rc_crypto/rand.rs
1/* This Source Code Form is subject to the terms of the Mozilla Public
2 * License, v. 2.0. If a copy of the MPL was not distributed with this
3 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
4
5// This file contains code that was copied from the ring crate which is under
6// the ISC license, reproduced below:
7
8// Copyright 2015-2017 Brian Smith.
9
10// Permission to use, copy, modify, and/or distribute this software for any
11// purpose with or without fee is hereby granted, provided that the above
12// copyright notice and this permission notice appear in all copies.
13
14// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHORS DISCLAIM ALL WARRANTIES
15// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
16// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
17// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
18// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
19// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
20// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
21
22use crate::error::*;
23
24/// Fill a buffer with cryptographically secure pseudo-random data.
25pub fn fill(dest: &mut [u8]) -> Result<()> {
26 Ok(nss::pk11::slot::generate_random(dest)?)
27}
28
29#[cfg(test)]
30mod tests {
31 use super::*;
32 use nss::ensure_initialized;
33
34 #[test]
35 fn random_fill() {
36 ensure_initialized();
37
38 let mut out = vec![0u8; 64];
39 assert!(fill(&mut out).is_ok());
40 // This check could *in theory* fail if we randomly generate all zeroes
41 // but we're treating that probability as negligible in practice.
42 assert_ne!(out, vec![0u8; 64]);
43
44 let mut out2 = vec![0u8; 64];
45 assert!(fill(&mut out2).is_ok());
46 assert_ne!(out, vec![0u8; 64]);
47 assert_ne!(out2, out);
48 }
49
50 #[test]
51 fn random_fill_empty() {
52 ensure_initialized();
53
54 let mut out = vec![0u8; 0];
55 assert!(fill(&mut out).is_ok());
56 assert_eq!(out, vec![0u8; 0]);
57 }
58
59 #[test]
60 fn random_fill_oddly_sized_arrays() {
61 ensure_initialized();
62
63 let sizes: [usize; 4] = [61, 63, 65, 67];
64 for size in &sizes {
65 let mut out = vec![0u8; *size];
66 assert!(fill(&mut out).is_ok());
67 assert_ne!(out, vec![0u8; *size]);
68 }
69 }
70
71 #[test]
72 fn random_fill_rejects_attempts_to_fill_gigantic_arrays() {
73 ensure_initialized();
74
75 let max_size: usize = i32::MAX as usize;
76 let mut out = vec![0u8; max_size + 1];
77 assert!(fill(&mut out).is_err());
78 }
79}