Project import generated by Copybara.
GitOrigin-RevId: 06b0c815d958bef0a60978d0766d65af839e37b6
Change-Id: Ifac0c45ae509ca8a8ed793fac5c981d4e23d3bf9
diff --git a/nearby/crypto/crypto_provider/src/p256.rs b/nearby/crypto/crypto_provider/src/p256.rs
index 90d3542..fd7b531 100644
--- a/nearby/crypto/crypto_provider/src/p256.rs
+++ b/nearby/crypto/crypto_provider/src/p256.rs
@@ -12,10 +12,9 @@
// See the License for the specific language governing permissions and
// limitations under the License.
-extern crate alloc;
+use tinyvec::ArrayVec;
use crate::elliptic_curve::{Curve, EcdhProvider, PublicKey};
-use alloc::vec::Vec;
use core::fmt::Debug;
/// Marker type for P256 implementation. This is used by EcdhProvider as its type parameter.
@@ -23,6 +22,24 @@
pub enum P256 {}
impl Curve for P256 {}
+/// Longest length for a sec-1 encoded P256 public key, which is the uncompressed format
+/// `04 || X || Y` as defined in section 2.3.3 of the SECG SEC 1 ("Elliptic Curve Cryptography")
+/// standard.
+const P256_PUBLIC_KEY_MAX_LENGTH: usize = 65;
+
+/// Whether an elliptic curve point should be compressed or not.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum PointCompression {
+ /// The elliptic curve point should be compressed (`02 || X` or `03 || X`),
+ /// as defined in section 2.3.3 of the SECG SEC 1 ("Elliptic Curve
+ /// Cryptography").
+ Compressed,
+ /// The elliptic curve point should be uncompressed (`04 || X || Y`), as
+ /// defined in section 2.3.3 of the SECG SEC 1 ("Elliptic Curve
+ /// Cryptography").
+ Uncompressed,
+}
+
/// Trait for a NIST-P256 public key.
pub trait P256PublicKey: Sized + PartialEq + Debug {
/// The error type associated with this implementation.
@@ -36,7 +53,10 @@
/// ("Elliptic Curve Cryptography") standard. Note that it is not necessarily true that
/// `from_sec1_bytes(bytes)?.to_sec1_bytes() == bytes` because of point compression. (But it is
/// always true that `from_sec1_bytes(key.to_sec1_bytes())? == key`).
- fn to_sec1_bytes(&self) -> Vec<u8>;
+ fn to_sec1_bytes(
+ &self,
+ point_compression: PointCompression,
+ ) -> ArrayVec<[u8; P256_PUBLIC_KEY_MAX_LENGTH]>;
/// Converts this public key's x and y coordinates on the elliptic curve to big endian octet
/// strings.
@@ -48,13 +68,14 @@
impl<P: P256PublicKey> PublicKey<P256> for P {
type Error = <Self as P256PublicKey>::Error;
+ type EncodedPublicKey = ArrayVec<[u8; P256_PUBLIC_KEY_MAX_LENGTH]>;
fn from_bytes(bytes: &[u8]) -> Result<Self, Self::Error> {
Self::from_sec1_bytes(bytes)
}
- fn to_bytes(&self) -> Vec<u8> {
- Self::to_sec1_bytes(self)
+ fn to_bytes(&self) -> Self::EncodedPublicKey {
+ Self::to_sec1_bytes(self, PointCompression::Uncompressed)
}
}
