Struct monocypher::chacha20::Context

pub struct Context(_);

Methods

impl Context

These functions provide an incremental interface for the Chacha20 encryption primitive.

Example

use monocypher::chacha20::Context;
use monocypher::utils::wipe;

   let mut key: [u8; 32] = [
       171, 107, 219, 186, 0, 173, 209, 50, 252, 77, 93, 85, 99, 106, 222, 162, 122, 140, 150,
       228, 61, 93, 186, 251, 45, 23, 222, 14, 121, 172, 147, 241,
   ];
   let nonce: [u8; 8] = [0, 0, 0, 0, 0, 0, 0, 1];

   let mut ctx = Context::new(&key, nonce);
   let mut ctx2 = Context::new(&key, nonce);
   let ciphertext = ctx.encrypt("test".as_bytes());
   let plaintext = ctx2.decrypt(&ciphertext);

   wipe(&mut key);

   assert_eq!(&plaintext, &"test".as_bytes())

pub fn new(key: &[u8], nonce: [u8; 8]) -> Context

Initialises a new context with the given key and nonce. Uses an 8-byte nonce, which is too small to be selected at random. Use a counter.

pub fn new_x(key: &[u8], nonce: [u8; 24]) -> Context

Initialises a new context with the given key and nonce. Uses a 24-byte nonce, which is big enough to be selected at random. Use your operating system to generate cryptographic secure random numbers. Read the about random number generators in the documentation

pub fn encrypt(&mut self, plaintext: &[u8]) -> Vec<u8>

Encrypts the given plaintext.

pub fn decrypt(&mut self, ciphertext: &[u8]) -> Vec<u8>

Decrypts the given ciphertext.

pub fn stream(&mut self, stream: &mut [u8])

Same as encrypt but with plaintext beeing NULL. Usefull as a non cryptographic user space random number generator.

pub fn chacha20_set_ctr(&mut self, ctr: u64)

Resets the internal counter of the context to the given number. Resuming the encryption will use the stream at the block number. May be used to en/decrypt part of a long message. Can also be used to implement AEAD constructions like the ones explained in RFC 7539.