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Change personalization to more closely align with the spec.

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This commit is contained in:
Sean Bowe 2018-03-17 10:24:55 -06:00
parent d09c4d6ce8
commit 8b6f113052
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GPG Key ID: 95684257D8F8B031
2 changed files with 53 additions and 56 deletions
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4
src/circuit/sapling/mod.rs
View File

@ -623,7 +623,7 @@ fn test_input_circuit_with_bls12_381() {
assert!(cs.is_satisfied());
assert_eq!(cs.num_constraints(), 98776);
assert_eq!(cs.hash(), "729850617d4e6d95cbf348f07cbe0c63b01d35718f24cbcf7df79e2c3e1a7648");
assert_eq!(cs.hash(), "d810fa887178359f3fc5723781a0750b750dd0c02aeb0b14ff19a343db9868f1");
assert_eq!(cs.num_inputs(), 8);
assert_eq!(cs.get_input(0, "ONE"), Fr::one());
@ -749,7 +749,7 @@ fn test_output_circuit_with_bls12_381() {
assert!(cs.is_satisfied());
assert_eq!(cs.num_constraints(), 7827);
assert_eq!(cs.hash(), "0c3d4ee7b0ac346836f177a471b2453c3558ea5760c526faad72feb65caf275b");
assert_eq!(cs.hash(), "e49724488227ae83b2360a5ddbda7e44c83e6f526a369cefeb747c5dd6aab7c7");
let expected_cm = payment_address.create_note(
value_commitment.value,

105
src/jubjub/mod.rs
View File

@ -192,25 +192,51 @@ impl JubjubBls12 {
fixed_base_circuit_generators: vec![],
};
// Create the bases for the Pedersen hashes
fn find_group_hash<E: JubjubEngine>(
m: &[u8],
personalization: &[u8; 8],
params: &E::Params
) -> edwards::Point<E, PrimeOrder>
{
// TODO: This currently does not match the specification
let mut cur = 0;
let mut pedersen_hash_generators = vec![];
let mut tag = m.to_vec();
let i = tag.len();
tag.push(0u8);
loop {
let gh = group_hash(
&tag,
personalization,
params
);
// TODO: This generates more bases for the Pedersen hashes
// than necessary, which is just a performance issue in
// practice.
while pedersen_hash_generators.len() < 5 {
let gh = group_hash(&[cur], constants::PEDERSEN_HASH_GENERATORS_PERSONALIZATION, &tmp_params);
// We don't want to overflow and start reusing generators
assert!(cur != u8::max_value());
cur += 1;
assert!(tag[i] != u8::max_value());
tag[i] += 1;
if let Some(gh) = gh {
pedersen_hash_generators.push(gh);
break gh;
}
}
}
// Create the bases for the Pedersen hashes
{
let mut pedersen_hash_generators = vec![];
for m in 0..5 {
use byteorder::{WriteBytesExt, BigEndian};
let mut segment_number = [0u8; 4];
(&mut segment_number[0..4]).write_u32::<BigEndian>(m).unwrap();
pedersen_hash_generators.push(
find_group_hash(
&segment_number,
constants::PEDERSEN_HASH_GENERATORS_PERSONALIZATION,
&tmp_params
)
);
}
// Check for duplicates, far worse than spec inconsistencies!
for (i, p1) in pedersen_hash_generators.iter().enumerate() {
@ -232,52 +258,23 @@ impl JubjubBls12 {
{
let mut fixed_base_generators = vec![edwards::Point::zero(); FixedGenerators::Max as usize];
{
// Each generator is found by invoking the group hash
// on tag 0x00, 0x01, ... until we find a valid result.
let find_first_gh = |personalization| {
let mut cur = 0u8;
fixed_base_generators[FixedGenerators::ProofGenerationKey as usize] =
find_group_hash(b"0", constants::PROOF_GENERATION_KEY_BASE_GENERATOR_PERSONALIZATION, &tmp_params);
loop {
let gh = group_hash::<Bls12>(&[cur], personalization, &tmp_params);
// We don't want to overflow.
assert!(cur != u8::max_value());
cur += 1;
fixed_base_generators[FixedGenerators::NoteCommitmentRandomness as usize] =
find_group_hash(b"0", constants::NOTE_COMMITMENT_RANDOMNESS_GENERATOR_PERSONALIZATION, &tmp_params);
if let Some(gh) = gh {
break gh;
}
}
};
fixed_base_generators[FixedGenerators::NullifierPosition as usize] =
find_group_hash(b"0", constants::NULLIFIER_POSITION_IN_TREE_GENERATOR_PERSONALIZATION, &tmp_params);
// Written this way for exhaustion (double entendre). There's no
// way to iterate over the variants of an enum, so it's hideous.
for c in 0..(FixedGenerators::Max as usize) {
let p = match c {
c if c == (FixedGenerators::ProofGenerationKey as usize) => {
constants::PROOF_GENERATION_KEY_BASE_GENERATOR_PERSONALIZATION
},
c if c == (FixedGenerators::NoteCommitmentRandomness as usize) => {
constants::NOTE_COMMITMENT_RANDOMNESS_GENERATOR_PERSONALIZATION
},
c if c == (FixedGenerators::NullifierPosition as usize) => {
constants::NULLIFIER_POSITION_IN_TREE_GENERATOR_PERSONALIZATION
},
c if c == (FixedGenerators::ValueCommitmentValue as usize) => {
constants::VALUE_COMMITMENT_VALUE_GENERATOR_PERSONALIZATION
},
c if c == (FixedGenerators::ValueCommitmentRandomness as usize) => {
constants::VALUE_COMMITMENT_RANDOMNESS_GENERATOR_PERSONALIZATION
},
c if c == (FixedGenerators::SpendingKeyGenerator as usize) => {
constants::SPENDING_KEY_GENERATOR_PERSONALIZATION
},
_ => unreachable!()
};
fixed_base_generators[FixedGenerators::ValueCommitmentValue as usize] =
find_group_hash(b"0", constants::VALUE_COMMITMENT_VALUE_GENERATOR_PERSONALIZATION, &tmp_params);
fixed_base_generators[c] = find_first_gh(p);
}
}
fixed_base_generators[FixedGenerators::ValueCommitmentRandomness as usize] =
find_group_hash(b"0", constants::VALUE_COMMITMENT_RANDOMNESS_GENERATOR_PERSONALIZATION, &tmp_params);
fixed_base_generators[FixedGenerators::SpendingKeyGenerator as usize] =
find_group_hash(b"0", constants::SPENDING_KEY_GENERATOR_PERSONALIZATION, &tmp_params);
// Check for duplicates, far worse than spec inconsistencies!
for (i, p1) in fixed_base_generators.iter().enumerate() {