Use a gamma distribution for mixin selection

This commit is contained in:
Luke Parker 2022-05-04 08:18:43 -04:00
parent f856faa762
commit 0f481773df
No known key found for this signature in database
GPG key ID: F9F1386DB1E119B6
6 changed files with 71 additions and 21 deletions

View file

@ -11,6 +11,7 @@ lazy_static = "1"
thiserror = "1"
rand_core = "0.6"
rand_distr = "0.4"
tiny-keccak = { version = "2.0", features = ["keccak"] }
blake2 = "0.10"

View file

@ -8,7 +8,6 @@ use curve25519_dalek::edwards::{EdwardsPoint, CompressedEdwardsY};
use monero::{
Hash,
cryptonote::hash::Hashable,
blockdata::{
transaction::{TxIn, Transaction},
block::Block
@ -237,13 +236,30 @@ impl Rpc {
).collect()
}
pub async fn get_high_output(&self, height: usize) -> Result<u64, RpcError> {
let block = self.get_block(height).await?;
Ok(
*self.get_o_indexes(
*block.tx_hashes.last().unwrap_or(&block.miner_tx.hash())
).await?.last().ok_or(RpcError::InvalidTransaction)?
)
pub async fn get_output_distribution(&self, height: usize) -> Result<Vec<u64>, RpcError> {
#[allow(dead_code)]
#[derive(Deserialize, Debug)]
pub struct Distribution {
distribution: Vec<u64>
}
#[allow(dead_code)]
#[derive(Deserialize, Debug)]
struct Distributions {
distributions: Vec<Distribution>
}
let mut distributions: JsonRpcResponse<Distributions> = self.rpc_call("json_rpc", Some(json!({
"method": "get_output_distribution",
"params": {
"binary": false,
"amounts": [0],
"cumulative": true,
"to_height": height
}
}))).await?;
Ok(distributions.result.distributions.swap_remove(0).distribution)
}
pub async fn publish_transaction(&self, tx: &Transaction) -> Result<(), RpcError> {

View file

@ -1,6 +1,9 @@
use std::collections::HashSet;
use lazy_static::lazy_static;
use rand_core::{RngCore, CryptoRng};
use rand_distr::{Distribution, Gamma};
use curve25519_dalek::edwards::EdwardsPoint;
@ -8,22 +11,48 @@ use monero::VarInt;
use crate::{transaction::SpendableOutput, rpc::{RpcError, Rpc}};
const LOCK_WINDOW: usize = 10;
const RECENT_WINDOW: usize = 15;
const BLOCK_TIME: usize = 120;
const BLOCKS_PER_YEAR: usize = 365 * 24 * 60 * 60 / BLOCK_TIME;
const TIP_APPLICATION: f64 = (LOCK_WINDOW * BLOCK_TIME) as f64;
const MIXINS: usize = 11;
lazy_static! {
static ref GAMMA: Gamma<f64> = Gamma::new(19.28, 1.0 / 1.61).unwrap();
}
async fn select_single<R: RngCore + CryptoRng>(
rng: &mut R,
rpc: &Rpc,
height: usize,
distribution: &[u64],
high: u64,
per_second: f64,
used: &mut HashSet<u64>
) -> Result<(u64, [EdwardsPoint; 2]), RpcError> {
let mut o;
let mut output = None;
while {
o = rng.next_u64() % u64::try_from(high).unwrap();
used.contains(&o) || {
output = rpc.get_outputs(&[o], height).await?[0];
output.is_none()
let mut age = GAMMA.sample(rng).exp();
if age > TIP_APPLICATION {
age -= TIP_APPLICATION;
} else {
age = (rng.next_u64() % u64::try_from(RECENT_WINDOW * BLOCK_TIME).unwrap()) as f64;
}
o = (age * per_second) as u64;
(o >= high) || {
o = high - 1 - o;
let i = distribution.partition_point(|s| *s < o);
let prev = if i == 0 { 0 } else { i - 1 };
let n = distribution[i] - distribution[prev];
o = distribution[prev] + (rng.next_u64() % n);
(n == 0) || used.contains(&o) || {
output = rpc.get_outputs(&[o], height).await?[0];
output.is_none()
}
}
} {}
used.insert(o);
@ -55,11 +84,13 @@ pub(crate) async fn select<R: RngCore + CryptoRng>(
));
}
let high = rpc.get_high_output(height - 1).await?;
let high_f = high as f64;
if (high_f as u64) != high {
panic!("Transaction output index exceeds f64");
}
let distribution = rpc.get_output_distribution(height).await?;
let high = distribution[distribution.len() - 1];
let per_second = {
let blocks = distribution.len().min(BLOCKS_PER_YEAR);
let outputs = high - distribution[distribution.len().saturating_sub(blocks + 1)];
(outputs as f64) / ((blocks * BLOCK_TIME) as f64)
};
let mut used = HashSet::<u64>::new();
for o in &outputs {
@ -70,7 +101,7 @@ pub(crate) async fn select<R: RngCore + CryptoRng>(
for (i, o) in outputs.iter().enumerate() {
let mut mixins = Vec::with_capacity(MIXINS);
for _ in 0 .. MIXINS {
mixins.push(select_single(rng, rpc, height, high, &mut used).await?);
mixins.push(select_single(rng, rpc, height, &distribution, high, per_second, &mut used).await?);
}
mixins.sort_by(|a, b| a.0.cmp(&b.0));
@ -85,7 +116,7 @@ pub(crate) async fn select<R: RngCore + CryptoRng>(
// it'd increase the amount of mixins required to create this transaction and some banned
// outputs may be the best options
used.remove(&mixins[m].0);
mixins[m] = select_single(rng, rpc, height, high, &mut used).await?;
mixins[m] = select_single(rng, rpc, height, &distribution, high, per_second, &mut used).await?;
}
mixins.sort_by(|a, b| a.0.cmp(&b.0));
}

View file

@ -207,7 +207,7 @@ async fn prepare_inputs<R: RngCore + CryptoRng>(
let mixins = mixins::select(
rng,
rpc,
rpc.get_height().await.map_err(|e| TransactionError::RpcError(e))?,
rpc.get_height().await.map_err(|e| TransactionError::RpcError(e))? - 10,
inputs
).await.map_err(|e| TransactionError::RpcError(e))?;

View file

@ -38,6 +38,7 @@ impl SignableTransaction {
rng: &mut R,
rpc: &Rpc,
keys: Rc<MultisigKeys<Ed25519>>,
height: usize,
included: &[usize]
) -> Result<TransactionMachine, TransactionError> {
let mut our_images = vec![];
@ -75,7 +76,7 @@ impl SignableTransaction {
let mixins = mixins::select(
&mut transcript.seeded_rng(b"mixins", None),
rpc,
rpc.get_height().await.map_err(|e| TransactionError::RpcError(e))?,
height,
&self.inputs
).await.map_err(|e| TransactionError::RpcError(e))?;

View file

@ -60,6 +60,7 @@ pub async fn send_multisig() {
&mut OsRng,
&rpc,
keys[i - 1].clone(),
rpc.get_height().await.unwrap() - 10,
&(1 ..= THRESHOLD).collect::<Vec<usize>>()
).await.unwrap()
);