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Remove generic ciphertext argument from Part and Ack messages.

This commit is contained in:
Andreas Fackler 2019-08-29 11:09:43 +02:00 committed by Andreas Fackler
parent 824a43100b
commit fe17fc9850
1 changed files with 48 additions and 40 deletions
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88
src/sync_key_gen.rs
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@ -174,12 +174,13 @@
use std::borrow::Borrow;
use std::collections::{BTreeMap, BTreeSet};
use std::fmt::{self, Debug, Formatter};
use std::string::ToString;
use std::sync::Arc;
use bincode;
use failure::Fail;
use rand::{self, Rng};
use serde::{de::DeserializeOwned, Deserialize, Serialize};
use serde::{Deserialize, Serialize};
use crate::crypto::{
self,
@ -193,38 +194,43 @@ use crate::NodeIdT;
/// A cryptographic key that allows decrypting messages that were encrypted to the key's owner.
pub trait SecretKey {
/// The encrypted form of a message in this cryptosystem.
type Ciphertext: Serialize + DeserializeOwned;
/// The decryption error type.
type Error: ToString;
/// Decrypts a ciphertext; returns `None` if it was invalid.
fn decrypt(&self, ct: &Self::Ciphertext) -> Option<Vec<u8>>;
/// Decrypts a ciphertext.
fn decrypt(&self, ct: &[u8]) -> Result<Vec<u8>, Self::Error>;
}
/// A cryptographic public key that allows encrypting messages to the key's owner.
pub trait PublicKey {
/// The encrypted form of a message in this cryptosystem.
type Ciphertext: Serialize + DeserializeOwned;
/// The encryption error type.
type Error: ToString;
/// The corresponding secret key type. The secret key is known only to the key's owner.
type SecretKey: SecretKey<Ciphertext = Self::Ciphertext>;
type SecretKey: SecretKey;
/// Encrypts a message to this key's owner and returns the ciphertext.
fn encrypt<M: AsRef<[u8]>, R: Rng>(&self, msg: M, rng: &mut R) -> Self::Ciphertext;
fn encrypt<M: AsRef<[u8]>, R: Rng>(&self, msg: M, rng: &mut R) -> Result<Vec<u8>, Self::Error>;
}
impl SecretKey for crypto::SecretKey {
type Ciphertext = crypto::Ciphertext;
type Error = bincode::Error;
fn decrypt(&self, ct: &crypto::Ciphertext) -> Option<Vec<u8>> {
self.decrypt(ct)
fn decrypt(&self, ct: &[u8]) -> Result<Vec<u8>, bincode::Error> {
self.decrypt(&bincode::deserialize(ct)?)
.ok_or_else(|| bincode::ErrorKind::Custom("Invalid ciphertext.".to_string()).into())
}
}
impl PublicKey for crypto::PublicKey {
type Ciphertext = crypto::Ciphertext;
type Error = bincode::Error;
type SecretKey = crypto::SecretKey;
fn encrypt<M: AsRef<[u8]>, R: Rng>(&self, msg: M, rng: &mut R) -> crypto::Ciphertext {
self.encrypt_with_rng(rng, msg)
fn encrypt<M: AsRef<[u8]>, R: Rng>(
&self,
msg: M,
rng: &mut R,
) -> Result<Vec<u8>, bincode::Error> {
bincode::serialize(&self.encrypt_with_rng(rng, msg))
}
}
@ -259,6 +265,9 @@ pub enum Error {
/// Failed to serialize message.
#[fail(display = "Serialization error: {}", _0)]
Serialize(String),
/// Failed to encrypt message parts for a peer.
#[fail(display = "Encryption error: {}", _0)]
Encrypt(String),
}
impl From<bincode::Error> for Error {
@ -267,6 +276,12 @@ impl From<bincode::Error> for Error {
}
}
impl Error {
fn encrypt<E: ToString>(err: E) -> Error {
Error::Encrypt(err.to_string())
}
}
/// A submission by a validator for the key generation. It must to be sent to all participating
/// nodes and handled by all of them, including the one that produced it.
///
@ -274,9 +289,9 @@ impl From<bincode::Error> for Error {
/// row of values. If this message receives enough `Ack`s, it will be used as summand to produce
/// the the key set in the end.
#[derive(Deserialize, Serialize, Clone, Hash, Eq, PartialEq)]
pub struct Part<C = crypto::Ciphertext>(BivarCommitment, Vec<C>);
pub struct Part(BivarCommitment, Vec<Vec<u8>>);
impl<C> Debug for Part<C> {
impl Debug for Part {
fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
f.debug_tuple("Part")
.field(&format!("<degree {}>", self.0.degree()))
@ -291,9 +306,9 @@ impl<C> Debug for Part<C> {
/// The message is only produced after we verified our row against the commitment in the `Part`.
/// For each node, it contains one encrypted value of that row.
#[derive(Deserialize, Serialize, Clone, Hash, Eq, PartialEq)]
pub struct Ack<C = crypto::Ciphertext>(u64, Vec<C>);
pub struct Ack(u64, Vec<Vec<u8>>);
impl<C> Debug for Ack<C> {
impl Debug for Ack {
fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
f.debug_tuple("Ack")
.field(&self.0)
@ -330,11 +345,11 @@ impl ProposalState {
}
/// The outcome of handling and verifying a `Part` message.
pub enum PartOutcome<C> {
pub enum PartOutcome {
/// The message was valid: the part of it that was encrypted to us matched the public
/// commitment, so we can multicast an `Ack` message for it. If we are an observer or we have
/// already handled the same `Part` before, this contains `None` instead.
Valid(Option<Ack<C>>),
Valid(Option<Ack>),
/// The message was invalid: We now know that the proposer is faulty, and dont' send an `Ack`.
Invalid(PartFault),
}
@ -347,9 +362,6 @@ pub enum AckOutcome {
Invalid(AckFault),
}
/// Either `None`, or a `Part` that can be used with the `PK` key type.
pub type OptPart<PK> = Option<Part<<PK as PublicKey>::Ciphertext>>;
/// A synchronous algorithm for dealerless distributed key generation.
///
/// It requires that all nodes handle all messages in the exact same order.
@ -381,7 +393,7 @@ impl<N: NodeIdT, PK: PublicKey> SyncKeyGen<N, PK> {
pub_keys: PubKeyMap<N, PK>,
threshold: usize,
rng: &mut R,
) -> Result<(Self, OptPart<PK>), Error> {
) -> Result<(Self, Option<Part>), Error> {
let our_idx = pub_keys
.keys()
.position(|id| *id == our_id)
@ -401,15 +413,15 @@ impl<N: NodeIdT, PK: PublicKey> SyncKeyGen<N, PK> {
let our_part = BivarPoly::random(threshold, rng);
let commit = our_part.commitment();
let encrypt = |(i, pk): (usize, &PK)| {
let row = our_part.row(i + 1);
Ok(pk.encrypt(&bincode::serialize(&row)?, rng))
let row = bincode::serialize(&our_part.row(i + 1))?;
Ok(pk.encrypt(&row, rng).map_err(Error::encrypt)?)
};
let rows = key_gen
.pub_keys
.values()
.enumerate()
.map(encrypt)
.collect::<Result<Vec<_>, Error>>()?;
.collect::<Result<Vec<Vec<u8>>, Error>>()?;
Ok((key_gen, Some(Part(commit, rows))))
}
@ -427,9 +439,9 @@ impl<N: NodeIdT, PK: PublicKey> SyncKeyGen<N, PK> {
pub fn handle_part<R: rand::Rng>(
&mut self,
sender_id: &N,
part: Part<PK::Ciphertext>,
part: Part,
rng: &mut R,
) -> Result<PartOutcome<PK::Ciphertext>, Error> {
) -> Result<PartOutcome, Error> {
let sender_idx = self.node_index(sender_id).ok_or(Error::UnknownSender)?;
let row = match self.handle_part_or_fault(sender_idx, part) {
Ok(Some(row)) => row,
@ -441,7 +453,7 @@ impl<N: NodeIdT, PK: PublicKey> SyncKeyGen<N, PK> {
for (idx, pk) in self.pub_keys.values().enumerate() {
let val = row.evaluate(idx + 1);
let ser_val = bincode::serialize(&FieldWrap(val))?;
values.push(pk.encrypt(ser_val, rng));
values.push(pk.encrypt(ser_val, rng).map_err(Error::encrypt)?);
}
Ok(PartOutcome::Valid(Some(Ack(sender_idx, values))))
}
@ -450,11 +462,7 @@ impl<N: NodeIdT, PK: PublicKey> SyncKeyGen<N, PK> {
///
/// All participating nodes must handle the exact same sequence of messages.
/// Note that `handle_ack` also needs to explicitly be called with this instance's own `Ack`s.
pub fn handle_ack(
&mut self,
sender_id: &N,
ack: Ack<PK::Ciphertext>,
) -> Result<AckOutcome, Error> {
pub fn handle_ack(&mut self, sender_id: &N, ack: Ack) -> Result<AckOutcome, Error> {
let sender_idx = self.node_index(sender_id).ok_or(Error::UnknownSender)?;
Ok(match self.handle_ack_or_fault(sender_idx, ack) {
Ok(()) => AckOutcome::Valid,
@ -529,7 +537,7 @@ impl<N: NodeIdT, PK: PublicKey> SyncKeyGen<N, PK> {
fn handle_part_or_fault(
&mut self,
sender_idx: u64,
Part(commit, rows): Part<PK::Ciphertext>,
Part(commit, rows): Part,
) -> Result<Option<Poly>, PartFault> {
if rows.len() != self.pub_keys.len() {
return Err(PartFault::RowCount);
@ -551,7 +559,7 @@ impl<N: NodeIdT, PK: PublicKey> SyncKeyGen<N, PK> {
let ser_row = self
.sec_key
.decrypt(&rows[our_idx as usize])
.ok_or(PartFault::DecryptRow)?;
.map_err(|_| PartFault::DecryptRow)?;
let row: Poly = bincode::deserialize(&ser_row).map_err(|_| PartFault::DeserializeRow)?;
if row.commitment() != commit_row {
return Err(PartFault::RowCommitment);
@ -563,7 +571,7 @@ impl<N: NodeIdT, PK: PublicKey> SyncKeyGen<N, PK> {
fn handle_ack_or_fault(
&mut self,
sender_idx: u64,
Ack(proposer_idx, values): Ack<PK::Ciphertext>,
Ack(proposer_idx, values): Ack,
) -> Result<(), AckFault> {
if values.len() != self.pub_keys.len() {
return Err(AckFault::ValueCount);
@ -583,7 +591,7 @@ impl<N: NodeIdT, PK: PublicKey> SyncKeyGen<N, PK> {
let ser_val = self
.sec_key
.decrypt(&values[our_idx as usize])
.ok_or(AckFault::DecryptValue)?;
.map_err(|_| AckFault::DecryptValue)?;
let val = bincode::deserialize::<FieldWrap<Fr>>(&ser_val)
.map_err(|_| AckFault::DeserializeValue)?
.into_inner();