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Merge pull request #284 from str4d/259-ovk-none 

zcash_primitives: Support ovk = ⊥ in note encryption
This commit is contained in:
ebfull 2020-09-09 14:32:57 -06:00 committed by GitHub
parent d65254e7cf 40e135783c
commit c7e9523dce
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
5 changed files with 105 additions and 81 deletions
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2
zcash_client_backend/src/welding_rig.rs
View File

@ -257,7 +257,7 @@ mod tests {
rseed,
};
let encryptor = SaplingNoteEncryption::new(
extfvk.fvk.ovk,
Some(extfvk.fvk.ovk),
note.clone(),
to.clone(),
Memo::default(),

6
zcash_client_sqlite/src/lib.rs
View File

@ -133,7 +133,7 @@ mod tests {
rseed,
};
let encryptor = SaplingNoteEncryption::new(
extfvk.fvk.ovk,
Some(extfvk.fvk.ovk),
note.clone(),
to.clone(),
Memo::default(),
@ -193,7 +193,7 @@ mod tests {
rseed,
};
let encryptor = SaplingNoteEncryption::new(
extfvk.fvk.ovk,
Some(extfvk.fvk.ovk),
note.clone(),
to,
Memo::default(),
@ -221,7 +221,7 @@ mod tests {
rseed,
};
let encryptor = SaplingNoteEncryption::new(
extfvk.fvk.ovk,
Some(extfvk.fvk.ovk),
note.clone(),
change_addr,
Memo::default(),

15
zcash_client_sqlite/src/transact.rs
View File

@ -1,7 +1,7 @@
//! Functions for creating transactions.
use ff::PrimeField;
use rand_core::{OsRng, RngCore};
use rand_core::OsRng;
use rusqlite::{types::ToSql, Connection, NO_PARAMS};
use std::convert::TryInto;
use std::path::Path;
@ -148,16 +148,9 @@ pub fn create_to_address<P: AsRef<Path>>(
// Apply the outgoing viewing key policy.
let ovk = match ovk_policy {
OvkPolicy::Sender => extfvk.fvk.ovk,
OvkPolicy::Custom(ovk) => ovk,
OvkPolicy::Discard => {
// Generate a random outgoing viewing key that the caller does not know.
// The probability of this colliding with a legitimate outgoing viewing
// key is negligible.
let mut ovk = [0; 32];
OsRng.fill_bytes(&mut ovk);
OutgoingViewingKey(ovk)
}
OvkPolicy::Sender => Some(extfvk.fvk.ovk),
OvkPolicy::Custom(ovk) => Some(ovk),
OvkPolicy::Discard => None,
};
// Target the next block, assuming we are up-to-date.

148
zcash_primitives/src/note_encryption.rs
View File

@ -152,6 +152,21 @@ fn kdf_sapling(dhsecret: jubjub::SubgroupPoint, epk: &jubjub::SubgroupPoint) ->
.finalize()
}
/// A symmetric key that can be used to recover a single Sapling output.
pub struct OutgoingCipherKey([u8; 32]);
impl From<[u8; 32]> for OutgoingCipherKey {
fn from(ock: [u8; 32]) -> Self {
OutgoingCipherKey(ock)
}
}
impl AsRef<[u8]> for OutgoingCipherKey {
fn as_ref(&self) -> &[u8] {
&self.0
}
}
/// Sapling PRF^ock.
///
/// Implemented per section 5.4.2 of the Zcash Protocol Specification.
@ -160,16 +175,21 @@ pub fn prf_ock(
cv: &jubjub::ExtendedPoint,
cmu: &bls12_381::Scalar,
epk: &jubjub::SubgroupPoint,
) -> Blake2bHash {
Blake2bParams::new()
.hash_length(32)
.personal(PRF_OCK_PERSONALIZATION)
.to_state()
.update(&ovk.0)
.update(&cv.to_bytes())
.update(&cmu.to_repr())
.update(&epk.to_bytes())
.finalize()
) -> OutgoingCipherKey {
OutgoingCipherKey(
Blake2bParams::new()
.hash_length(32)
.personal(PRF_OCK_PERSONALIZATION)
.to_state()
.update(&ovk.0)
.update(&cv.to_bytes())
.update(&cmu.to_repr())
.update(&epk.to_bytes())
.finalize()
.as_bytes()
.try_into()
.unwrap(),
)
}
/// An API for encrypting Sapling notes.
@ -201,7 +221,7 @@ pub fn prf_ock(
/// let diversifier = Diversifier([0; 11]);
/// let pk_d = diversifier.g_d().unwrap();
/// let to = PaymentAddress::from_parts(diversifier, pk_d).unwrap();
/// let ovk = OutgoingViewingKey([0; 32]);
/// let ovk = Some(OutgoingViewingKey([0; 32]));
///
/// let value = 1000;
/// let rcv = jubjub::Fr::random(&mut rng);
@ -213,29 +233,34 @@ pub fn prf_ock(
/// let note = to.create_note(value, Rseed::BeforeZip212(rcm)).unwrap();
/// let cmu = note.cmu();
///
/// let enc = SaplingNoteEncryption::new(ovk, note, to, Memo::default(), &mut rng);
/// let mut enc = SaplingNoteEncryption::new(ovk, note, to, Memo::default(), &mut rng);
/// let encCiphertext = enc.encrypt_note_plaintext();
/// let outCiphertext = enc.encrypt_outgoing_plaintext(&cv.commitment().into(), &cmu);
/// ```
pub struct SaplingNoteEncryption {
pub struct SaplingNoteEncryption<R: RngCore + CryptoRng> {
epk: jubjub::SubgroupPoint,
esk: jubjub::Fr,
note: Note,
to: PaymentAddress,
memo: Memo,
ovk: OutgoingViewingKey,
/// `None` represents the `ovk = ⊥` case.
ovk: Option<OutgoingViewingKey>,
rng: R,
}
impl SaplingNoteEncryption {
impl<R: RngCore + CryptoRng> SaplingNoteEncryption<R> {
/// Creates a new encryption context for the given note.
pub fn new<R: RngCore + CryptoRng>(
ovk: OutgoingViewingKey,
///
/// Setting `ovk` to `None` represents the `ovk = ⊥` case, where the note cannot be
/// recovered by the sender.
pub fn new(
ovk: Option<OutgoingViewingKey>,
note: Note,
to: PaymentAddress,
memo: Memo,
rng: &mut R,
) -> SaplingNoteEncryption {
let esk = note.generate_or_derive_esk(rng);
mut rng: R,
) -> Self {
let esk = note.generate_or_derive_esk(&mut rng);
let epk = note.g_d * esk;
SaplingNoteEncryption {
@ -245,6 +270,7 @@ impl SaplingNoteEncryption {
to,
memo,
ovk,
rng,
}
}
@ -297,20 +323,33 @@ impl SaplingNoteEncryption {
/// Generates `outCiphertext` for this note.
pub fn encrypt_outgoing_plaintext(
&self,
&mut self,
cv: &jubjub::ExtendedPoint,
cmu: &bls12_381::Scalar,
) -> [u8; OUT_CIPHERTEXT_SIZE] {
let key = prf_ock(&self.ovk, &cv, &cmu, &self.epk);
let (ock, input) = if let Some(ovk) = &self.ovk {
let ock = prf_ock(ovk, &cv, &cmu, &self.epk);
let mut input = [0u8; OUT_PLAINTEXT_SIZE];
input[0..32].copy_from_slice(&self.note.pk_d.to_bytes());
input[32..OUT_PLAINTEXT_SIZE].copy_from_slice(self.esk.to_repr().as_ref());
let mut input = [0u8; OUT_PLAINTEXT_SIZE];
input[0..32].copy_from_slice(&self.note.pk_d.to_bytes());
input[32..OUT_PLAINTEXT_SIZE].copy_from_slice(self.esk.to_repr().as_ref());
(ock, input)
} else {
// ovk = ⊥
let mut ock = OutgoingCipherKey([0; 32]);
let mut input = [0u8; OUT_PLAINTEXT_SIZE];
self.rng.fill_bytes(&mut ock.0);
self.rng.fill_bytes(&mut input);
(ock, input)
};
let mut output = [0u8; OUT_CIPHERTEXT_SIZE];
assert_eq!(
ChachaPolyIetf::aead_cipher()
.seal_to(&mut output, &input, &[], key.as_bytes(), &[0u8; 12])
.seal_to(&mut output, &input, &[], ock.as_ref(), &[0u8; 12])
.unwrap(),
OUT_CIPHERTEXT_SIZE
);
@ -468,7 +507,7 @@ pub fn try_sapling_compact_note_decryption<P: consensus::Parameters>(
/// For decryption using a Full Viewing Key see [`try_sapling_output_recovery`].
pub fn try_sapling_output_recovery_with_ock<P: consensus::Parameters>(
height: u32,
ock: &[u8],
ock: &OutgoingCipherKey,
cmu: &bls12_381::Scalar,
epk: &jubjub::SubgroupPoint,
enc_ciphertext: &[u8],
@ -480,7 +519,7 @@ pub fn try_sapling_output_recovery_with_ock<P: consensus::Parameters>(
let mut op = [0; OUT_CIPHERTEXT_SIZE];
assert_eq!(
ChachaPolyIetf::aead_cipher()
.open_to(&mut op, &out_ciphertext, &[], &ock, &[0u8; 12])
.open_to(&mut op, &out_ciphertext, &[], ock.as_ref(), &[0u8; 12])
.ok()?,
OUT_PLAINTEXT_SIZE
);
@ -583,7 +622,7 @@ pub fn try_sapling_output_recovery<P: consensus::Parameters>(
) -> Option<(Note, PaymentAddress, Memo)> {
try_sapling_output_recovery_with_ock::<P>(
height,
prf_ock(&ovk, &cv, &cmu, &epk).as_bytes(),
&prf_ock(&ovk, &cv, &cmu, &epk),
cmu,
epk,
enc_ciphertext,
@ -593,7 +632,6 @@ pub fn try_sapling_output_recovery<P: consensus::Parameters>(
#[cfg(test)]
mod tests {
use blake2b_simd::Hash as Blake2bHash;
use crypto_api_chachapoly::ChachaPolyIetf;
use ff::{Field, PrimeField};
use group::Group;
@ -606,8 +644,9 @@ mod tests {
use super::{
kdf_sapling, prf_ock, sapling_ka_agree, try_sapling_compact_note_decryption,
try_sapling_note_decryption, try_sapling_output_recovery,
try_sapling_output_recovery_with_ock, Memo, SaplingNoteEncryption, COMPACT_NOTE_SIZE,
ENC_CIPHERTEXT_SIZE, NOTE_PLAINTEXT_SIZE, OUT_CIPHERTEXT_SIZE, OUT_PLAINTEXT_SIZE,
try_sapling_output_recovery_with_ock, Memo, OutgoingCipherKey, SaplingNoteEncryption,
COMPACT_NOTE_SIZE, ENC_CIPHERTEXT_SIZE, NOTE_PLAINTEXT_SIZE, OUT_CIPHERTEXT_SIZE,
OUT_PLAINTEXT_SIZE,
};
use crate::{
consensus::{
@ -741,7 +780,7 @@ mod tests {
mut rng: &mut R,
) -> (
OutgoingViewingKey,
Blake2bHash,
OutgoingCipherKey,
jubjub::Fr,
jubjub::ExtendedPoint,
bls12_381::Scalar,
@ -782,7 +821,7 @@ mod tests {
);
let ock_output_recovery = try_sapling_output_recovery_with_ock::<TestNetwork>(
height,
ock.as_bytes(),
&ock,
&cmu,
&epk,
&enc_ciphertext,
@ -801,7 +840,7 @@ mod tests {
mut rng: &mut R,
) -> (
OutgoingViewingKey,
Blake2bHash,
OutgoingCipherKey,
jubjub::Fr,
jubjub::ExtendedPoint,
bls12_381::Scalar,
@ -827,22 +866,13 @@ mod tests {
let cmu = note.cmu();
let ovk = OutgoingViewingKey([0; 32]);
let ne = SaplingNoteEncryption::new(ovk, note, pa, Memo([0; 512]), &mut rng);
let epk = ne.epk();
let mut ne = SaplingNoteEncryption::new(Some(ovk), note, pa, Memo([0; 512]), &mut rng);
let epk = ne.epk().clone();
let enc_ciphertext = ne.encrypt_note_plaintext();
let out_ciphertext = ne.encrypt_outgoing_plaintext(&cv, &cmu);
let ock = prf_ock(&ovk, &cv, &cmu, &epk);
(
ovk,
ock,
ivk,
cv,
cmu,
epk.clone(),
enc_ciphertext,
out_ciphertext,
)
(ovk, ock, ivk, cv, cmu, epk, enc_ciphertext, out_ciphertext)
}
fn reencrypt_enc_ciphertext(
@ -859,7 +889,7 @@ mod tests {
let mut op = [0; OUT_CIPHERTEXT_SIZE];
assert_eq!(
ChachaPolyIetf::aead_cipher()
.open_to(&mut op, out_ciphertext, &[], ock.as_bytes(), &[0u8; 12])
.open_to(&mut op, out_ciphertext, &[], ock.as_ref(), &[0u8; 12])
.unwrap(),
OUT_PLAINTEXT_SIZE
);
@ -1351,7 +1381,7 @@ mod tests {
assert_eq!(
try_sapling_output_recovery_with_ock::<TestNetwork>(
height,
&[0u8; 32],
&OutgoingCipherKey([0u8; 32]),
&cmu,
&epk,
&enc_ciphertext,
@ -1416,7 +1446,7 @@ mod tests {
assert_eq!(
try_sapling_output_recovery_with_ock::<TestNetwork>(
height,
&ock.as_bytes(),
&ock,
&bls12_381::Scalar::random(&mut rng),
&epk,
&enc_ctext,
@ -1454,7 +1484,7 @@ mod tests {
assert_eq!(
try_sapling_output_recovery_with_ock::<TestNetwork>(
height,
&ock.as_bytes(),
&ock,
&cmu,
&jubjub::SubgroupPoint::random(&mut rng),
&enc_ciphertext,
@ -1493,7 +1523,7 @@ mod tests {
assert_eq!(
try_sapling_output_recovery_with_ock::<TestNetwork>(
height,
&ock.as_bytes(),
&ock,
&cmu,
&epk,
&enc_ciphertext,
@ -1532,7 +1562,7 @@ mod tests {
assert_eq!(
try_sapling_output_recovery_with_ock::<TestNetwork>(
height,
&ock.as_bytes(),
&ock,
&cmu,
&epk,
&enc_ciphertext,
@ -1582,7 +1612,7 @@ mod tests {
assert_eq!(
try_sapling_output_recovery_with_ock::<TestNetwork>(
height,
&ock.as_bytes(),
&ock,
&cmu,
&epk,
&enc_ciphertext,
@ -1629,7 +1659,7 @@ mod tests {
assert_eq!(
try_sapling_output_recovery_with_ock::<TestNetwork>(
height,
&ock.as_bytes(),
&ock,
&cmu,
&epk,
&enc_ciphertext,
@ -1676,7 +1706,7 @@ mod tests {
assert_eq!(
try_sapling_output_recovery_with_ock::<TestNetwork>(
height,
&ock.as_bytes(),
&ock,
&cmu,
&epk,
&enc_ciphertext,
@ -1715,7 +1745,7 @@ mod tests {
assert_eq!(
try_sapling_output_recovery_with_ock::<TestNetwork>(
height,
&ock.as_bytes(),
&ock,
&cmu,
&epk,
&enc_ciphertext,
@ -1776,7 +1806,7 @@ mod tests {
let ovk = OutgoingViewingKey(tv.ovk);
let ock = prf_ock(&ovk, &cv, &cmu, &epk);
assert_eq!(ock.as_bytes(), tv.ock);
assert_eq!(ock.as_ref(), tv.ock);
let to = PaymentAddress::from_parts(Diversifier(tv.default_d), pk_d).unwrap();
let note = to.create_note(tv.v, Rseed::BeforeZip212(rcm)).unwrap();
@ -1825,7 +1855,7 @@ mod tests {
// Test encryption
//
let mut ne = SaplingNoteEncryption::new(ovk, note, to, Memo(tv.memo), &mut OsRng);
let mut ne = SaplingNoteEncryption::new(Some(ovk), note, to, Memo(tv.memo), OsRng);
// Swap in the ephemeral keypair from the test vectors
ne.esk = esk;
ne.epk = epk;

15
zcash_primitives/src/transaction/builder.rs
View File

@ -76,7 +76,8 @@ struct SpendDescriptionInfo {
}
pub struct SaplingOutput {
ovk: OutgoingViewingKey,
/// `None` represents the `ovk = ⊥` case.
ovk: Option<OutgoingViewingKey>,
to: PaymentAddress,
note: Note,
memo: Memo,
@ -86,7 +87,7 @@ impl SaplingOutput {
pub fn new<R: RngCore + CryptoRng, P: consensus::Parameters>(
height: u32,
rng: &mut R,
ovk: OutgoingViewingKey,
ovk: Option<OutgoingViewingKey>,
to: PaymentAddress,
value: Amount,
memo: Option<Memo>,
@ -122,7 +123,7 @@ impl SaplingOutput {
ctx: &mut P::SaplingProvingContext,
rng: &mut R,
) -> OutputDescription {
let encryptor = SaplingNoteEncryption::new(
let mut encryptor = SaplingNoteEncryption::new(
self.ovk,
self.note.clone(),
self.to.clone(),
@ -396,7 +397,7 @@ impl<P: consensus::Parameters, R: RngCore + CryptoRng> Builder<P, R> {
/// Adds a Sapling address to send funds to.
pub fn add_sapling_output(
&mut self,
ovk: OutgoingViewingKey,
ovk: Option<OutgoingViewingKey>,
to: PaymentAddress,
value: Amount,
memo: Option<Memo>,
@ -502,7 +503,7 @@ impl<P: consensus::Parameters, R: RngCore + CryptoRng> Builder<P, R> {
return Err(Error::NoChangeAddress);
};
self.add_sapling_output(change_address.0, change_address.1, change, None)?;
self.add_sapling_output(Some(change_address.0), change_address.1, change, None)?;
}
//
@ -728,7 +729,7 @@ mod tests {
let mut builder = Builder::<TestNetwork, OsRng>::new(0);
assert_eq!(
builder.add_sapling_output(ovk, to, Amount::from_i64(-1).unwrap(), None),
builder.add_sapling_output(Some(ovk), to, Amount::from_i64(-1).unwrap(), None),
Err(Error::InvalidAmount)
);
}
@ -840,7 +841,7 @@ mod tests {
}
let extfvk = ExtendedFullViewingKey::from(&extsk);
let ovk = extfvk.fvk.ovk;
let ovk = Some(extfvk.fvk.ovk);
let to = extfvk.default_address().unwrap().1;
// Fail if there is only a Sapling output