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Make it possible for callers to search for valid Sapling diversifiers.

This commit is contained in:
Kris Nuttycombe 2021-09-03 17:33:46 -06:00
parent 2c97bb1711
commit 28112de234
1 changed files with 22 additions and 11 deletions
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33
zcash_primitives/src/zip32.rs
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@ -140,6 +140,26 @@ impl DiversifierKey {
DiversifierKey(dk)
}
fn try_diversifier_internal(ff: &FF1<Aes256>, j: DiversifierIndex) -> Option<Diversifier> {
// Generate d_j
let enc = ff
.encrypt(&[], &BinaryNumeralString::from_bytes_le(&j.0[..]))
.unwrap();
let mut d_j = [0; 11];
d_j.copy_from_slice(&enc.to_bytes_le());
let diversifier = Diversifier(d_j);
// Return (j, d_j) if valid, else increment j and try again
diversifier.g_d().map(|_| diversifier)
}
/// Attempts to produce a diversifier at the given index. Returns None
/// if the index does not produce a valid diversifier.
pub fn try_diversifier(&self, j: DiversifierIndex) -> Option<Diversifier> {
let ff = FF1::<Aes256>::new(&self.0, 2).unwrap();
Self::try_diversifier_internal(&ff, j)
}
/// Returns the first index starting from j that generates a valid
/// diversifier, along with the corresponding diversifier. Returns
/// an error if the diversifier space is exhausted.
@ -149,17 +169,8 @@ impl DiversifierKey {
) -> Result<(DiversifierIndex, Diversifier), ()> {
let ff = FF1::<Aes256>::new(&self.0, 2).unwrap();
loop {
// Generate d_j
let enc = ff
.encrypt(&[], &BinaryNumeralString::from_bytes_le(&j.0[..]))
.unwrap();
let mut d_j = [0; 11];
d_j.copy_from_slice(&enc.to_bytes_le());
let d_j = Diversifier(d_j);
// Return (j, d_j) if valid, else increment j and try again
match d_j.g_d() {
Some(_) => return Ok((j, d_j)),
match Self::try_diversifier_internal(&ff, j) {
Some(d_j) => return Ok((j, d_j)),
None => {
if j.increment().is_err() {
return Err(());