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[zk-token-sdk] divide fee encryption into two ciphertexts (#28472) 

* divide fee encryption into two ciphertexts

* clippy

* update range proof

* add fee ciphertext decryption

* clean up split_u64 function

* remove unnecessary casting
This commit is contained in:
samkim-crypto 2022-11-30 15:11:38 +09:00 committed by GitHub
parent 3d6eb16753
commit 11efaf75a4
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GPG Key ID: 4AEE18F83AFDEB23
5 changed files with 343 additions and 265 deletions
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8
zk-token-sdk/src/errors.rs
View File

@ -11,8 +11,6 @@ pub enum ProofError {
#[error("proof generation failed")]
Generation,
#[error("proof failed to verify")]
Verification,
#[error("range proof failed to verify")]
RangeProof,
#[error("equality proof failed to verify")]
EqualityProof,
@ -30,6 +28,12 @@ pub enum ProofError {
CiphertextDeserialization,
#[error("invalid scalar data")]
ScalarDeserialization,
#[error("invalid public key data")]
PubkeyDeserialization,
#[error("ciphertext does not exist in proof data")]
MissingCiphertext,
#[error("transfer amount split failed")]
TransferSplit,
}
#[derive(Error, Clone, Debug, Eq, PartialEq)]

33
zk-token-sdk/src/instruction/mod.rs
View File

@ -15,7 +15,6 @@ use {
errors::ProofError,
},
curve25519_dalek::scalar::Scalar,
subtle::ConstantTimeEq,
};
pub use {
close_account::CloseAccountData, pubkey_validity::PubkeyValidityData, transfer::TransferData,
@ -32,30 +31,32 @@ pub trait Verifiable {
#[derive(Debug, Copy, Clone)]
pub enum Role {
Source,
Dest,
Destination,
Auditor,
WithdrawWithheldAuthority,
}
/// Takes in a 64-bit number `amount` and a bit length `bit_length`. It returns:
/// - the `bit_length` low bits of `amount` interpretted as u64
/// - the (64 - `bit_length`) high bits of `amount` interpretted as u64
#[cfg(not(target_os = "solana"))]
pub fn split_u64(
amount: u64,
lo_bit_length: usize,
hi_bit_length: usize,
) -> Result<(u64, u64), ProofError> {
assert!(lo_bit_length <= 64);
assert!(hi_bit_length <= 64);
if !bool::from((amount >> (lo_bit_length + hi_bit_length)).ct_eq(&0u64)) {
return Err(ProofError::TransferAmount);
pub fn split_u64(amount: u64, bit_length: usize) -> (u64, u64) {
if bit_length == 64 {
(amount, 0)
} else {
let lo = amount << (64 - bit_length) >> (64 - bit_length);
let hi = amount >> bit_length;
(lo, hi)
}
}
let lo = amount << (64 - lo_bit_length) >> (64 - lo_bit_length);
let hi = amount >> lo_bit_length;
Ok((lo, hi))
#[cfg(not(target_os = "solana"))]
pub fn combine_lo_hi_u64(amount_lo: u64, amount_hi: u64, bit_length: usize) -> u64 {
if bit_length == 64 {
amount_lo
} else {
amount_lo + (amount_hi << bit_length)
}
}
#[cfg(not(target_os = "solana"))]

75
zk-token-sdk/src/instruction/transfer.rs
View File

@ -68,11 +68,7 @@ impl TransferData {
(destination_pubkey, auditor_pubkey): (&ElGamalPubkey, &ElGamalPubkey),
) -> Result<Self, ProofError> {
// split and encrypt transfer amount
let (amount_lo, amount_hi) = split_u64(
transfer_amount,
TRANSFER_AMOUNT_LO_BITS,
TRANSFER_AMOUNT_HI_BITS,
)?;
let (amount_lo, amount_hi) = split_u64(transfer_amount, TRANSFER_AMOUNT_LO_BITS);
let (ciphertext_lo, opening_lo) = TransferAmountEncryption::new(
amount_lo,
@ -151,15 +147,20 @@ impl TransferData {
let ciphertext_lo: TransferAmountEncryption = self.ciphertext_lo.try_into()?;
let handle_lo = match role {
Role::Source => ciphertext_lo.source_handle,
Role::Dest => ciphertext_lo.destination_handle,
Role::Auditor => ciphertext_lo.auditor_handle,
Role::Source => Some(ciphertext_lo.source_handle),
Role::Destination => Some(ciphertext_lo.destination_handle),
Role::Auditor => Some(ciphertext_lo.auditor_handle),
Role::WithdrawWithheldAuthority => None,
};
Ok(ElGamalCiphertext {
commitment: ciphertext_lo.commitment,
handle: handle_lo,
})
if let Some(handle) = handle_lo {
Ok(ElGamalCiphertext {
commitment: ciphertext_lo.commitment,
handle,
})
} else {
Err(ProofError::MissingCiphertext)
}
}
/// Extracts the lo ciphertexts associated with a transfer data
@ -167,15 +168,20 @@ impl TransferData {
let ciphertext_hi: TransferAmountEncryption = self.ciphertext_hi.try_into()?;
let handle_hi = match role {
Role::Source => ciphertext_hi.source_handle,
Role::Dest => ciphertext_hi.destination_handle,
Role::Auditor => ciphertext_hi.auditor_handle,
Role::Source => Some(ciphertext_hi.source_handle),
Role::Destination => Some(ciphertext_hi.destination_handle),
Role::Auditor => Some(ciphertext_hi.auditor_handle),
Role::WithdrawWithheldAuthority => None,
};
Ok(ElGamalCiphertext {
commitment: ciphertext_hi.commitment,
handle: handle_hi,
})
if let Some(handle) = handle_hi {
Ok(ElGamalCiphertext {
commitment: ciphertext_hi.commitment,
handle,
})
} else {
Err(ProofError::MissingCiphertext)
}
}
/// Decrypts transfer amount from transfer data
@ -449,11 +455,11 @@ impl TransferPubkeys {
let (source_pubkey, destination_pubkey, auditor_pubkey) = array_refs![bytes, 32, 32, 32];
let source_pubkey =
ElGamalPubkey::from_bytes(source_pubkey).ok_or(ProofError::Verification)?;
ElGamalPubkey::from_bytes(source_pubkey).ok_or(ProofError::Decryption)?;
let destination_pubkey =
ElGamalPubkey::from_bytes(destination_pubkey).ok_or(ProofError::Verification)?;
ElGamalPubkey::from_bytes(destination_pubkey).ok_or(ProofError::Decryption)?;
let auditor_pubkey =
ElGamalPubkey::from_bytes(auditor_pubkey).ok_or(ProofError::Verification)?;
ElGamalPubkey::from_bytes(auditor_pubkey).ok_or(ProofError::Decryption)?;
Ok(Self {
source_pubkey,
@ -574,26 +580,7 @@ mod test {
assert!(transfer_data.verify().is_ok());
// Case 4: transfer amount too big
// create source account spendable ciphertext
let spendable_balance: u64 = u64::max_value();
let spendable_ciphertext = source_keypair.public.encrypt(spendable_balance);
// transfer amount
let transfer_amount: u64 = 1u64 << (TRANSFER_AMOUNT_LO_BITS + TRANSFER_AMOUNT_HI_BITS);
// create transfer data
let transfer_data = TransferData::new(
transfer_amount,
(spendable_balance, &spendable_ciphertext),
&source_keypair,
(&dest_pk, &auditor_pk),
);
assert!(transfer_data.is_err());
// Case 5: invalid destination or auditor pubkey
// Case 4: invalid destination or auditor pubkey
let spendable_balance: u64 = 0;
let spendable_ciphertext = source_keypair.public.encrypt(spendable_balance);
@ -667,7 +654,9 @@ mod test {
);
assert_eq!(
transfer_data.decrypt_amount(Role::Dest, &dest_sk).unwrap(),
transfer_data
.decrypt_amount(Role::Destination, &dest_sk)
.unwrap(),
550000_u64,
);

490
zk-token-sdk/src/instruction/transfer_with_fee.rs
View File

@ -14,13 +14,12 @@ use {
errors::ProofError,
instruction::{
combine_lo_hi_ciphertexts, combine_lo_hi_commitments, combine_lo_hi_openings,
split_u64, transfer::TransferAmountEncryption, Role, Verifiable,
combine_lo_hi_u64, split_u64, transfer::TransferAmountEncryption, Role, Verifiable,
},
range_proof::RangeProof,
sigma_proofs::{
equality_proof::CtxtCommEqualityProof,
fee_proof::FeeSigmaProof,
validity_proof::{AggregatedValidityProof, ValidityProof},
equality_proof::CtxtCommEqualityProof, fee_proof::FeeSigmaProof,
validity_proof::AggregatedValidityProof,
},
transcript::TranscriptProtocol,
},
@ -45,7 +44,11 @@ const TRANSFER_AMOUNT_LO_NEGATED_BITS: usize = 16;
#[cfg(not(target_os = "solana"))]
const TRANSFER_AMOUNT_HI_BITS: usize = 32;
#[cfg(not(target_os = "solana"))]
const TRANSFER_DELTA_BITS: usize = 64;
const TRANSFER_DELTA_BITS: usize = 48;
#[cfg(not(target_os = "solana"))]
const FEE_AMOUNT_LO_BITS: usize = 16;
#[cfg(not(target_os = "solana"))]
const FEE_AMOUNT_HI_BITS: usize = 32;
#[cfg(not(target_os = "solana"))]
lazy_static::lazy_static! {
@ -58,10 +61,10 @@ lazy_static::lazy_static! {
#[derive(Clone, Copy, Pod, Zeroable)]
#[repr(C)]
pub struct TransferWithFeeData {
/// Group encryption of the low 32 bites of the transfer amount
/// Group encryption of the low 16 bites of the transfer amount
pub ciphertext_lo: pod::TransferAmountEncryption,
/// Group encryption of the high 32 bits of the transfer amount
/// Group encryption of the high 48 bits of the transfer amount
pub ciphertext_hi: pod::TransferAmountEncryption,
/// The public encryption keys associated with the transfer: source, dest, and auditor
@ -70,8 +73,11 @@ pub struct TransferWithFeeData {
/// The final spendable ciphertext after the transfer,
pub new_source_ciphertext: pod::ElGamalCiphertext,
// transfer fee encryption
pub fee_ciphertext: pod::FeeEncryption,
// transfer fee encryption of the low 16 bits of the transfer fee amount
pub fee_ciphertext_lo: pod::FeeEncryption,
// transfer fee encryption of the hi 32 bits of the transfer fee amount
pub fee_ciphertext_hi: pod::FeeEncryption,
// fee parameters
pub fee_parameters: pod::FeeParameters,
@ -91,11 +97,7 @@ impl TransferWithFeeData {
withdraw_withheld_authority_pubkey: &ElGamalPubkey,
) -> Result<Self, ProofError> {
// split and encrypt transfer amount
let (amount_lo, amount_hi) = split_u64(
transfer_amount,
TRANSFER_AMOUNT_LO_BITS,
TRANSFER_AMOUNT_HI_BITS,
)?;
let (amount_lo, amount_hi) = split_u64(transfer_amount, TRANSFER_AMOUNT_LO_BITS);
let (ciphertext_lo, opening_lo) = TransferAmountEncryption::new(
amount_lo,
@ -132,7 +134,9 @@ impl TransferWithFeeData {
TRANSFER_AMOUNT_LO_BITS,
);
// calculate and encrypt fee
// calculate fee
//
// TODO: add comment on delta fee
let (fee_amount, delta_fee) =
calculate_fee(transfer_amount, fee_parameters.fee_rate_basis_points)
.ok_or(ProofError::Generation)?;
@ -141,8 +145,17 @@ impl TransferWithFeeData {
let fee_to_encrypt =
u64::conditional_select(&fee_parameters.maximum_fee, &fee_amount, below_max);
let (fee_ciphertext, opening_fee) = FeeEncryption::new(
fee_to_encrypt,
// split and encrypt fee
let (fee_to_encrypt_lo, fee_to_encrypt_hi) = split_u64(fee_to_encrypt, FEE_AMOUNT_LO_BITS);
let (fee_ciphertext_lo, opening_fee_lo) = FeeEncryption::new(
fee_to_encrypt_lo,
destination_pubkey,
withdraw_withheld_authority_pubkey,
);
let (fee_ciphertext_hi, opening_fee_hi) = FeeEncryption::new(
fee_to_encrypt_hi,
destination_pubkey,
withdraw_withheld_authority_pubkey,
);
@ -157,14 +170,16 @@ impl TransferWithFeeData {
let pod_ciphertext_lo: pod::TransferAmountEncryption = ciphertext_lo.to_pod();
let pod_ciphertext_hi: pod::TransferAmountEncryption = ciphertext_hi.to_pod();
let pod_new_source_ciphertext: pod::ElGamalCiphertext = new_source_ciphertext.into();
let pod_fee_ciphertext: pod::FeeEncryption = fee_ciphertext.to_pod();
let pod_fee_ciphertext_lo: pod::FeeEncryption = fee_ciphertext_lo.to_pod();
let pod_fee_ciphertext_hi: pod::FeeEncryption = fee_ciphertext_hi.to_pod();
let mut transcript = TransferWithFeeProof::transcript_new(
&pod_transfer_with_fee_pubkeys,
&pod_ciphertext_lo,
&pod_ciphertext_hi,
&pod_new_source_ciphertext,
&pod_fee_ciphertext,
&pod_fee_ciphertext_lo,
&pod_fee_ciphertext_hi,
);
let proof = TransferWithFeeProof::new(
@ -173,7 +188,8 @@ impl TransferWithFeeData {
source_keypair,
(destination_pubkey, auditor_pubkey),
(new_spendable_balance, &new_source_ciphertext),
(fee_to_encrypt, &fee_ciphertext, &opening_fee),
(fee_to_encrypt_lo, &fee_ciphertext_lo, &opening_fee_lo),
(fee_to_encrypt_hi, &fee_ciphertext_hi, &opening_fee_hi),
delta_fee,
withdraw_withheld_authority_pubkey,
fee_parameters,
@ -185,7 +201,8 @@ impl TransferWithFeeData {
ciphertext_hi: pod_ciphertext_hi,
transfer_with_fee_pubkeys: pod_transfer_with_fee_pubkeys,
new_source_ciphertext: pod_new_source_ciphertext,
fee_ciphertext: pod_fee_ciphertext,
fee_ciphertext_lo: pod_fee_ciphertext_lo,
fee_ciphertext_hi: pod_fee_ciphertext_hi,
fee_parameters: fee_parameters.into(),
proof,
})
@ -196,15 +213,20 @@ impl TransferWithFeeData {
let ciphertext_lo: TransferAmountEncryption = self.ciphertext_lo.try_into()?;
let handle_lo = match role {
Role::Source => ciphertext_lo.source_handle,
Role::Dest => ciphertext_lo.destination_handle,
Role::Auditor => ciphertext_lo.auditor_handle,
Role::Source => Some(ciphertext_lo.source_handle),
Role::Destination => Some(ciphertext_lo.destination_handle),
Role::Auditor => Some(ciphertext_lo.auditor_handle),
Role::WithdrawWithheldAuthority => None,
};
Ok(ElGamalCiphertext {
commitment: ciphertext_lo.commitment,
handle: handle_lo,
})
if let Some(handle) = handle_lo {
Ok(ElGamalCiphertext {
commitment: ciphertext_lo.commitment,
handle,
})
} else {
Err(ProofError::MissingCiphertext)
}
}
/// Extracts the lo ciphertexts associated with a transfer-with-fee data
@ -212,15 +234,66 @@ impl TransferWithFeeData {
let ciphertext_hi: TransferAmountEncryption = self.ciphertext_hi.try_into()?;
let handle_hi = match role {
Role::Source => ciphertext_hi.source_handle,
Role::Dest => ciphertext_hi.destination_handle,
Role::Auditor => ciphertext_hi.auditor_handle,
Role::Source => Some(ciphertext_hi.source_handle),
Role::Destination => Some(ciphertext_hi.destination_handle),
Role::Auditor => Some(ciphertext_hi.auditor_handle),
Role::WithdrawWithheldAuthority => None,
};
Ok(ElGamalCiphertext {
commitment: ciphertext_hi.commitment,
handle: handle_hi,
})
if let Some(handle) = handle_hi {
Ok(ElGamalCiphertext {
commitment: ciphertext_hi.commitment,
handle,
})
} else {
Err(ProofError::MissingCiphertext)
}
}
/// Extracts the lo fee ciphertexts associated with a transfer_with_fee data
fn fee_ciphertext_lo(&self, role: Role) -> Result<ElGamalCiphertext, ProofError> {
let fee_ciphertext_lo: FeeEncryption = self.fee_ciphertext_lo.try_into()?;
let fee_handle_lo = match role {
Role::Source => None,
Role::Destination => Some(fee_ciphertext_lo.destination_handle),
Role::Auditor => None,
Role::WithdrawWithheldAuthority => {
Some(fee_ciphertext_lo.withdraw_withheld_authority_handle)
}
};
if let Some(handle) = fee_handle_lo {
Ok(ElGamalCiphertext {
commitment: fee_ciphertext_lo.commitment,
handle,
})
} else {
Err(ProofError::MissingCiphertext)
}
}
/// Extracts the hi fee ciphertexts associated with a transfer_with_fee data
fn fee_ciphertext_hi(&self, role: Role) -> Result<ElGamalCiphertext, ProofError> {
let fee_ciphertext_hi: FeeEncryption = self.fee_ciphertext_hi.try_into()?;
let fee_handle_hi = match role {
Role::Source => None,
Role::Destination => Some(fee_ciphertext_hi.destination_handle),
Role::Auditor => None,
Role::WithdrawWithheldAuthority => {
Some(fee_ciphertext_hi.withdraw_withheld_authority_handle)
}
};
if let Some(handle) = fee_handle_hi {
Ok(ElGamalCiphertext {
commitment: fee_ciphertext_hi.commitment,
handle,
})
} else {
Err(ProofError::MissingCiphertext)
}
}
/// Decrypts transfer amount from transfer-with-fee data
@ -232,10 +305,26 @@ impl TransferWithFeeData {
let amount_hi = ciphertext_hi.decrypt_u32(sk);
if let (Some(amount_lo), Some(amount_hi)) = (amount_lo, amount_hi) {
let two_power = 1 << TRANSFER_AMOUNT_LO_BITS;
Ok(amount_lo + two_power * amount_hi)
let shifted_amount_hi = amount_hi << TRANSFER_AMOUNT_LO_BITS;
Ok(amount_lo + shifted_amount_hi)
} else {
Err(ProofError::Verification)
Err(ProofError::Decryption)
}
}
/// Decrypts transfer amount from transfer-with-fee data
pub fn decrypt_fee_amount(&self, role: Role, sk: &ElGamalSecretKey) -> Result<u64, ProofError> {
let ciphertext_lo = self.fee_ciphertext_lo(role)?;
let ciphertext_hi = self.fee_ciphertext_hi(role)?;
let fee_amount_lo = ciphertext_lo.decrypt_u32(sk);
let fee_amount_hi = ciphertext_hi.decrypt_u32(sk);
if let (Some(fee_amount_lo), Some(fee_amount_hi)) = (fee_amount_lo, fee_amount_hi) {
let shifted_fee_amount_hi = fee_amount_hi << FEE_AMOUNT_LO_BITS;
Ok(fee_amount_lo + shifted_fee_amount_hi)
} else {
Err(ProofError::Decryption)
}
}
}
@ -248,7 +337,8 @@ impl Verifiable for TransferWithFeeData {
&self.ciphertext_lo,
&self.ciphertext_hi,
&self.new_source_ciphertext,
&self.fee_ciphertext,
&self.fee_ciphertext_lo,
&self.fee_ciphertext_hi,
);
let ciphertext_lo = self.ciphertext_lo.try_into()?;
@ -256,7 +346,8 @@ impl Verifiable for TransferWithFeeData {
let pubkeys_transfer_with_fee = self.transfer_with_fee_pubkeys.try_into()?;
let new_source_ciphertext = self.new_source_ciphertext.try_into()?;
let fee_ciphertext = self.fee_ciphertext.try_into()?;
let fee_ciphertext_lo = self.fee_ciphertext_lo.try_into()?;
let fee_ciphertext_hi = self.fee_ciphertext_hi.try_into()?;
let fee_parameters = self.fee_parameters.into();
self.proof.verify(
@ -264,7 +355,8 @@ impl Verifiable for TransferWithFeeData {
&ciphertext_hi,
&pubkeys_transfer_with_fee,
&new_source_ciphertext,
&fee_ciphertext,
&fee_ciphertext_lo,
&fee_ciphertext_hi,
fee_parameters,
&mut transcript,
)
@ -280,7 +372,7 @@ pub struct TransferWithFeeProof {
pub equality_proof: pod::CtxtCommEqualityProof,
pub ciphertext_amount_validity_proof: pod::AggregatedValidityProof,
pub fee_sigma_proof: pod::FeeSigmaProof,
pub fee_ciphertext_validity_proof: pod::ValidityProof,
pub fee_ciphertext_validity_proof: pod::AggregatedValidityProof,
pub range_proof: pod::RangeProof256,
}
@ -292,7 +384,8 @@ impl TransferWithFeeProof {
ciphertext_lo: &pod::TransferAmountEncryption,
ciphertext_hi: &pod::TransferAmountEncryption,
new_source_ciphertext: &pod::ElGamalCiphertext,
fee_ciphertext: &pod::FeeEncryption,
fee_ciphertext_lo: &pod::FeeEncryption,
fee_ciphertext_hi: &pod::FeeEncryption,
) -> Transcript {
let mut transcript = Transcript::new(b"FeeProof");
@ -319,11 +412,18 @@ impl TransferWithFeeProof {
transcript.append_ciphertext(b"ctxt-new-source", new_source_ciphertext);
transcript.append_commitment(b"comm-fee", &fee_ciphertext.commitment);
transcript.append_handle(b"fee-dest-handle", &fee_ciphertext.destination_handle);
transcript.append_commitment(b"comm-fee-lo", &fee_ciphertext_lo.commitment);
transcript.append_handle(b"handle-fee-lo-dest", &fee_ciphertext_lo.destination_handle);
transcript.append_handle(
b"handle-fee-auditor",
&fee_ciphertext.withdraw_withheld_authority_handle,
b"handle-fee-lo-auditor",
&fee_ciphertext_lo.withdraw_withheld_authority_handle,
);
transcript.append_commitment(b"comm-fee-hi", &fee_ciphertext_hi.commitment);
transcript.append_handle(b"handle-fee-hi-dest", &fee_ciphertext_hi.destination_handle);
transcript.append_handle(
b"handle-fee-hi-auditor",
&fee_ciphertext_hi.withdraw_withheld_authority_handle,
);
transcript
@ -337,8 +437,9 @@ impl TransferWithFeeProof {
source_keypair: &ElGamalKeypair,
(destination_pubkey, auditor_pubkey): (&ElGamalPubkey, &ElGamalPubkey),
(source_new_balance, new_source_ciphertext): (u64, &ElGamalCiphertext),
(fee_amount, fee_ciphertext, opening_fee): (u64, &FeeEncryption, &PedersenOpening),
// fee parameters
(fee_amount_lo, fee_ciphertext_lo, opening_fee_lo): (u64, &FeeEncryption, &PedersenOpening),
(fee_amount_hi, fee_ciphertext_hi, opening_fee_hi): (u64, &FeeEncryption, &PedersenOpening),
delta_fee: u64,
withdraw_withheld_authority_pubkey: &ElGamalPubkey,
fee_parameters: FeeParameters,
@ -349,13 +450,9 @@ impl TransferWithFeeProof {
// generate a Pedersen commitment for the remaining balance in source
let (new_source_commitment, opening_source) = Pedersen::new(source_new_balance);
let (claimed_commitment, opening_claimed) = Pedersen::new(delta_fee);
let pod_new_source_commitment: pod::PedersenCommitment = new_source_commitment.into();
let pod_claimed_commitment: pod::PedersenCommitment = claimed_commitment.into();
transcript.append_commitment(b"commitment-new-source", &pod_new_source_commitment);
transcript.append_commitment(b"commitment-claimed", &pod_claimed_commitment);
// generate equality_proof
let equality_proof = CtxtCommEqualityProof::new(
@ -374,88 +471,91 @@ impl TransferWithFeeProof {
transcript,
);
// compute claimed delta commitment
let (claimed_commitment, opening_claimed) = Pedersen::new(delta_fee);
let pod_claimed_commitment: pod::PedersenCommitment = claimed_commitment.into();
transcript.append_commitment(b"commitment-claimed", &pod_claimed_commitment);
let combined_commitment = combine_lo_hi_commitments(
&ciphertext_lo.commitment,
&ciphertext_hi.commitment,
TRANSFER_AMOUNT_LO_BITS,
);
let combined_opening =
combine_lo_hi_openings(opening_lo, opening_hi, TRANSFER_AMOUNT_LO_BITS);
let combined_fee_amount =
combine_lo_hi_u64(fee_amount_lo, fee_amount_hi, TRANSFER_AMOUNT_LO_BITS);
let combined_fee_commitment = combine_lo_hi_commitments(
&fee_ciphertext_lo.commitment,
&fee_ciphertext_hi.commitment,
TRANSFER_AMOUNT_LO_BITS,
);
let combined_fee_opening =
combine_lo_hi_openings(opening_fee_lo, opening_fee_hi, TRANSFER_AMOUNT_LO_BITS);
// compute real delta commitment
let (delta_commitment, opening_delta) = compute_delta_commitment_and_opening(
(&ciphertext_lo.commitment, opening_lo),
(&ciphertext_hi.commitment, opening_hi),
(&fee_ciphertext.commitment, opening_fee),
(&combined_commitment, &combined_opening),
(&combined_fee_commitment, &combined_fee_opening),
fee_parameters.fee_rate_basis_points,
);
let pod_delta_commitment: pod::PedersenCommitment = delta_commitment.into();
transcript.append_commitment(b"commitment-delta", &pod_delta_commitment);
// generate fee sigma proof
let fee_sigma_proof = FeeSigmaProof::new(
(fee_amount, &fee_ciphertext.commitment, opening_fee),
(
combined_fee_amount,
&combined_fee_commitment,
&combined_fee_opening,
),
(delta_fee, &delta_commitment, &opening_delta),
(&claimed_commitment, &opening_claimed),
fee_parameters.maximum_fee,
transcript,
);
let fee_ciphertext_validity_proof = ValidityProof::new(
// generate ciphertext validity proof for fee ciphertexts
let fee_ciphertext_validity_proof = AggregatedValidityProof::new(
(destination_pubkey, withdraw_withheld_authority_pubkey),
fee_amount,
opening_fee,
(fee_amount_lo, fee_amount_hi),
(opening_fee_lo, opening_fee_hi),
transcript,
);
// generate the range proof
let opening_claimed_negated = &PedersenOpening::default() - &opening_claimed;
let range_proof = if TRANSFER_AMOUNT_LO_BITS == 32 {
RangeProof::new(
vec![
source_new_balance,
transfer_amount_lo,
transfer_amount_hi,
delta_fee,
MAX_FEE_BASIS_POINTS - delta_fee,
],
vec![
TRANSFER_SOURCE_AMOUNT_BITS,
TRANSFER_AMOUNT_LO_BITS,
TRANSFER_AMOUNT_HI_BITS,
TRANSFER_DELTA_BITS,
TRANSFER_DELTA_BITS,
],
vec![
&opening_source,
opening_lo,
opening_hi,
&opening_claimed,
&opening_claimed_negated,
],
transcript,
)
} else {
let transfer_amount_lo_negated =
((1 << TRANSFER_AMOUNT_LO_NEGATED_BITS) - 1) - transfer_amount_lo;
let opening_lo_negated = &PedersenOpening::default() - opening_lo;
RangeProof::new(
vec![
source_new_balance,
transfer_amount_lo,
transfer_amount_lo_negated,
transfer_amount_hi,
delta_fee,
MAX_FEE_BASIS_POINTS - delta_fee,
],
vec![
TRANSFER_SOURCE_AMOUNT_BITS,
TRANSFER_AMOUNT_LO_BITS,
TRANSFER_AMOUNT_LO_NEGATED_BITS,
TRANSFER_AMOUNT_HI_BITS,
TRANSFER_DELTA_BITS,
TRANSFER_DELTA_BITS,
],
vec![
&opening_source,
opening_lo,
&opening_lo_negated,
opening_hi,
&opening_claimed,
&opening_claimed_negated,
],
transcript,
)
};
let range_proof = RangeProof::new(
vec![
source_new_balance,
transfer_amount_lo,
transfer_amount_hi,
delta_fee,
MAX_FEE_BASIS_POINTS - delta_fee,
fee_amount_lo,
fee_amount_hi,
],
vec![
TRANSFER_SOURCE_AMOUNT_BITS, // 64
TRANSFER_AMOUNT_LO_BITS, // 16
TRANSFER_AMOUNT_HI_BITS, // 32
TRANSFER_DELTA_BITS, // 48
TRANSFER_DELTA_BITS, // 48
FEE_AMOUNT_LO_BITS, // 16
FEE_AMOUNT_HI_BITS, // 32
],
vec![
&opening_source,
opening_lo,
opening_hi,
&opening_claimed,
&opening_claimed_negated,
opening_fee_lo,
opening_fee_hi,
],
transcript,
);
Self {
new_source_commitment: pod_new_source_commitment,
@ -474,13 +574,13 @@ impl TransferWithFeeProof {
ciphertext_hi: &TransferAmountEncryption,
transfer_with_fee_pubkeys: &TransferWithFeePubkeys,
new_spendable_ciphertext: &ElGamalCiphertext,
fee_ciphertext: &FeeEncryption,
// fee parameters
fee_ciphertext_lo: &FeeEncryption,
fee_ciphertext_hi: &FeeEncryption,
fee_parameters: FeeParameters,
transcript: &mut Transcript,
) -> Result<(), ProofError> {
transcript.append_commitment(b"commitment-new-source", &self.new_source_commitment);
transcript.append_commitment(b"commitment-claimed", &self.claimed_commitment);
let new_source_commitment: PedersenCommitment = self.new_source_commitment.try_into()?;
let claimed_commitment: PedersenCommitment = self.claimed_commitment.try_into()?;
@ -489,7 +589,7 @@ impl TransferWithFeeProof {
let ciphertext_amount_validity_proof: AggregatedValidityProof =
self.ciphertext_amount_validity_proof.try_into()?;
let fee_sigma_proof: FeeSigmaProof = self.fee_sigma_proof.try_into()?;
let fee_ciphertext_validity_proof: ValidityProof =
let fee_ciphertext_validity_proof: AggregatedValidityProof =
self.fee_ciphertext_validity_proof.try_into()?;
let range_proof: RangeProof = self.range_proof.try_into()?;
@ -517,30 +617,51 @@ impl TransferWithFeeProof {
)?;
// verify fee sigma proof
let delta_commitment = compute_delta_commitment(
transcript.append_commitment(b"commitment-claimed", &self.claimed_commitment);
let combined_commitment = combine_lo_hi_commitments(
&ciphertext_lo.commitment,
&ciphertext_hi.commitment,
&fee_ciphertext.commitment,
TRANSFER_AMOUNT_LO_BITS,
);
let combined_fee_commitment = combine_lo_hi_commitments(
&fee_ciphertext_lo.commitment,
&fee_ciphertext_hi.commitment,
TRANSFER_AMOUNT_LO_BITS,
);
let delta_commitment = compute_delta_commitment(
&combined_commitment,
&combined_fee_commitment,
fee_parameters.fee_rate_basis_points,
);
let pod_delta_commitment: pod::PedersenCommitment = delta_commitment.into();
transcript.append_commitment(b"commitment-delta", &pod_delta_commitment);
// verify fee sigma proof
fee_sigma_proof.verify(
&fee_ciphertext.commitment,
&combined_fee_commitment,
&delta_commitment,
&claimed_commitment,
fee_parameters.maximum_fee,
transcript,
)?;
// verify ciphertext validity proof for fee ciphertexts
fee_ciphertext_validity_proof.verify(
&fee_ciphertext.commitment,
(
&transfer_with_fee_pubkeys.destination_pubkey,
&transfer_with_fee_pubkeys.withdraw_withheld_authority_pubkey,
),
(&fee_ciphertext_lo.commitment, &fee_ciphertext_hi.commitment),
(
&fee_ciphertext.destination_handle,
&fee_ciphertext.withdraw_withheld_authority_handle,
&fee_ciphertext_lo.destination_handle,
&fee_ciphertext_hi.destination_handle,
),
(
&fee_ciphertext_lo.withdraw_withheld_authority_handle,
&fee_ciphertext_hi.withdraw_withheld_authority_handle,
),
transcript,
)?;
@ -549,34 +670,27 @@ impl TransferWithFeeProof {
let new_source_commitment = self.new_source_commitment.try_into()?;
let claimed_commitment_negated = &(*COMMITMENT_MAX_FEE_BASIS_POINTS) - &claimed_commitment;
if TRANSFER_AMOUNT_LO_BITS == 32 {
range_proof.verify(
vec![
&new_source_commitment,
&ciphertext_lo.commitment,
&ciphertext_hi.commitment,
&claimed_commitment,
&claimed_commitment_negated,
],
vec![64, 32, 32, 64, 64],
transcript,
)?;
} else {
let commitment_lo_negated = &(*COMMITMENT_MAX) - &ciphertext_lo.commitment;
range_proof.verify(
vec![
&new_source_commitment,
&ciphertext_lo.commitment,
&commitment_lo_negated,
&ciphertext_hi.commitment,
&claimed_commitment,
&claimed_commitment_negated,
],
vec![64, 16, 16, 32, 64, 64],
transcript,
)?;
}
range_proof.verify(
vec![
&new_source_commitment,
&ciphertext_lo.commitment,
&ciphertext_hi.commitment,
&claimed_commitment,
&claimed_commitment_negated,
&fee_ciphertext_lo.commitment,
&fee_ciphertext_hi.commitment,
],
vec![
TRANSFER_SOURCE_AMOUNT_BITS, // 64
TRANSFER_AMOUNT_LO_BITS, // 16
TRANSFER_AMOUNT_HI_BITS, // 32
TRANSFER_DELTA_BITS, // 48
TRANSFER_DELTA_BITS, // 48
FEE_AMOUNT_LO_BITS, // 16
FEE_AMOUNT_HI_BITS, // 32
],
transcript,
)?;
Ok(())
}
@ -610,14 +724,14 @@ impl TransferWithFeePubkeys {
array_refs![bytes, 32, 32, 32, 32];
let source_pubkey =
ElGamalPubkey::from_bytes(source_pubkey).ok_or(ProofError::Verification)?;
let destination_pubkey =
ElGamalPubkey::from_bytes(destination_pubkey).ok_or(ProofError::Verification)?;
ElGamalPubkey::from_bytes(source_pubkey).ok_or(ProofError::PubkeyDeserialization)?;
let destination_pubkey = ElGamalPubkey::from_bytes(destination_pubkey)
.ok_or(ProofError::PubkeyDeserialization)?;
let auditor_pubkey =
ElGamalPubkey::from_bytes(auditor_pubkey).ok_or(ProofError::Verification)?;
ElGamalPubkey::from_bytes(auditor_pubkey).ok_or(ProofError::PubkeyDeserialization)?;
let withdraw_withheld_authority_pubkey =
ElGamalPubkey::from_bytes(withdraw_withheld_authority_pubkey)
.ok_or(ProofError::Verification)?;
.ok_or(ProofError::PubkeyDeserialization)?;
Ok(Self {
source_pubkey,
@ -716,36 +830,28 @@ fn calculate_fee(transfer_amount: u64, fee_rate_basis_points: u16) -> Option<(u6
#[cfg(not(target_os = "solana"))]
fn compute_delta_commitment_and_opening(
(commitment_lo, opening_lo): (&PedersenCommitment, &PedersenOpening),
(commitment_hi, opening_hi): (&PedersenCommitment, &PedersenOpening),
(fee_commitment, opening_fee): (&PedersenCommitment, &PedersenOpening),
(combined_commitment, combined_opening): (&PedersenCommitment, &PedersenOpening),
(combined_fee_commitment, combined_fee_opening): (&PedersenCommitment, &PedersenOpening),
fee_rate_basis_points: u16,
) -> (PedersenCommitment, PedersenOpening) {
let fee_rate_scalar = Scalar::from(fee_rate_basis_points);
let delta_commitment = combined_fee_commitment * Scalar::from(MAX_FEE_BASIS_POINTS)
- combined_commitment * &fee_rate_scalar;
let delta_opening = combined_fee_opening * Scalar::from(MAX_FEE_BASIS_POINTS)
- combined_opening * &fee_rate_scalar;
let delta_commitment = fee_commitment * Scalar::from(MAX_FEE_BASIS_POINTS)
- &(&combine_lo_hi_commitments(commitment_lo, commitment_hi, TRANSFER_AMOUNT_LO_BITS)
* &fee_rate_scalar);
let opening_delta = opening_fee * Scalar::from(MAX_FEE_BASIS_POINTS)
- &(&combine_lo_hi_openings(opening_lo, opening_hi, TRANSFER_AMOUNT_LO_BITS)
* &fee_rate_scalar);
(delta_commitment, opening_delta)
(delta_commitment, delta_opening)
}
#[cfg(not(target_os = "solana"))]
fn compute_delta_commitment(
commitment_lo: &PedersenCommitment,
commitment_hi: &PedersenCommitment,
fee_commitment: &PedersenCommitment,
combined_commitment: &PedersenCommitment,
combined_fee_commitment: &PedersenCommitment,
fee_rate_basis_points: u16,
) -> PedersenCommitment {
let fee_rate_scalar = Scalar::from(fee_rate_basis_points);
fee_commitment * Scalar::from(MAX_FEE_BASIS_POINTS)
- &(&combine_lo_hi_commitments(commitment_lo, commitment_hi, TRANSFER_AMOUNT_LO_BITS)
* &fee_rate_scalar)
combined_fee_commitment * Scalar::from(MAX_FEE_BASIS_POINTS)
- combined_commitment * &fee_rate_scalar
}
#[cfg(test)]
@ -829,29 +935,7 @@ mod test {
assert!(fee_data.verify().is_ok());
// Case 4: transfer amount too big
let spendable_balance: u64 = u64::max_value();
let spendable_ciphertext = source_keypair.public.encrypt(spendable_balance);
let transfer_amount: u64 = 1u64 << (TRANSFER_AMOUNT_LO_BITS + TRANSFER_AMOUNT_HI_BITS);
let fee_parameters = FeeParameters {
fee_rate_basis_points: 400,
maximum_fee: 3,
};
let fee_data = TransferWithFeeData::new(
transfer_amount,
(spendable_balance, &spendable_ciphertext),
&source_keypair,
(&destination_pubkey, &auditor_pubkey),
fee_parameters,
&withdraw_withheld_authority_pubkey,
);
assert!(fee_data.is_err());
// Case 5: invalid destination, auditor, or withdraw authority pubkeys
// Case 4: invalid destination, auditor, or withdraw authority pubkeys
let spendable_balance: u64 = 120;
let spendable_ciphertext = source_keypair.public.encrypt(spendable_balance);

2
zk-token-sdk/src/zk_token_elgamal/ops.rs
View File

@ -201,7 +201,7 @@ mod tests {
fn test_transfer_arithmetic() {
// transfer amount
let transfer_amount: u64 = 55;
let (amount_lo, amount_hi) = split_u64(transfer_amount, 16, 32).unwrap();
let (amount_lo, amount_hi) = split_u64(transfer_amount, 16);
// generate public keys
let source_pk = ElGamalKeypair::new_rand().public;