1use super::scalar::Scalar;
 2use crate::group::CompressedGroup;
 3use ark_ff::{BigInteger, PrimeField};
 4use ark_serialize::CanonicalSerialize;
 5use merlin::Transcript;
 6
 7pub trait ProofTranscript {
 8    fn append_protocol_name(&mut self, protocol_name: &'static [u8]);
 9    fn append_scalar(&mut self, label: &'static [u8], scalar: &Scalar);
10    fn append_point(&mut self, label: &'static [u8], point: &CompressedGroup);
11    fn challenge_scalar(&mut self, label: &'static [u8]) -> Scalar;
12    fn challenge_vector(&mut self, label: &'static [u8], len: usize) -> Vec<Scalar>;
13}
14
15impl ProofTranscript for Transcript {
16    fn append_protocol_name(&mut self, protocol_name: &'static [u8]) {
17        self.append_message(b"protocol-name", protocol_name);
18    }
19
20    fn append_scalar(&mut self, label: &'static [u8], scalar: &Scalar) {
21        self.append_message(label, scalar.into_repr().to_bytes_le().as_slice());
22    }
23
24    fn append_point(&mut self, label: &'static [u8], point: &CompressedGroup) {
25        let mut point_encoded = Vec::new();
26        point.serialize(&mut point_encoded).unwrap();
27        self.append_message(label, point_encoded.as_slice());
28    }
29
30    fn challenge_scalar(&mut self, label: &'static [u8]) -> Scalar {
31        let mut buf = [0u8; 64];
32        self.challenge_bytes(label, &mut buf);
33        Scalar::from_le_bytes_mod_order(&buf)
34    }
35
36    fn challenge_vector(&mut self, label: &'static [u8], len: usize) -> Vec<Scalar> {
37        (0..len)
38            .map(|_i| self.challenge_scalar(label))
39            .collect::<Vec<Scalar>>()
40    }
41}
42
43pub trait AppendToTranscript {
44    fn append_to_transcript(&self, label: &'static [u8], transcript: &mut Transcript);
45}
46
47impl AppendToTranscript for Scalar {
48    fn append_to_transcript(&self, label: &'static [u8], transcript: &mut Transcript) {
49        transcript.append_scalar(label, self);
50    }
51}
52
53impl AppendToTranscript for [Scalar] {
54    fn append_to_transcript(&self, label: &'static [u8], transcript: &mut Transcript) {
55        transcript.append_message(label, b"begin_append_vector");
56        for item in self {
57            transcript.append_scalar(label, item);
58        }
59        transcript.append_message(label, b"end_append_vector");
60    }
61}
62
63impl AppendToTranscript for CompressedGroup {
64    fn append_to_transcript(&self, label: &'static [u8], transcript: &mut Transcript) {
65        transcript.append_point(label, self);
66    }
67}