openethereum/ethstore/src/random.rs

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2016-12-11 19:30:54 +01:00
// Copyright 2015, 2016 Parity Technologies (UK) Ltd.
// This file is part of Parity.
// Parity is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// Parity is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with Parity. If not, see <http://www.gnu.org/licenses/>.
use rand::{Rng, OsRng};
use itertools::Itertools;
pub trait Random {
fn random() -> Self where Self: Sized;
}
impl Random for [u8; 16] {
fn random() -> Self {
let mut result = [0u8; 16];
let mut rng = OsRng::new().unwrap();
rng.fill_bytes(&mut result);
result
}
}
impl Random for [u8; 32] {
fn random() -> Self {
let mut result = [0u8; 32];
let mut rng = OsRng::new().unwrap();
rng.fill_bytes(&mut result);
result
}
}
/// Generate a string which is a random phrase of a number of lowercase words.
///
/// `words` is the number of words, chosen from a dictionary of 7,530. An value of
/// 12 gives 155 bits of entropy (almost saturating address space); 20 gives 258 bits
/// which is enough to saturate 32-byte key space
pub fn random_phrase(words: usize) -> String {
lazy_static! {
static ref WORDS: Vec<String> = String::from_utf8_lossy(include_bytes!("../res/wordlist.txt"))
.lines()
.map(|s| s.to_owned())
.collect();
}
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let mut rng = OsRng::new().expect("Not able to operate without random source.");
(0..words).map(|_| rng.choose(&WORDS).unwrap()).join(" ")
}
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/// Generate a random string of given length.
pub fn random_string(length: usize) -> String {
let mut rng = OsRng::new().expect("Not able to operate without random source.");
rng.gen_ascii_chars().take(length).collect()
}
#[cfg(test)]
mod tests {
use super::random_phrase;
#[test]
fn should_produce_right_number_of_words() {
let p = random_phrase(10);
assert_eq!(p.split(" ").count(), 10);
}
#[test]
fn should_not_include_carriage_return() {
let p = random_phrase(10);
assert!(!p.contains('\r'), "Carriage return should be trimmed.");
}
}