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implement 0.5.1 rand_core API

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this is for interop with the curve25519-dalek crate
This commit is contained in:
bunnie 2023-02-26 01:00:02 +08:00
parent 64d5644ecf
commit f3c28b4e20
2 changed files with 37 additions and 28 deletions
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2
services/trng/Cargo.toml
View file

@ -17,7 +17,7 @@ num-traits = {version = "0.2.14", default-features = false}
susres = {package = "xous-api-susres", version = "0.9.28"}
rkyv = {version = "0.4.3", default-features = false, features = ["const_generics"]}
xous-ipc = "0.9.33"
rand_core = "0.5.1" # the 0.5.1 API is necessary for compatibility with curve25519-dalek crates
utralib = { version = "0.1.13", optional = true, default-features = false }
[target.'cfg(any(windows,unix))'.dependencies]

63
services/trng/src/lib.rs
View file

@ -4,6 +4,8 @@ pub mod api;
use num_traits::*;
use xous::{send_message, CID};
use xous_ipc::Buffer;
// the 0.5.1 API is necessary for compatibility with curve25519-dalek crates
use rand_core::{RngCore, CryptoRng};
#[derive(Debug)]
pub struct Trng {
@ -117,15 +119,42 @@ impl Trng {
.or(Err(xous::Error::InternalError))?;
Ok(buf.to_original().unwrap())
}
/// This is copied out of the 0.5 API for rand_core
pub fn fill_bytes_via_next(&mut self, dest: &mut [u8]) {
use core::mem::transmute;
let mut left = dest;
while left.len() >= 8 {
let (l, r) = {left}.split_at_mut(8);
left = r;
let chunk: [u8; 8] = unsafe {
transmute(self.next_u64().to_le())
};
l.copy_from_slice(&chunk);
}
let n = left.len();
if n > 4 {
let chunk: [u8; 8] = unsafe {
transmute(self.next_u64().to_le())
};
left.copy_from_slice(&chunk[..n]);
} else if n > 0 {
let chunk: [u8; 4] = unsafe {
transmute(self.next_u32().to_le())
};
left.copy_from_slice(&chunk[..n]);
}
}
}
impl RngCore for Trng {
// legacy (0.5) trng apis
pub fn next_u32(&mut self) -> u32 {
fn next_u32(&mut self) -> u32 {
self.get_u32().expect("couldn't get random u32 from server")
}
pub fn next_u64(&mut self) -> u64 {
fn next_u64(&mut self) -> u64 {
self.get_u64().expect("couldn't get random u64 from server")
}
pub fn fill_bytes(&mut self, dest: &mut [u8]) {
fn fill_bytes(&mut self, dest: &mut [u8]) {
// smaller than 64 bytes (512 bits), just use 8x next_u64 calls to fill.
if dest.len() < 64 {
return self.fill_bytes_via_next(dest);
@ -184,33 +213,13 @@ impl Trng {
.into_remainder();
self.fill_bytes_via_next(leftovers);
}
/// This is copied out of the 0.5 API for rand_core
fn fill_bytes_via_next(&mut self, dest: &mut [u8]) {
use core::mem::transmute;
let mut left = dest;
while left.len() >= 8 {
let (l, r) = {left}.split_at_mut(8);
left = r;
let chunk: [u8; 8] = unsafe {
transmute(self.next_u64().to_le())
};
l.copy_from_slice(&chunk);
}
let n = left.len();
if n > 4 {
let chunk: [u8; 8] = unsafe {
transmute(self.next_u64().to_le())
};
left.copy_from_slice(&chunk[..n]);
} else if n > 0 {
let chunk: [u8; 4] = unsafe {
transmute(self.next_u32().to_le())
};
left.copy_from_slice(&chunk[..n]);
}
fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), rand_core::Error> {
Ok(self.fill_bytes(dest))
}
}
impl CryptoRng for Trng {}
use core::sync::atomic::{AtomicU32, Ordering};
static REFCOUNT: AtomicU32 = AtomicU32::new(0);
impl Drop for Trng {