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samkim-cryptosamkim-crypto
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add proof extraction logic for confidential mint and burn
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‎token/confidential-transfer/proof-extraction/src/burn.rs

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use {
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crate::{encryption::PodBurnAmountCiphertext, errors::TokenProofExtractionError},
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solana_zk_sdk::{
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encryption::pod::elgamal::{PodElGamalCiphertext, PodElGamalPubkey},
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zk_elgamal_proof_program::proof_data::{
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BatchedGroupedCiphertext2HandlesValidityProofContext, BatchedRangeProofContext,
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CiphertextCommitmentEqualityProofContext,
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},
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},
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};
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/// The public keys associated with a confidential burn
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pub struct BurnPubkeys {
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pub source: PodElGamalPubkey,
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pub auditor: PodElGamalPubkey,
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}
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/// The proof context information needed to process a confidential burn
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/// instruction
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pub struct BurnProofContext {
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pub burn_amount_ciphertext_lo: PodBurnAmountCiphertext,
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pub burn_amount_ciphertext_hi: PodBurnAmountCiphertext,
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pub burn_pubkeys: BurnPubkeys,
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pub remaining_balance_ciphertext: PodElGamalCiphertext,
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}
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impl BurnProofContext {
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pub fn verify_and_extract(
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equality_proof_context: &CiphertextCommitmentEqualityProofContext,
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ciphertext_validity_proof_context: &BatchedGroupedCiphertext2HandlesValidityProofContext,
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range_proof_context: &BatchedRangeProofContext,
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) -> Result<Self, TokenProofExtractionError> {
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// The equality proof context consists of the source ElGamal public key, the new
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// source available balance ciphertext, and the new source avaialble
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// balance commitment. The public key should be checked with ciphertext
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// validity proof context for consistency and the commitment should be
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// checked with range proof for consistency. The public key and
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// the cihpertext should be returned as part of `BurnProofContext`.
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let CiphertextCommitmentEqualityProofContext {
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pubkey: source_elgamal_pubkey_from_equality_proof,
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ciphertext: remaining_balance_ciphertext,
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commitment: remaining_balance_commitment,
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} = equality_proof_context;
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// The ciphertext validity proof context consists of the source ElGamal public
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// key, the auditor ElGamal public key, and the grouped ElGamal
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// ciphertexts for the low and high bits of the burn amount. The source
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// ElGamal public key should be checked with equality
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// proof for consistency and the rest of the data should be returned as part of
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// `BurnProofContext`.
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let BatchedGroupedCiphertext2HandlesValidityProofContext {
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first_pubkey: source_elgamal_pubkey_from_validity_proof,
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second_pubkey: auditor_elgamal_pubkey,
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grouped_ciphertext_lo: burn_amount_ciphertext_lo,
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grouped_ciphertext_hi: burn_amount_ciphertext_hi,
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} = ciphertext_validity_proof_context;
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// The range proof context consists of the Pedersen commitments and bit-lengths
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// for which the range proof is proved. The commitments must consist of
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// three commitments pertaining to the new source available balance, the
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// low bits of the burn amount, and high bits of the burn
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// amount. These commitments must be checked for bit lengths `64`, `16`,
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// and `32`.
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let BatchedRangeProofContext {
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commitments: range_proof_commitments,
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bit_lengths: range_proof_bit_lengths,
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} = range_proof_context;
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// check that the source pubkey is consistent between equality and ciphertext
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// validity proofs
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if source_elgamal_pubkey_from_equality_proof != source_elgamal_pubkey_from_validity_proof {
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return Err(TokenProofExtractionError::ElGamalPubkeyMismatch);
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}
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// check that the range proof was created for the correct set of Pedersen
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// commitments
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let burn_amount_commitment_lo = burn_amount_ciphertext_lo.extract_commitment();
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let burn_amount_commitment_hi = burn_amount_ciphertext_hi.extract_commitment();
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let expected_commitments = [
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*remaining_balance_commitment,
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burn_amount_commitment_lo,
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burn_amount_commitment_hi,
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];
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if !range_proof_commitments
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.iter()
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.zip(expected_commitments.iter())
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.all(|(proof_commitment, expected_commitment)| proof_commitment == expected_commitment)
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{
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return Err(TokenProofExtractionError::PedersenCommitmentMismatch);
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}
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// check that the range proof was created for the correct number of bits
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const REMAINING_BALANCE_BIT_LENGTH: u8 = 64;
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const BURN_AMOUNT_LO_BIT_LENGTH: u8 = 16;
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const BURN_AMOUNT_HI_BIT_LENGTH: u8 = 32;
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const PADDING_BIT_LENGTH: u8 = 16;
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let expected_bit_lengths = [
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REMAINING_BALANCE_BIT_LENGTH,
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BURN_AMOUNT_LO_BIT_LENGTH,
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BURN_AMOUNT_HI_BIT_LENGTH,
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PADDING_BIT_LENGTH,
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]
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.iter();
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if !range_proof_bit_lengths
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.iter()
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.zip(expected_bit_lengths)
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.all(|(proof_len, expected_len)| proof_len == expected_len)
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{
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return Err(TokenProofExtractionError::RangeProofLengthMismatch);
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}
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let burn_pubkeys = BurnPubkeys {
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source: *source_elgamal_pubkey_from_equality_proof,
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auditor: *auditor_elgamal_pubkey,
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};
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Ok(BurnProofContext {
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burn_amount_ciphertext_lo: PodBurnAmountCiphertext(*burn_amount_ciphertext_lo),
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burn_amount_ciphertext_hi: PodBurnAmountCiphertext(*burn_amount_ciphertext_hi),
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burn_pubkeys,
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remaining_balance_ciphertext: *remaining_balance_ciphertext,
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})
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}
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}

‎token/confidential-transfer/proof-extraction/src/encryption.rs

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@@ -46,3 +46,11 @@ impl PodFeeCiphertext {
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.map_err(|_| TokenProofExtractionError::CiphertextExtraction)
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}
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}
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#[derive(Clone, Copy, Debug, Eq, PartialEq)]
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#[repr(C)]
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pub struct PodBurnAmountCiphertext(pub(crate) PodGroupedElGamalCiphertext2Handles);
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#[derive(Clone, Copy, Debug, Eq, PartialEq)]
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#[repr(C)]
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pub struct PodMintAmountCiphertext(pub(crate) PodGroupedElGamalCiphertext2Handles);

‎token/confidential-transfer/proof-extraction/src/lib.rs

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pub mod burn;
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pub mod encryption;
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pub mod errors;
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pub mod mint;
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pub mod transfer;
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pub mod transfer_with_fee;
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pub mod withdraw;

‎token/confidential-transfer/proof-extraction/src/mint.rs

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use {
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crate::{encryption::PodMintAmountCiphertext, errors::TokenProofExtractionError},
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solana_zk_sdk::{
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encryption::pod::elgamal::PodElGamalPubkey,
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zk_elgamal_proof_program::proof_data::{
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BatchedGroupedCiphertext2HandlesValidityProofContext, BatchedRangeProofContext,
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},
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},
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};
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/// The public keys associated with a confidential mint
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pub struct MintPubkeys {
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pub destination: PodElGamalPubkey,
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pub auditor: PodElGamalPubkey,
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}
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/// The proof context information needed to process a confidential mint
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/// instruction
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pub struct MintProofContext {
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pub mint_amount_ciphertext_lo: PodMintAmountCiphertext,
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pub mint_amount_ciphertext_hi: PodMintAmountCiphertext,
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pub mint_pubkeys: MintPubkeys,
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}
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impl MintProofContext {
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pub fn verify_and_extract(
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ciphertext_validity_proof_context: &BatchedGroupedCiphertext2HandlesValidityProofContext,
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range_proof_context: &BatchedRangeProofContext,
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) -> Result<Self, TokenProofExtractionError> {
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// The ciphertext validity proof context consists of the destination ElGamal
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// public key, the auditor ElGamal public key, and the grouped ElGamal
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// ciphertexts for the low and high bits of the burn amount. These
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// fields should be returned as part of `MintProofContext`.
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let BatchedGroupedCiphertext2HandlesValidityProofContext {
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first_pubkey: destination_elgamal_pubkey,
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second_pubkey: auditor_elgamal_pubkey,
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grouped_ciphertext_lo: mint_amount_ciphertext_lo,
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grouped_ciphertext_hi: mint_amount_ciphertext_hi,
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} = ciphertext_validity_proof_context;
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// The range proof context consists of the Pedersen commitments and bit-lengths
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// for which the range proof is proved. The commitments must consist of
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// two commitments pertaining to the the
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// low bits of the mint amount, and high bits of the mint
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// amount. These commitments must be checked for bit lengths `16` and
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// and `32`.
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let BatchedRangeProofContext {
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commitments: range_proof_commitments,
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bit_lengths: range_proof_bit_lengths,
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} = range_proof_context;
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// check that the range proof was created for the correct set of Pedersen
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// commitments
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let mint_amount_commitment_lo = mint_amount_ciphertext_lo.extract_commitment();
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let mint_amount_commitment_hi = mint_amount_ciphertext_hi.extract_commitment();
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let expected_commitments = [mint_amount_commitment_lo, mint_amount_commitment_hi];
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if !range_proof_commitments
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.iter()
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.zip(expected_commitments.iter())
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.all(|(proof_commitment, expected_commitment)| proof_commitment == expected_commitment)
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{
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return Err(TokenProofExtractionError::PedersenCommitmentMismatch);
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}
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// check that the range proof was created for the correct number of bits
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const MINT_AMOUNT_LO_BIT_LENGTH: u8 = 16;
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const MINT_AMOUNT_HI_BIT_LENGTH: u8 = 32;
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const PADDING_BIT_LENGTH: u8 = 16;
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let expected_bit_lengths = [
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MINT_AMOUNT_LO_BIT_LENGTH,
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MINT_AMOUNT_HI_BIT_LENGTH,
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PADDING_BIT_LENGTH,
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]
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.iter();
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if !range_proof_bit_lengths
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.iter()
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.zip(expected_bit_lengths)
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.all(|(proof_len, expected_len)| proof_len == expected_len)
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{
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return Err(TokenProofExtractionError::RangeProofLengthMismatch);
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}
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let mint_pubkeys = MintPubkeys {
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destination: *destination_elgamal_pubkey,
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auditor: *auditor_elgamal_pubkey,
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};
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Ok(MintProofContext {
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mint_amount_ciphertext_lo: PodMintAmountCiphertext(*mint_amount_ciphertext_lo),
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mint_amount_ciphertext_hi: PodMintAmountCiphertext(*mint_amount_ciphertext_hi),
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mint_pubkeys,
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})
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}
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}

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