From 447e447377fe473aa1dc3e11a4df6f0f36851724 Mon Sep 17 00:00:00 2001
From: STEVAN Antoine <antoine.stevan@isae-supaero.fr>
Date: Fri, 7 Jun 2024 10:54:21 +0000
Subject: [PATCH] add "long full recoding" test (dragoon/komodo!147)
this will
- recode for $\#steps \in [10, 20, 100]$
- at $t = 0$, $k$ random shards among the $n$ encoded will be selected at random
- at $t \geq 1$, all $k$ shards will be used to recode $k$ brand new shards
- make sure the last set of $k$ shards recoded $\#steps$ together can decode the data
## example with $(k, n) = (3, 5)$ and $\#steps = 3$
- $(s_i)_{1 \leq i \leq k}$ are the $k$ source shards
- $(e_j)_{1 \leq j \leq n}$ are the $n$ encoded shards
- $(m_i)_{1 \leq i \leq k}$ are the $k$ randomly selected shards
- $(n_i)_{1 \leq i \leq k}$ are the shards after step $1$
- $(o_i)_{1 \leq i \leq k}$ are the shards after step $2$
- $(p_i)_{1 \leq i \leq k}$ are the shards after step $3$
- the $(p_i)_{1 \leq i \leq k}$ will be used for decoding
```mermaid
graph TD;
s1 --> e1; s1 --> e2; s1 --> e3; s1 --> e4; s1 --> e5;
s2 --> e1; s2 --> e2; s2 --> e3; s2 --> e4; s2 --> e5;
s3 --> e1; s3 --> e2; s3 --> e3; s3 --> e4; s3 --> e5;
e1 --> m1;
e3 --> m2;
e4 --> m3;
m1 --> n1; m1 --> n2; m1 --> n3;
m2 --> n1; m2 --> n2; m2 --> n3;
m3 --> n1; m3 --> n2; m3 --> n3;
n1 --> o1; n1 --> o2; n1 --> o3;
n2 --> o1; n2 --> o2; n2 --> o3;
n3 --> o1; n3 --> o2; n3 --> o3;
o1 --> p1; o1 --> p2; o1 --> p3;
o2 --> p1; o2 --> p2; o2 --> p3;
o3 --> p1; o3 --> p2; o3 --> p3;
```
---
src/fec.rs | 44 ++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 44 insertions(+)
diff --git a/src/fec.rs b/src/fec.rs
index a1fd2da6..cbbae67b 100644
--- a/src/fec.rs
+++ b/src/fec.rs
@@ -206,6 +206,7 @@ mod tests {
};
use itertools::Itertools;
+ use rand::seq::SliceRandom;
use super::recode_with_coeffs;
@@ -441,6 +442,49 @@ mod tests {
}
}
+ // (encode) | (select k) | (recode) | (decode)
+ // *
+ // * * * * ... * * \
+ // * ------> * ---------> * --> * ... * --> * |--> ?
+ // * * * * ... * * /
+ // * \__(#steps)_/
+ //
+ // k n k k k k
+ fn long_full_end_to_end_with_recoding_template<F: PrimeField>(
+ data: &[u8],
+ k: usize,
+ n: usize,
+ nb_steps: usize,
+ ) {
+ let mut rng = ark_std::test_rng();
+ let test_case = format!("TEST | data: {} bytes, k: {}, n: {}", data.len(), k, n,);
+
+ let mut shards = encode::<F>(data, &Matrix::random(k, n, &mut rng))
+ .unwrap_or_else(|_| panic!("could not encode {test_case}"));
+ shards.shuffle(&mut rng);
+ shards.truncate(k);
+
+ for _ in 0..nb_steps {
+ shards = (0..k)
+ .map(|_| recode_random(&shards, &mut rng).unwrap().unwrap())
+ .collect();
+ }
+
+ let actual = decode::<F>(shards).unwrap_or_else(|_| panic!("could not decode {test_case}"));
+ assert_eq!(data, actual, "bad decoded data with {test_case}",);
+ }
+
+ #[test]
+ fn long_full_end_to_end_with_recoding() {
+ let bytes = bytes();
+
+ for (k, n) in [(3, 5), (5, 5), (8, 10)] {
+ for nb_steps in [10, 20, 100] {
+ long_full_end_to_end_with_recoding_template::<Fr>(&bytes, k, n, nb_steps);
+ }
+ }
+ }
+
fn create_fake_shard<F: PrimeField>(linear_combination: &[F], bytes: &[u8]) -> Shard<F> {
Shard {
k: 2,
--
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