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Enforce public vs private keys via types

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This commit is contained in:
Valentin Tolmer
2021-06-15 14:47:35 -07:00
committed by Kevin Lewi
parent cd85efc603
commit 210e0e99df
8 changed files with 139 additions and 77 deletions
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src/keypair.rs
+81 -20
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@@ -37,8 +37,8 @@ impl<T> SizedBytesExt for T where T: SizedBytes {}
/// A Keypair trait with public-private verification
#[derive(Clone, Debug, PartialEq, Eq)]
pub struct KeyPair<G> {
pk: Key,
sk: Key,
pk: PublicKey,
sk: PrivateKey,
_g: PhantomData<G>,
}
@@ -58,18 +58,18 @@ impl<G> Drop for KeyPair<G> {
impl<G: Group> KeyPair<G> {
/// The public key component
pub fn public(&self) -> &Key {
pub fn public(&self) -> &PublicKey {
&self.pk
}
/// The private key component
pub fn private(&self) -> &Key {
pub fn private(&self) -> &PrivateKey {
&self.sk
}
/// A constructor that receives public and private key independently as
/// bytes
pub fn new(public: Key, private: Key) -> Result<Self, InternalPakeError> {
pub fn new(public: PublicKey, private: PrivateKey) -> Result<Self, InternalPakeError> {
Ok(Self {
pk: public,
sk: private,
@@ -83,29 +83,35 @@ impl<G: Group> KeyPair<G> {
let sk_bytes = G::scalar_as_bytes(&sk);
let pk = G::base_point().mult_by_slice(sk_bytes);
Self {
pk: Key(pk.to_arr().to_vec()),
sk: Key(sk_bytes.to_vec()),
pk: PublicKey(Key(pk.to_arr().to_vec())),
sk: PrivateKey(Key(sk_bytes.to_vec())),
_g: PhantomData,
}
}
/// Obtaining a public key from secret bytes. At all times, we should have
/// &public_from_private(self.private()) == self.public()
pub(crate) fn public_from_private(bytes: &Key) -> Key {
pub(crate) fn public_from_private(bytes: &PrivateKey) -> PublicKey {
let bytes_data = GenericArray::<u8, G::ScalarLen>::from_slice(&bytes.0[..]);
Key(G::base_point().mult_by_slice(bytes_data).to_arr().to_vec())
PublicKey(Key(G::base_point()
.mult_by_slice(bytes_data)
.to_arr()
.to_vec()))
}
/// Check whether a public key is valid. This is meant to be applied on
/// material provided through the network which fits the key
/// representation (i.e. can be mapped to a curve point), but presents
/// some risk - e.g. small subgroup check
pub(crate) fn check_public_key(key: Key) -> Result<Key, InternalPakeError> {
pub(crate) fn check_public_key(key: PublicKey) -> Result<PublicKey, InternalPakeError> {
G::from_element_slice(GenericArray::from_slice(&key.0)).map(|_| key)
}
/// Computes the diffie hellman function on a public key and private key
pub(crate) fn diffie_hellman(pk: Key, sk: Key) -> Result<Vec<u8>, InternalPakeError> {
pub(crate) fn diffie_hellman(
pk: PublicKey,
sk: PrivateKey,
) -> Result<Vec<u8>, InternalPakeError> {
let pk_data = GenericArray::<u8, G::ElemLen>::from_slice(&pk.0[..]);
let point = G::from_element_slice(pk_data)?;
let secret_data = GenericArray::<u8, G::ScalarLen>::from_slice(&sk.0[..]);
@@ -114,7 +120,7 @@ impl<G: Group> KeyPair<G> {
/// Obtains a KeyPair from a slice representing the private key
pub fn from_private_key_slice(input: &[u8]) -> Result<Self, InternalPakeError> {
let sk = Key::from_arr(GenericArray::from_slice(input))?;
let sk = PrivateKey(Key::from_arr(GenericArray::from_slice(input))?);
let pk = Self::public_from_private(&sk);
Self::new(pk, sk)
}
@@ -122,8 +128,8 @@ impl<G: Group> KeyPair<G> {
#[cfg(test)]
pub fn as_byte_ptrs(&self) -> Vec<(*const u8, usize)> {
vec![
(self.pk.as_ptr(), <Key as SizedBytes>::Len::to_usize()),
(self.sk.as_ptr(), <Key as SizedBytes>::Len::to_usize()),
(self.pk.as_ptr(), KeyLen::to_usize()),
(self.sk.as_ptr(), KeyLen::to_usize()),
]
}
}
@@ -145,6 +151,8 @@ impl<G: Group + Debug> KeyPair<G> {
}
}
type KeyLen = U32;
/// A minimalist key type built around a \[u8; 32\]
#[derive(Debug, PartialEq, Eq, Clone, Zeroize)]
// Ensure Key material is zeroed after use.
@@ -160,18 +168,71 @@ impl Deref for Key {
}
}
impl SizedBytes for Key {
type Len = U32;
fn to_arr(&self) -> GenericArray<u8, Self::Len> {
// Don't make it implement SizedBytes so that it's not constructible outside of this module.
impl Key {
fn to_arr(&self) -> GenericArray<u8, KeyLen> {
GenericArray::clone_from_slice(&self.0[..])
}
fn from_arr(key_bytes: &GenericArray<u8, Self::Len>) -> Result<Self, TryFromSizedBytesError> {
fn from_arr(key_bytes: &GenericArray<u8, KeyLen>) -> Result<Self, TryFromSizedBytesError> {
Ok(Key(key_bytes.to_vec()))
}
}
/// Wrapper around a Key to enforce that it's a private one.
#[derive(Debug, PartialEq, Eq, Clone, Zeroize)]
// Ensure Key material is zeroed after use.
#[zeroize(drop)]
#[repr(transparent)]
pub struct PrivateKey(Key);
impl Deref for PrivateKey {
type Target = Key;
fn deref(&self) -> &Self::Target {
&self.0
}
}
impl SizedBytes for PrivateKey {
type Len = KeyLen;
fn to_arr(&self) -> GenericArray<u8, Self::Len> {
self.0.to_arr()
}
fn from_arr(key_bytes: &GenericArray<u8, Self::Len>) -> Result<Self, TryFromSizedBytesError> {
Ok(PrivateKey(Key::from_arr(key_bytes)?))
}
}
/// Wrapper around a Key to enforce that it's a public one.
#[derive(Debug, PartialEq, Eq, Clone, Zeroize)]
// Ensure Key material is zeroed after use.
#[zeroize(drop)]
#[repr(transparent)]
pub struct PublicKey(Key);
impl Deref for PublicKey {
type Target = Key;
fn deref(&self) -> &Self::Target {
&self.0
}
}
impl SizedBytes for PublicKey {
type Len = KeyLen;
fn to_arr(&self) -> GenericArray<u8, Self::Len> {
self.0.to_arr()
}
fn from_arr(key_bytes: &GenericArray<u8, Self::Len>) -> Result<Self, TryFromSizedBytesError> {
Ok(PublicKey(Key::from_arr(key_bytes)?))
}
}
#[cfg(test)]
mod tests {
use super::*;
@@ -183,7 +244,7 @@ mod tests {
#[test]
fn test_zeroize_key() -> Result<(), ProtocolError> {
let key_len = <Key as SizedBytes>::Len::to_usize();
let key_len = KeyLen::to_usize();
let mut key = Key(vec![1u8; key_len]);
let ptr = key.as_ptr();