mirror of
https://github.com/arnaucube/ark-r1cs-std.git
synced 2026-01-10 16:01:28 +01:00
Add UInt64 used for representing Merkle tree node locations
This commit is contained in:
weikeng
Pratyush Mishra
@@ -6,6 +6,7 @@ use algebra::Field;
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use r1cs_core::{ConstraintSystem, SynthesisError};
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pub mod boolean;
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pub mod uint64;
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pub mod uint32;
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pub mod uint8;
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@@ -167,9 +167,14 @@ impl UInt32 {
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// Make some arbitrary bounds for ourselves to avoid overflows
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// in the scalar field
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assert!(ConstraintF::Params::MODULUS_BITS >= 64);
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assert!(operands.len() >= 2); // Weird trivial cases that should never happen
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assert!(operands.len() >= 1);
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assert!(operands.len() <= 10);
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if operands.len() == 1 {
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return Ok(operands[0].clone());
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}
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// Compute the maximum value of the sum so we allocate enough bits for
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// the result
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let mut max_value = (operands.len() as u64) * u64::from(u32::max_value());
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549
r1cs-std/src/bits/uint64.rs
Normal file
549
r1cs-std/src/bits/uint64.rs
Normal file
@@ -0,0 +1,549 @@
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use algebra::{Field, FpParameters, PrimeField};
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use r1cs_core::{ConstraintSystem, LinearCombination, SynthesisError};
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use crate::{
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boolean::{AllocatedBit, Boolean},
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prelude::*,
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Assignment, Vec,
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};
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/// Represents an interpretation of 64 `Boolean` objects as an
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/// unsigned integer.
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#[derive(Clone, Debug)]
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pub struct UInt64 {
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// Least significant bit_gadget first
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bits: Vec<Boolean>,
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value: Option<u64>,
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}
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impl UInt64 {
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/// Construct a constant `UInt64` from a `u64`
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pub fn constant(value: u64) -> Self {
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let mut bits = Vec::with_capacity(64);
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let mut tmp = value;
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for _ in 0..64 {
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if tmp & 1 == 1 {
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bits.push(Boolean::constant(true))
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} else {
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bits.push(Boolean::constant(false))
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}
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tmp >>= 1;
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}
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UInt64 {
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bits,
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value: Some(value),
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}
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}
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/// Allocate a `UInt64` in the constraint system
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pub fn alloc<ConstraintF, CS>(mut cs: CS, value: Option<u64>) -> Result<Self, SynthesisError>
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where
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ConstraintF: Field,
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CS: ConstraintSystem<ConstraintF>,
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{
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let values = match value {
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Some(mut val) => {
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let mut v = Vec::with_capacity(64);
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for _ in 0..64 {
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v.push(Some(val & 1 == 1));
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val >>= 1;
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}
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v
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},
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None => vec![None; 64],
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};
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let bits = values
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.into_iter()
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.enumerate()
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.map(|(i, v)| {
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Ok(Boolean::from(AllocatedBit::alloc(
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cs.ns(|| format!("allocated bit_gadget {}", i)),
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|| v.get(),
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)?))
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})
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.collect::<Result<Vec<_>, SynthesisError>>()?;
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Ok(UInt64 { bits, value })
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}
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/// Turns this `UInt64` into its little-endian byte order representation.
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pub fn to_bits_le(&self) -> Vec<Boolean> {
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self.bits.clone()
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}
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/// Converts a little-endian byte order representation of bits into a
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/// `UInt64`.
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pub fn from_bits_le(bits: &[Boolean]) -> Self {
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assert_eq!(bits.len(), 64);
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let bits = bits.to_vec();
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let mut value = Some(0u64);
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for b in bits.iter().rev() {
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value.as_mut().map(|v| *v <<= 1);
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match b {
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&Boolean::Constant(b) => {
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if b {
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value.as_mut().map(|v| *v |= 1);
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}
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},
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&Boolean::Is(ref b) => match b.get_value() {
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Some(true) => {
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value.as_mut().map(|v| *v |= 1);
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},
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Some(false) => {},
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None => value = None,
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},
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&Boolean::Not(ref b) => match b.get_value() {
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Some(false) => {
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value.as_mut().map(|v| *v |= 1);
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},
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Some(true) => {},
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None => value = None,
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},
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}
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}
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Self { value, bits }
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}
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pub fn rotr(&self, by: usize) -> Self {
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let by = by % 64;
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let new_bits = self
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.bits
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.iter()
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.skip(by)
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.chain(self.bits.iter())
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.take(64)
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.cloned()
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.collect();
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UInt64 {
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bits: new_bits,
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value: self.value.map(|v| v.rotate_right(by as u32)),
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}
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}
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/// XOR this `UInt64` with another `UInt64`
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pub fn xor<ConstraintF, CS>(&self, mut cs: CS, other: &Self) -> Result<Self, SynthesisError>
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where
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ConstraintF: Field,
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CS: ConstraintSystem<ConstraintF>,
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{
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let new_value = match (self.value, other.value) {
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(Some(a), Some(b)) => Some(a ^ b),
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_ => None,
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};
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let bits = self
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.bits
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.iter()
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.zip(other.bits.iter())
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.enumerate()
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.map(|(i, (a, b))| Boolean::xor(cs.ns(|| format!("xor of bit_gadget {}", i)), a, b))
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.collect::<Result<_, _>>()?;
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Ok(UInt64 {
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bits,
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value: new_value,
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})
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}
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/// Perform modular addition of several `UInt64` objects.
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pub fn addmany<ConstraintF, CS>(mut cs: CS, operands: &[Self]) -> Result<Self, SynthesisError>
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where
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ConstraintF: PrimeField,
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CS: ConstraintSystem<ConstraintF>,
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{
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// Make some arbitrary bounds for ourselves to avoid overflows
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// in the scalar field
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assert!(ConstraintF::Params::MODULUS_BITS >= 128);
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assert!(operands.len() >= 1);
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assert!(operands.len() <= 10);
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if operands.len() == 1 {
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return Ok(operands[0].clone());
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}
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// Compute the maximum value of the sum so we allocate enough bits for
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// the result
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let mut max_value = (operands.len() as u128) * u128::from(u64::max_value());
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// Keep track of the resulting value
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let mut result_value = Some(0u64 as u128);
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// This is a linear combination that we will enforce to be "zero"
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let mut lc = LinearCombination::zero();
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let mut all_constants = true;
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// Iterate over the operands
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for op in operands {
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// Accumulate the value
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match op.value {
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Some(val) => {
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result_value.as_mut().map(|v| *v += u128::from(val));
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},
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None => {
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// If any of our operands have unknown value, we won't
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// know the value of the result
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result_value = None;
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},
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}
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// Iterate over each bit_gadget of the operand and add the operand to
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// the linear combination
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let mut coeff = ConstraintF::one();
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for bit in &op.bits {
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match *bit {
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Boolean::Is(ref bit) => {
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all_constants = false;
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// Add coeff * bit_gadget
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lc += (coeff, bit.get_variable());
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},
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Boolean::Not(ref bit) => {
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all_constants = false;
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// Add coeff * (1 - bit_gadget) = coeff * ONE - coeff * bit_gadget
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lc = lc + (coeff, CS::one()) - (coeff, bit.get_variable());
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},
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Boolean::Constant(bit) => {
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if bit {
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lc += (coeff, CS::one());
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}
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},
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}
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coeff.double_in_place();
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}
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}
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// The value of the actual result is modulo 2^64
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let modular_value = result_value.map(|v| v as u64);
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if all_constants && modular_value.is_some() {
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// We can just return a constant, rather than
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// unpacking the result into allocated bits.
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return Ok(UInt64::constant(modular_value.unwrap()));
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}
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// Storage area for the resulting bits
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let mut result_bits = vec![];
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// Allocate each bit_gadget of the result
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let mut coeff = ConstraintF::one();
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let mut i = 0;
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while max_value != 0 {
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// Allocate the bit_gadget
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let b = AllocatedBit::alloc(cs.ns(|| format!("result bit_gadget {}", i)), || {
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result_value.map(|v| (v >> i) & 1 == 1).get()
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})?;
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// Subtract this bit_gadget from the linear combination to ensure the sums
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// balance out
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lc = lc - (coeff, b.get_variable());
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result_bits.push(b.into());
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max_value >>= 1;
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i += 1;
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coeff.double_in_place();
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}
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// Enforce that the linear combination equals zero
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cs.enforce(|| "modular addition", |lc| lc, |lc| lc, |_| lc);
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// Discard carry bits that we don't care about
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result_bits.truncate(64);
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Ok(UInt64 {
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bits: result_bits,
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value: modular_value,
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})
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}
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}
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impl<ConstraintF: Field> ToBytesGadget<ConstraintF> for UInt64 {
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#[inline]
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fn to_bytes<CS: ConstraintSystem<ConstraintF>>(
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&self,
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_cs: CS,
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) -> Result<Vec<UInt8>, SynthesisError> {
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let value_chunks = match self.value.map(|val| {
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use algebra::bytes::ToBytes;
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let mut bytes = [0u8; 8];
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val.write(bytes.as_mut()).unwrap();
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bytes
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}) {
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Some(chunks) => [
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Some(chunks[0]),
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Some(chunks[1]),
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Some(chunks[2]),
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Some(chunks[3]),
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Some(chunks[4]),
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Some(chunks[5]),
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Some(chunks[6]),
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Some(chunks[7]),
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],
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None => [None, None, None, None, None, None, None, None],
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};
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let mut bytes = Vec::new();
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for (i, chunk8) in self.to_bits_le().chunks(8).enumerate() {
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let byte = UInt8 {
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bits: chunk8.to_vec(),
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value: value_chunks[i],
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};
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bytes.push(byte);
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}
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Ok(bytes)
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}
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fn to_bytes_strict<CS: ConstraintSystem<ConstraintF>>(
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&self,
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cs: CS,
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) -> Result<Vec<UInt8>, SynthesisError> {
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self.to_bytes(cs)
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}
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}
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impl PartialEq for UInt64 {
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fn eq(&self, other: &Self) -> bool {
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self.value.is_some() && other.value.is_some() && self.value == other.value
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}
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}
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impl Eq for UInt64 {}
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impl<ConstraintF: Field> ConditionalEqGadget<ConstraintF> for UInt64 {
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fn conditional_enforce_equal<CS: ConstraintSystem<ConstraintF>>(
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&self,
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mut cs: CS,
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other: &Self,
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condition: &Boolean,
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) -> Result<(), SynthesisError> {
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for (i, (a, b)) in self.bits.iter().zip(&other.bits).enumerate() {
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a.conditional_enforce_equal(
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&mut cs.ns(|| format!("uint64_equal_{}", i)),
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b,
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condition,
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)?;
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}
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Ok(())
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}
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fn cost() -> usize {
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64 * <Boolean as ConditionalEqGadget<ConstraintF>>::cost()
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}
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}
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#[cfg(test)]
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mod test {
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use super::UInt64;
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use crate::{bits::boolean::Boolean, test_constraint_system::TestConstraintSystem, Vec};
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use algebra::{bls12_381::Fr, One, Zero};
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use r1cs_core::ConstraintSystem;
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use rand::{Rng, SeedableRng};
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use rand_xorshift::XorShiftRng;
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#[test]
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fn test_uint64_from_bits() {
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let mut rng = XorShiftRng::seed_from_u64(1231275789u64);
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for _ in 0..1000 {
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let v = (0..64)
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.map(|_| Boolean::constant(rng.gen()))
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.collect::<Vec<_>>();
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let b = UInt64::from_bits_le(&v);
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for (i, bit_gadget) in b.bits.iter().enumerate() {
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match bit_gadget {
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&Boolean::Constant(bit_gadget) => {
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assert!(bit_gadget == ((b.value.unwrap() >> i) & 1 == 1));
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},
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_ => unreachable!(),
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}
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}
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let expected_to_be_same = b.to_bits_le();
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for x in v.iter().zip(expected_to_be_same.iter()) {
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match x {
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(&Boolean::Constant(true), &Boolean::Constant(true)) => {},
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(&Boolean::Constant(false), &Boolean::Constant(false)) => {},
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_ => unreachable!(),
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}
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}
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}
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}
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#[test]
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fn test_uint64_xor() {
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let mut rng = XorShiftRng::seed_from_u64(1231275789u64);
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for _ in 0..1000 {
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let mut cs = TestConstraintSystem::<Fr>::new();
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let a: u64 = rng.gen();
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let b: u64 = rng.gen();
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let c: u64 = rng.gen();
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let mut expected = a ^ b ^ c;
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let a_bit = UInt64::alloc(cs.ns(|| "a_bit"), Some(a)).unwrap();
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let b_bit = UInt64::constant(b);
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let c_bit = UInt64::alloc(cs.ns(|| "c_bit"), Some(c)).unwrap();
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let r = a_bit.xor(cs.ns(|| "first xor"), &b_bit).unwrap();
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let r = r.xor(cs.ns(|| "second xor"), &c_bit).unwrap();
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assert!(cs.is_satisfied());
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assert!(r.value == Some(expected));
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for b in r.bits.iter() {
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match b {
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&Boolean::Is(ref b) => {
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assert!(b.get_value().unwrap() == (expected & 1 == 1));
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},
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&Boolean::Not(ref b) => {
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assert!(!b.get_value().unwrap() == (expected & 1 == 1));
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},
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&Boolean::Constant(b) => {
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assert!(b == (expected & 1 == 1));
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},
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}
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expected >>= 1;
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}
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}
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}
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#[test]
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fn test_uint64_addmany_constants() {
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let mut rng = XorShiftRng::seed_from_u64(1231275789u64);
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for _ in 0..1000 {
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let mut cs = TestConstraintSystem::<Fr>::new();
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let a: u64 = rng.gen();
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let b: u64 = rng.gen();
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let c: u64 = rng.gen();
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let a_bit = UInt64::constant(a);
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let b_bit = UInt64::constant(b);
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let c_bit = UInt64::constant(c);
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let mut expected = a.wrapping_add(b).wrapping_add(c);
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let r = UInt64::addmany(cs.ns(|| "addition"), &[a_bit, b_bit, c_bit]).unwrap();
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assert!(r.value == Some(expected));
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for b in r.bits.iter() {
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match b {
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&Boolean::Is(_) => panic!(),
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&Boolean::Not(_) => panic!(),
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&Boolean::Constant(b) => {
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assert!(b == (expected & 1 == 1));
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},
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}
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expected >>= 1;
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}
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}
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}
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#[test]
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fn test_uint64_addmany() {
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let mut rng = XorShiftRng::seed_from_u64(1231275789u64);
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for _ in 0..1000 {
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let mut cs = TestConstraintSystem::<Fr>::new();
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let a: u64 = rng.gen();
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let b: u64 = rng.gen();
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let c: u64 = rng.gen();
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let d: u64 = rng.gen();
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let mut expected = (a ^ b).wrapping_add(c).wrapping_add(d);
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|
||||
let a_bit = UInt64::alloc(cs.ns(|| "a_bit"), Some(a)).unwrap();
|
||||
let b_bit = UInt64::constant(b);
|
||||
let c_bit = UInt64::constant(c);
|
||||
let d_bit = UInt64::alloc(cs.ns(|| "d_bit"), Some(d)).unwrap();
|
||||
|
||||
let r = a_bit.xor(cs.ns(|| "xor"), &b_bit).unwrap();
|
||||
let r = UInt64::addmany(cs.ns(|| "addition"), &[r, c_bit, d_bit]).unwrap();
|
||||
|
||||
assert!(cs.is_satisfied());
|
||||
|
||||
assert!(r.value == Some(expected));
|
||||
|
||||
for b in r.bits.iter() {
|
||||
match b {
|
||||
&Boolean::Is(ref b) => {
|
||||
assert!(b.get_value().unwrap() == (expected & 1 == 1));
|
||||
},
|
||||
&Boolean::Not(ref b) => {
|
||||
assert!(!b.get_value().unwrap() == (expected & 1 == 1));
|
||||
},
|
||||
&Boolean::Constant(_) => unreachable!(),
|
||||
}
|
||||
|
||||
expected >>= 1;
|
||||
}
|
||||
|
||||
// Flip a bit_gadget and see if the addition constraint still works
|
||||
if cs.get("addition/result bit_gadget 0/boolean").is_zero() {
|
||||
cs.set("addition/result bit_gadget 0/boolean", Fr::one());
|
||||
} else {
|
||||
cs.set("addition/result bit_gadget 0/boolean", Fr::zero());
|
||||
}
|
||||
|
||||
assert!(!cs.is_satisfied());
|
||||
}
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn test_uint64_rotr() {
|
||||
let mut rng = XorShiftRng::seed_from_u64(1231275789u64);
|
||||
|
||||
let mut num = rng.gen();
|
||||
|
||||
let a = UInt64::constant(num);
|
||||
|
||||
for i in 0..64 {
|
||||
let b = a.rotr(i);
|
||||
|
||||
assert!(b.value.unwrap() == num);
|
||||
|
||||
let mut tmp = num;
|
||||
for b in &b.bits {
|
||||
match b {
|
||||
&Boolean::Constant(b) => {
|
||||
assert_eq!(b, tmp & 1 == 1);
|
||||
},
|
||||
_ => unreachable!(),
|
||||
}
|
||||
|
||||
tmp >>= 1;
|
||||
}
|
||||
|
||||
num = num.rotate_right(1);
|
||||
}
|
||||
}
|
||||
}
|
||||
Reference in New Issue
Block a user