1// Copyright 2015-2021 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//! Authenticated Encryption with Associated Data (AEAD).
16//!
17//! See [Authenticated encryption: relations among notions and analysis of the
18//! generic composition paradigm][AEAD] for an introduction to the concept of
19//! AEADs.
20//!
21//! [AEAD]: https://eprint.iacr.org/2000/025.pdf
22//! [`crypto.cipher.AEAD`]: https://golang.org/pkg/crypto/cipher/#AEAD
23
24use super::{Algorithm, LessSafeKey, MAX_KEY_LEN};
25use crate::{error, hkdf};
26
27/// An AEAD key without a designated role or nonce sequence.
28pub struct UnboundKey {
29 inner: LessSafeKey,
30}
31
32impl UnboundKey {
33 /// Constructs a `UnboundKey`.
34 ///
35 /// Fails if `key_bytes.len() != algorithm.key_len()`.
36 #[inline]
37 pub fn new(
38 algorithm: &'static Algorithm,
39 key_bytes: &[u8],
40 ) -> Result<Self, error::Unspecified> {
41 Ok(Self {
42 inner: LessSafeKey::new_(algorithm, key_bytes)?,
43 })
44 }
45
46 /// The key's AEAD algorithm.
47 #[inline]
48 pub fn algorithm(&self) -> &'static Algorithm {
49 self.inner.algorithm()
50 }
51
52 #[inline]
53 pub(super) fn into_inner(self) -> LessSafeKey {
54 self.inner
55 }
56}
57
58impl core::fmt::Debug for UnboundKey {
59 fn fmt(&self, f: &mut core::fmt::Formatter) -> Result<(), core::fmt::Error> {
60 self.inner.fmt_debug(type_name:"UnboundKey", f)
61 }
62}
63
64impl From<hkdf::Okm<'_, &'static Algorithm>> for UnboundKey {
65 fn from(okm: hkdf::Okm<&'static Algorithm>) -> Self {
66 let mut key_bytes: [u8; 32] = [0; MAX_KEY_LEN];
67 let key_bytes: &mut [u8] = &mut key_bytes[..okm.len().key_len];
68 let algorithm: &Algorithm = *okm.len();
69 okm.fill(out:key_bytes).unwrap();
70 Self {
71 inner: LessSafeKey::new_(algorithm, key_bytes).unwrap(),
72 }
73 }
74}
75