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Update test vectors and fix test
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I was using the wrong seed; we now get it from the test vectors.

Source: https://github.com/zcash/zcash-test-vectors
Revision: 4505cb843828209c0038cb83075ccbde818e9c34
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@str4d
str4d committed Nov 13, 2024
1 parent 4d72c47 commit 4d4b38c
Showing 1 changed file with 91 additions and 16 deletions.
107 changes: 91 additions & 16 deletions src/arbitrary.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -33,6 +33,22 @@ pub struct SecretKey {
inner: HardenedOnlyKey<Arbitrary>,
}

fn with_ikm<F, T>(context_string: &[u8], seed: &[u8], f: F) -> T
where
F: FnOnce(&[&[u8]]) -> T,
{
let context_len =
u8::try_from(context_string.len()).expect("context string should be at most 252 bytes");
assert!((1..=252).contains(&context_len));

let seed_len = u8::try_from(seed.len()).expect("seed should be at most 252 bytes");
assert!((32..=252).contains(&seed_len));

let ikm = &[&[context_len], context_string, &[seed_len], seed];

f(ikm)
}

impl SecretKey {
/// Derives an arbitrary key at the given path from the given seed.
///
Expand Down Expand Up @@ -64,18 +80,9 @@ impl SecretKey {
/// - the context string is empty or longer than 252 bytes.
/// - the seed is shorter than 32 bytes or longer than 252 bytes.
fn master(context_string: &[u8], seed: &[u8]) -> Self {
let context_len =
u8::try_from(context_string.len()).expect("context string should be at most 252 bytes");
assert!((1..=252).contains(&context_len));

let seed_len = u8::try_from(seed.len()).expect("seed should be at most 252 bytes");
assert!((32..=252).contains(&seed_len));

let ikm = &[&[context_len], context_string, &[seed_len], seed];

Self {
with_ikm(context_string, seed, |ikm| Self {
inner: HardenedOnlyKey::master(ikm),
}
})
}

/// Derives a child key from a parent key at a given index.
Expand Down Expand Up @@ -120,18 +127,38 @@ impl SecretKey {

#[cfg(test)]
mod tests {
use crate::ChildIndex;
use crate::{arbitrary::with_ikm, ChildIndex};

use super::SecretKey;

struct TestVector {
context_string: &'static [u8],
seed: [u8; 32],
ikm: Option<&'static [u8]>,
path: &'static [u32],
sk: [u8; 32],
c: [u8; 32],
}

// From https://github.com/zcash-hackworks/zcash-test-vectors/blob/master/zip_0032_arbitrary.py
const TEST_VECTORS: &'static [TestVector] = &[
TestVector {
context_string: &[
0x5a, 0x63, 0x61, 0x73, 0x68, 0x20, 0x74, 0x65, 0x73, 0x74, 0x20, 0x76, 0x65, 0x63,
0x74, 0x6f, 0x72, 0x73,
],
seed: [
0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d,
0x0e, 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b,
0x1c, 0x1d, 0x1e, 0x1f,
],
ikm: Some(&[
0x12, 0x5a, 0x63, 0x61, 0x73, 0x68, 0x20, 0x74, 0x65, 0x73, 0x74, 0x20, 0x76, 0x65,
0x63, 0x74, 0x6f, 0x72, 0x73, 0x20, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15,
0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
]),
path: &[],
sk: [
0xe9, 0xda, 0x88, 0x06, 0x40, 0x9d, 0xc3, 0xc3, 0xeb, 0xd1, 0xfc, 0x2a, 0x71, 0xc8,
0x79, 0xc1, 0x3d, 0xd7, 0xaa, 0x93, 0xed, 0xe8, 0x03, 0xbf, 0x1a, 0x83, 0x41, 0x4b,
Expand All @@ -144,6 +171,17 @@ mod tests {
],
},
TestVector {
context_string: &[
0x5a, 0x63, 0x61, 0x73, 0x68, 0x20, 0x74, 0x65, 0x73, 0x74, 0x20, 0x76, 0x65, 0x63,
0x74, 0x6f, 0x72, 0x73,
],
seed: [
0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d,
0x0e, 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b,
0x1c, 0x1d, 0x1e, 0x1f,
],
ikm: None,
path: &[2147483649],
sk: [
0xe8, 0x40, 0x9a, 0xaa, 0x83, 0x2c, 0xc2, 0x37, 0x8f, 0x2b, 0xad, 0xeb, 0x77, 0x15,
0x05, 0x62, 0x15, 0x37, 0x42, 0xfe, 0xe8, 0x76, 0xdc, 0xf4, 0x78, 0x3a, 0x6c, 0xcd,
Expand All @@ -156,6 +194,17 @@ mod tests {
],
},
TestVector {
context_string: &[
0x5a, 0x63, 0x61, 0x73, 0x68, 0x20, 0x74, 0x65, 0x73, 0x74, 0x20, 0x76, 0x65, 0x63,
0x74, 0x6f, 0x72, 0x73,
],
seed: [
0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d,
0x0e, 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b,
0x1c, 0x1d, 0x1e, 0x1f,
],
ikm: None,
path: &[2147483649, 2147483650],
sk: [
0x46, 0x4f, 0x90, 0xa3, 0x64, 0xcf, 0xf8, 0x05, 0xfe, 0xe9, 0x3a, 0x85, 0xb7, 0x2f,
0x48, 0x94, 0xce, 0x4e, 0x13, 0x58, 0xdc, 0xdc, 0x1e, 0x61, 0xa3, 0xd4, 0x30, 0x30,
Expand All @@ -168,6 +217,17 @@ mod tests {
],
},
TestVector {
context_string: &[
0x5a, 0x63, 0x61, 0x73, 0x68, 0x20, 0x74, 0x65, 0x73, 0x74, 0x20, 0x76, 0x65, 0x63,
0x74, 0x6f, 0x72, 0x73,
],
seed: [
0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d,
0x0e, 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b,
0x1c, 0x1d, 0x1e, 0x1f,
],
ikm: None,
path: &[2147483649, 2147483650, 2147483651],
sk: [
0xfc, 0x4b, 0x6e, 0x93, 0xb0, 0xe4, 0x2f, 0x7a, 0x76, 0x2c, 0xa0, 0xc6, 0x52, 0x2c,
0xcd, 0x10, 0x45, 0xca, 0xb5, 0x06, 0xb3, 0x72, 0x45, 0x2a, 0xf7, 0x30, 0x6c, 0x87,
Expand All @@ -184,21 +244,36 @@ mod tests {
#[test]
fn test_vectors() {
let context_string = b"Zcash test vectors";
let seed = [0; 32];
let full_path = [
ChildIndex::hardened(1),
ChildIndex::hardened(2),
ChildIndex::hardened(3),
];

for (i, tv) in TEST_VECTORS.iter().enumerate() {
assert_eq!(tv.context_string, context_string);

let path = tv
.path
.into_iter()
.map(|i| ChildIndex::from_index(*i).expect("hardened"))
.collect::<std::vec::Vec<_>>();
assert_eq!(&full_path[..i], &path);

// The derived master key should be identical to the key at the empty path.
if i == 0 {
let sk = SecretKey::master(context_string, &seed);
if let Some(mut tv_ikm) = tv.ikm {
with_ikm(tv.context_string, &tv.seed, |ikm| {
for part in ikm {
assert_eq!(*part, &tv_ikm[..part.len()]);
tv_ikm = &tv_ikm[part.len()..];
}
});

let sk = SecretKey::master(context_string, &tv.seed);
assert_eq!((sk.data(), sk.chain_code().as_bytes()), (&tv.sk, &tv.c));
}

let sk = SecretKey::from_path(context_string, &seed, &full_path[..i]);
let sk = SecretKey::from_path(tv.context_string, &tv.seed, &path);
assert_eq!(sk.data(), &tv.sk);
assert_eq!(sk.chain_code().as_bytes(), &tv.c);
}
Expand Down

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