use alloc::boxed::Box;
use alloc::sync::Arc;
use alloc::vec::Vec;
use core::fmt;
use core::fmt::{Debug, Formatter};
use core::sync::atomic::{AtomicUsize, Ordering};
use subtle::ConstantTimeEq;
use super::ring_like::aead;
use super::ring_like::rand::{SecureRandom, SystemRandom};
use crate::error::Error;
#[cfg(debug_assertions)]
use crate::log::debug;
use crate::polyfill::try_split_at;
use crate::rand::GetRandomFailed;
use crate::server::ProducesTickets;
pub struct Ticketer {}
impl Ticketer {
#[cfg(feature = "std")]
pub fn new() -> Result<Arc<dyn ProducesTickets>, Error> {
Ok(Arc::new(crate::ticketer::TicketRotator::new(
6 * 60 * 60,
make_ticket_generator,
)?))
}
#[cfg(not(feature = "std"))]
pub fn new<M: crate::lock::MakeMutex>(
time_provider: &'static dyn TimeProvider,
) -> Result<Arc<dyn ProducesTickets>, Error> {
Ok(Arc::new(crate::ticketer::TicketSwitcher::new::<M>(
6 * 60 * 60,
make_ticket_generator,
time_provider,
)?))
}
}
fn make_ticket_generator() -> Result<Box<dyn ProducesTickets>, GetRandomFailed> {
Ok(Box::new(AeadTicketer::new()?))
}
struct AeadTicketer {
alg: &'static aead::Algorithm,
key: aead::LessSafeKey,
key_name: [u8; 16],
lifetime: u32,
maximum_ciphertext_len: AtomicUsize,
}
impl AeadTicketer {
fn new() -> Result<Self, GetRandomFailed> {
let mut key = [0u8; 32];
SystemRandom::new()
.fill(&mut key)
.map_err(|_| GetRandomFailed)?;
let key = aead::UnboundKey::new(TICKETER_AEAD, &key).unwrap();
let mut key_name = [0u8; 16];
SystemRandom::new()
.fill(&mut key_name)
.map_err(|_| GetRandomFailed)?;
Ok(Self {
alg: TICKETER_AEAD,
key: aead::LessSafeKey::new(key),
key_name,
lifetime: 60 * 60 * 12,
maximum_ciphertext_len: AtomicUsize::new(0),
})
}
}
impl ProducesTickets for AeadTicketer {
fn enabled(&self) -> bool {
true
}
fn lifetime(&self) -> u32 {
self.lifetime
}
fn encrypt(&self, message: &[u8]) -> Option<Vec<u8>> {
let mut nonce_buf = [0u8; 12];
SystemRandom::new()
.fill(&mut nonce_buf)
.ok()?;
let nonce = aead::Nonce::assume_unique_for_key(nonce_buf);
let aad = aead::Aad::from(self.key_name);
let mut ciphertext = Vec::with_capacity(
self.key_name.len() + nonce_buf.len() + message.len() + self.key.algorithm().tag_len(),
);
ciphertext.extend(self.key_name);
ciphertext.extend(nonce_buf);
ciphertext.extend(message);
let ciphertext = self
.key
.seal_in_place_separate_tag(
nonce,
aad,
&mut ciphertext[self.key_name.len() + nonce_buf.len()..],
)
.map(|tag| {
ciphertext.extend(tag.as_ref());
ciphertext
})
.ok()?;
self.maximum_ciphertext_len
.fetch_max(ciphertext.len(), Ordering::SeqCst);
Some(ciphertext)
}
fn decrypt(&self, ciphertext: &[u8]) -> Option<Vec<u8>> {
if ciphertext.len()
> self
.maximum_ciphertext_len
.load(Ordering::SeqCst)
{
#[cfg(debug_assertions)]
debug!("rejected over-length ticket");
return None;
}
let (alleged_key_name, ciphertext) = try_split_at(ciphertext, self.key_name.len())?;
let (nonce, ciphertext) = try_split_at(ciphertext, self.alg.nonce_len())?;
if ConstantTimeEq::ct_ne(&self.key_name[..], alleged_key_name).into() {
#[cfg(debug_assertions)]
debug!("rejected ticket with wrong ticket_name");
return None;
}
let nonce = aead::Nonce::try_assume_unique_for_key(nonce).ok()?;
let mut out = Vec::from(ciphertext);
let plain_len = self
.key
.open_in_place(nonce, aead::Aad::from(alleged_key_name), &mut out)
.ok()?
.len();
out.truncate(plain_len);
Some(out)
}
}
impl Debug for AeadTicketer {
fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
f.debug_struct("AeadTicketer")
.field("alg", &self.alg)
.field("lifetime", &self.lifetime)
.finish()
}
}
static TICKETER_AEAD: &aead::Algorithm = &aead::CHACHA20_POLY1305;
#[cfg(test)]
mod tests {
use core::time::Duration;
use pki_types::UnixTime;
use super::*;
#[test]
fn basic_pairwise_test() {
let t = Ticketer::new().unwrap();
assert!(t.enabled());
let cipher = t.encrypt(b"hello world").unwrap();
let plain = t.decrypt(&cipher).unwrap();
assert_eq!(plain, b"hello world");
}
#[test]
fn refuses_decrypt_before_encrypt() {
let t = Ticketer::new().unwrap();
assert_eq!(t.decrypt(b"hello"), None);
}
#[test]
fn refuses_decrypt_larger_than_largest_encryption() {
let t = Ticketer::new().unwrap();
let mut cipher = t.encrypt(b"hello world").unwrap();
assert_eq!(t.decrypt(&cipher), Some(b"hello world".to_vec()));
cipher.push(0);
assert_eq!(t.decrypt(&cipher), None);
}
#[test]
fn ticketrotator_switching_test() {
let t = Arc::new(crate::ticketer::TicketRotator::new(1, make_ticket_generator).unwrap());
let now = UnixTime::now();
let cipher1 = t.encrypt(b"ticket 1").unwrap();
assert_eq!(t.decrypt(&cipher1).unwrap(), b"ticket 1");
{
t.maybe_roll(UnixTime::since_unix_epoch(Duration::from_secs(
now.as_secs() + 10,
)));
}
let cipher2 = t.encrypt(b"ticket 2").unwrap();
assert_eq!(t.decrypt(&cipher1).unwrap(), b"ticket 1");
assert_eq!(t.decrypt(&cipher2).unwrap(), b"ticket 2");
{
t.maybe_roll(UnixTime::since_unix_epoch(Duration::from_secs(
now.as_secs() + 20,
)));
}
let cipher3 = t.encrypt(b"ticket 3").unwrap();
assert!(t.decrypt(&cipher1).is_none());
assert_eq!(t.decrypt(&cipher2).unwrap(), b"ticket 2");
assert_eq!(t.decrypt(&cipher3).unwrap(), b"ticket 3");
}
#[test]
fn ticketrotator_remains_usable_over_temporary_ticketer_creation_failure() {
let mut t = crate::ticketer::TicketRotator::new(1, make_ticket_generator).unwrap();
let now = UnixTime::now();
let cipher1 = t.encrypt(b"ticket 1").unwrap();
assert_eq!(t.decrypt(&cipher1).unwrap(), b"ticket 1");
t.generator = fail_generator;
{
t.maybe_roll(UnixTime::since_unix_epoch(Duration::from_secs(
now.as_secs() + 10,
)));
}
let cipher2 = t.encrypt(b"ticket 2").unwrap();
assert_eq!(t.decrypt(&cipher1).unwrap(), b"ticket 1");
assert_eq!(t.decrypt(&cipher2).unwrap(), b"ticket 2");
t.generator = make_ticket_generator;
{
t.maybe_roll(UnixTime::since_unix_epoch(Duration::from_secs(
now.as_secs() + 20,
)));
}
let cipher3 = t.encrypt(b"ticket 3").unwrap();
assert!(t.decrypt(&cipher1).is_some());
assert_eq!(t.decrypt(&cipher2).unwrap(), b"ticket 2");
assert_eq!(t.decrypt(&cipher3).unwrap(), b"ticket 3");
}
#[test]
fn ticketswitcher_switching_test() {
#[expect(deprecated)]
let t = Arc::new(crate::ticketer::TicketSwitcher::new(1, make_ticket_generator).unwrap());
let now = UnixTime::now();
let cipher1 = t.encrypt(b"ticket 1").unwrap();
assert_eq!(t.decrypt(&cipher1).unwrap(), b"ticket 1");
{
t.maybe_roll(UnixTime::since_unix_epoch(Duration::from_secs(
now.as_secs() + 10,
)));
}
let cipher2 = t.encrypt(b"ticket 2").unwrap();
assert_eq!(t.decrypt(&cipher1).unwrap(), b"ticket 1");
assert_eq!(t.decrypt(&cipher2).unwrap(), b"ticket 2");
{
t.maybe_roll(UnixTime::since_unix_epoch(Duration::from_secs(
now.as_secs() + 20,
)));
}
let cipher3 = t.encrypt(b"ticket 3").unwrap();
assert!(t.decrypt(&cipher1).is_none());
assert_eq!(t.decrypt(&cipher2).unwrap(), b"ticket 2");
assert_eq!(t.decrypt(&cipher3).unwrap(), b"ticket 3");
}
#[test]
fn ticketswitcher_recover_test() {
#[expect(deprecated)]
let mut t = crate::ticketer::TicketSwitcher::new(1, make_ticket_generator).unwrap();
let now = UnixTime::now();
let cipher1 = t.encrypt(b"ticket 1").unwrap();
assert_eq!(t.decrypt(&cipher1).unwrap(), b"ticket 1");
t.generator = fail_generator;
{
t.maybe_roll(UnixTime::since_unix_epoch(Duration::from_secs(
now.as_secs() + 10,
)));
}
t.generator = make_ticket_generator;
let cipher2 = t.encrypt(b"ticket 2").unwrap();
assert_eq!(t.decrypt(&cipher1).unwrap(), b"ticket 1");
assert_eq!(t.decrypt(&cipher2).unwrap(), b"ticket 2");
{
t.maybe_roll(UnixTime::since_unix_epoch(Duration::from_secs(
now.as_secs() + 20,
)));
}
let cipher3 = t.encrypt(b"ticket 3").unwrap();
assert!(t.decrypt(&cipher1).is_none());
assert_eq!(t.decrypt(&cipher2).unwrap(), b"ticket 2");
assert_eq!(t.decrypt(&cipher3).unwrap(), b"ticket 3");
}
#[test]
fn aeadticketer_is_debug_and_producestickets() {
use alloc::format;
use super::*;
let t = make_ticket_generator().unwrap();
let expect = format!("AeadTicketer {{ alg: {TICKETER_AEAD:?}, lifetime: 43200 }}");
assert_eq!(format!("{:?}", t), expect);
assert!(t.enabled());
assert_eq!(t.lifetime(), 43200);
}
fn fail_generator() -> Result<Box<dyn ProducesTickets>, GetRandomFailed> {
Err(GetRandomFailed)
}
}