mirror of https://github.com/zcash/halo2.git
Implement `Domain::batch_epk` for note decryption
Improves throughput of batched trial decryption by around 10%.
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parent
8c15cc25be
commit
8e13986101
23
src/keys.rs
23
src/keys.rs
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@ -6,7 +6,7 @@ use std::mem;
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use aes::Aes256;
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use blake2b_simd::{Hash as Blake2bHash, Params};
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use fpe::ff1::{BinaryNumeralString, FF1};
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use group::GroupEncoding;
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use group::{prime::PrimeCurveAffine, Curve, GroupEncoding};
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use halo2::arithmetic::FieldExt;
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use pasta_curves::pallas;
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use rand::RngCore;
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@ -567,15 +567,34 @@ impl SharedSecret {
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self.0.to_bytes()
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}
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/// Only for use in batched note encryption.
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pub(crate) fn batch_to_affine(shared_secrets: &[Option<Self>]) -> Vec<pallas::Affine> {
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let secrets: Vec<_> = shared_secrets
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.iter()
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.filter_map(|s| s.as_ref().map(|s| *(s.0)))
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.collect();
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let mut secrets_affine = vec![pallas::Affine::identity(); shared_secrets.len()];
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group::Curve::batch_normalize(&secrets, &mut secrets_affine);
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secrets_affine
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}
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/// Defined in [Zcash Protocol Spec § 5.4.5.6: Orchard Key Agreement][concreteorchardkdf].
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///
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/// [concreteorchardkdf]: https://zips.z.cash/protocol/nu5.pdf#concreteorchardkdf
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pub(crate) fn kdf_orchard(self, ephemeral_key: &EphemeralKeyBytes) -> Blake2bHash {
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Self::kdf_orchard_inner(self.0.to_affine(), ephemeral_key)
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}
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/// Only for direct use in batched note encryption.
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pub(crate) fn kdf_orchard_inner(
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secret: pallas::Affine,
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ephemeral_key: &EphemeralKeyBytes,
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) -> Blake2bHash {
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Params::new()
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.hash_length(32)
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.personal(KDF_ORCHARD_PERSONALIZATION)
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.to_state()
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.update(&self.0.to_bytes())
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.update(&secret.to_bytes())
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.update(&ephemeral_key.0)
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.finalize()
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}
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@ -141,6 +141,24 @@ impl Domain for OrchardDomain {
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secret.kdf_orchard(ephemeral_key)
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}
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fn batch_kdf<'a>(
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items: impl Iterator<Item = (Option<Self::SharedSecret>, &'a EphemeralKeyBytes)>,
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) -> Vec<Option<Self::SymmetricKey>> {
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let (shared_secrets, ephemeral_keys): (Vec<_>, Vec<_>) = items.unzip();
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let secrets_affine = SharedSecret::batch_to_affine(&shared_secrets);
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let mut secrets_affine = secrets_affine.into_iter();
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shared_secrets
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.into_iter()
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.map(|s| s.and_then(|_| secrets_affine.next()))
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.zip(ephemeral_keys.into_iter())
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.map(|(secret, ephemeral_key)| {
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secret.map(|dhsecret| SharedSecret::kdf_orchard_inner(dhsecret, ephemeral_key))
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})
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.collect()
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}
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fn note_plaintext_bytes(
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note: &Self::Note,
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_: &Self::Recipient,
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