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Add bytes serde for KeyPair (#7)
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* Add bytes serde for KeyPair

* cargo fmt
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@durch
durch authored Jul 12, 2021
1 parent 8d2347c commit c6b372e
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Showing 3 changed files with 75 additions and 140 deletions.
6 changes: 0 additions & 6 deletions coconut-rs/Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -20,12 +20,6 @@ thiserror = "1.0"
sha2 = "0.9"
sha3 = "0.9"

[dependencies.serde]
version = "1.0"
features = ["derive"]
optional = true
default-features = false

[dependencies.ff]
version = "0.10"
default-features = false
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207 changes: 74 additions & 133 deletions coconut-rs/src/scheme/keygen.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -27,19 +27,9 @@ use group::Curve;
use std::convert::TryFrom;
use std::convert::TryInto;

#[cfg(feature = "serde")]
use serde::de::Visitor;
#[cfg(feature = "serde")]
use serde::{self, Deserialize, Deserializer, Serialize, Serializer};

// #[cfg(feature = "serde")]
// use crate::utils::ScalarDef;

#[derive(Debug, Clone)]
#[cfg_attr(test, derive(PartialEq))]
// #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub struct SecretKey {
// #[cfg_attr(feature = "serde", serde(with = "ScalarSerdeHelper"))]
pub(crate) x: Scalar,
pub(crate) ys: Vec<Scalar>,
}
Expand Down Expand Up @@ -268,6 +258,8 @@ impl VerificationKey {
}
}

#[derive(Debug)]
#[cfg_attr(test, derive(PartialEq))]
pub struct KeyPair {
secret_key: SecretKey,
verification_key: VerificationKey,
Expand All @@ -284,131 +276,65 @@ impl KeyPair {
pub fn verification_key(&self) -> VerificationKey {
self.verification_key.clone()
}

pub fn to_bytes(&self) -> Vec<u8> {
// Schema is coconutkeypair[14]|secret_key_len[8]|secret_key[secret_key_len]|verification_key_len[8]|verification_key[verification_key_len]|signer_index[8] - optional
let mut byts = vec![];
let marker_btyes = "coconutkeypair".as_bytes();
let secret_key_bytes = self.secret_key.to_bytes();
let secret_key_len = (secret_key_bytes.len() as u64).to_le_bytes();
let verification_key_bytes = self.verification_key.to_bytes();
let verification_key_len = (verification_key_bytes.len() as u64).to_le_bytes();
byts.extend_from_slice(marker_btyes);
byts.extend_from_slice(&secret_key_len);
byts.extend_from_slice(&secret_key_bytes);
byts.extend_from_slice(&verification_key_len);
byts.extend_from_slice(&verification_key_bytes);
if let Some(index) = self.index {
byts.extend_from_slice(&index.to_le_bytes())
}
byts
}

pub fn from_bytes(bytes: &[u8]) -> Result<Self> {
KeyPair::try_from(bytes)
}
}

// #[cfg(feature = "serde")]
// impl Serialize for SecretKey {
// fn serialize<S>(&self, serializer: S) -> core::result::Result<S::Ok, S::Error>
// where
// S: Serializer,
// {
// use serde::ser::SerializeStruct;
// use serde::ser::SerializeTuple;
//
// let mut state = serializer.serialize_struct("SecretKey", 2)?;
//
// state.serialize_field("x", &self.x);
// state.serialize_field("ys", &self.ys);
//
// // state.serialize_field("x")
//
// // let mut tup = serializer.serialize_tuple(32)?;
// // for byte in self.to_bytes().iter() {
// // tup.serialize_element(byte)?;
// // }
// state.end()
// }
// }
//
// #[cfg(feature = "serde")]
// impl<'de> Deserialize<'de> for SecretKey {
// fn deserialize<D>(deserializer: D) -> core::result::Result<Self, D::Error>
// where
// D: Deserializer<'de>,
// {
// #[derive(Deserialize)]
// #[serde(field_identifier, rename_all = "lowercase")]
// enum Field {
// X,
// Ys,
// }
//
// struct SecretKeyVisitor;
//
// impl<'de> Visitor<'de> for SecretKeyVisitor {
// type Value = SecretKey;
//
// fn expecting(&self, formatter: &mut core::fmt::Formatter) -> core::fmt::Result {
// formatter.write_str("a 32-byte ElGamal private key on BLS12_381 curve")
// }
//
// fn visit_seq<A>(self, mut seq: A) -> core::result::Result<SecretKey, A::Error>
// where
// A: serde::de::SeqAccess<'de>,
// {
// let mut bytes = [0u8; 32];
// // I think this way makes it way more readable than the iterator approach
// #[allow(clippy::needless_range_loop)]
// for i in 0..32 {
// bytes[i] = seq
// .next_element()?
// .ok_or_else(|| serde::de::Error::invalid_length(i, &"expected 32 bytes"))?;
// }
//
// SecretKey::from_bytes(&bytes).ok_or_else(|| {
// serde::de::Error::custom(&"private key scalar was not canonically encoded")
// })
// }
// }
//
// deserializer.deserialize_tuple(32, SecretKeyVisitor)
// }
// }
//
// #[cfg(feature = "serde")]
// impl Serialize for VerificationKey {
// fn serialize<S>(&self, serializer: S) -> core::result::Result<S::Ok, S::Error>
// where
// S: Serializer,
// {
// use serde::ser::SerializeTuple;
// let mut tup = serializer.serialize_tuple(48)?;
// for byte in self.to_bytes().iter() {
// tup.serialize_element(byte)?;
// }
// tup.end()
// }
// }
//
// #[cfg(feature = "serde")]
// impl<'de> Deserialize<'de> for VerificationKey {
// fn deserialize<D>(deserializer: D) -> core::result::Result<Self, D::Error>
// where
// D: Deserializer<'de>,
// {
// struct VerificationKeyVisitor;
//
// impl<'de> Visitor<'de> for VerificationKeyVisitor {
// type Value = VerificationKey;
//
// fn expecting(&self, formatter: &mut core::fmt::Formatter) -> core::fmt::Result {
// formatter.write_str("a 48-byte compressed ElGamal public key on BLS12_381 curve")
// }
//
// fn visit_seq<A>(self, mut seq: A) -> core::result::Result<VerificationKey, A::Error>
// where
// A: serde::de::SeqAccess<'de>,
// {
// let mut bytes = [0u8; 48];
// // I think this way makes it way more readable than the iterator approach
// #[allow(clippy::needless_range_loop)]
// for i in 0..48 {
// bytes[i] = seq
// .next_element()?
// .ok_or_else(|| serde::de::Error::invalid_length(i, &"expected 48 bytes"))?;
// }
//
// VerificationKey::from_bytes(&bytes).ok_or_else(|| {
// serde::de::Error::custom(
// &"public key G1 curve point was not canonically encoded",
// )
// })
// }
// }
//
// deserializer.deserialize_tuple(48, VerificationKeyVisitor)
// }
// }
impl TryFrom<&[u8]> for KeyPair {
type Error = CoconutError;

fn try_from(bytes: &[u8]) -> Result<KeyPair> {
let header_len = 14;
let secret_key_len =
u64::from_le_bytes(bytes[header_len..header_len + 8].try_into().unwrap()) as usize;
let secret_key = SecretKey::try_from(&bytes[14 + 8..14 + 8 + secret_key_len])?;
let verification_key_len = u64::from_le_bytes(
bytes[header_len + 8 + secret_key_len..header_len + 8 + secret_key_len + 8]
.try_into()
.unwrap(),
) as usize;
let verification_key = VerificationKey::try_from(
&bytes[header_len + 8 + secret_key_len + 8
..header_len + 8 + secret_key_len + 8 + verification_key_len],
)?;
let consumed_bytes = header_len + 8 + secret_key_len + 8 + verification_key_len;
let index = if consumed_bytes < bytes.len() {
Some(u64::from_le_bytes(
bytes[consumed_bytes..consumed_bytes + 8]
.try_into()
.unwrap(),
))
} else {
None
};
Ok(KeyPair {
secret_key,
verification_key,
index,
})
}
}

/// Generate a single Coconut keypair ((x, y0, y1...), (g2^x, g2^y0, ...)).
/// It is not suitable for threshold credentials as all subsequent calls to `keygen` generate keys
Expand Down Expand Up @@ -496,6 +422,21 @@ mod tests {
use super::*;
use crate::scheme::setup::setup;

#[test]
fn keypair_bytes_roundtrip() {
let mut params1 = setup(1).unwrap();
let mut params5 = setup(5).unwrap();

let keypair1 = keygen(&mut params1);
let keypair5 = keygen(&mut params5);

let bytes1 = keypair1.to_bytes();
let bytes5 = keypair5.to_bytes();

assert_eq!(KeyPair::from_bytes(&bytes1).unwrap(), keypair1);
assert_eq!(KeyPair::from_bytes(&bytes5).unwrap(), keypair5);
}

#[test]
fn secret_key_bytes_roundtrip() {
let mut params1 = setup(1).unwrap();
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2 changes: 1 addition & 1 deletion coconut-rs/src/scheme/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -87,7 +87,7 @@ impl Signature {
aggregate_signatures(sigs, indices)
}

pub fn to_bytes(&self) -> [u8; 96] {
pub fn to_bytes(self) -> [u8; 96] {
let mut bytes = [0u8; 96];
bytes[..48].copy_from_slice(&self.0.to_affine().to_compressed());
bytes[48..].copy_from_slice(&self.1.to_affine().to_compressed());
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