Crate crypto_secretbox

Expand description

§RustCrypto: `crypto_secretbox`

crypto_secretbox is an authenticated symmetric encryption cipher amenable to fast, constant-time implementations in software, combining either the Salsa20 stream cipher (with XSalsa20 192-bit nonce extension) or ChaCha20 stream cipher with the Poly1305 universal hash function, which acts as a message authentication code.

This algorithm has largely been replaced by the newer IETF variant of ChaCha20Poly1305 (and the associated XChaCha20Poly1305) AEAD ciphers (RFC 8439), but is useful for interoperability with legacy NaCl-based protocols.

Documentation

§Security Warning

No security audits of this crate have ever been performed, and it has not been thoroughly assessed to ensure its operation is constant-time on common CPU architectures.

USE AT YOUR OWN RISK!

§License

Licensed under either of:

at your option.

§Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.

§Usage

use crypto_secretbox::{
    aead::{Aead, AeadCore, KeyInit, OsRng},
    XSalsa20Poly1305, Nonce
};

let key = XSalsa20Poly1305::generate_key(&mut OsRng);
let cipher = XSalsa20Poly1305::new(&key);
let nonce = XSalsa20Poly1305::generate_nonce(&mut OsRng); // unique per message
let ciphertext = cipher.encrypt(&nonce, b"plaintext message".as_ref())?;
let plaintext = cipher.decrypt(&nonce, ciphertext.as_ref())?;
assert_eq!(&plaintext, b"plaintext message");

§In-place Usage (eliminates `alloc` requirement)

This crate has an optional alloc feature which can be disabled in e.g. microcontroller environments that don’t have a heap.

The AeadInPlace::encrypt_in_place and AeadInPlace::decrypt_in_place methods accept any type that impls the aead::Buffer trait which contains the plaintext for encryption or ciphertext for decryption.

Note that if you enable the heapless feature of this crate, you will receive an impl of aead::Buffer for heapless::Vec (re-exported from the aead crate as [aead::heapless::Vec]), which can then be passed as the buffer parameter to the in-place encrypt and decrypt methods:

use crypto_secretbox::{
    aead::{AeadCore, AeadInPlace, KeyInit, OsRng, heapless::Vec},
    XSalsa20Poly1305, Nonce,
};

let key = XSalsa20Poly1305::generate_key(&mut OsRng);
let cipher = XSalsa20Poly1305::new(&key);
let nonce = XSalsa20Poly1305::generate_nonce(&mut OsRng); // unique per message

let mut buffer: Vec<u8, 128> = Vec::new(); // Note: buffer needs 16-bytes overhead for auth tag
buffer.extend_from_slice(b"plaintext message");

// Encrypt `buffer` in-place, replacing the plaintext contents with ciphertext
cipher.encrypt_in_place(&nonce, b"", &mut buffer)?;

// `buffer` now contains the message ciphertext
assert_ne!(&buffer, b"plaintext message");

// Decrypt `buffer` in-place, replacing its ciphertext context with the original plaintext
cipher.decrypt_in_place(&nonce, b"", &mut buffer)?;
assert_eq!(&buffer, b"plaintext message");

use crypto_secretbox::XSalsa20Poly1305;
use crypto_secretbox::aead::{AeadCore, AeadInPlace, KeyInit, generic_array::GenericArray};
use crypto_secretbox::aead::heapless::Vec;

let key = GenericArray::from_slice(b"an example very very secret key.");
let cipher = XSalsa20Poly1305::new(key);

let nonce = GenericArray::from_slice(b"extra long unique nonce!"); // 24-bytes; unique

let mut buffer: Vec<u8, 128> = Vec::new();
buffer.extend_from_slice(b"plaintext message");

// Encrypt `buffer` in-place, replacing the plaintext contents with ciphertext
cipher.encrypt_in_place(nonce, b"", &mut buffer).expect("encryption failure!");

// `buffer` now contains the message ciphertext
assert_ne!(&buffer, b"plaintext message");

// Decrypt `buffer` in-place, replacing its ciphertext context with the original plaintext
cipher.decrypt_in_place(nonce, b"", &mut buffer).expect("decryption failure!");
assert_eq!(&buffer, b"plaintext message");

Re-exports§

pub use aead;
pub use cipher;

Modules§

consts

Structs§

Error: Error type.
SecretBox: The NaCl crypto_secretbox authenticated symmetric encryption primitive, generic

Traits§

AeadCore: Authenticated Encryption with Associated Data (AEAD) algorithm core trait.
AeadInPlace: In-place stateless AEAD trait.
Kdf: Key derivation function: trait for abstracting over HSalsa20 and HChaCha20.
KeyInit: Types which can be initialized from key.
KeySizeUser: Types which use key for initialization.

Type Aliases§

Key: Key type.
Nonce: Nonce type.
Tag: Poly1305 tag.
XSalsa20Poly1305: crypto_secretbox instantiated with the XSalsa20 stream cipher.