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use curve25519_dalek::edwards::{CompressedEdwardsY, EdwardsPoint};
use ed25519_dalek::Keypair;
use ed25519_dalek::{ExpandedSecretKey, Signature};
use ed25519_dalek::{PublicKey, SecretKey};
use sha2::{Digest, Sha512};
use x25519_dalek::StaticSecret;
use crate::{ed25519::*, error};
pub const CURVE_NAME_ED25519: &str = "Ed25519";
#[cfg(target_os = "ios")]
use crate::{
ed25519::private::Ed25519PrivateKey, ed25519::public::Ed25519PublicKey,
x25519::private::X25519PrivateKey, x25519::public::X25519PublicKey,
};
pub fn keypair_validation(
private_key: &SecretKey,
public_key: &PublicKey,
) -> Result<bool, error::CoreError> {
let keypair: Keypair = keypair::construct_from_secret_key(private_key);
if keypair.public.to_bytes() != (*public_key).to_bytes() {
let core_error = error::CoreError::KeyInvalidError {
name: CURVE_NAME_ED25519,
reason: "The given public key and private key do not match.",
};
return Err(core_error);
}
let expanded_private: ExpandedSecretKey = ExpandedSecretKey::from(private_key);
let message: &[u8] = b"Test";
let signature: Signature = expanded_private.sign(message, public_key);
match public_key.verify(message, &signature) {
Ok(()) => Ok(true),
Err(_) => {
let core_error = error::CoreError::KeyInvalidError {
name: CURVE_NAME_ED25519,
reason: "The given public key and private key do not match.",
};
Err(core_error)
}
}
}
pub fn ed25519_public_key_to_x25519(public_key: &PublicKey) -> x25519_dalek::PublicKey {
let public_key_bytes: [u8; 32] = (*public_key).to_bytes();
let mut bits: [u8; 32] = [0u8; 32];
bits.copy_from_slice(&public_key_bytes[..32]);
let compressed = CompressedEdwardsY(bits);
let edwardspoint: EdwardsPoint = compressed.decompress().unwrap();
let x25519_public_key: x25519_dalek::PublicKey = edwardspoint.to_montgomery().to_bytes().into();
x25519_public_key
}
pub fn ed25519_private_key_to_x25519(private_key: &SecretKey) -> StaticSecret {
let mut private_key_x25519 = [0; 32];
private_key_x25519.copy_from_slice(&Sha512::digest(&(private_key.as_bytes())[0..32])[0..32]);
private_key_x25519[0] &= 248;
private_key_x25519[31] &= 127;
private_key_x25519[31] |= 64;
private_key_x25519.into()
}
#[no_mangle]
#[cfg(target_os = "ios")]
pub unsafe extern "C" fn c_key_utils_ed25519_public_key_to_x25519(
public_key: *mut Ed25519PublicKey,
) -> *mut X25519PublicKey {
let ed25519_public_key = &mut *public_key;
let x25519_public_key = X25519PublicKey {
raw: ed25519_public_key_to_x25519(&ed25519_public_key.raw),
};
Box::into_raw(Box::new(x25519_public_key))
}
#[no_mangle]
#[cfg(target_os = "ios")]
pub unsafe extern "C" fn c_key_utils_ed25519_private_key_to_x25519(
private_key: *mut Ed25519PrivateKey,
) -> *mut X25519PrivateKey {
let ed25519_private_key = &mut *private_key;
let x25519_private_key = X25519PrivateKey {
raw: ed25519_private_key_to_x25519(&ed25519_private_key.raw),
};
Box::into_raw(Box::new(x25519_private_key))
}
#[cfg(test)]
mod tests {
use crate::{ed25519, key_utils};
use rand::rngs::OsRng;
use x25519_dalek::{EphemeralSecret, PublicKey, StaticSecret};
#[test]
fn it_works() {
assert_eq!(2 + 2, 4);
}
#[test]
fn it_validates_a_valid_keypair() {
let keypair = ed25519::keypair::create_keypair();
assert!(key_utils::keypair_validation(&keypair.secret, &keypair.public).is_ok());
}
#[test]
fn it_validates_an_invalid_keypair() {
let keypair1 = ed25519::keypair::create_keypair();
let keypair2 = ed25519::keypair::create_keypair();
assert!(!(key_utils::keypair_validation(&keypair1.secret, &keypair2.public).is_ok()));
}
#[test]
fn it_converts_an_ed25519_public_key_to_x25519() {
let keypair = ed25519::keypair::create_keypair();
let pubkey = key_utils::ed25519_public_key_to_x25519(&keypair.public);
assert_ne!(pubkey.as_bytes(), &[0; 32]);
}
#[test]
fn it_converts_an_ed25519_private_key_to_x25519() {
let keypair = ed25519::keypair::create_keypair();
let private_key = key_utils::ed25519_private_key_to_x25519(&keypair.secret);
assert_ne!(private_key.to_bytes(), [0; 32]);
}
#[test]
fn it_conducts_diffie_hellman_on_two_ed25519_keypairs() {
let alice = ed25519::keypair::create_keypair();
let alice_private = key_utils::ed25519_private_key_to_x25519(&alice.secret);
let alice_public = key_utils::ed25519_public_key_to_x25519(&alice.public);
let bob = ed25519::keypair::create_keypair();
let bob_private = key_utils::ed25519_private_key_to_x25519(&bob.secret);
let bob_public = key_utils::ed25519_public_key_to_x25519(&bob.public);
let alice_private_ephemeral = EphemeralSecret::new(&mut OsRng);
let alice_public_ephemeral = PublicKey::from(&alice_private_ephemeral);
let alice_shared_secret1 = alice_private_ephemeral.diffie_hellman(&bob_public);
let bob_private_static: StaticSecret = StaticSecret::from(bob_private.to_bytes());
let bob_shared_secret1 = bob_private_static.diffie_hellman(&alice_public_ephemeral);
assert_eq!(
alice_shared_secret1.as_bytes(),
bob_shared_secret1.as_bytes()
);
let bob_private_ephemeral = EphemeralSecret::new(&mut OsRng);
let bob_public_ephemeral = PublicKey::from(&bob_private_ephemeral);
let bob_shared_secret2 = bob_private_ephemeral.diffie_hellman(&alice_public);
let alice_private_static: StaticSecret = StaticSecret::from(alice_private.to_bytes());
let alice_shared_secret2 = alice_private_static.diffie_hellman(&bob_public_ephemeral);
assert_eq!(
alice_shared_secret2.as_bytes(),
bob_shared_secret2.as_bytes()
);
}
}