Fuzzytags for Groups with Tweaked Hashes (Prototype)
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0687943a5c
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@ -18,7 +18,6 @@ curve25519-dalek = { package = "curve25519-dalek", version="3.2", features=["se
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sha3 = "0.9.1"
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serde = {version="1.0.123", features=["derive"]}
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bit-vec = {version="0.6.3"}
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brute-force = {version="0.1.1", features=["curve25519"], optional=true}
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rayon = {version="1.5.0", optional=true}
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[dev-dependencies]
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@ -35,6 +34,6 @@ name = "entangled"
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harness = false
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[features]
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entangled = ["brute-force"]
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entangled = []
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bulk_verify = ["rayon"]
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simd = ["curve25519-dalek/simd_backend"]
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@ -3,7 +3,7 @@ use fuzzytags::{RootSecret, TaggingKey};
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use rand::rngs::OsRng;
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use std::time::Duration;
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fn benchmark_entangled(c: &mut Criterion) {
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fn benchmark_entangled5(c: &mut Criterion) {
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let mut group = c.benchmark_group("entangling");
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group.measurement_time(Duration::new(10, 0));
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group.sample_size(10);
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@ -11,12 +11,25 @@ fn benchmark_entangled(c: &mut Criterion) {
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for p in [24].iter() {
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let secret_key_1 = RootSecret::<24>::generate(&mut rng);
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let secret_key_2 = RootSecret::<24>::generate(&mut rng);
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let secret_key_3 = RootSecret::<24>::generate(&mut rng);
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let secret_key_4 = RootSecret::<24>::generate(&mut rng);
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let secret_key_5 = RootSecret::<24>::generate(&mut rng);
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let public_key_1 = secret_key_1.tagging_key();
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let public_key_2 = secret_key_2.tagging_key();
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let public_key_3 = secret_key_3.tagging_key();
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let public_key_4 = secret_key_4.tagging_key();
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let public_key_5 = secret_key_5.tagging_key();
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group.bench_with_input(BenchmarkId::from_parameter(p), p, |b, _gamma| {
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b.iter(|| {
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TaggingKey::generate_entangled_tag(
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vec![public_key_1.clone(), public_key_2.clone()],
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vec![
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public_key_1.clone(),
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public_key_2.clone(),
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public_key_3.clone(),
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public_key_4.clone(),
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public_key_5.clone(),
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],
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&mut rng,
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*p,
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)
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@ -25,5 +38,5 @@ fn benchmark_entangled(c: &mut Criterion) {
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}
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}
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criterion_group!(benches, benchmark_entangled);
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criterion_group!(benches, benchmark_entangled5);
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criterion_main!(benches);
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@ -1,5 +1,5 @@
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use criterion::{criterion_group, criterion_main, BenchmarkId, Criterion};
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use fuzzytags::{RootSecret};
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use fuzzytags::RootSecret;
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use rand::rngs::OsRng;
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use std::time::Duration;
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177
src/lib.rs
177
src/lib.rs
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@ -15,11 +15,7 @@ use std::fmt;
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use std::fmt::{Display, Formatter};
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use std::ops::{Mul, Sub};
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#[cfg(feature = "entangled")]
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use brute_force::adaptors;
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#[cfg(feature = "entangled")]
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use brute_force::brute_force;
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use rand::Rng;
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use rand_core::{CryptoRng, RngCore};
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#[cfg(feature = "bulk_verify")]
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use rayon::iter::IndexedParallelIterator;
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@ -27,6 +23,7 @@ use rayon::iter::IndexedParallelIterator;
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use rayon::iter::IntoParallelRefIterator;
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#[cfg(feature = "bulk_verify")]
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use rayon::iter::ParallelIterator;
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use std::borrow::BorrowMut;
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#[cfg(feature = "bulk_verify")]
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use std::sync::mpsc::channel;
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@ -41,6 +38,7 @@ use std::sync::mpsc::channel;
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pub struct Tag<const GAMMA: u8> {
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u: RistrettoPoint,
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y: Scalar,
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z: Vec<u8>,
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ciphertexts: BitVec,
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}
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@ -70,7 +68,7 @@ impl<'de, const GAMMA: u8> Deserialize<'de> for Tag<{ GAMMA }> {
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type Value = Tag<{ GAMMA }>;
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fn expecting(&self, formatter: &mut ::core::fmt::Formatter) -> ::core::fmt::Result {
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formatter.write_str("64 bytes + GAMMA+bits of data")
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formatter.write_str("64 bytes + GAMMA Bytes + GAMMA + bits of data")
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}
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fn visit_seq<A>(self, mut seq: A) -> Result<Tag<{ GAMMA }>, A::Error>
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@ -90,12 +88,13 @@ impl<'de, const GAMMA: u8> Deserialize<'de> for Tag<{ GAMMA }> {
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_ => break,
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}
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}
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Tag::<GAMMA>::decompress(&bytes).ok_or(serde::de::Error::custom("invalid fuzzytag"))
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}
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}
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// support up to GAMMA = 64
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deserializer.deserialize_tuple(72, FuzzyTagVisitor::<GAMMA>)
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deserializer.deserialize_tuple((72 + GAMMA) as usize, FuzzyTagVisitor::<GAMMA>)
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}
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}
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@ -122,6 +121,7 @@ impl<const GAMMA: u8> Tag<{ GAMMA }> {
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let mut bytes = vec![];
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bytes.extend_from_slice(self.u.compress().as_bytes());
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bytes.extend_from_slice(self.y.as_bytes());
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bytes.extend_from_slice(self.z.as_slice());
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bytes.extend_from_slice(self.ciphertexts.to_bytes().as_slice());
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bytes
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}
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@ -145,9 +145,10 @@ impl<const GAMMA: u8> Tag<{ GAMMA }> {
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/// assert_eq!(tag, decompressed_tag);
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/// ```
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pub fn decompress(bytes: &[u8]) -> Option<Tag<{ GAMMA }>> {
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if bytes.len() > 64 {
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if bytes.len() > (64 + GAMMA as usize) {
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let (u_bytes, rest) = bytes.split_at(32);
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let (y_bytes, ciphertext) = rest.split_at(32);
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let (y_bytes, rest) = rest.split_at(32);
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let (z_bytes, ciphertext) = rest.split_at({ GAMMA } as usize);
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// if the ciphertext is too short, then this is an invalid tag
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let min_bytes = GAMMA / 8;
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@ -160,13 +161,20 @@ impl<const GAMMA: u8> Tag<{ GAMMA }> {
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Ok(fixed_size) => fixed_size,
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_ => return None,
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};
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let mut ciphertexts = BitVec::from_bytes(ciphertext);
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ciphertexts.truncate(GAMMA as usize);
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return match (
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CompressedRistretto::from_slice(u_bytes).decompress(),
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Scalar::from_canonical_bytes(y_bytes_fixed),
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z_bytes.to_vec(),
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) {
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(Some(u), Some(y)) => Some(Tag { u, y, ciphertexts }),
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(Some(u), Some(y), z) => Some(Tag {
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u,
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y,
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z: z,
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ciphertexts,
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}),
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_ => None,
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};
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}
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@ -178,9 +186,10 @@ impl<const GAMMA: u8> Display for Tag<{ GAMMA }> {
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fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
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write!(
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f,
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"{} {} {}",
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"{} {} {} {}",
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hex::encode(self.u.compress().as_bytes()),
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hex::encode(self.y.as_bytes()),
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hex::encode(self.z.as_slice()),
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hex::encode(self.ciphertexts.to_bytes())
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)
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}
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@ -257,6 +266,25 @@ impl<const GAMMA: u8> RootSecret<{ GAMMA }> {
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TaggingKey::<GAMMA> { 0: tagging_key }
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}
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/// derive the tagging key for this secret
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/// Example:
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/// ```
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/// use fuzzytags::RootSecret;
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/// use rand::rngs::OsRng;
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/// let mut rng = OsRng;
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/// let secret = RootSecret::<24>::generate(&mut rng);
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/// let anti_key = secret.anti_key();
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/// ```
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pub fn anti_key(&self) -> TaggingKey<{ GAMMA }> {
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let g = RISTRETTO_BASEPOINT_POINT;
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let mut tagging_key = vec![];
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for sk_i in self.secret.iter() {
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let pk_i = g.mul(sk_i.invert());
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tagging_key.push(pk_i);
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}
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TaggingKey::<GAMMA> { 0: tagging_key }
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}
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/// precompute the first part of h
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fn pre_h(u: RistrettoPoint, w: RistrettoPoint) -> PrecomputeH {
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let mut hash = sha3::Sha3_256::new();
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@ -266,6 +294,11 @@ impl<const GAMMA: u8> RootSecret<{ GAMMA }> {
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return PrecomputeH(hash);
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}
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fn nonce_h(mut hash: PrecomputeH, nonce: u8) -> PrecomputeH {
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hash.0.update(vec![nonce]);
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hash
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}
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/// compute the rest of h from a precomputed hash
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fn post_h(mut hash: PrecomputeH, h: RistrettoPoint) -> u8 {
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hash.0.update(h.compress().as_bytes());
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@ -353,7 +386,9 @@ impl<const GAMMA: u8> DetectionKey<{ GAMMA }> {
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return false;
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}
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let m = RootSecret::<GAMMA>::g(tag.u, &tag.ciphertexts);
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let mut bitvec = BitVec::from_bytes(&*tag.z);
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bitvec.append(tag.ciphertexts.clone().borrow_mut());
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let m = RootSecret::<GAMMA>::g(tag.u, &bitvec);
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let g = RISTRETTO_BASEPOINT_POINT;
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// Re-derive w = g^z from the public tag.
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@ -370,9 +405,10 @@ impl<const GAMMA: u8> DetectionKey<{ GAMMA }> {
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// for each secret part...
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let mut result = 0;
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for (x_i, c_i) in self.0.iter().zip(&tag.ciphertexts) {
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for (nonce_i, (x_i, c_i)) in self.0.iter().zip(&tag.ciphertexts).enumerate() {
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// re-derive the key from the tag
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let k_i = RootSecret::<GAMMA>::post_h(pre_h.clone(), tag.u.mul(x_i));
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let nonce_h = RootSecret::<GAMMA>::nonce_h(pre_h.clone(), tag.z[nonce_i]);
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let k_i = RootSecret::<GAMMA>::post_h(nonce_h, tag.u.mul(x_i));
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// calculate the "original" plaintext
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let b_i = k_i ^ (c_i as u8);
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@ -418,7 +454,10 @@ impl<const GAMMA: u8> DetectionKey<{ GAMMA }> {
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return vec![];
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}
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let m = RootSecret::<GAMMA>::g(tag.u, &tag.ciphertexts);
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let mut bitvec = BitVec::from_bytes(&*tag.z);
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bitvec.append(tag.ciphertexts.clone().borrow_mut());
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let m = RootSecret::<GAMMA>::g(tag.u, &bitvec);
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let g = RISTRETTO_BASEPOINT_POINT;
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// Re-derive w = g^z from the public tag.
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@ -440,9 +479,10 @@ impl<const GAMMA: u8> DetectionKey<{ GAMMA }> {
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.enumerate()
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.for_each_with(tx.clone(), |tx, (index, detection_key)| {
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let mut result = 0;
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for (x_i, c_i) in detection_key.0.iter().zip(&tag.ciphertexts) {
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for (nonce_i, (x_i, c_i)) in detection_key.0.iter().zip(&tag.ciphertexts).enumerate() {
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// re-derive the key from the tag
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let k_i = RootSecret::<GAMMA>::post_h(pre_h.clone(), tag.u.mul(x_i));
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let nonce_h = RootSecret::<GAMMA>::nonce_h(pre_h.clone(), tag.z[nonce_i]);
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let k_i = RootSecret::<GAMMA>::post_h(nonce_h, tag.u.mul(x_i));
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// calculate the "original" plaintext
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let b_i = k_i ^ (c_i as u8);
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@ -516,8 +556,14 @@ impl<const GAMMA: u8> TaggingKey<{ GAMMA }> {
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// construct the ciphertext portion of the tag
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let mut ciphertexts = BitVec::with_capacity(GAMMA.into());
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for h_i in self.0.iter() {
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let k_i = RootSecret::<GAMMA>::post_h(pre_h.clone(), h_i.mul(r));
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let mut nonces = vec![];
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for _i in 0..GAMMA {
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nonces.push(rng.gen())
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}
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for (nonce_i, h_i) in self.0.iter().enumerate() {
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let nonce_h = RootSecret::<GAMMA>::nonce_h(pre_h.clone(), nonces[nonce_i]);
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let k_i = RootSecret::<GAMMA>::post_h(nonce_h, h_i.mul(r));
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// encrypt a plaintext of all 1's
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let c_i = k_i ^ 0x01;
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ciphertexts.push(c_i == 0x01);
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@ -538,10 +584,17 @@ impl<const GAMMA: u8> TaggingKey<{ GAMMA }> {
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// used to derive the key.
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// finally calculate a `y` = 1/r * (z-m) which will be used to re-derive `w`
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let m = RootSecret::<GAMMA>::g(u, &ciphertexts);
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let mut bitvec = BitVec::from_bytes(&*nonces);
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bitvec.append(ciphertexts.clone().borrow_mut());
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let m = RootSecret::<GAMMA>::g(u, &bitvec);
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let y = r.invert().mul(z.sub(m));
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return Tag { u, y, ciphertexts };
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return Tag {
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u,
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y,
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z: nonces,
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ciphertexts,
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};
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}
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#[cfg(feature = "entangled")]
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@ -578,23 +631,41 @@ impl<const GAMMA: u8> TaggingKey<{ GAMMA }> {
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tagging_key_precomputes.push(precompute);
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}
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let config = brute_force::Config::default();
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// generate some random points...
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let f = |z: &Scalar| {
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loop {
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let z = Scalar::random(rng);
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let w = g.mul(z);
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let pre_h = RootSecret::<GAMMA>::pre_h(u, w);
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let mut key = vec![];
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let mut nonces = vec![];
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for (i, precompute) in tagging_key_precomputes[0].iter().enumerate() {
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let k_i = RootSecret::<GAMMA>::post_h(pre_h.clone(), *precompute);
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for _nonce_attmepts in 0..=255 {
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let nonce: u8 = rng.gen();
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let mut success = true;
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let nonce_h = RootSecret::<GAMMA>::nonce_h(pre_h.clone(), nonce);
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let k_i = RootSecret::<GAMMA>::post_h(nonce_h.clone(), *precompute);
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if i < length {
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for precompute in tagging_key_precomputes.iter().skip(1) {
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let n_k_i = RootSecret::<GAMMA>::post_h(pre_h.clone(), precompute[i]);
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let n_k_i = RootSecret::<GAMMA>::post_h(nonce_h.clone(), precompute[i]);
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if k_i != n_k_i {
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return None;
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success = false;
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break;
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}
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}
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key.push(k_i)
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}
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if success {
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nonces.push(nonce);
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key.push(k_i);
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break;
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}
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}
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continue;
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}
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// generate the tag
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@ -606,11 +677,17 @@ impl<const GAMMA: u8> TaggingKey<{ GAMMA }> {
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}
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// This is the same as generate_tag, kept separate to avoid over-decomposition
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let m = RootSecret::<GAMMA>::g(u, &ciphertexts);
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let mut bitvec = BitVec::from_bytes(&*nonces);
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bitvec.append(ciphertexts.clone().borrow_mut());
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let m = RootSecret::<GAMMA>::g(u, &bitvec);
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let y = r.invert().mul(z.sub(m));
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return Some(Tag { u, y, ciphertexts });
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return Tag {
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u,
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y,
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z: nonces,
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ciphertexts,
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};
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brute_force(config, adaptors::auto_advance(f))
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}
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}
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}
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@ -697,7 +774,7 @@ mod tests {
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// it takes ~2 minutes on a standard desktop to find a length=24 match for 2 parties, so for testing let's keep things light
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let len = 16;
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let entangled_tag = TaggingKey::generate_entangled_tag(tagging_keys, &mut rng, len);
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println!("{}", entangled_tag);
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println!("entangled tag: {}", entangled_tag);
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for secret in secrets.iter() {
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let detection_key = secret.extract_detection_key(len);
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assert!(detection_key.test_tag(&entangled_tag));
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@ -710,26 +787,26 @@ mod tests {
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fn test_check_multiple() {
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use crate::TaggingKey;
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let mut rng = OsRng;
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let secrets: Vec<RootSecret<24>> = (0..2)
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let secrets: Vec<RootSecret<24>> = (0..5)
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.map(|_x| RootSecret::<24>::generate(&mut rng))
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.collect();
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let tagging_keys: Vec<TaggingKey<24>> = secrets.iter().map(|x| x.tagging_key()).collect();
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// it takes ~2 minutes on a standard desktop to find a length=24 match for 2 parties, so for testing let's keep things light
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let entangled_tag = TaggingKey::generate_entangled_tag(tagging_keys, &mut rng, 16);
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let entangled_tag = TaggingKey::generate_entangled_tag(tagging_keys, &mut rng, 24);
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let detection_keys = secrets
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.iter()
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.map(|x| x.extract_detection_key(16))
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.collect();
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let results = DetectionKey::test_tag_bulk(&detection_keys, &entangled_tag);
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assert_eq!(results.len(), 2);
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assert_eq!(results.len(), 5);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn correctness() {
|
||||
let number_of_messages = 100;
|
||||
let mut rng = OsRng;
|
||||
let secret = RootSecret::<16>::generate(&mut rng);
|
||||
let secret = RootSecret::<24>::generate(&mut rng);
|
||||
for i in 0..number_of_messages {
|
||||
let tag = secret.tagging_key().generate_tag(&mut rng);
|
||||
println!("{}: {}", i, tag);
|
||||
|
@ -741,6 +818,7 @@ mod tests {
|
|||
let tag = Tag {
|
||||
u: RistrettoPoint::default(),
|
||||
y: Scalar::default(),
|
||||
z: vec![],
|
||||
ciphertexts: BitVec::from_elem(24, false),
|
||||
};
|
||||
tag
|
||||
|
@ -750,6 +828,7 @@ mod tests {
|
|||
let mut tag = Tag {
|
||||
u: RistrettoPoint::default(),
|
||||
y: Scalar::default(),
|
||||
z: vec![],
|
||||
ciphertexts: BitVec::from_elem(24, false),
|
||||
};
|
||||
tag.ciphertexts.set_all();
|
||||
|
@ -798,21 +877,37 @@ mod tests {
|
|||
#[test]
|
||||
fn false_positives() {
|
||||
let mut rng = OsRng;
|
||||
let number_of_messages = 1000;
|
||||
let secret = RootSecret::<24>::generate(&mut rng);
|
||||
let number_of_reference_checks = 100;
|
||||
let number_of_messages = 100;
|
||||
let limit = 1;
|
||||
let mut false_positives = 0;
|
||||
let total_attempts = number_of_reference_checks * number_of_messages;
|
||||
|
||||
let secret = RootSecret::<24>::generate(&mut rng);
|
||||
for _i in 0..number_of_reference_checks {
|
||||
let secret = RootSecret::<24>::generate(&mut rng);
|
||||
for _i in 0..number_of_messages {
|
||||
let secret2 = RootSecret::<24>::generate(&mut rng);
|
||||
let tag = secret2.tagging_key().generate_tag(&mut rng);
|
||||
assert!(secret2.extract_detection_key(3).test_tag(&tag));
|
||||
if secret.extract_detection_key(3).test_tag(&tag) == true {
|
||||
assert!(secret2.extract_detection_key(limit).test_tag(&tag));
|
||||
if secret.extract_detection_key(limit).test_tag(&tag) == true {
|
||||
false_positives += 1;
|
||||
}
|
||||
}
|
||||
}
|
||||
println!(
|
||||
"Expected False Positive Rate: {}\nActual False Positive Rate: {}",
|
||||
secret.extract_detection_key(3).false_positive_probability(),
|
||||
(false_positives as f64 / number_of_messages as f64)
|
||||
secret
|
||||
.extract_detection_key(limit)
|
||||
.false_positive_probability(),
|
||||
(false_positives as f64 / (total_attempts) as f64)
|
||||
);
|
||||
assert!(
|
||||
secret
|
||||
.extract_detection_key(limit)
|
||||
.false_positive_probability()
|
||||
- (false_positives as f64 / (total_attempts) as f64)
|
||||
< 0.01
|
||||
);
|
||||
}
|
||||
}
|
||||
|
|
Loading…
Reference in New Issue