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Move verify_batch() to new batch module.

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Isis Lovecruft 2019-11-21 00:31:10 +00:00
parent 8f848793f3
commit ee67f36ba9
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GPG key ID: AB41313533E8E812
2 changed files with 6 additions and 123 deletions
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127
src/ed25519.rs
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@ -7,9 +7,8 @@
// Authors:
// - isis agora lovecruft <isis@patternsinthevoid.net>
//! ed25519 keypairs and batch verification.
//! ed25519 keypairs.
#[allow(unused_imports)]
use core::default::Default;
use rand::{CryptoRng, RngCore};
@ -19,139 +18,21 @@ use serde::de::Error as SerdeError;
#[cfg(feature = "serde")]
use serde::de::Visitor;
#[cfg(feature = "serde")]
use serde::{Deserialize, Serialize};
#[cfg(feature = "serde")]
use serde::{Deserializer, Serializer};
use serde::{Deserialize, Deserializer, Serialize, Serializer};
pub use sha2::Sha512;
use curve25519_dalek::digest::generic_array::typenum::U64;
pub use curve25519_dalek::digest::Digest;
#[cfg(all(feature = "batch", any(feature = "alloc", feature = "std")))]
use curve25519_dalek::constants;
#[cfg(all(feature = "batch", any(feature = "alloc", feature = "std")))]
use curve25519_dalek::edwards::EdwardsPoint;
#[cfg(all(feature = "batch", any(feature = "alloc", feature = "std")))]
use curve25519_dalek::scalar::Scalar;
#[cfg(all(feature = "batch", any(feature = "std", feature = "alloc")))]
pub use crate::batch::*;
pub use crate::constants::*;
pub use crate::errors::*;
pub use crate::public::*;
pub use crate::secret::*;
pub use crate::signature::*;
/// Verify a batch of `signatures` on `messages` with their respective `public_keys`.
///
/// # Inputs
///
/// * `messages` is a slice of byte slices, one per signed message.
/// * `signatures` is a slice of `Signature`s.
/// * `public_keys` is a slice of `PublicKey`s.
/// * `csprng` is an implementation of `Rng + CryptoRng`.
///
/// # Returns
///
/// * A `Result` whose `Ok` value is an emtpy tuple and whose `Err` value is a
/// `SignatureError` containing a description of the internal error which
/// occured.
///
/// # Examples
///
/// ```
/// extern crate ed25519_dalek;
/// extern crate rand;
///
/// use ed25519_dalek::verify_batch;
/// use ed25519_dalek::Keypair;
/// use ed25519_dalek::PublicKey;
/// use ed25519_dalek::Signature;
/// use rand::rngs::OsRng;
///
/// # fn main() {
/// let mut csprng = OsRng{};
/// let keypairs: Vec<Keypair> = (0..64).map(|_| Keypair::generate(&mut csprng)).collect();
/// let msg: &[u8] = b"They're good dogs Brant";
/// let messages: Vec<&[u8]> = (0..64).map(|_| msg).collect();
/// let signatures: Vec<Signature> = keypairs.iter().map(|key| key.sign(&msg)).collect();
/// let public_keys: Vec<PublicKey> = keypairs.iter().map(|key| key.public).collect();
///
/// let result = verify_batch(&messages[..], &signatures[..], &public_keys[..]);
/// assert!(result.is_ok());
/// # }
/// ```
#[cfg(all(feature = "batch", any(feature = "alloc", feature = "std")))]
#[allow(non_snake_case)]
pub fn verify_batch(
messages: &[&[u8]],
signatures: &[Signature],
public_keys: &[PublicKey],
) -> Result<(), SignatureError>
{
if signatures.len() != messages.len() ||
signatures.len() != public_keys.len() ||
public_keys.len() != messages.len() {
return Err(SignatureError(InternalError::ArrayLengthError{
name_a: "signatures", length_a: signatures.len(),
name_b: "messages", length_b: messages.len(),
name_c: "public_keys", length_c: public_keys.len(),
}));
}
#[cfg(feature = "alloc")]
use alloc::vec::Vec;
#[cfg(feature = "std")]
use std::vec::Vec;
use core::iter::once;
use rand::{Rng, thread_rng};
use curve25519_dalek::traits::IsIdentity;
use curve25519_dalek::traits::VartimeMultiscalarMul;
// Select a random 128-bit scalar for each signature.
let zs: Vec<Scalar> = signatures
.iter()
.map(|_| Scalar::from(thread_rng().gen::<u128>()))
.collect();
// Compute the basepoint coefficient, ∑ s[i]z[i] (mod l)
let B_coefficient: Scalar = signatures
.iter()
.map(|sig| sig.s)
.zip(zs.iter())
.map(|(s, z)| z * s)
.sum();
// Compute H(R || A || M) for each (signature, public_key, message) triplet
let hrams = (0..signatures.len()).map(|i| {
let mut h: Sha512 = Sha512::default();
h.input(signatures[i].R.as_bytes());
h.input(public_keys[i].as_bytes());
h.input(&messages[i]);
Scalar::from_hash(h)
});
// Multiply each H(R || A || M) by the random value
let zhrams = hrams.zip(zs.iter()).map(|(hram, z)| hram * z);
let Rs = signatures.iter().map(|sig| sig.R.decompress());
let As = public_keys.iter().map(|pk| Some(pk.1));
let B = once(Some(constants::ED25519_BASEPOINT_POINT));
// Compute (-∑ z[i]s[i] (mod l)) B + ∑ z[i]R[i] + ∑ (z[i]H(R||A||M)[i] (mod l)) A[i] = 0
let id = EdwardsPoint::optional_multiscalar_mul(
once(-B_coefficient).chain(zs.iter().cloned()).chain(zhrams),
B.chain(Rs).chain(As),
).ok_or_else(|| SignatureError(InternalError::VerifyError))?;
if id.is_identity() {
Ok(())
} else {
Err(SignatureError(InternalError::VerifyError))
}
}
/// An ed25519 keypair.
#[derive(Debug, Default)] // we derive Default in order to use the clear() method in Drop
pub struct Keypair {

2
src/lib.rs
View file

@ -247,6 +247,8 @@ extern crate rand;
extern crate serde;
extern crate sha2;
#[cfg(all(feature = "batch", any(feature = "std", feature = "alloc")))]
mod batch;
mod constants;
mod ed25519;
mod errors;