miden_crypto/dsa/rpo_falcon512/keys/
public_key.rsuse alloc::string::ToString;
use core::ops::Deref;
use num::Zero;
use super::{
super::{Rpo256, LOG_N, N, PK_LEN},
ByteReader, ByteWriter, Deserializable, DeserializationError, FalconFelt, Felt, Polynomial,
Serializable, Signature, Word,
};
use crate::dsa::rpo_falcon512::FALCON_ENCODING_BITS;
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct PublicKey(Word);
impl PublicKey {
pub fn new(pub_key: Word) -> Self {
Self(pub_key)
}
pub fn verify(&self, message: Word, signature: &Signature) -> bool {
signature.verify(message, self.0)
}
}
impl From<PubKeyPoly> for PublicKey {
fn from(pk_poly: PubKeyPoly) -> Self {
let pk_felts: Polynomial<Felt> = pk_poly.0.into();
let pk_digest = Rpo256::hash_elements(&pk_felts.coefficients).into();
Self(pk_digest)
}
}
impl From<PublicKey> for Word {
fn from(key: PublicKey) -> Self {
key.0
}
}
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct PubKeyPoly(pub Polynomial<FalconFelt>);
impl Deref for PubKeyPoly {
type Target = Polynomial<FalconFelt>;
fn deref(&self) -> &Self::Target {
&self.0
}
}
impl From<Polynomial<FalconFelt>> for PubKeyPoly {
fn from(pk_poly: Polynomial<FalconFelt>) -> Self {
Self(pk_poly)
}
}
impl Serializable for &PubKeyPoly {
fn write_into<W: ByteWriter>(&self, target: &mut W) {
let mut buf = [0_u8; PK_LEN];
buf[0] = LOG_N;
let mut acc = 0_u32;
let mut acc_len: u32 = 0;
let mut input_pos = 1;
for c in self.0.coefficients.iter() {
let c = c.value();
acc = (acc << FALCON_ENCODING_BITS) | c as u32;
acc_len += FALCON_ENCODING_BITS;
while acc_len >= 8 {
acc_len -= 8;
buf[input_pos] = (acc >> acc_len) as u8;
input_pos += 1;
}
}
if acc_len > 0 {
buf[input_pos] = (acc >> (8 - acc_len)) as u8;
}
target.write(buf);
}
}
impl Deserializable for PubKeyPoly {
fn read_from<R: ByteReader>(source: &mut R) -> Result<Self, DeserializationError> {
let buf = source.read_array::<PK_LEN>()?;
if buf[0] != LOG_N {
return Err(DeserializationError::InvalidValue(format!(
"Failed to decode public key: expected the first byte to be {LOG_N} but was {}",
buf[0]
)));
}
let mut acc = 0_u32;
let mut acc_len = 0;
let mut output = [FalconFelt::zero(); N];
let mut output_idx = 0;
for &byte in buf.iter().skip(1) {
acc = (acc << 8) | (byte as u32);
acc_len += 8;
if acc_len >= FALCON_ENCODING_BITS {
acc_len -= FALCON_ENCODING_BITS;
let w = (acc >> acc_len) & 0x3fff;
let element = w.try_into().map_err(|err| {
DeserializationError::InvalidValue(format!(
"Failed to decode public key: {err}"
))
})?;
output[output_idx] = element;
output_idx += 1;
}
}
if (acc & ((1u32 << acc_len) - 1)) == 0 {
Ok(Polynomial::new(output.to_vec()).into())
} else {
Err(DeserializationError::InvalidValue(
"Failed to decode public key: input not fully consumed".to_string(),
))
}
}
}