Module 0x1::confidential_range_proofs

The confidential_range_proofs module provides range proof verification helpers used by the Confidential Asset protocol. Proof enums and their verify/prove functions live in confidential_asset (since Move disallows friend modules from constructing/destructuring enum variants).

• Constants
• Function assert_valid_range_proof
• Function verify_batch_range_proof
• Function get_bulletproofs_dst
• Function verify_batch_range_proof_internal
• Specification
  • Function verify_batch_range_proof_internal

use 0x1::confidential_balance;
use 0x1::error;
use 0x1::features;
use 0x1::ristretto255;
use 0x1::ristretto255_bulletproofs;

Constants

The native functions have not been rolled out yet.

const E_NATIVE_FUN_NOT_AVAILABLE: u64 = 4;

DST exceeds 256 bytes.

const E_DST_TOO_LONG: u64 = 3;

const BULLETPROOFS_DST: vector<u8> = [65, 112, 116, 111, 115, 67, 111, 110, 102, 105, 100, 101, 110, 116, 105, 97, 108, 65, 115, 115, 101, 116, 47, 66, 117, 108, 108, 101, 116, 112, 114, 111, 111, 102, 82, 97, 110, 103, 101, 80, 114, 111, 111, 102];

const ERANGE_PROOF_VERIFICATION_FAILED: u64 = 2;

Function assert_valid_range_proof

Asserts that the given commitment chunks are each in [0, 2^16) via a range proof.

public(friend) fun assert_valid_range_proof(commitments: &vector<ristretto255::CompressedRistretto>, zkrp: &ristretto255_bulletproofs::RangeProof)

public(friend) fun assert_valid_range_proof(
    commitments: &vector<CompressedRistretto>,
    zkrp: &RangeProof
) {
    assert!(
        verify_batch_range_proof(
            commitments,
            &ristretto255::basepoint(),
            &ristretto255::hash_to_point_base(),
            zkrp,
            confidential_balance::get_chunk_size_bits(),
            BULLETPROOFS_DST
        ),
        error::out_of_range(ERANGE_PROOF_VERIFICATION_FAILED)
    );
}

Function verify_batch_range_proof

Verifies a batch range proof for commitments, ensuring all committed values are in [0, 2^num_bits).

fun verify_batch_range_proof(comms: &vector<ristretto255::CompressedRistretto>, val_base: &ristretto255::RistrettoPoint, rand_base: &ristretto255::RistrettoPoint, proof: &ristretto255_bulletproofs::RangeProof, num_bits: u64, dst: vector<u8>): bool

fun verify_batch_range_proof(
    comms: &vector<CompressedRistretto>,
    val_base: &RistrettoPoint, rand_base: &RistrettoPoint,
    proof: &RangeProof, num_bits: u64, dst: vector<u8>): bool
{
    assert!(features::bulletproofs_batch_enabled(), error::invalid_state(E_NATIVE_FUN_NOT_AVAILABLE));
    assert!(dst.length() <= 256, error::invalid_argument(E_DST_TOO_LONG));

    let comms = comms.map_ref(|com| com.point_to_bytes());

    verify_batch_range_proof_internal(
        comms,
        val_base, rand_base,
        bulletproofs::range_proof_to_bytes(proof), num_bits, dst
    )
}

Function get_bulletproofs_dst

Returns the DST for the range proofs.

#[view]
public fun get_bulletproofs_dst(): vector<u8>

public fun get_bulletproofs_dst(): vector<u8> {
    BULLETPROOFS_DST
}

Function verify_batch_range_proof_internal

fun verify_batch_range_proof_internal(comms: vector<vector<u8>>, val_base: &ristretto255::RistrettoPoint, rand_base: &ristretto255::RistrettoPoint, proof: vector<u8>, num_bits: u64, dst: vector<u8>): bool

native fun verify_batch_range_proof_internal(
    comms: vector<vector<u8>>,
    val_base: &RistrettoPoint,
    rand_base: &RistrettoPoint,
    proof: vector<u8>,
    num_bits: u64,
    dst: vector<u8>): bool;

Specification

Function verify_batch_range_proof_internal

fun verify_batch_range_proof_internal(comms: vector<vector<u8>>, val_base: &ristretto255::RistrettoPoint, rand_base: &ristretto255::RistrettoPoint, proof: vector<u8>, num_bits: u64, dst: vector<u8>): bool

pragma opaque;