Performance Improvements #2

Merged
sarah merged 9 commits from perf into trunk 2021-05-22 19:51:46 +00:00
6 changed files with 276 additions and 134 deletions

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@ -1,7 +1,7 @@
[package]
name = "fuzzytags"
description = "a probabilistic cryptographic structure for metadata resistant tagging"
version = "0.4.2"
version = "0.5.0"
repository = "https://git.openprivacy.ca/openprivacy/fuzzytags"
authors = ["Sarah Jamie Lewis <sarah@openprivacy.ca>"]
edition = "2018"
@ -12,12 +12,13 @@ keywords = ["fuzzytags","privacy","metadata-resistance","ristretto","cryptograph
[dependencies]
hex = "0.4.2"
rand = "0.7.3"
curve25519-dalek = {version="3.0.0", features=["serde"]}
rand_core = "0.6.0"
rand ="0.8.3"
curve25519-dalek = { package = "curve25519-dalek-ng", version="4.0.1", features=["serde"]}
sha3 = "0.9.1"
serde = {version="1.0.123", features=["derive"]}
bit-vec = {version="0.6.3"}
brute-force = {version="0.1.0", features=["curve25519"], optional=true}
brute-force = {git="https://git.openprivacy.ca/sarah/brute-force.git", version="0.2.0", features=["curve25519"], optional=true}
rayon = {version="1.5.0", optional=true}
[dev-dependencies]
@ -29,6 +30,11 @@ bincode = "1.3.1"
name = "fuzzy_tags_benches"
harness = false
[[bench]]
name = "entangled"
harness = false
[features]
entangled = ["brute-force"]
bulk_verify = ["rayon"]
bulk_verify = ["rayon"]
simd = ["curve25519-dalek/simd_backend"]

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@ -88,7 +88,9 @@ provided them (depending on the efficiency of the decryption method).
A party first needs to generate `RootSecret`
use fuzzytags::RootSecret;
let secret = RootSecret::<24>::generate();
use rand::rngs::OsRng;
let mut rng = OsRng::default();
let secret = RootSecret::<24>::generate(&mut rng);
From the secret detection key a party can derive a `DetectionKey` which can be given to adversarial server to
fuzzily detect tags on behalf of the party.
@ -104,12 +106,14 @@ validate against a random public key with a maximum probability of _2^-gamma_.
Once in possession of a tagging key, a party in a metadata resistant app can use it to generate tags:
use fuzzytags::RootSecret;
let secret = RootSecret::<24>::generate();
use rand::rngs::OsRng;
let mut rng = OsRng::default();
let secret = RootSecret::<24>::generate(&mut rng);
let tagging_key = secret.tagging_key();
// Give public key to a another party...
// and then they can do...
let tag = tagging_key.generate_tag();
let tag = tagging_key.generate_tag(&mut rng);
These tags can then be attached to a message in a metadata resistant system.
@ -120,14 +124,16 @@ First it is necessary to extract a detection key for a given false positive prob
This extracted key can then be given to an adversarial server. The server can then test a given tag against the detection key e.g.:
use fuzzytags::RootSecret;
let secret = RootSecret::<24>::generate();
use rand::rngs::OsRng;
let mut rng = OsRng::default();
let secret = RootSecret::<24>::generate(&mut rng);
let tagging_key = secret.tagging_key();
// extract a detection key
let detection_key = secret.extract_detection_key(5);
// Give the tagging key to a another party...
// and then they can do...
let tag = tagging_key.generate_tag();
let tag = tagging_key.generate_tag(&mut rng);
// The server can now do this:
if detection_key.test_tag(&tag) {
@ -144,14 +150,16 @@ opens up applications like **multiple broadcast** and **deniable sending**.
use fuzzytags::{RootSecret, TaggingKey};
let secret_1 = RootSecret::<24>::generate();
let secret_2 = RootSecret::<24>::generate();
use rand::rngs::OsRng;
let mut rng = OsRng::default();
let secret_1 = RootSecret::<24>::generate(&mut rng);
let secret_2 = RootSecret::<24>::generate(&mut rng);
let tagging_key_1 = secret_1.tagging_key(); // give this to a sender
let tagging_key_2 = secret_2.tagging_key(); // give this to a sender
// Will validate for detection keys derived from both secret_1 and secret_2 up
// to n=8
#[cfg(feature = "entangled")]
let tag = TaggingKey::generate_entangled_tag(vec![tagging_key_1,tagging_key_2], 8);
let tag = TaggingKey::generate_entangled_tag(vec![tagging_key_1,tagging_key_2], &mut rng, 8);
## Serialization
@ -161,13 +169,15 @@ of different approaches e.g.:
use fuzzytags::RootSecret;
use fuzzytags::Tag;
use rand::rngs::OsRng;
let secret = RootSecret::<24>::generate();
let mut rng = OsRng::default();
let secret = RootSecret::<24>::generate(&mut rng);
let tagging_key = secret.tagging_key();
// Give public key to a another party...
// and then they can do...
let tag = tagging_key.generate_tag();
let tag = tagging_key.generate_tag(&mut rng);
// An example using JSON serialization...see serde doc for other formats:
let serialized_tag = serde_json::to_string(&tag).unwrap();
@ -183,6 +193,14 @@ We use [criterion](https://crates.io/crates/criterion) for benchmarking, and ben
Results will be in `target/criterion/report/index.html`.
### AVX2
This crate has support for the avx2 under the feature `simd`, to take advantage of this feature it is
necessary to build with `RUSTFLAGS="-C target_feature=+avx2"` e.g.
`env RUSTFLAGS="-C target_feature=+avx2" cargo test --release --features "bulk_verify,entangled,simd"`
This results in a 40%+ performance improvements on the provided benchmarks.
## Credits and Contributions

29
benches/entangled.rs Normal file
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@ -0,0 +1,29 @@
use criterion::{criterion_group, criterion_main, BenchmarkId, Criterion};
use fuzzytags::{RootSecret, TaggingKey};
use rand::rngs::OsRng;
use std::time::Duration;
fn benchmark_entangled(c: &mut Criterion) {
let mut group = c.benchmark_group("entangling");
group.measurement_time(Duration::new(10, 0));
group.sample_size(10);
let mut rng = OsRng::default();
for p in [24].iter() {
let secret_key_1 = RootSecret::<24>::generate(&mut rng);
let secret_key_2 = RootSecret::<24>::generate(&mut rng);
let public_key_1 = secret_key_1.tagging_key();
let public_key_2 = secret_key_2.tagging_key();
group.bench_with_input(BenchmarkId::from_parameter(p), p, |b, _gamma| {
b.iter(|| {
TaggingKey::generate_entangled_tag(
vec![public_key_1.clone(), public_key_2.clone()],
&mut rng,
*p,
)
})
});
}
}
criterion_group!(benches, benchmark_entangled);
criterion_main!(benches);

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@ -1,15 +1,19 @@
use criterion::{criterion_group, criterion_main, BenchmarkId, Criterion};
use fuzzytags::RootSecret;
use fuzzytags::{RootSecret, TaggingKey};
use rand::rngs::OsRng;
use std::time::Duration;
fn benchmark_generate_tag(c: &mut Criterion) {
let mut group = c.benchmark_group("generate_tags");
group.measurement_time(Duration::new(10, 0));
group.sample_size(1000);
let secret_key = RootSecret::<24>::generate();
let mut rng = OsRng::default();
let secret_key = RootSecret::<24>::generate(&mut rng);
let public_key = secret_key.tagging_key();
for p in [5, 10, 15].iter() {
let public_key = secret_key.tagging_key();
group.bench_with_input(BenchmarkId::from_parameter(p), p, |b, _gamma| b.iter(|| public_key.generate_tag()));
group.bench_with_input(BenchmarkId::from_parameter(p), p, |b, _gamma| {
b.iter(|| public_key.generate_tag(&mut rng))
});
}
}
@ -17,12 +21,16 @@ fn benchmark_test_tag(c: &mut Criterion) {
let mut group = c.benchmark_group("test_tags");
group.measurement_time(Duration::new(10, 0));
group.sample_size(1000);
let secret_key = RootSecret::<24>::generate();
let mut rng = OsRng::default();
for p in [5, 10, 15].iter() {
let tag = secret_key.tagging_key().generate_tag();
let secret_key = RootSecret::<24>::generate(&mut rng);
for p in [5, 10, 15, 24].iter() {
let detection_key = secret_key.extract_detection_key(*p);
group.bench_with_input(BenchmarkId::from_parameter(p), p, |b, _gamma| b.iter(|| detection_key.test_tag(&tag)));
group.bench_with_input(BenchmarkId::from_parameter(p), p, |b, _gamma| {
let tag = secret_key.tagging_key().generate_tag(&mut rng);
b.iter(|| detection_key.test_tag(&tag))
});
}
}

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@ -2,8 +2,15 @@ max_width = 200
hard_tabs = false
tab_spaces = 4
newline_style = "Auto"
use_small_heuristics = "Default"
indent_style = "Block"
use_small_heuristics = "Default"
fn_call_width = 60
attr_fn_like_width = 70
struct_lit_width = 18
struct_variant_width = 35
array_width = 60
chain_width = 60
single_line_if_else_max_width = 50
wrap_comments = false
format_code_in_doc_comments = false
comment_width = 80
@ -54,7 +61,7 @@ use_field_init_shorthand = false
force_explicit_abi = true
condense_wildcard_suffixes = false
color = "Auto"
required_version = "1.4.34"
required_version = "1.4.37"
unstable_features = false
disable_all_formatting = false
skip_children = false

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@ -1,6 +1,5 @@
#![deny(missing_docs)]
#![feature(external_doc)]
#![feature(const_generics)]
#![doc(include = "../README.md")]
#![doc(include = "../ANONYMITY.md")]
#![doc(html_logo_url = "https://git.openprivacy.ca/openprivacy/fuzzytags/media/branch/trunk/FuzzyTags_Logo.png")]
@ -10,9 +9,8 @@ use curve25519_dalek::digest::Digest;
use curve25519_dalek::ristretto::{CompressedRistretto, RistrettoPoint};
use curve25519_dalek::scalar::Scalar;
use curve25519_dalek::traits::MultiscalarMul;
use rand::rngs::OsRng;
use serde::{de::Visitor, Deserialize, Deserializer, Serialize, Serializer};
use sha3::Sha3_512;
use sha3::{Sha3_256, Sha3_512};
use std::convert::TryFrom;
use std::fmt;
use std::fmt::{Display, Formatter};
@ -23,6 +21,7 @@ use brute_force::adaptors;
#[cfg(feature = "entangled")]
use brute_force::brute_force;
use rand_core::{CryptoRng, RngCore};
#[cfg(feature = "bulk_verify")]
use rayon::iter::IndexedParallelIterator;
#[cfg(feature = "bulk_verify")]
@ -81,7 +80,10 @@ impl<'de, const GAMMA: u8> Deserialize<'de> for Tag<{ GAMMA }> {
{
let mut bytes = vec![];
for i in 0..64 {
bytes.push(seq.next_element()?.ok_or(serde::de::Error::invalid_length(i, &"expected at least 64 bytes"))?);
bytes.push(seq.next_element()?.ok_or(serde::de::Error::invalid_length(
i,
&"expected at least 64 bytes",
))?);
}
loop {
match seq.next_element().unwrap_or(None) {
@ -104,15 +106,17 @@ impl<const GAMMA: u8> Tag<{ GAMMA }> {
/// Ciphertext is right-padded with zeros to the nearest byte
/// You probably want to use one of the many serde `serialize` apis instead (see README)
/// ```
/// use rand::rngs::OsRng;
/// use fuzzytags::RootSecret;
/// let secret = RootSecret::<24>::generate();
/// let mut rng = OsRng;
/// let secret = RootSecret::<24>::generate(&mut rng);
/// let tagging_key = secret.tagging_key();
/// // extract a detection key
/// let detection_key = secret.extract_detection_key(5);
///
/// // Give tagging key to a another party...
/// // and then they can do...
/// let tag = tagging_key.generate_tag();
/// let tag = tagging_key.generate_tag(&mut rng);
/// let compressed_tag = tag.compress();
/// ```
pub fn compress(&self) -> Vec<u8> {
@ -127,14 +131,16 @@ impl<const GAMMA: u8> Tag<{ GAMMA }> {
/// You probably want to use one of the many serde `deserialize` apis instead (see README)
/// ```
/// use fuzzytags::{RootSecret, Tag};
/// let secret = RootSecret::<24>::generate();
/// use rand::rngs::OsRng;
/// let mut rng = OsRng;
/// let secret = RootSecret::<24>::generate(&mut rng);
/// let tagging_key = secret.tagging_key();
/// // extract a detection key
/// let detection_key = secret.extract_detection_key(5);
///
/// // Give tagging key to a another party...
/// // and then they can do...
/// let tag = tagging_key.generate_tag();
/// let tag = tagging_key.generate_tag(&mut rng);
/// let compressed_tag = tag.compress();
/// let decompressed_tag = Tag::decompress(&compressed_tag).unwrap();
/// assert_eq!(tag, decompressed_tag);
@ -157,7 +163,10 @@ impl<const GAMMA: u8> Tag<{ GAMMA }> {
};
let mut ciphertexts = BitVec::from_bytes(ciphertext);
ciphertexts.truncate(GAMMA as usize);
return match (CompressedRistretto::from_slice(u_bytes).decompress(), Scalar::from_canonical_bytes(y_bytes_fixed)) {
return match (
CompressedRistretto::from_slice(u_bytes).decompress(),
Scalar::from_canonical_bytes(y_bytes_fixed),
) {
(Some(u), Some(y)) => Some(Tag { u, y, ciphertexts }),
_ => None,
};
@ -178,6 +187,12 @@ impl<const GAMMA: u8> Display for Tag<{ GAMMA }> {
}
}
/// PrecomputeH is an encapsulation around the precomputation of the H function which
/// significantly speeds up testing. We define it for some additional type safety (to
/// prevent us from passing an uninitialized hash function to post_h
#[derive(Clone)]
struct PrecomputeH(Sha3_256);
/// The complete secret. Can't directly be used for testing. Instead you will need to generate
/// a DetectionKey using `extract_detection_key`
#[derive(Serialize, Deserialize)]
@ -194,16 +209,17 @@ impl<const GAMMA: u8> RootSecret<{ GAMMA }> {
/// Example:
/// ```
/// use fuzzytags::{RootSecret};
/// let secret = RootSecret::<24>::generate();
/// use rand::rngs::OsRng;
/// let mut rng = OsRng;
/// let secret = RootSecret::<24>::generate(&mut rng);
/// ```
pub fn generate() -> RootSecret<{ GAMMA }> {
let mut rng = OsRng::default();
pub fn generate<R: RngCore + CryptoRng>(rng: &mut R) -> RootSecret<{ GAMMA }> {
let mut secret = vec![];
for _i in 0..GAMMA {
let sk_i = Scalar::random(&mut rng);
let sk_i = Scalar::random(rng);
secret.push(sk_i);
}
RootSecret::<GAMMA> { secret: secret }
RootSecret::<GAMMA> { secret }
}
/// extract a detection key for a given false positive (p = 2^-n)
@ -213,7 +229,9 @@ impl<const GAMMA: u8> RootSecret<{ GAMMA }> {
/// Example:
/// ```
/// use fuzzytags::{RootSecret};
/// let secret = RootSecret::<24>::generate();
/// use rand::rngs::OsRng;
/// let mut rng = OsRng;
/// let secret = RootSecret::<24>::generate(&mut rng);
/// let detection_key = secret.extract_detection_key(2);
/// ```
pub fn extract_detection_key(&self, n: usize) -> DetectionKey<{ GAMMA }> {
@ -225,7 +243,9 @@ impl<const GAMMA: u8> RootSecret<{ GAMMA }> {
/// Example:
/// ```
/// use fuzzytags::RootSecret;
/// let secret = RootSecret::<24>::generate();
/// use rand::rngs::OsRng;
/// let mut rng = OsRng;
/// let secret = RootSecret::<24>::generate(&mut rng);
/// let tagging_key = secret.tagging_key();
/// ```
pub fn tagging_key(&self) -> TaggingKey<{ GAMMA }> {
@ -238,14 +258,19 @@ impl<const GAMMA: u8> RootSecret<{ GAMMA }> {
TaggingKey::<GAMMA> { 0: tagging_key }
}
/// a hash function that takes 3 ristretto points as a parameter and outputs 0 or 1.
fn h(u: RistrettoPoint, h: RistrettoPoint, w: RistrettoPoint) -> u8 {
/// precompute the first part of h
fn pre_h(u: RistrettoPoint, w: RistrettoPoint) -> PrecomputeH {
let mut hash = sha3::Sha3_256::new();
hash.update(&[GAMMA]);
hash.update(u.compress().as_bytes());
hash.update(h.compress().as_bytes());
hash.update(w.compress().as_bytes());
return hash.finalize().as_slice()[0] & 0x01;
return PrecomputeH(hash);
}
/// compute the rest of h from a precomputed hash
fn post_h(mut hash: PrecomputeH, h: RistrettoPoint) -> u8 {
hash.0.update(h.compress().as_bytes());
return hash.0.finalize().as_slice()[0] & 0x01;
}
/// a hash function which takes a ristretto point and a vector of ciphertexts and outputs a
@ -286,7 +311,9 @@ impl<const GAMMA: u8> DetectionKey<{ GAMMA }> {
/// calculate the ideal false positive rate of this detection key
/// ```
/// use fuzzytags::RootSecret;
/// let secret = RootSecret::<24>::generate();
/// use rand::rngs::OsRng;
/// let mut rng = OsRng;
/// let secret = RootSecret::<24>::generate(&mut rng);
/// let tagging_key = secret.tagging_key();
/// // extract a detection key
/// let detection_key = secret.extract_detection_key(5);
@ -300,14 +327,16 @@ impl<const GAMMA: u8> DetectionKey<{ GAMMA }> {
/// Example:
/// ```
/// use fuzzytags::RootSecret;
/// let secret = RootSecret::<24>::generate();
/// use rand::rngs::OsRng;
/// let mut rng = OsRng;
/// let secret = RootSecret::<24>::generate(&mut rng);
/// let tagging_key = secret.tagging_key();
/// // extract a detection key
/// let detection_key = secret.extract_detection_key(5);
///
/// // Give tagging key to a another party...
/// // and then they can do...
/// let tag = tagging_key.generate_tag();
/// let tag = tagging_key.generate_tag(&mut rng);
///
/// // The server can now do this:
/// if detection_key.test_tag(&tag) {
@ -338,30 +367,28 @@ impl<const GAMMA: u8> DetectionKey<{ GAMMA }> {
// See below for a full explanation as to the reason for this:
let w = RistrettoPoint::multiscalar_mul(&[m, tag.y], &[g, tag.u]);
let pre_h = RootSecret::<GAMMA>::pre_h(tag.u, w);
// for each secret part...
let mut result = true;
for (i, x_i) in self.0.iter().enumerate() {
let mut result = 0;
for (x_i, c_i) in self.0.iter().zip(&tag.ciphertexts) {
// re-derive the key from the tag
let k_i = RootSecret::<GAMMA>::h(tag.u, tag.u.mul(x_i), w);
let k_i = RootSecret::<GAMMA>::post_h(pre_h.clone(), tag.u.mul(x_i));
// calculate the "original" plaintext
let c_i = match tag.ciphertexts.get(i) {
Some(true) => 0x01,
Some(false) => 0x00,
_ => 0x00,
// we've run out of ciphertext, it doesn't really matter what we put here, the rest of the test will fail
// since the security of k_i is modelled as a random oracle, (k_i ^ 0) should also be random
};
let b_i = k_i ^ c_i;
if b_i != 1 {
let b_i = k_i ^ (c_i as u8);
// short circuit
if b_i != 0x01 {
return false;
}
// assert that the plaintext is all 1's
result = result & (b_i == 1);
result += 1;
}
return result;
// Assert that number of sequential ones is equal to the length of the detection key
// If it isn't it indicates that the tag ciphertext is shorter than the verification key,
// Given the checks on deserialization that should never happen, but we throw in a check
// here anyway for defense in depth.
return result == self.0.len();
}
/// A bulk testing function that takes in an vector of detection keys and returns a vector
@ -371,10 +398,12 @@ impl<const GAMMA: u8> DetectionKey<{ GAMMA }> {
/// ```
/// use fuzzytags::{TaggingKey, DetectionKey};
/// use fuzzytags::RootSecret;
/// let secrets: Vec<RootSecret<24>> = (0..2).map(|_x| RootSecret::<24>::generate()).collect();
/// use rand::rngs::OsRng;
/// let mut rng = OsRng;
/// let secrets: Vec<RootSecret<24>> = (0..2).map(|_x| RootSecret::<24>::generate(&mut rng)).collect();
/// let tagging_keys: Vec<TaggingKey<24>> = secrets.iter().map(|x| x.tagging_key()).collect();
/// // it takes ~15 minutes on a standard desktop to find a length=24 match for 2 parties, so for testing let's keep things light
/// let entangled_tag = TaggingKey::generate_entangled_tag(tagging_keys, 16);
/// let entangled_tag = TaggingKey::generate_entangled_tag(tagging_keys, &mut rng, 16);
/// let detection_keys = secrets.iter().map(|x| x.extract_detection_key(16)).collect();
///
/// let results = DetectionKey::test_tag_bulk(&detection_keys, &entangled_tag);
@ -403,41 +432,36 @@ impl<const GAMMA: u8> DetectionKey<{ GAMMA }> {
// See below for a full explanation as to the reason for this:
let w = RistrettoPoint::multiscalar_mul(&[m, tag.y], &[g, tag.u]);
let (tx, rx) = channel();
let pre_h = RootSecret::<GAMMA>::pre_h(tag.u, w);
// for each secret part...
let mut results: Vec<usize> = vec![];
detection_keys.par_iter().enumerate().for_each_with(tx.clone(), |tx, (index, detection_key)| {
let mut result = true;
for (i, x_i) in detection_key.0.iter().enumerate() {
// re-derive the key from the tag
let k_i = RootSecret::<GAMMA>::h(tag.u, tag.u.mul(x_i), w);
detection_keys
.par_iter()
.enumerate()
.for_each_with(tx.clone(), |tx, (index, detection_key)| {
let mut result = 0;
for (x_i, c_i) in detection_key.0.iter().zip(&tag.ciphertexts) {
// re-derive the key from the tag
let k_i = RootSecret::<GAMMA>::post_h(pre_h.clone(), tag.u.mul(x_i));
// calculate the "original" plaintext
let c_i = match tag.ciphertexts.get(i) {
Some(true) => 0x01,
Some(false) => 0x00,
_ => 0x00,
// we've run out of ciphertext, it doesn't really matter what we put here, the rest of the test will fail
// since the security of k_i is modelled as a random oracle, (k_i ^ 0) should also be random
};
// calculate the "original" plaintext
let b_i = k_i ^ (c_i as u8);
let b_i = k_i ^ c_i;
if b_i != 1 {
result = false;
break;
if b_i != 1 {
break;
}
// assert that the plaintext is all 1's
result += 1;
}
// assert that the plaintext is all 1's
result = result & (b_i == 1);
}
if result {
match tx.send(index) {
_ => {
// TODO...surface this error...
if result == detection_key.0.len() {
match tx.send(index) {
_ => {
// TODO...surface this error...
}
}
}
}
});
});
std::mem::drop(tx);
loop {
@ -473,24 +497,28 @@ impl<const GAMMA: u8> TaggingKey<{ GAMMA }> {
/// Example:
/// ```
/// use fuzzytags::{RootSecret};
/// let secret = RootSecret::<24>::generate();
/// use rand::rngs::OsRng;
/// let mut rng = OsRng;
/// let secret = RootSecret::<24>::generate(&mut rng);
/// let tagging_key = secret.tagging_key(); // give this to a sender
/// let tag = tagging_key.generate_tag();
/// let tag = tagging_key.generate_tag(&mut rng);
/// ```
pub fn generate_tag(&self) -> Tag<{ GAMMA }> {
let mut rng = OsRng::default();
let g = RISTRETTO_BASEPOINT_POINT;
pub fn generate_tag<R: RngCore + CryptoRng>(&self, rng: &mut R) -> Tag<{ GAMMA }> {
// generate some random points...
let r = Scalar::random(&mut rng);
let u = g.mul(r);
let z = Scalar::random(&mut rng);
let w = g.mul(z);
let r = Scalar::random(rng);
let u = RISTRETTO_BASEPOINT_POINT.mul(r);
let z = Scalar::random(rng);
let w = RISTRETTO_BASEPOINT_POINT.mul(z);
// precompute the first part of the `H` hash function
let pre_h = RootSecret::<GAMMA>::pre_h(u, w);
// construct the ciphertext portion of the tag
let mut ciphertexts = BitVec::new();
for (_i, h_i) in self.0.iter().enumerate() {
let k_i = RootSecret::<GAMMA>::h(u, h_i.mul(r), w);
let mut ciphertexts = BitVec::with_capacity(GAMMA.into());
for h_i in self.0.iter() {
let k_i = RootSecret::<GAMMA>::post_h(pre_h.clone(), h_i.mul(r));
// encrypt a plaintext of all 1's
let c_i = k_i ^ 0x01;
ciphertexts.push(c_i == 0x01);
@ -524,20 +552,21 @@ impl<const GAMMA: u8> TaggingKey<{ GAMMA }> {
/// Example:
/// ```
/// use fuzzytags::{RootSecret, TaggingKey};
/// let secret_1 = RootSecret::<24>::generate();
/// let secret_2 = RootSecret::<24>::generate();
/// use rand::rngs::OsRng;
/// let mut rng = OsRng;
/// let secret_1 = RootSecret::<24>::generate(&mut rng);
/// let secret_2 = RootSecret::<24>::generate(&mut rng);
/// let tagging_key_1 = secret_1.tagging_key(); // give this to a sender
/// let tagging_key_2 = secret_2.tagging_key(); // give this to a sender
/// // Will validate for detection keys derived from both secret_1 and secret_2 up
/// // to n=8
/// // Sender can now do...tag will validate on detection keys of length 8 or lower.
/// let tag = TaggingKey::generate_entangled_tag(vec![tagging_key_1,tagging_key_2], 8);
/// let tag = TaggingKey::generate_entangled_tag(vec![tagging_key_1,tagging_key_2], &mut rng, 8);
/// ```
pub fn generate_entangled_tag(tagging_keys: Vec<TaggingKey<{ GAMMA }>>, length: usize) -> Tag<{ GAMMA }> {
let mut rng = OsRng::default();
pub fn generate_entangled_tag<R: RngCore + CryptoRng>(tagging_keys: Vec<TaggingKey<{ GAMMA }>>, rng: &mut R, length: usize) -> Tag<{ GAMMA }> {
let g = RISTRETTO_BASEPOINT_POINT;
// generate some random points...
let r = Scalar::random(&mut rng);
let r = Scalar::random(rng);
let u = g.mul(r);
// Compute and cache some public points that we will be using over and over again
@ -551,14 +580,16 @@ impl<const GAMMA: u8> TaggingKey<{ GAMMA }> {
}
let config = brute_force::Config::default();
let f = |z: &Scalar| {
let w = g.mul(z);
let pre_h = RootSecret::<GAMMA>::pre_h(u, w);
let mut key = vec![];
for (i, precompute) in tagging_key_precomputes[0].iter().enumerate() {
let k_i = RootSecret::<GAMMA>::h(u, *precompute, w);
let k_i = RootSecret::<GAMMA>::post_h(pre_h.clone(), *precompute);
if i < length {
for precompute in tagging_key_precomputes.iter().skip(1) {
let n_k_i = RootSecret::<GAMMA>::h(u, precompute[i], w);
let n_k_i = RootSecret::<GAMMA>::post_h(pre_h.clone(), precompute[i]);
if k_i != n_k_i {
return None;
}
@ -590,15 +621,18 @@ mod tests {
use bit_vec::BitVec;
use curve25519_dalek::ristretto::RistrettoPoint;
use curve25519_dalek::scalar::Scalar;
use rand::rngs::OsRng;
use sha3::Digest;
#[test]
fn test_compression() {
let secret = RootSecret::<24>::generate();
let mut rng = OsRng;
let secret = RootSecret::<24>::generate(&mut rng);
let tagging_key = secret.tagging_key();
// Give tagging key to a another party...
// and then they can do...
let tag = tagging_key.generate_tag();
let tag = tagging_key.generate_tag(&mut rng);
let compressed_tag = tag.compress();
let decompressed_tag = Tag::<24>::decompress(&compressed_tag).unwrap();
assert_eq!(tag, decompressed_tag);
@ -607,8 +641,9 @@ mod tests {
#[test]
fn test_serialization() {
// generate some new keys...
let secret = RootSecret::<15>::generate();
let tag = secret.tagging_key().generate_tag();
let mut rng = OsRng;
let secret = RootSecret::<15>::generate(&mut rng);
let tag = secret.tagging_key().generate_tag(&mut rng);
let detection_key = secret.extract_detection_key(10);
let serialized_tag = serde_json::to_string(&tag).unwrap();
println!("{}", serialized_tag);
@ -617,8 +652,8 @@ mod tests {
assert_eq!(true, detection_key.test_tag(&deserialized_tag));
// generate some new keys...
let secret = RootSecret::<24>::generate();
let tag = secret.tagging_key().generate_tag();
let secret = RootSecret::<24>::generate(&mut rng);
let tag = secret.tagging_key().generate_tag(&mut rng);
let detection_key = secret.extract_detection_key(10);
let serialized_tag = serde_json::to_string(&tag).unwrap();
let deserialized_tag: Tag<24> = serde_json::from_str(&serialized_tag).unwrap();
@ -654,13 +689,18 @@ mod tests {
#[cfg(feature = "entangled")]
fn test_multiple() {
use crate::TaggingKey;
let secrets: Vec<RootSecret<24>> = (0..2).map(|_x| RootSecret::<24>::generate()).collect();
let mut rng = OsRng;
let secrets: Vec<RootSecret<24>> = (0..2)
.map(|_x| RootSecret::<24>::generate(&mut rng))
.collect();
let tagging_keys: Vec<TaggingKey<24>> = secrets.iter().map(|x| x.tagging_key()).collect();
// it takes ~15 minutes on a standard desktop to find a length=24 match for 2 parties, so for testing let's keep things light
let entangled_tag = TaggingKey::generate_entangled_tag(tagging_keys, 16);
// 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
let len = 16;
let entangled_tag = TaggingKey::generate_entangled_tag(tagging_keys, &mut rng, len);
println!("{}", entangled_tag);
for secret in secrets.iter() {
let detection_key = secret.extract_detection_key(16);
let detection_key = secret.extract_detection_key(len);
assert!(detection_key.test_tag(&entangled_tag));
println!("{}", detection_key);
}
@ -670,11 +710,17 @@ mod tests {
#[cfg(feature = "bulk_verify")]
fn test_check_multiple() {
use crate::TaggingKey;
let secrets: Vec<RootSecret<24>> = (0..2).map(|_x| RootSecret::<24>::generate()).collect();
let mut rng = OsRng;
let secrets: Vec<RootSecret<24>> = (0..2)
.map(|_x| RootSecret::<24>::generate(&mut rng))
.collect();
let tagging_keys: Vec<TaggingKey<24>> = secrets.iter().map(|x| x.tagging_key()).collect();
// it takes ~15 minutes on a standard desktop to find a length=24 match for 2 parties, so for testing let's keep things light
let entangled_tag = TaggingKey::generate_entangled_tag(tagging_keys, 16);
let detection_keys = secrets.iter().map(|x| x.extract_detection_key(16)).collect();
// 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
let entangled_tag = TaggingKey::generate_entangled_tag(tagging_keys, &mut rng, 16);
let detection_keys = secrets
.iter()
.map(|x| x.extract_detection_key(16))
.collect();
let results = DetectionKey::test_tag_bulk(&detection_keys, &entangled_tag);
assert_eq!(results.len(), 2);
@ -683,9 +729,10 @@ mod tests {
#[test]
fn correctness() {
let number_of_messages = 100;
let secret = RootSecret::<16>::generate();
let mut rng = OsRng;
let secret = RootSecret::<16>::generate(&mut rng);
for i in 0..number_of_messages {
let tag = secret.tagging_key().generate_tag();
let tag = secret.tagging_key().generate_tag(&mut rng);
println!("{}: {}", i, tag);
assert!(secret.extract_detection_key(5).test_tag(&tag));
}
@ -710,13 +757,39 @@ mod tests {
tag
}
/// a hash function that takes 3 ristretto points as a parameter and outputs 0 or 1.
fn h(u: RistrettoPoint, h: RistrettoPoint, w: RistrettoPoint) -> u8 {
let mut hash = sha3::Sha3_256::new();
hash.update(&[24]);
hash.update(u.compress().as_bytes());
hash.update(w.compress().as_bytes());
hash.update(h.compress().as_bytes());
return hash.finalize().as_slice()[0] & 0x01;
}
#[test]
fn assert_h_and_pre_post_h() {
let mut rng = OsRng;
for _ in 0..100 {
let a = RistrettoPoint::random(&mut rng);
let b = RistrettoPoint::random(&mut rng);
let c = RistrettoPoint::random(&mut rng);
assert_eq!(
RootSecret::<24>::post_h(RootSecret::<24>::pre_h(a, b), c),
h(a, c, b)
);
}
}
#[test]
// Thanks to Lee Bousfield who noticed an all zeros or all ones tag would
// validate against a tagging key with 50% probability, allowing universal
// broadcast, which overall seems like a bad idea...
// Test to make sure that doesn't happen.
fn test_zero_tag() {
let secret = RootSecret::<24>::generate();
let mut rng = OsRng;
let secret = RootSecret::<24>::generate(&mut rng);
let tag = gen_zero_tag_zero();
assert_eq!(false, secret.extract_detection_key(6).test_tag(&tag));
let tag = gen_zero_tag_one();
@ -725,12 +798,13 @@ mod tests {
#[test]
fn false_positives() {
let mut rng = OsRng;
let number_of_messages = 1000;
let secret = RootSecret::<24>::generate();
let secret = RootSecret::<24>::generate(&mut rng);
let mut false_positives = 0;
for _i in 0..number_of_messages {
let secret2 = RootSecret::<24>::generate();
let tag = secret2.tagging_key().generate_tag();
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 {
false_positives += 1;