Struct halo2_backend::transcript::Challenge255

pub struct Challenge255<C: CurveAffine>(/* private fields */);

A 255-bit challenge.

Methods from Deref<Target = [u8; 32]>

pub fn as_ascii(&self) -> Option<&[AsciiChar; N]>

🔬This is a nightly-only experimental API. (ascii_char)

Converts this array of bytes into a array of ASCII characters, or returns None if any of the characters is non-ASCII.

Examples

#![feature(ascii_char)]
#![feature(const_option)]

const HEX_DIGITS: [std::ascii::Char; 16] =
    *b"0123456789abcdef".as_ascii().unwrap();

assert_eq!(HEX_DIGITS[1].as_str(), "1");
assert_eq!(HEX_DIGITS[10].as_str(), "a");

pub unsafe fn as_ascii_unchecked(&self) -> &[AsciiChar; N]

🔬This is a nightly-only experimental API. (ascii_char)

Converts this array of bytes into a array of ASCII characters, without checking whether they’re valid.

Safety

Every byte in the array must be in 0..=127, or else this is UB.

pub fn as_slice(&self) -> &[T]

Returns a slice containing the entire array. Equivalent to &s[..].

pub fn each_ref(&self) -> [&T; N]

Borrows each element and returns an array of references with the same size as self.

Example

let floats = [3.1, 2.7, -1.0];
let float_refs: [&f64; 3] = floats.each_ref();
assert_eq!(float_refs, [&3.1, &2.7, &-1.0]);

This method is particularly useful if combined with other methods, like map. This way, you can avoid moving the original array if its elements are not Copy.

let strings = ["Ferris".to_string(), "♥".to_string(), "Rust".to_string()];
let is_ascii = strings.each_ref().map(|s| s.is_ascii());
assert_eq!(is_ascii, [true, false, true]);

// We can still access the original array: it has not been moved.
assert_eq!(strings.len(), 3);

pub fn split_array_ref<const M: usize>(&self) -> (&[T; M], &[T])

🔬This is a nightly-only experimental API. (split_array)

Divides one array reference into two at an index.

The first will contain all indices from [0, M) (excluding the index M itself) and the second will contain all indices from [M, N) (excluding the index N itself).

Panics

Panics if M > N.

Examples

#![feature(split_array)]

let v = [1, 2, 3, 4, 5, 6];

{
   let (left, right) = v.split_array_ref::<0>();
   assert_eq!(left, &[]);
   assert_eq!(right, &[1, 2, 3, 4, 5, 6]);
}

{
    let (left, right) = v.split_array_ref::<2>();
    assert_eq!(left, &[1, 2]);
    assert_eq!(right, &[3, 4, 5, 6]);
}

{
    let (left, right) = v.split_array_ref::<6>();
    assert_eq!(left, &[1, 2, 3, 4, 5, 6]);
    assert_eq!(right, &[]);
}

pub fn rsplit_array_ref<const M: usize>(&self) -> (&[T], &[T; M])

🔬This is a nightly-only experimental API. (split_array)

Divides one array reference into two at an index from the end.

The first will contain all indices from [0, N - M) (excluding the index N - M itself) and the second will contain all indices from [N - M, N) (excluding the index N itself).

Panics

Panics if M > N.

Examples

#![feature(split_array)]

let v = [1, 2, 3, 4, 5, 6];

{
   let (left, right) = v.rsplit_array_ref::<0>();
   assert_eq!(left, &[1, 2, 3, 4, 5, 6]);
   assert_eq!(right, &[]);
}

{
    let (left, right) = v.rsplit_array_ref::<2>();
    assert_eq!(left, &[1, 2, 3, 4]);
    assert_eq!(right, &[5, 6]);
}

{
    let (left, right) = v.rsplit_array_ref::<6>();
    assert_eq!(left, &[]);
    assert_eq!(right, &[1, 2, 3, 4, 5, 6]);
}

Trait Implementations

impl<C: Clone + CurveAffine> Clone for Challenge255<C>

fn clone(&self) -> Challenge255<C>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<C: Debug + CurveAffine> Debug for Challenge255<C>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<C: CurveAffine> Deref for Challenge255<C>

type Target = [u8; 32]

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl<C: CurveAffine> EncodedChallenge<C> for Challenge255<C>

where C::Scalar: FromUniformBytes<64>,

type Input = [u8; 64]

The Input type used to derive the challenge encoding. For example, an input from the Poseidon hash would be a base field element; an input from the Blake2b hash would be a [u8; 64].

fn new(challenge_input: &[u8; 64]) -> Self

Get an encoded challenge from a given input challenge.

fn get_scalar(&self) -> C::Scalar

Get a scalar field element from an encoded challenge.

fn as_challenge_scalar<T>(&self) -> ChallengeScalar<C, T>

Cast an encoded challenge as a typed ChallengeScalar.

impl<R: Read, C: CurveAffine> Transcript<C, Challenge255<C>> for Blake2bRead<R, C, Challenge255<C>>

where C::Scalar: FromUniformBytes<64>,

fn squeeze_challenge(&mut self) -> Challenge255<C>

Squeeze an encoded verifier challenge from the transcript.

fn common_point(&mut self, point: C) -> Result<()>

Writing the point to the transcript without writing it to the proof, treating it as a common input.

fn common_scalar(&mut self, scalar: C::Scalar) -> Result<()>

Writing the scalar to the transcript without writing it to the proof, treating it as a common input.

fn squeeze_challenge_scalar<T>(&mut self) -> ChallengeScalar<C, T>

Squeeze a typed challenge (in the scalar field) from the transcript.

impl<W: Write, C: CurveAffine> Transcript<C, Challenge255<C>> for Blake2bWrite<W, C, Challenge255<C>>

where C::Scalar: FromUniformBytes<64>,

fn squeeze_challenge(&mut self) -> Challenge255<C>

Squeeze an encoded verifier challenge from the transcript.

fn common_point(&mut self, point: C) -> Result<()>

Writing the point to the transcript without writing it to the proof, treating it as a common input.

fn common_scalar(&mut self, scalar: C::Scalar) -> Result<()>

Writing the scalar to the transcript without writing it to the proof, treating it as a common input.

fn squeeze_challenge_scalar<T>(&mut self) -> ChallengeScalar<C, T>

Squeeze a typed challenge (in the scalar field) from the transcript.

impl<R: Read, C: CurveAffine> Transcript<C, Challenge255<C>> for Keccak256Read<R, C, Challenge255<C>>

where C::Scalar: FromUniformBytes<64>,

fn squeeze_challenge(&mut self) -> Challenge255<C>

Squeeze an encoded verifier challenge from the transcript.

fn common_point(&mut self, point: C) -> Result<()>

Writing the point to the transcript without writing it to the proof, treating it as a common input.

fn common_scalar(&mut self, scalar: C::Scalar) -> Result<()>

Writing the scalar to the transcript without writing it to the proof, treating it as a common input.

fn squeeze_challenge_scalar<T>(&mut self) -> ChallengeScalar<C, T>

Squeeze a typed challenge (in the scalar field) from the transcript.

impl<W: Write, C: CurveAffine> Transcript<C, Challenge255<C>> for Keccak256Write<W, C, Challenge255<C>>

where C::Scalar: FromUniformBytes<64>,

fn squeeze_challenge(&mut self) -> Challenge255<C>

Squeeze an encoded verifier challenge from the transcript.

fn common_point(&mut self, point: C) -> Result<()>

Writing the point to the transcript without writing it to the proof, treating it as a common input.

fn common_scalar(&mut self, scalar: C::Scalar) -> Result<()>

Writing the scalar to the transcript without writing it to the proof, treating it as a common input.

fn squeeze_challenge_scalar<T>(&mut self) -> ChallengeScalar<C, T>

Squeeze a typed challenge (in the scalar field) from the transcript.

impl<R: Read, C: CurveAffine> TranscriptRead<C, Challenge255<C>> for Blake2bRead<R, C, Challenge255<C>>

where C::Scalar: FromUniformBytes<64>,

fn read_point(&mut self) -> Result<C>

Read a curve point from the prover.

fn read_scalar(&mut self) -> Result<C::Scalar>

Read a curve scalar from the prover.

impl<R: Read, C: CurveAffine> TranscriptRead<C, Challenge255<C>> for Keccak256Read<R, C, Challenge255<C>>

where C::Scalar: FromUniformBytes<64>,

fn read_point(&mut self) -> Result<C>

Read a curve point from the prover.

fn read_scalar(&mut self) -> Result<C::Scalar>

Read a curve scalar from the prover.

impl<R: Read, C: CurveAffine> TranscriptReadBuffer<R, C, Challenge255<C>> for Blake2bRead<R, C, Challenge255<C>>

where C::Scalar: FromUniformBytes<64>,

fn init(reader: R) -> Self

Initialize a transcript given an input buffer.

impl<R: Read, C: CurveAffine> TranscriptReadBuffer<R, C, Challenge255<C>> for Keccak256Read<R, C, Challenge255<C>>

where C::Scalar: FromUniformBytes<64>,

fn init(reader: R) -> Self

Initialize a transcript given an input buffer.

impl<W: Write, C: CurveAffine> TranscriptWrite<C, Challenge255<C>> for Blake2bWrite<W, C, Challenge255<C>>

where C::Scalar: FromUniformBytes<64>,

fn write_point(&mut self, point: C) -> Result<()>

Write a curve point to the proof and the transcript.

fn write_scalar(&mut self, scalar: C::Scalar) -> Result<()>

Write a scalar to the proof and the transcript.

impl<W: Write, C: CurveAffine> TranscriptWrite<C, Challenge255<C>> for Keccak256Write<W, C, Challenge255<C>>

where C::Scalar: FromUniformBytes<64>,

fn write_point(&mut self, point: C) -> Result<()>

Write a curve point to the proof and the transcript.

fn write_scalar(&mut self, scalar: C::Scalar) -> Result<()>

Write a scalar to the proof and the transcript.

impl<W: Write, C: CurveAffine> TranscriptWriterBuffer<W, C, Challenge255<C>> for Blake2bWrite<W, C, Challenge255<C>>

where C::Scalar: FromUniformBytes<64>,

fn init(writer: W) -> Self

Initialize a transcript given an output buffer.

fn finalize(self) -> W

Conclude the interaction and return the output buffer (writer).

impl<W: Write, C: CurveAffine> TranscriptWriterBuffer<W, C, Challenge255<C>> for Keccak256Write<W, C, Challenge255<C>>

where C::Scalar: FromUniformBytes<64>,

fn init(writer: W) -> Self

Initialize a transcript given an output buffer.

fn finalize(self) -> W

Conclude the interaction and return the output buffer (writer).

impl<C: Copy + CurveAffine> Copy for Challenge255<C>