aws_lc_rs/aead/
nonce.rs

1// Copyright 2018 Brian Smith.
2// SPDX-License-Identifier: ISC
3// Modifications copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
4// SPDX-License-Identifier: Apache-2.0 OR ISC
5
6use crate::endian::{ArrayEncoding, BigEndian, Encoding, FromArray, LittleEndian};
7use crate::error;
8use crate::iv::FixedLength;
9
10/// A nonce for a single AEAD opening or sealing operation.
11///
12/// The user must ensure, for a particular key, that each nonce is unique.
13///
14/// `Nonce` intentionally doesn't implement `Clone` to ensure that each one is
15/// consumed at most once.
16pub struct Nonce(pub(crate) FixedLength<NONCE_LEN>);
17
18impl Nonce {
19    /// Constructs a `Nonce` with the given value, assuming that the value is
20    /// unique for the lifetime of the key it is being used with.
21    ///
22    /// Fails if `value` isn't `NONCE_LEN` bytes long.
23    /// # Errors
24    /// `error::Unspecified` when byte slice length is not `NONCE_LEN`
25    #[inline]
26    pub fn try_assume_unique_for_key(value: &[u8]) -> Result<Self, error::Unspecified> {
27        Ok(Self(FixedLength::<NONCE_LEN>::try_from(value)?))
28    }
29
30    /// Constructs a `Nonce` with the given value, assuming that the value is
31    /// unique for the lifetime of the key it is being used with.
32    #[inline]
33    #[must_use]
34    pub fn assume_unique_for_key(value: [u8; NONCE_LEN]) -> Self {
35        Self(FixedLength::<NONCE_LEN>::from(value))
36    }
37}
38
39impl AsRef<[u8; NONCE_LEN]> for Nonce {
40    #[inline]
41    fn as_ref(&self) -> &[u8; NONCE_LEN] {
42        self.0.as_ref()
43    }
44}
45
46impl From<&[u8; NONCE_LEN]> for Nonce {
47    #[inline]
48    fn from(bytes: &[u8; NONCE_LEN]) -> Self {
49        Self(FixedLength::from(bytes))
50    }
51}
52
53/// Deprecated. Encodes each `u32` as little-endian.
54///
55/// Prefer [`Nonce::assume_unique_for_key`] with explicitly encoded bytes, e.g.
56/// built with [`u32::to_le_bytes`].
57// `#[deprecated]` on an impl has no effect on users (no warning, and rustdoc
58// does not render it), so the doc comment above is what directs them.
59#[allow(useless_deprecated)] // https://github.com/rust-lang/rust/issues/39935
60#[deprecated(
61    since = "1.6.0",
62    note = "Use `Nonce::assume_unique_for_key` with explicitly encoded bytes."
63)]
64impl From<&[u32; NONCE_LEN / 4]> for Nonce {
65    #[inline]
66    fn from(values: &[u32; NONCE_LEN / 4]) -> Self {
67        Nonce::from(&LittleEndian::<u32>::from_array(values))
68    }
69}
70
71impl From<&[BigEndian<u32>; NONCE_LEN / 4]> for Nonce {
72    #[inline]
73    fn from(values: &[BigEndian<u32>; NONCE_LEN / 4]) -> Self {
74        Nonce(FixedLength::from(values.as_byte_array()))
75    }
76}
77
78impl From<&[LittleEndian<u32>; NONCE_LEN / 4]> for Nonce {
79    #[inline]
80    fn from(nonce: &[LittleEndian<u32>; NONCE_LEN / 4]) -> Self {
81        Nonce(FixedLength::from(nonce.as_byte_array()))
82    }
83}
84
85impl From<BigEndian<u32>> for Nonce {
86    #[inline]
87    fn from(number: BigEndian<u32>) -> Self {
88        Nonce::from([BigEndian::ZERO, BigEndian::ZERO, number].as_byte_array())
89    }
90}
91
92pub const IV_LEN: usize = 16;
93impl From<&[u8; IV_LEN]> for Nonce {
94    #[inline]
95    fn from(bytes: &[u8; IV_LEN]) -> Self {
96        let mut nonce_bytes = [0u8; NONCE_LEN];
97        nonce_bytes.copy_from_slice(&bytes[0..NONCE_LEN]);
98        Nonce(FixedLength::from(nonce_bytes))
99    }
100}
101
102/// All the AEADs we support use 96-bit nonces.
103pub const NONCE_LEN: usize = 96 / 8;
104
105#[cfg(test)]
106mod tests {
107
108    #[test]
109    fn test_nonce_from_byte_array() {
110        use crate::aead::nonce::IV_LEN;
111        use crate::aead::Nonce;
112        let iv: [u8; IV_LEN] = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16];
113        let nonce = Nonce::from(&iv);
114
115        assert_eq!(&[1u8, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12], nonce.as_ref());
116    }
117}
aws_lc_rs/aead/nonce.rs

aws_lc_rs/aead/
nonce.rs
