Performance improvement during testing.
By splitting up the hash function H(U, x_iU, W) we can precompute the application of U and W, and only apply x_iU during the main detection key loop. Saving about 9.6% of the overall time.
This commit is contained in:
parent
931ca3050a
commit
33f2fa9a88
|
@ -9,7 +9,9 @@ fn benchmark_generate_tag(c: &mut Criterion) {
|
|||
let secret_key = RootSecret::<24>::generate();
|
||||
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())
|
||||
});
|
||||
}
|
||||
}
|
||||
|
||||
|
@ -22,7 +24,9 @@ fn benchmark_test_tag(c: &mut Criterion) {
|
|||
for p in [5, 10, 15].iter() {
|
||||
let tag = secret_key.tagging_key().generate_tag();
|
||||
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| {
|
||||
b.iter(|| detection_key.test_tag(&tag))
|
||||
});
|
||||
}
|
||||
}
|
||||
|
||||
|
|
11
rustfmt.toml
11
rustfmt.toml
|
@ -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
|
||||
|
|
102
src/lib.rs
102
src/lib.rs
|
@ -12,7 +12,7 @@ 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};
|
||||
|
@ -32,6 +32,13 @@ use rayon::iter::ParallelIterator;
|
|||
#[cfg(feature = "bulk_verify")]
|
||||
use std::sync::mpsc::channel;
|
||||
|
||||
#[cfg(feature = "encrypt_to_tag")]
|
||||
use secretbox::CipherType::Salsa20;
|
||||
#[cfg(feature = "encrypt_to_tag")]
|
||||
use secretbox::SecretBox;
|
||||
#[cfg(feature = "encrypt_to_tag")]
|
||||
use std::string::FromUtf8Error;
|
||||
|
||||
/// A tag is a probabilistic cryptographic structure. When constructed for a given `TaggingKey`
|
||||
/// it will pass the `DetectionKey::test_tag` 100% of the time. For other tagging keys
|
||||
/// it will pass the test with probability `GAMMA` related to the security parameter of the system.
|
||||
|
@ -81,7 +88,10 @@ 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) {
|
||||
|
@ -157,7 +167,10 @@ 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 +191,12 @@ 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)]
|
||||
|
@ -203,7 +222,7 @@ impl<const GAMMA: u8> RootSecret<{ GAMMA }> {
|
|||
let sk_i = Scalar::random(&mut rng);
|
||||
secret.push(sk_i);
|
||||
}
|
||||
RootSecret::<GAMMA> { secret: secret }
|
||||
RootSecret::<GAMMA> { secret }
|
||||
}
|
||||
|
||||
/// extract a detection key for a given false positive (p = 2^-n)
|
||||
|
@ -238,13 +257,28 @@ impl<const GAMMA: u8> RootSecret<{ GAMMA }> {
|
|||
TaggingKey::<GAMMA> { 0: tagging_key }
|
||||
}
|
||||
|
||||
/// 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(w.compress().as_bytes());
|
||||
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 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(&[GAMMA]);
|
||||
hash.update(u.compress().as_bytes());
|
||||
hash.update(h.compress().as_bytes());
|
||||
hash.update(w.compress().as_bytes());
|
||||
hash.update(h.compress().as_bytes());
|
||||
return hash.finalize().as_slice()[0] & 0x01;
|
||||
}
|
||||
|
||||
|
@ -338,30 +372,28 @@ 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
|
||||
|
@ -406,7 +438,10 @@ impl<const GAMMA: u8> DetectionKey<{ GAMMA }> {
|
|||
|
||||
// for each secret part...
|
||||
let mut results: Vec<usize> = vec![];
|
||||
detection_keys.par_iter().enumerate().for_each_with(tx.clone(), |tx, (index, detection_key)| {
|
||||
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
|
||||
|
@ -586,10 +621,11 @@ impl<const GAMMA: u8> TaggingKey<{ GAMMA }> {
|
|||
|
||||
#[cfg(test)]
|
||||
mod tests {
|
||||
use crate::{DetectionKey, RootSecret, Tag};
|
||||
use crate::{RootSecret, Tag};
|
||||
use bit_vec::BitVec;
|
||||
use curve25519_dalek::ristretto::RistrettoPoint;
|
||||
use curve25519_dalek::scalar::Scalar;
|
||||
use rand::rngs::OsRng;
|
||||
|
||||
#[test]
|
||||
fn test_compression() {
|
||||
|
@ -674,7 +710,10 @@ mod tests {
|
|||
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();
|
||||
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);
|
||||
|
@ -710,6 +749,21 @@ mod tests {
|
|||
tag
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn assert_h_and_pre_post_h() {
|
||||
let mut rng = OsRng::default();
|
||||
|
||||
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),
|
||||
RootSecret::<24>::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
|
||||
|
|
Loading…
Reference in New Issue