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use core::{mem::size_of, usize};
use crate::errors::InvalidParams;
#[derive(Clone, Copy)]
pub struct ScryptParams {
pub(crate) log_n: u8,
pub(crate) r: u32,
pub(crate) p: u32,
}
impl ScryptParams {
pub fn new(log_n: u8, r: u32, p: u32) -> Result<ScryptParams, InvalidParams> {
let cond1 = (log_n as usize) < size_of::<usize>() * 8;
let cond2 = size_of::<usize>() >= size_of::<u32>();
let cond3 = r <= usize::MAX as u32 && p < usize::MAX as u32;
if !(r > 0 && p > 0 && cond1 && (cond2 || cond3)) {
return Err(InvalidParams);
}
let r = r as usize;
let p = p as usize;
let n: usize = 1 << log_n;
let r128 = r.checked_mul(128).ok_or(InvalidParams)?;
r128.checked_mul(n).ok_or(InvalidParams)?;
r128.checked_mul(p).ok_or(InvalidParams)?;
if (log_n as usize) >= r * 16 {
return Err(InvalidParams);
}
if r * p >= 0x4000_0000 {
return Err(InvalidParams);
}
Ok(ScryptParams {
log_n,
r: r as u32,
p: p as u32,
})
}
pub fn recommended() -> ScryptParams {
ScryptParams {
log_n: 15,
r: 8,
p: 1,
}
}
}