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)]
17 use core::iter::repeat;
18 use core::num::Wrapping as w;
20 use {Rng, SeedableRng, Rand};
25 const RAND_SIZE_LEN: usize = 8;
26 const RAND_SIZE: u32 = 1 << RAND_SIZE_LEN;
27 const RAND_SIZE_USIZE: usize = 1 << RAND_SIZE_LEN;
29 /// A random number generator that uses the ISAAC algorithm[1].
31 /// The ISAAC algorithm is generally accepted as suitable for
32 /// cryptographic purposes, but this implementation has not be
33 /// verified as such. Prefer a generator like `OsRng` that defers to
34 /// the operating system for cases that need high security.
36 /// [1]: Bob Jenkins, [*ISAAC: A fast cryptographic random number
37 /// generator*](http://www.burtleburtle.net/bob/rand/isaacafa.html)
41 rsl: [w32; RAND_SIZE_USIZE],
42 mem: [w32; RAND_SIZE_USIZE],
48 static EMPTY: IsaacRng = IsaacRng {
50 rsl: [w(0); RAND_SIZE_USIZE],
51 mem: [w(0); RAND_SIZE_USIZE],
52 a: w(0), b: w(0), c: w(0),
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) {
99 a=a+$arr[i ]; b=b+$arr[i+1];
100 c=c+$arr[i+2]; d=d+$arr[i+3];
101 e=e+$arr[i+4]; f=f+$arr[i+5];
102 g=g+$arr[i+6]; h=h+$arr[i+7];
104 self.mem[i ]=a; self.mem[i+1]=b;
105 self.mem[i+2]=c; self.mem[i+3]=d;
106 self.mem[i+4]=e; self.mem[i+5]=f;
107 self.mem[i+6]=g; self.mem[i+7]=h;
115 for i in (0..RAND_SIZE_USIZE).step_by(8) {
117 self.mem[i ]=a; self.mem[i+1]=b;
118 self.mem[i+2]=c; self.mem[i+3]=d;
119 self.mem[i+4]=e; self.mem[i+5]=f;
120 self.mem[i+6]=g; self.mem[i+7]=h;
127 /// Refills the output buffer (`self.rsl`)
129 #[allow(unsigned_negation)]
130 fn isaac(&mut self) {
131 self.c = self.c + w(1);
134 let mut b = self.b + self.c;
136 const MIDPOINT: usize = RAND_SIZE_USIZE / 2;
139 ($x:expr) => (self.mem[($x >> 2).0 as usize & (RAND_SIZE_USIZE - 1)] )
142 let r = [(0, MIDPOINT), (MIDPOINT, 0)];
143 for &(mr_offset, m2_offset) in r.iter() {
145 macro_rules! rngstepp {
146 ($j:expr, $shift:expr) => {{
148 let mix = a << $shift;
150 let x = self.mem[base + mr_offset];
151 a = (a ^ mix) + self.mem[base + m2_offset];
152 let y = ind!(x) + a + b;
153 self.mem[base + mr_offset] = y;
155 b = ind!(y >> RAND_SIZE_LEN) + x;
156 self.rsl[base + mr_offset] = b;
160 macro_rules! rngstepn {
161 ($j:expr, $shift:expr) => {{
163 let mix = a >> $shift;
165 let x = self.mem[base + mr_offset];
166 a = (a ^ mix) + self.mem[base + m2_offset];
167 let y = ind!(x) + a + b;
168 self.mem[base + mr_offset] = y;
170 b = ind!(y >> RAND_SIZE_LEN) + x;
171 self.rsl[base + mr_offset] = b;
175 for i in (0..MIDPOINT).step_by(4) {
176 rngstepp!(i + 0, 13);
179 rngstepn!(i + 3, 16);
185 self.cnt = RAND_SIZE;
189 // Cannot be derived because [u32; 256] does not implement Clone
190 impl Clone for IsaacRng {
191 fn clone(&self) -> IsaacRng {
196 impl Rng for IsaacRng {
198 fn next_u32(&mut self) -> u32 {
200 // make some more numbers
205 // self.cnt is at most RAND_SIZE, but that is before the
206 // subtraction above. We want to index without bounds
207 // checking, but this could lead to incorrect code if someone
208 // misrefactors, so we check, sometimes.
210 // (Changes here should be reflected in Isaac64Rng.next_u64.)
211 debug_assert!(self.cnt < RAND_SIZE);
213 // (the % is cheaply telling the optimiser that we're always
214 // in bounds, without unsafe. NB. this is a power of two, so
215 // it optimises to a bitwise mask).
216 self.rsl[(self.cnt % RAND_SIZE) as usize].0
220 impl<'a> SeedableRng<&'a [u32]> for IsaacRng {
221 fn reseed(&mut self, seed: &'a [u32]) {
222 // make the seed into [seed[0], seed[1], ..., seed[seed.len()
223 // - 1], 0, 0, ...], to fill rng.rsl.
224 let seed_iter = seed.iter().cloned().chain(repeat(0));
226 for (rsl_elem, seed_elem) in self.rsl.iter_mut().zip(seed_iter) {
227 *rsl_elem = w(seed_elem);
237 /// Create an ISAAC random number generator with a seed. This can
238 /// be any length, although the maximum number of elements used is
239 /// 256 and any more will be silently ignored. A generator
240 /// constructed with a given seed will generate the same sequence
241 /// of values as all other generators constructed with that seed.
242 fn from_seed(seed: &'a [u32]) -> IsaacRng {
249 impl Rand for IsaacRng {
250 fn rand<R: Rng>(other: &mut R) -> IsaacRng {
253 let ptr = ret.rsl.as_mut_ptr() as *mut u8;
255 let slice = slice::from_raw_parts_mut(ptr, RAND_SIZE_USIZE * 4);
256 other.fill_bytes(slice);
268 const RAND_SIZE_64_LEN: usize = 8;
269 const RAND_SIZE_64: usize = 1 << RAND_SIZE_64_LEN;
271 /// A random number generator that uses ISAAC-64[1], the 64-bit
272 /// variant of the ISAAC algorithm.
274 /// The ISAAC algorithm is generally accepted as suitable for
275 /// cryptographic purposes, but this implementation has not be
276 /// verified as such. Prefer a generator like `OsRng` that defers to
277 /// the operating system for cases that need high security.
279 /// [1]: Bob Jenkins, [*ISAAC: A fast cryptographic random number
280 /// generator*](http://www.burtleburtle.net/bob/rand/isaacafa.html)
282 pub struct Isaac64Rng {
284 rsl: [w64; RAND_SIZE_64],
285 mem: [w64; RAND_SIZE_64],
291 static EMPTY_64: Isaac64Rng = Isaac64Rng {
293 rsl: [w(0); RAND_SIZE_64],
294 mem: [w(0); RAND_SIZE_64],
295 a: w(0), b: w(0), c: w(0),
299 /// Create a 64-bit ISAAC random number generator using the
300 /// default fixed seed.
301 pub fn new_unseeded() -> Isaac64Rng {
302 let mut rng = EMPTY_64;
307 /// Initialises `self`. If `use_rsl` is true, then use the current value
308 /// of `rsl` as a seed, otherwise construct one algorithmically (not
310 fn init(&mut self, use_rsl: bool) {
313 let mut $var = w(0x9e3779b97f4a7c13);
316 init!(a); init!(b); init!(c); init!(d);
317 init!(e); init!(f); init!(g); init!(h);
321 a=a-e; f=f^(h>>9); h=h+a;
322 b=b-f; g=g^(a<<9); a=a+b;
323 c=c-g; h=h^(b>>23); b=b+c;
324 d=d-h; a=a^(c<<15); c=c+d;
325 e=e-a; b=b^(d>>14); d=d+e;
326 f=f-b; c=c^(e<<20); e=e+f;
327 g=g-c; d=d^(f>>17); f=f+g;
328 h=h-d; e=e^(g<<14); g=g+h;
337 macro_rules! memloop {
339 for i in (0..RAND_SIZE_64 / 8).map(|i| i * 8) {
340 a=a+$arr[i ]; b=b+$arr[i+1];
341 c=c+$arr[i+2]; d=d+$arr[i+3];
342 e=e+$arr[i+4]; f=f+$arr[i+5];
343 g=g+$arr[i+6]; h=h+$arr[i+7];
345 self.mem[i ]=a; self.mem[i+1]=b;
346 self.mem[i+2]=c; self.mem[i+3]=d;
347 self.mem[i+4]=e; self.mem[i+5]=f;
348 self.mem[i+6]=g; self.mem[i+7]=h;
356 for i in (0..RAND_SIZE_64 / 8).map(|i| i * 8) {
358 self.mem[i ]=a; self.mem[i+1]=b;
359 self.mem[i+2]=c; self.mem[i+3]=d;
360 self.mem[i+4]=e; self.mem[i+5]=f;
361 self.mem[i+6]=g; self.mem[i+7]=h;
368 /// Refills the output buffer (`self.rsl`)
369 fn isaac64(&mut self) {
370 self.c = self.c + w(1);
373 let mut b = self.b + self.c;
374 const MIDPOINT: usize = RAND_SIZE_64 / 2;
375 const MP_VEC: [(usize, usize); 2] = [(0,MIDPOINT), (MIDPOINT, 0)];
378 *self.mem.get_unchecked((($x >> 3).0 as usize) & (RAND_SIZE_64 - 1))
382 for &(mr_offset, m2_offset) in MP_VEC.iter() {
383 for base in (0..MIDPOINT / 4).map(|i| i * 4) {
385 macro_rules! rngstepp {
386 ($j:expr, $shift:expr) => {{
387 let base = base + $j;
388 let mix = a ^ (a << $shift);
389 let mix = if $j == 0 {!mix} else {mix};
392 let x = *self.mem.get_unchecked(base + mr_offset);
393 a = mix + *self.mem.get_unchecked(base + m2_offset);
394 let y = ind!(x) + a + b;
395 *self.mem.get_unchecked_mut(base + mr_offset) = y;
397 b = ind!(y >> RAND_SIZE_64_LEN) + x;
398 *self.rsl.get_unchecked_mut(base + mr_offset) = b;
403 macro_rules! rngstepn {
404 ($j:expr, $shift:expr) => {{
405 let base = base + $j;
406 let mix = a ^ (a >> $shift);
407 let mix = if $j == 0 {!mix} else {mix};
410 let x = *self.mem.get_unchecked(base + mr_offset);
411 a = mix + *self.mem.get_unchecked(base + m2_offset);
412 let y = ind!(x) + a + b;
413 *self.mem.get_unchecked_mut(base + mr_offset) = y;
415 b = ind!(y >> RAND_SIZE_64_LEN) + x;
416 *self.rsl.get_unchecked_mut(base + mr_offset) = b;
430 self.cnt = RAND_SIZE_64;
434 // Cannot be derived because [u32; 256] does not implement Clone
435 impl Clone for Isaac64Rng {
436 fn clone(&self) -> Isaac64Rng {
441 impl Rng for Isaac64Rng {
442 // FIXME #7771: having next_u32 like this should be unnecessary
444 fn next_u32(&mut self) -> u32 {
445 self.next_u64() as u32
449 fn next_u64(&mut self) -> u64 {
451 // make some more numbers
456 // See corresponding location in IsaacRng.next_u32 for
458 debug_assert!(self.cnt < RAND_SIZE_64);
459 self.rsl[(self.cnt % RAND_SIZE_64) as usize].0
463 impl<'a> SeedableRng<&'a [u64]> for Isaac64Rng {
464 fn reseed(&mut self, seed: &'a [u64]) {
465 // make the seed into [seed[0], seed[1], ..., seed[seed.len()
466 // - 1], 0, 0, ...], to fill rng.rsl.
467 let seed_iter = seed.iter().cloned().chain(repeat(0));
469 for (rsl_elem, seed_elem) in self.rsl.iter_mut().zip(seed_iter) {
470 *rsl_elem = w(seed_elem);
480 /// Create an ISAAC random number generator with a seed. This can
481 /// be any length, although the maximum number of elements used is
482 /// 256 and any more will be silently ignored. A generator
483 /// constructed with a given seed will generate the same sequence
484 /// of values as all other generators constructed with that seed.
485 fn from_seed(seed: &'a [u64]) -> Isaac64Rng {
486 let mut rng = EMPTY_64;
492 impl Rand for Isaac64Rng {
493 fn rand<R: Rng>(other: &mut R) -> Isaac64Rng {
494 let mut ret = EMPTY_64;
496 let ptr = ret.rsl.as_mut_ptr() as *mut u8;
498 let slice = slice::from_raw_parts_mut(ptr, RAND_SIZE_64 * 8);
499 other.fill_bytes(slice);
514 use std::prelude::v1::*;
516 use core::iter::order;
517 use {Rng, SeedableRng};
518 use super::{IsaacRng, Isaac64Rng};
521 fn test_rng_32_rand_seeded() {
522 let s = ::test::rng().gen_iter::<u32>().take(256).collect::<Vec<u32>>();
523 let mut ra: IsaacRng = SeedableRng::from_seed(&s[..]);
524 let mut rb: IsaacRng = SeedableRng::from_seed(&s[..]);
525 assert!(order::equals(ra.gen_ascii_chars().take(100),
526 rb.gen_ascii_chars().take(100)));
529 fn test_rng_64_rand_seeded() {
530 let s = ::test::rng().gen_iter::<u64>().take(256).collect::<Vec<u64>>();
531 let mut ra: Isaac64Rng = SeedableRng::from_seed(&s[..]);
532 let mut rb: Isaac64Rng = SeedableRng::from_seed(&s[..]);
533 assert!(order::equals(ra.gen_ascii_chars().take(100),
534 rb.gen_ascii_chars().take(100)));
538 fn test_rng_32_seeded() {
539 let seed: &[_] = &[1, 23, 456, 7890, 12345];
540 let mut ra: IsaacRng = SeedableRng::from_seed(seed);
541 let mut rb: IsaacRng = SeedableRng::from_seed(seed);
542 assert!(order::equals(ra.gen_ascii_chars().take(100),
543 rb.gen_ascii_chars().take(100)));
546 fn test_rng_64_seeded() {
547 let seed: &[_] = &[1, 23, 456, 7890, 12345];
548 let mut ra: Isaac64Rng = SeedableRng::from_seed(seed);
549 let mut rb: Isaac64Rng = SeedableRng::from_seed(seed);
550 assert!(order::equals(ra.gen_ascii_chars().take(100),
551 rb.gen_ascii_chars().take(100)));
555 fn test_rng_32_reseed() {
556 let s = ::test::rng().gen_iter::<u32>().take(256).collect::<Vec<u32>>();
557 let mut r: IsaacRng = SeedableRng::from_seed(&s[..]);
558 let string1: String = r.gen_ascii_chars().take(100).collect();
562 let string2: String = r.gen_ascii_chars().take(100).collect();
563 assert_eq!(string1, string2);
566 fn test_rng_64_reseed() {
567 let s = ::test::rng().gen_iter::<u64>().take(256).collect::<Vec<u64>>();
568 let mut r: Isaac64Rng = SeedableRng::from_seed(&s[..]);
569 let string1: String = r.gen_ascii_chars().take(100).collect();
573 let string2: String = r.gen_ascii_chars().take(100).collect();
574 assert_eq!(string1, string2);
578 fn test_rng_32_true_values() {
579 let seed: &[_] = &[1, 23, 456, 7890, 12345];
580 let mut ra: IsaacRng = SeedableRng::from_seed(seed);
581 // Regression test that isaac is actually using the above vector
582 let v = (0..10).map(|_| ra.next_u32()).collect::<Vec<_>>();
584 vec!(2558573138, 873787463, 263499565, 2103644246, 3595684709,
585 4203127393, 264982119, 2765226902, 2737944514, 3900253796));
587 let seed: &[_] = &[12345, 67890, 54321, 9876];
588 let mut rb: IsaacRng = SeedableRng::from_seed(seed);
589 // skip forward to the 10000th number
590 for _ in 0..10000 { rb.next_u32(); }
592 let v = (0..10).map(|_| rb.next_u32()).collect::<Vec<_>>();
594 vec!(3676831399, 3183332890, 2834741178, 3854698763, 2717568474,
595 1576568959, 3507990155, 179069555, 141456972, 2478885421));
598 fn test_rng_64_true_values() {
599 let seed: &[_] = &[1, 23, 456, 7890, 12345];
600 let mut ra: Isaac64Rng = SeedableRng::from_seed(seed);
601 // Regression test that isaac is actually using the above vector
602 let v = (0..10).map(|_| ra.next_u64()).collect::<Vec<_>>();
604 vec!(547121783600835980, 14377643087320773276, 17351601304698403469,
605 1238879483818134882, 11952566807690396487, 13970131091560099343,
606 4469761996653280935, 15552757044682284409, 6860251611068737823,
607 13722198873481261842));
609 let seed: &[_] = &[12345, 67890, 54321, 9876];
610 let mut rb: Isaac64Rng = SeedableRng::from_seed(seed);
611 // skip forward to the 10000th number
612 for _ in 0..10000 { rb.next_u64(); }
614 let v = (0..10).map(|_| rb.next_u64()).collect::<Vec<_>>();
616 vec!(18143823860592706164, 8491801882678285927, 2699425367717515619,
617 17196852593171130876, 2606123525235546165, 15790932315217671084,
618 596345674630742204, 9947027391921273664, 11788097613744130851,
619 10391409374914919106));
623 fn test_rng_clone() {
624 let seed: &[_] = &[1, 23, 456, 7890, 12345];
625 let mut rng: Isaac64Rng = SeedableRng::from_seed(seed);
626 let mut clone = rng.clone();
628 assert_eq!(rng.next_u64(), clone.next_u64());