1 | // Copyright 2018 Brian Smith. |
2 | // |
3 | // Permission to use, copy, modify, and/or distribute this software for any |
4 | // purpose with or without fee is hereby granted, provided that the above |
5 | // copyright notice and this permission notice appear in all copies. |
6 | // |
7 | // THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHORS DISCLAIM ALL WARRANTIES |
8 | // WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF |
9 | // MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY |
10 | // SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES |
11 | // WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION |
12 | // OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN |
13 | // CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. |
14 | |
15 | use crate::error; |
16 | |
17 | /// A nonce for a single AEAD opening or sealing operation. |
18 | /// |
19 | /// The user must ensure, for a particular key, that each nonce is unique. |
20 | /// |
21 | /// `Nonce` intentionally doesn't implement `Clone` to ensure that each one is |
22 | /// consumed at most once. |
23 | pub struct Nonce([u8; NONCE_LEN]); |
24 | |
25 | impl Nonce { |
26 | /// Constructs a `Nonce` with the given value, assuming that the value is |
27 | /// unique for the lifetime of the key it is being used with. |
28 | /// |
29 | /// Fails if `value` isn't `NONCE_LEN` bytes long. |
30 | #[inline ] |
31 | pub fn try_assume_unique_for_key(value: &[u8]) -> Result<Self, error::Unspecified> { |
32 | let value: &[u8; NONCE_LEN] = value.try_into()?; |
33 | Ok(Self::assume_unique_for_key(*value)) |
34 | } |
35 | |
36 | /// Constructs a `Nonce` with the given value, assuming that the value is |
37 | /// unique for the lifetime of the key it is being used with. |
38 | #[inline ] |
39 | pub fn assume_unique_for_key(value: [u8; NONCE_LEN]) -> Self { |
40 | Self(value) |
41 | } |
42 | } |
43 | |
44 | impl AsRef<[u8; NONCE_LEN]> for Nonce { |
45 | fn as_ref(&self) -> &[u8; NONCE_LEN] { |
46 | &self.0 |
47 | } |
48 | } |
49 | |
50 | /// All the AEADs we support use 96-bit nonces. |
51 | pub const NONCE_LEN: usize = 96 / 8; |
52 | |