+6]; h=h+$arr[i+7];
103 self.mem[i ]=a; self.mem[i+1]=b;
104 self.mem[i+2]=c; self.mem[i+3]=d;
105 self.mem[i+4]=e; self.mem[i+5]=f;
106 self.mem[i+6]=g; self.mem[i+7]=h;
114 for i in (0..RAND_SIZE_USIZE).step_by(8) {
116 self.mem[i ]=a; self.mem[i+1]=b;
117 self.mem[i+2]=c; self.mem[i+3]=d;
118 self.mem[i+4]=e; self.mem[i+5]=f;
119 self.mem[i+6]=g; self.mem[i+7]=h;
126 /// Refills the output buffer (`self.rsl`)
128 fn isaac(&mut self) {
129 self.c = self.c + w(1);
132 let mut b = self.b + self.c;
134 const MIDPOINT: usize = RAND_SIZE_USIZE / 2;
137 ($x:expr) => (self.mem[($x >> 2).0 as usize & (RAND_SIZE_USIZE - 1)] )
140 let r = [(0, MIDPOINT), (MIDPOINT, 0)];
141 for &(mr_offset, m2_offset) in &r {
143 macro_rules! rngstepp {
144 ($j:expr, $shift:expr) => {{
146 let mix = a << $shift;
148 let x = self.mem[base + mr_offset];
149 a = (a ^ mix) + self.mem[base + m2_offset];
150 let y = ind!(x) + a + b;
151 self.mem[base + mr_offset] = y;
153 b = ind!(y >> RAND_SIZE_LEN) + x;
154 self.rsl[base + mr_offset] = b;
158 macro_rules! rngstepn {
159 ($j:expr, $shift:expr) => {{
161 let mix = a >> $shift;
163 let x = self.mem[base + mr_offset];
164 a = (a ^ mix) + self.mem[base + m2_offset];
165 let y = ind!(x) + a + b;
166 self.mem[base + mr_offset] = y;
168 b = ind!(y >> RAND_SIZE_LEN) + x;
169 self.rsl[base + mr_offset] = b;
173 for i in (0..MIDPOINT).step_by(4) {
174 rngstepp!(i + 0, 13);
177 rngstepn!(i + 3, 16);
183 self.cnt = RAND_SIZE;
187 // Cannot be derived because [u32; 256] does not implement Clone
188 impl Clone for IsaacRng {
189 fn clone(&self) -> IsaacRng {
194 impl Rng for IsaacRng {
196 fn next_u32(&mut self) -> u32 {
198 // make some more numbers
203 // self.cnt is at most RAND_SIZE, but that is before the
204 // subtraction above. We want to index without bounds
205 // checking, but this could lead to incorrect code if someone
206 // misrefactors, so we check, sometimes.
208 // (Changes here should be reflected in Isaac64Rng.next_u64.)
209 debug_assert!(self.cnt < RAND_SIZE);
211 // (the % is cheaply telling the optimiser that we're always
212 // in bounds, without unsafe. NB. this is a power of two, so
213 // it optimises to a bitwise mask).
214 self.rsl[(self.cnt % RAND_SIZE) as usize].0
218 impl<'a> SeedableRng<&'a [u32]> for IsaacRng {
219 fn reseed(&mut self, seed: &'a [u32]) {
220 // make the seed into [seed[0], seed[1], ..., seed[seed.len()
221 // - 1], 0, 0, ...], to fill rng.rsl.
222 let seed_iter = seed.iter().cloned().chain(repeat(0));
224 for (rsl_elem, seed_elem) in self.rsl.iter_mut().zip(seed_iter) {
225 *rsl_elem = w(seed_elem);
235 /// Create an ISAAC random number generator with a seed. This can
236 /// be any length, although the maximum number of elements used is
237 /// 256 and any more will be silently ignored. A generator
238 /// constructed with a given seed will generate the same sequence
239 /// of values as all other generators constructed with that seed.
240 fn from_seed(seed: &'a [u32]) -> IsaacRng {
247 impl Rand for IsaacRng {
248 fn rand<R: Rng>(other: &mut R) -> IsaacRng {
251 let ptr = ret.rsl.as_mut_ptr() as *mut u8;
253 let slice = slice::from_raw_parts_mut(ptr, RAND_SIZE_USIZE * 4);
254 other.fill_bytes(slice);
266 const RAND_SIZE_64_LEN: usize = 8;
267 const RAND_SIZE_64: usize = 1 << RAND_SIZE_64_LEN;
269 /// A random number generator that uses ISAAC-64[1], the 64-bit
270 /// variant of the ISAAC algorithm.
272 /// The ISAAC algorithm is generally accepted as suitable for
273 /// cryptographic purposes, but this implementation has not be
274 /// verified as such. Prefer a generator like `OsRng` that defers to
275 /// the operating system for cases that need high security.
277 /// [1]: Bob Jenkins, [*ISAAC: A fast cryptographic random number
278 /// generator*](http://www.burtleburtle.net/bob/rand/isaacafa.html)
280 pub struct Isaac64Rng {
282 rsl: [w64; RAND_SIZE_64],
283 mem: [w64; RAND_SIZE_64],
289 static EMPTY_64: Isaac64Rng = Isaac64Rng {
291 rsl: [w(0); RAND_SIZE_64],
292 mem: [w(0); RAND_SIZE_64],
293 a: w(0), b: w(0), c: w(0),
297 /// Create a 64-bit ISAAC random number generator using the
298 /// default fixed seed.
299 pub fn new_unseeded() -> Isaac64Rng {
300 let mut rng = EMPTY_64;
305 /// Initialises `self`. If `use_rsl` is true, then use the current value
306 /// of `rsl` as a seed, otherwise construct one algorithmically (not
308 fn init(&mut self, use_rsl: bool) {
311 let mut $var = w(0x9e3779b97f4a7c13);
314 init!(a); init!(b); init!(c); init!(d);
315 init!(e); init!(f); init!(g); init!(h);
319 a=a-e; f=f^(h>>9); h=h+a;
320 b=b-f; g=g^(a<<9); a=a+b;
321 c=c-g; h=h^(b>>23); b=b+c;
322 d=d-h; a=a^(c<<15); c=c+d;
323 e=e-a; b=b^(d>>14); d=d+e;
324 f=f-b; c=c^(e<<20); e=e+f;
325 g=g-c; d=d^(f>>17); f=f+g;
326 h=h-d; e=e^(g<<14); g=g+h;
335 macro_rules! memloop {
337 for i in (0..RAND_SIZE_64 / 8).map(|i| i * 8) {
338 a=a+$arr[i ]; b=b+$arr[i+1];
339 c=c+$arr[i+2]; d=d+$arr[i+3];
340 e=e+$arr[i+4]; f=f+$arr[i+5];
341 g=g+$arr[i+6]; h=h+$arr[i+7];
343 self.mem[i ]=a; self.mem[i+1]=b;
344 self.mem[i+2]=c; self.mem[i+3]=d;
345 self.mem[i+4]=e; self.mem[i+5]=f;
346 self.mem[i+6]=g; self.mem[i+7]=h;
354 for i in (0..RAND_SIZE_64 / 8).map(|i| i * 8) {
356 self.mem[i ]=a; self.mem[i+1]=b;
357 self.mem[i+2]=c; self.mem[i+3]=d;
358 self.mem[i+4]=e; self.mem[i+5]=f;
359 self.mem[i+6]=g; self.mem[i+7]=h;
366 /// Refills the output buffer (`self.rsl`)
367 fn isaac64(&mut self) {
368 self.c = self.c + w(1);
371 let mut b = self.b + self.c;
372 const MIDPOINT: usize = RAND_SIZE_64 / 2;
373 const MP_VEC: [(usize, usize); 2] = [(0,MIDPOINT), (MIDPOINT, 0)];
376 *self.mem.get_unchecked((($x >> 3).0 as usize) & (RAND_SIZE_64 - 1))
380 for &(mr_offset, m2_offset) in &MP_VEC {
381 for base in (0..MIDPOINT / 4).map(|i| i * 4) {
383 macro_rules! rngstepp {
384 ($j:expr, $shift:expr) => {{
385 let base = base + $j;
386 let mix = a ^ (a << $shift);
387 let mix = if $j == 0 {!mix} else {mix};
390 let x = *self.mem.get_unchecked(base + mr_offset);
391 a = mix + *self.mem.get_unchecked(base + m2_offset);
392 let y = ind!(x) + a + b;
393 *self.mem.get_unchecked_mut(base + mr_offset) = y;
395 b = ind!(y >> RAND_SIZE_64_LEN) + x;
396 *self.rsl.get_unchecked_mut(base + mr_offset) = b;
401 macro_rules! rngstepn {
402 ($j:expr, $shift:expr) => {{
403 let base = base + $j;
404 let mix = a ^ (a >> $shift);
405 let mix = if $j == 0 {!mix} else {mix};
408 let x = *self.mem.get_unchecked(base + mr_offset);
409 a = mix + *self.mem.get_unchecked(base + m2_offset);
410 let y = ind!(x) + a + b;
411 *self.mem.get_unchecked_mut(base + mr_offset) = y;
413 b = ind!(y >> RAND_SIZE_64_LEN) + x;
414 *self.rsl.get_unchecked_mut(base + mr_offset) = b;
428 self.cnt = RAND_SIZE_64;
432 // Cannot be derived because [u32; 256] does not implement Clone
433 impl Clone for Isaac64Rng {
434 fn clone(&self) -> Isaac64Rng {
439 impl Rng for Isaac64Rng {
440 // FIXME #7771: having next_u32 like this should be unnecessary
442 fn next_u32(&mut self) -> u32 {
443 self.next_u64() as u32
447 fn next_u64(&mut self) -> u64 {
449 // make some more numbers
454 // See corresponding location in IsaacRng.next_u32 for
456 debug_assert!(self.cnt < RAND_SIZE_64);
457 self.rsl[(self.cnt % RAND_SIZE_64) as usize].0
461 impl<'a> SeedableRng<&'a [u64]> for Isaac64Rng {
462 fn reseed(&mut self, seed: &'a [u64]) {
463 // make the seed into [seed[0], seed[1], ..., seed[seed.len()
464 // - 1], 0, 0, ...], to fill rng.rsl.
465 let seed_iter = seed.iter().cloned().chain(repeat(0));
467 for (rsl_elem, seed_elem) in self.rsl.iter_mut().zip(seed_iter) {
468 *rsl_elem = w(seed_elem);
478 /// Create an ISAAC random number generator with a seed. This can
479 /// be any length, although the maximum number of elements used is
480 /// 256 and any more will be silently ignored. A generator
481 /// constructed with a given seed will generate the same sequence
482 /// of values as all other generators constructed with that seed.
483 fn from_seed(seed: &'a [u64]) -> Isaac64Rng {
484 let mut rng = EMPTY_64;
490 impl Rand for Isaac64Rng {
491 fn rand<R: Rng>(other: &mut R) -> Isaac64Rng {
492 let mut ret = EMPTY_64;
494 let ptr = ret.rsl.as_mut_ptr() as *mut u8;
496 let slice = slice::from_raw_parts_mut(ptr, RAND_SIZE_64 * 8);
497 other.fill_bytes(slice);
512 use std::prelude::v1::*;
514 use core::iter::order;
515 use {Rng, SeedableRng};
516 use super::{IsaacRng, Isaac64Rng};
519 fn test_rng_32_rand_seeded() {
520 let s = ::test::rng().gen_iter::<u32>().take(256).collect::<Vec<u32>>();
521 let mut ra: IsaacRng = SeedableRng::from_seed(&s[..]);
522 let mut rb: IsaacRng = SeedableRng::from_seed(&s[..]);
523 assert!(order::equals(ra.gen_ascii_chars().take(100),
524 rb.gen_ascii_chars().take(100)));
527 fn test_rng_64_rand_seeded() {
528 let s = ::test::rng().gen_iter::<u64>().take(256).collect::<Vec<u64>>();
529 let mut ra: Isaac64Rng = SeedableRng::from_seed(&s[..]);
530 let mut rb: Isaac64Rng = SeedableRng::from_seed(&s[..]);
531 assert!(order::equals(ra.gen_ascii_chars().take(100),
532 rb.gen_ascii_chars().take(100)));
536 fn test_rng_32_seeded() {
537 let seed: &[_] = &[1, 23, 456, 7890, 12345];
538 let mut ra: IsaacRng = SeedableRng::from_seed(seed);
539 let mut rb: IsaacRng = SeedableRng::from_seed(seed);
540 assert!(order::equals(ra.gen_ascii_chars().take(100),
541 rb.gen_ascii_chars().take(100)));
544 fn test_rng_64_seeded() {
545 let seed: &[_] = &[1, 23, 456, 7890, 12345];
546 let mut ra: Isaac64Rng = SeedableRng::from_seed(seed);
547 let mut rb: Isaac64Rng = SeedableRng::from_seed(seed);
548 assert!(order::equals(ra.gen_ascii_chars().take(100),
549 rb.gen_ascii_chars().take(100)));
553 fn test_rng_32_reseed() {
554 let s = ::test::rng().gen_iter::<u32>().take(256).collect::<Vec<u32>>();
555 let mut r: IsaacRng = SeedableRng::from_seed(&s[..]);
556 let string1: String = r.gen_ascii_chars().take(100).collect();
560 let string2: String = r.gen_ascii_chars().take(100).collect();
561 assert_eq!(string1, string2);
564 fn test_rng_64_reseed() {
565 let s = ::test::rng().gen_iter::<u64>().take(256).collect::<Vec<u64>>();
566 let mut r: Isaac64Rng = SeedableRng::from_seed(&s[..]);
567 let string1: String = r.gen_ascii_chars().take(100).collect();
571 let string2: String = r.gen_ascii_chars().take(100).collect();
572 assert_eq!(string1, string2);
576 fn test_rng_32_true_values() {
577 let seed: &[_] = &[1, 23, 456, 7890, 12345];
578 let mut ra: IsaacRng = SeedableRng::from_seed(seed);
579 // Regression test that isaac is actually using the above vector
580 let v = (0..10).map(|_| ra.next_u32()).collect::<Vec<_>>();
582 vec!(2558573138, 873787463, 263499565, 2103644246, 3595684709,
583 4203127393, 264982119, 2765226902, 2737944514, 3900253796));
585 let seed: &[_] = &[12345, 67890, 54321, 9876];
586 let mut rb: IsaacRng = SeedableRng::from_seed(seed);
587 // skip forward to the 10000th number
588 for _ in 0..10000 { rb.next_u32(); }
590 let v = (0..10).map(|_| rb.next_u32()).collect::<Vec<_>>();
592 vec!(3676831399, 3183332890, 2834741178, 3854698763, 2717568474,
593 1576568959, 3507990155, 179069555, 141456972, 2478885421));
596 fn test_rng_64_true_values() {
597 let seed: &[_] = &[1, 23, 456, 7890, 12345];
598 let mut ra: Isaac64Rng = SeedableRng::from_seed(seed);
599 // Regression test that isaac is actually using the above vector
600 let v = (0..10).map(|_| ra.next_u64()).collect::<Vec<_>>();
602 vec!(547121783600835980, 14377643087320773276, 17351601304698403469,
603 1238879483818134882, 11952566807690396487, 13970131091560099343,
604 4469761996653280935, 15552757044682284409, 6860251611068737823,
605 13722198873481261842));
607 let seed: &[_] = &[12345, 67890, 54321, 9876];
608 let mut rb: Isaac64Rng = SeedableRng::from_seed(seed);
609 // skip forward to the 10000th number
610 for _ in 0..10000 { rb.next_u64(); }
612 let v = (0..10).map(|_| rb.next_u64()).collect::<Vec<_>>();
614 vec!(18143823860592706164, 8491801882678285927, 2699425367717515619,
615 17196852593171130876, 2606123525235546165, 15790932315217671084,
616 596345674630742204, 9947027391921273664, 11788097613744130851,
617 10391409374914919106));
621 fn test_rng_clone() {
622 let seed: &[_] = &[1, 23, 456, 7890, 12345];
623 let mut rng: Isaac64Rng = SeedableRng::from_seed(seed);
624 let mut clone = rng.clone();
626 assert_eq!(rng.next_u64(), clone.next_u64());