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25 lines
924 B
Rust
25 lines
924 B
Rust
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use std_shims::{sync::OnceLock, vec::Vec};
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use dalek_ff_group::{Scalar, EdwardsPoint};
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use monero_generators::{hash_to_point as raw_hash_to_point};
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use crate::{hash, hash_to_scalar as dalek_hash};
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// Monero starts BP+ transcripts with the following constant.
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static TRANSCRIPT_CELL: OnceLock<[u8; 32]> = OnceLock::new();
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pub(crate) fn TRANSCRIPT() -> [u8; 32] {
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// Why this uses a hash_to_point is completely unknown.
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*TRANSCRIPT_CELL
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.get_or_init(|| raw_hash_to_point(hash(b"bulletproof_plus_transcript")).compress().to_bytes())
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}
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pub(crate) fn hash_to_scalar(data: &[u8]) -> Scalar {
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Scalar(dalek_hash(data))
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}
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pub(crate) fn initial_transcript(commitments: core::slice::Iter<'_, EdwardsPoint>) -> Scalar {
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let commitments_hash =
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hash_to_scalar(&commitments.flat_map(|V| V.compress().to_bytes()).collect::<Vec<_>>());
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hash_to_scalar(&[TRANSCRIPT().as_ref(), &commitments_hash.to_bytes()].concat())
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}
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