Merge "RootCanal: Implement ECDH for BR/EDR" (9054db7e) · Commits · e / os / android_packages_modules_Bluetooth

tools/rootcanal/lmp/Android.bp

+6 −0

Original line number	Diff line number	Diff line
		@@ -21,9 +21,12 @@ rust_ffi {
		rustlibs: [
		"libbt_packets",
		"libbytes",
		"libnum_bigint",
		"libnum_integer",
		"libnum_traits",
		"libthiserror",
		"libpin_utils",
		"librand",
		],
		include_dirs: ["include"],
		}
		@@ -55,8 +58,11 @@ rust_test_host {
		rustlibs: [
		"libbt_packets",
		"libbytes",
		"libnum_bigint",
		"libnum_integer",
		"libnum_traits",
		"libthiserror",
		"libpin_utils",
		"librand",
		],
		}

tools/rootcanal/lmp/src/ec.rs

0 → 100644

+471 −0

Original line number	Diff line number	Diff line
		/******************************************************************************
		*
		* Copyright 2022 The Android Open Source Project
		*
		* Licensed under the Apache License, Version 2.0 (the "License");
		* you may not use this file except in compliance with the License.
		* You may obtain a copy of the License at:
		*
		* http://www.apache.org/licenses/LICENSE-2.0
		*
		* Unless required by applicable law or agreed to in writing, software
		* distributed under the License is distributed on an "AS IS" BASIS,
		* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
		* See the License for the specific language governing permissions and
		* limitations under the License.
		*
		******************************************************************************/

		/******************************************************************************
		* IMPORTANT
		*
		* These cryptography methods do not provide any security or correctness
		* ensurance.
		* They should be used only in Bluetooth emulation, not including any production
		* environment.
		*
		******************************************************************************/

		use num_bigint::{BigInt, Sign};
		use num_integer::Integer;
		use num_traits::{One, Signed, Zero};
		use rand::{thread_rng, Rng};
		use std::convert::TryInto;
		use std::marker::PhantomData;

		#[derive(Debug, Clone, PartialEq)]
		pub enum PublicKey {
		P192([u8; P192r1::PUBLIC_KEY_SIZE]),
		P256([u8; P256r1::PUBLIC_KEY_SIZE]),
		}

		impl PublicKey {
		pub fn new(size: usize) -> Option<Self> {
		match size {
		P192r1::PUBLIC_KEY_SIZE => Some(Self::P192([0; P192r1::PUBLIC_KEY_SIZE])),
		P256r1::PUBLIC_KEY_SIZE => Some(Self::P256([0; P256r1::PUBLIC_KEY_SIZE])),
		_ => None,
		}
		}

		fn from_bytes(bytes: &[u8]) -> Option<Self> {
		if let Ok(inner) = bytes.try_into() {
		Some(PublicKey::P192(inner))
		} else if let Ok(inner) = bytes.try_into() {
		Some(PublicKey::P256(inner))
		} else {
		None
		}
		}

		pub fn as_slice(&self) -> &[u8] {
		match self {
		PublicKey::P192(inner) => inner,
		PublicKey::P256(inner) => inner,
		}
		}

		pub fn size(&self) -> usize {
		self.as_slice().len()
		}

		pub fn as_mut_slice(&mut self) -> &mut [u8] {
		match self {
		PublicKey::P192(inner) => inner,
		PublicKey::P256(inner) => inner,
		}
		}

		fn get_x(&self) -> BigInt {
		BigInt::from_signed_bytes_le(&self.as_slice()[0..self.size() / 2])
		}

		fn get_y(&self) -> BigInt {
		BigInt::from_signed_bytes_le(&self.as_slice()[self.size() / 2..self.size()])
		}

		fn to_point<Curve: EllipticCurve>(&self) -> Point<Curve> {
		Point::new(&self.get_x(), &self.get_y())
		}
		}

		#[derive(Debug, Clone, PartialEq)]
		pub enum PrivateKey {
		P192([u8; P192r1::PRIVATE_KEY_SIZE]),
		P256([u8; P256r1::PRIVATE_KEY_SIZE]),
		}

		#[derive(Debug, Clone, PartialEq)]
		pub enum DhKey {
		P192([u8; P192r1::PUBLIC_KEY_SIZE]),
		P256([u8; P256r1::PUBLIC_KEY_SIZE]),
		}

		impl DhKey {
		fn from_bytes(bytes: &[u8]) -> Option<Self> {
		if let Ok(inner) = bytes.try_into() {
		Some(DhKey::P192(inner))
		} else if let Ok(inner) = bytes.try_into() {
		Some(DhKey::P256(inner))
		} else {
		None
		}
		}
		}

		impl PrivateKey {
		// Generate a private key in range[1,2**191]
		pub fn generate_p192() -> Self {
		let random_bytes: [u8; P192r1::PRIVATE_KEY_SIZE] = thread_rng().gen();
		let mut key = BigInt::from_signed_bytes_le(&random_bytes);

		if key.is_negative() {
		key = -key;
		}
		if key < BigInt::one() {
		key = BigInt::one();
		}
		let buf = key.to_signed_bytes_le();
		let mut inner = [0; P192r1::PRIVATE_KEY_SIZE];
		inner[0..buf.len()].copy_from_slice(&buf);
		Self::P192(inner)
		}

		pub fn generate_p256() -> Self {
		let random_bytes: [u8; P256r1::PRIVATE_KEY_SIZE] = thread_rng().gen();
		let mut key = BigInt::from_signed_bytes_le(&random_bytes);

		if key.is_negative() {
		key = -key;
		}
		if key < BigInt::one() {
		key = BigInt::one();
		}
		let buf = key.to_signed_bytes_le();
		let mut inner = [0; P256r1::PRIVATE_KEY_SIZE];
		inner[0..buf.len()].copy_from_slice(&buf);
		Self::P256(inner)
		}

		pub fn as_slice(&self) -> &[u8] {
		match self {
		PrivateKey::P192(inner) => inner,
		PrivateKey::P256(inner) => inner,
		}
		}

		fn to_bigint(&self) -> BigInt {
		BigInt::from_signed_bytes_le(self.as_slice())
		}

		pub fn derive(&self) -> PublicKey {
		let bytes = match self {
		PrivateKey::P192(_) => {
		Point::<P192r1>::generate_public_key(&self.to_bigint()).to_bytes()
		}
		PrivateKey::P256(_) => {
		Point::<P256r1>::generate_public_key(&self.to_bigint()).to_bytes()
		}
		}
		.unwrap();
		PublicKey::from_bytes(&bytes).unwrap()
		}

		pub fn shared_secret(&self, peer_public_key: PublicKey) -> DhKey {
		let bytes = match self {
		PrivateKey::P192(_) => {
		(&peer_public_key.to_point::<P192r1>() * &self.to_bigint()).to_bytes()
		}
		PrivateKey::P256(_) => {
		(&peer_public_key.to_point::<P256r1>() * &self.to_bigint()).to_bytes()
		}
		}
		.unwrap();
		DhKey::from_bytes(&bytes).unwrap()
		}
		}

		// Modular Inverse
		fn mod_inv(x: &BigInt, m: &BigInt) -> Option<BigInt> {
		let egcd = x.extended_gcd(m);
		if !egcd.gcd.is_one() {
		None
		} else {
		Some(egcd.x % m)
		}
		}

		trait EllipticCurve {
		type Param: AsRef<[u8]>;
		const A: i32;
		const P: Self::Param;
		const G_X: Self::Param;
		const G_Y: Self::Param;
		const PRIVATE_KEY_SIZE: usize;
		const PUBLIC_KEY_SIZE: usize;

		fn p() -> BigInt {
		BigInt::from_bytes_be(Sign::Plus, Self::P.as_ref())
		}
		}

		#[derive(Debug, Clone, PartialEq)]
		struct P192r1;

		impl EllipticCurve for P192r1 {
		type Param = [u8; 24];

		const A: i32 = -3;
		const P: Self::Param = [
		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
		0xfe, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
		];
		const G_X: Self::Param = [
		0x18, 0x8d, 0xa8, 0x0e, 0xb0, 0x30, 0x90, 0xf6, 0x7c, 0xbf, 0x20, 0xeb, 0x43, 0xa1, 0x88,
		0x00, 0xf4, 0xff, 0x0a, 0xfd, 0x82, 0xff, 0x10, 0x12,
		];
		const G_Y: Self::Param = [
		0x07, 0x19, 0x2b, 0x95, 0xff, 0xc8, 0xda, 0x78, 0x63, 0x10, 0x11, 0xed, 0x6b, 0x24, 0xcd,
		0xd5, 0x73, 0xf9, 0x77, 0xa1, 0x1e, 0x79, 0x48, 0x11,
		];
		const PRIVATE_KEY_SIZE: usize = 24;
		const PUBLIC_KEY_SIZE: usize = 48;
		}

		#[derive(Debug, Clone, PartialEq)]
		struct P256r1;

		impl EllipticCurve for P256r1 {
		type Param = [u8; 32];

		const A: i32 = -3;
		const P: Self::Param = [
		0xff, 0xff, 0xff, 0xff, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
		0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
		0xff, 0xff,
		];
		const G_X: Self::Param = [
		0x6b, 0x17, 0xd1, 0xf2, 0xe1, 0x2c, 0x42, 0x47, 0xf8, 0xbc, 0xe6, 0xe5, 0x63, 0xa4, 0x40,
		0xf2, 0x77, 0x03, 0x7d, 0x81, 0x2d, 0xeb, 0x33, 0xa0, 0xf4, 0xa1, 0x39, 0x45, 0xd8, 0x98,
		0xc2, 0x96,
		];
		const G_Y: Self::Param = [
		0x4f, 0xe3, 0x42, 0xe2, 0xfe, 0x1a, 0x7f, 0x9b, 0x8e, 0xe7, 0xeb, 0x4a, 0x7c, 0x0f, 0x9e,
		0x16, 0x2b, 0xce, 0x33, 0x57, 0x6b, 0x31, 0x5e, 0xce, 0xcb, 0xb6, 0x40, 0x68, 0x37, 0xbf,
		0x51, 0xf5,
		];
		const PRIVATE_KEY_SIZE: usize = 32;
		const PUBLIC_KEY_SIZE: usize = 64;
		}

		#[derive(Debug, PartialEq)]
		enum Point<Curve> {
		Infinite(PhantomData<Curve>),
		Finite { x: BigInt, y: BigInt, _curve: PhantomData<Curve> },
		}

		impl<Curve> Point<Curve>
		where
		Curve: EllipticCurve,
		{
		fn o() -> Self {
		Point::Infinite(PhantomData)
		}

		fn generate_public_key(private_key: &BigInt) -> Self {
		&Self::g() * private_key
		}

		fn new(x: &BigInt, y: &BigInt) -> Self {
		Point::Finite { x: x.clone(), y: y.clone(), _curve: PhantomData }
		}

		fn g() -> Self {
		Self::new(
		&BigInt::from_bytes_be(Sign::Plus, Curve::G_X.as_ref()),
		&BigInt::from_bytes_be(Sign::Plus, Curve::G_Y.as_ref()),
		)
		}

		#[cfg(test)]
		fn get_x(&self) -> Option<BigInt> {
		match self {
		Point::Infinite(_) => None,
		Point::Finite { x, .. } => Some(x.clone()),
		}
		}

		fn to_bytes(&self) -> Option<Vec<u8>> {
		match self {
		Point::Infinite(_) => None,
		Point::Finite { x, y, _curve: _ } => {
		let mut x = x.to_signed_bytes_le();
		x.resize(Curve::PRIVATE_KEY_SIZE, 0);
		let mut y = y.to_signed_bytes_le();
		y.resize(Curve::PRIVATE_KEY_SIZE, 0);
		x.append(&mut y);
		Some(x)
		}
		}
		}
		}

		impl<Curve> Clone for Point<Curve>
		where
		Curve: EllipticCurve,
		{
		fn clone(&self) -> Self {
		match self {
		Point::Infinite(_) => Point::o(),
		Point::Finite { x, y, .. } => Point::new(x, y),
		}
		}
		}

		// Elliptic Curve Group Addition
		// https://mathworld.wolfram.com/EllipticCurve.html
		impl<Curve> std::ops::Add<&Point<Curve>> for &Point<Curve>
		where
		Curve: EllipticCurve,
		{
		type Output = Point<Curve>;

		fn add(self, rhs: &Point<Curve>) -> Self::Output {
		// P + O = O + P = P
		match (self, rhs) {
		(Point::Infinite(_), Point::Infinite(_)) => Self::Output::o(),
		(Point::Infinite(_), Point::Finite { .. }) => rhs.clone(),
		(Point::Finite { .. }, Point::Infinite(_)) => self.clone(),
		(
		Point::Finite { _curve: _, x: x1, y: y1 },
		Point::Finite { _curve: _, x: x2, y: y2 },
		) => {
		// P + (-P) = O
		if x1 == x2 && y1 == &(-y2) {
		return Self::Output::o();
		}
		let p = &Curve::p();
		// d(x^3 + ax + b) / dx = (3x^2 + a) / 2y
		let slope = if x1 == x2 {
		(&(3 * x1.pow(2) + Curve::A) * &mod_inv(&(2 * y1), p).unwrap()) % p
		} else {
		// dy/dx = (y2 - y1) / (x2 - x1)
		(&(y2 - y1) * &mod_inv(&(x2 - x1), p).unwrap()) % p
		};
		// Solving (x-p)(x-q)(x-r) = x^3 + ax + b
		// => x = d^2 - x1 - x2
		let x = (slope.pow(2) - x1 - x2) % p;
		let y = (slope * (x1 - &x) - y1) % p;
		Point::new(&x, &y)
		}
		}
		}
		}

		impl<Curve> std::ops::Mul<&BigInt> for &Point<Curve>
		where
		Curve: EllipticCurve,
		{
		type Output = Point<Curve>;

		fn mul(self, rhs: &BigInt) -> Self::Output {
		let mut addend = self.clone();
		let mut result = Point::o();
		let mut i = rhs.clone();

		// O(logN) double-and-add multiplication
		while !i.is_zero() {
		if i.is_odd() {
		result = &result + &addend;
		}
		addend = &addend + &addend;
		i /= 2;
		}
		result
		}
		}

		#[cfg(test)]
		mod tests {
		use crate::ec::*;
		use num_bigint::BigInt;

		struct EcTestCase<const N: usize> {
		pub priv_a: [u8; N],
		pub priv_b: [u8; N],
		pub pub_a: [u8; N],
		pub dh_x: [u8; N],
		}

		// Private A, Private B, Public A(x), DHKey
		const P192_TEST_CASES: [EcTestCase<48>; 4] = [
		EcTestCase::<48> {
		priv_a: *b"07915f86918ddc27005df1d6cf0c142b625ed2eff4a518ff",
		priv_b: *b"1e636ca790b50f68f15d8dbe86244e309211d635de00e16d",
		pub_a: *b"15207009984421a6586f9fc3fe7e4329d2809ea51125f8ed",
		dh_x: *b"fb3ba2012c7e62466e486e229290175b4afebc13fdccee46",
		},
		EcTestCase::<48> {
		priv_a: *b"52ec1ca6e0ec973c29065c3ca10be80057243002f09bb43e",
		priv_b: *b"57231203533e9efe18cc622fd0e34c6a29c6e0fa3ab3bc53",
		pub_a: *b"45571f027e0d690795d61560804da5de789a48f94ab4b07e",
		dh_x: *b"a20a34b5497332aa7a76ab135cc0c168333be309d463c0c0",
		},
		EcTestCase::<48> {
		priv_a: *b"00a0df08eaf51e6e7be519d67c6749ea3f4517cdd2e9e821",
		priv_b: *b"2bf5e0d1699d50ca5025e8e2d9b13244b4d322a328be1821",
		pub_a: *b"2ed35b430fa45f9d329186d754eeeb0495f0f653127f613d",
		dh_x: *b"3b3986ba70790762f282a12a6d3bcae7a2ca01e25b87724e",
		},
		EcTestCase::<48> {
		priv_a: *b"030a4af66e1a4d590a83e0284fca5cdf83292b84f4c71168",
		priv_b: *b"12448b5c69ecd10c0471060f2bf86345c5e83c03d16bae2c",
		pub_a: *b"f24a6899218fa912e7e4a8ba9357cb8182958f9fa42c968c",
		dh_x: *b"4a78f83fba757c35f94abea43e92effdd2bc700723c61939",
		},
		];

		// Private A, Private B, Public A(x), DHKey
		const P256_TEST_CASES: [EcTestCase<64>; 2] = [
		EcTestCase::<64> {
		priv_a: *b"3f49f6d4a3c55f3874c9b3e3d2103f504aff607beb40b7995899b8a6cd3c1abd",
		priv_b: *b"55188b3d32f6bb9a900afcfbeed4e72a59cb9ac2f19d7cfb6b4fdd49f47fc5fd",
		pub_a: *b"20b003d2f297be2c5e2c83a7e9f9a5b9eff49111acf4fddbcc0301480e359de6",
		dh_x: *b"ec0234a357c8ad05341010a60a397d9b99796b13b4f866f1868d34f373bfa698",
		},
		EcTestCase::<64> {
		priv_a: *b"06a516693c9aa31a6084545d0c5db641b48572b97203ddffb7ac73f7d0457663",
		priv_b: *b"529aa0670d72cd6497502ed473502b037e8803b5c60829a5a3caa219505530ba",
		pub_a: *b"2c31a47b5779809ef44cb5eaaf5c3e43d5f8faad4a8794cb987e9b03745c78dd",
		dh_x: *b"ab85843a2f6d883f62e5684b38e307335fe6e1945ecd19604105c6f23221eb69",
		},
		];

		#[test]
		fn p192() {
		for test_case in P192_TEST_CASES {
		let priv_a = BigInt::parse_bytes(&test_case.priv_a, 16).unwrap();
		let priv_b = BigInt::parse_bytes(&test_case.priv_b, 16).unwrap();
		let pub_a = Point::<P192r1>::generate_public_key(&priv_a);
		let pub_b = Point::<P192r1>::generate_public_key(&priv_b);
		assert_eq!(pub_a.get_x().unwrap(), BigInt::parse_bytes(&test_case.pub_a, 16).unwrap());
		let shared = &pub_a * &priv_b;
		assert_eq!(shared.get_x().unwrap(), BigInt::parse_bytes(&test_case.dh_x, 16).unwrap());
		assert_eq!((&pub_a * &priv_b).get_x().unwrap(), (&pub_b * &priv_a).get_x().unwrap());
		}
		}

		#[test]
		fn p256() {
		for test_case in P256_TEST_CASES {
		let priv_a = BigInt::parse_bytes(&test_case.priv_a, 16).unwrap();
		let priv_b = BigInt::parse_bytes(&test_case.priv_b, 16).unwrap();
		let pub_a = Point::<P256r1>::generate_public_key(&priv_a);
		let pub_b = Point::<P256r1>::generate_public_key(&priv_b);
		assert_eq!(pub_a.get_x().unwrap(), BigInt::parse_bytes(&test_case.pub_a, 16).unwrap());
		let shared = &pub_a * &priv_b;
		assert_eq!(shared.get_x().unwrap(), BigInt::parse_bytes(&test_case.dh_x, 16).unwrap());
		assert_eq!((&pub_a * &priv_b).get_x().unwrap(), (&pub_b * &priv_a).get_x().unwrap());
		}
		}
		}

tools/rootcanal/lmp/src/lib.rs

+1 −0

Original line number	Diff line number	Diff line
		//! Link Manager implemented in Rust

		mod ec;
		mod either;
		mod ffi;
		mod future;

tools/rootcanal/lmp/src/procedure/mod.rs

+7 −0

Original line number	Diff line number	Diff line
		@@ -3,6 +3,7 @@ use std::future::Future;
		use std::pin::Pin;
		use std::task::{self, Poll};

		use crate::ec::PrivateKey;
		use crate::packets::{hci, lmp};

		pub trait Context {
		@@ -39,6 +40,12 @@ pub trait Context {

		SendAcceptedLmpPacketFuture(self, opcode)
		}

		fn get_private_key(&self) -> Option<PrivateKey> {
		None
		}

		fn set_private_key(&self, _key: &PrivateKey) {}
		}

		/// Future for Context::receive_hci_command and Context::receive_lmp_packet

tools/rootcanal/lmp/src/procedure/secure_simple_pairing.rs

+53 −61

Original line number	Diff line number	Diff line
		@@ -4,6 +4,7 @@ use std::convert::TryInto;

		use num_traits::{FromPrimitive, ToPrimitive};

		use crate::ec::{DhKey, PrivateKey, PublicKey};
		use crate::either::Either;
		use crate::packets::{hci, lmp};
		use crate::procedure::{authentication, features, Context};
		@@ -28,45 +29,6 @@ enum AuthenticationMethod {
		PasskeyEntry,
		}

		const P192_PUBLIC_KEY_SIZE: usize = 48;
		const P256_PUBLIC_KEY_SIZE: usize = 64;

		enum PublicKey {
		P192([u8; P192_PUBLIC_KEY_SIZE]),
		P256([u8; P256_PUBLIC_KEY_SIZE]),
		}

		impl PublicKey {
		fn generate(key_size: usize) -> Option<PublicKey> {
		match key_size {
		P192_PUBLIC_KEY_SIZE => Some(PublicKey::P192([0; P192_PUBLIC_KEY_SIZE])),
		P256_PUBLIC_KEY_SIZE => Some(PublicKey::P256([0; P256_PUBLIC_KEY_SIZE])),
		_ => None,
		}
		}

		fn as_slice(&self) -> &[u8] {
		match self {
		PublicKey::P192(inner) => inner,
		PublicKey::P256(inner) => inner,
		}
		}

		fn as_mut_slice(&mut self) -> &mut [u8] {
		match self {
		PublicKey::P192(inner) => inner,
		PublicKey::P256(inner) => inner,
		}
		}

		fn get_size(&self) -> usize {
		match self {
		PublicKey::P192(_) => P192_PUBLIC_KEY_SIZE,
		PublicKey::P256(_) => P256_PUBLIC_KEY_SIZE,
		}
		}
		}

		#[derive(Clone, Copy)]
		struct AuthenticationParams {
		io_capability: hci::IoCapability,
		@@ -101,19 +63,19 @@ fn authentication_method(
		}

		// Bluetooth Core, Vol 3, Part C, 5.2.2.6
		fn link_key_type(auth_method: AuthenticationMethod, public_key: PublicKey) -> hci::KeyType {
		fn link_key_type(auth_method: AuthenticationMethod, dh_key: DhKey) -> hci::KeyType {
		use hci::KeyType::*;
		use AuthenticationMethod::*;

		match (public_key, auth_method) {
		(PublicKey::P256(_), OutOfBand \| PasskeyEntry \| NumericComparaisonUserConfirm) => {
		match (dh_key, auth_method) {
		(DhKey::P256(_), OutOfBand \| PasskeyEntry \| NumericComparaisonUserConfirm) => {
		AuthenticatedP256
		}
		(PublicKey::P192(_), OutOfBand \| PasskeyEntry \| NumericComparaisonUserConfirm) => {
		(DhKey::P192(_), OutOfBand \| PasskeyEntry \| NumericComparaisonUserConfirm) => {
		AuthenticatedP192
		}
		(PublicKey::P256(_), NumericComparaisonJustWork) => UnauthenticatedP256,
		(PublicKey::P192(_), NumericComparaisonJustWork) => UnauthenticatedP192,
		(DhKey::P256(_), NumericComparaisonJustWork) => UnauthenticatedP256,
		(DhKey::P192(_), NumericComparaisonJustWork) => UnauthenticatedP192,
		}
		}

		@@ -125,7 +87,7 @@ async fn send_public_key(ctx: &impl Context, transaction_id: u8, public_key: Pub
		transaction_id,
		major_type: 1,
		minor_type: 1,
		payload_length: public_key.get_size() as u8,
		payload_length: public_key.size() as u8,
		}
		.build(),
		)
		@@ -145,7 +107,7 @@ async fn send_public_key(ctx: &impl Context, transaction_id: u8, public_key: Pub
		async fn receive_public_key(ctx: &impl Context, transaction_id: u8) -> PublicKey {
		let key_size: usize =
		ctx.receive_lmp_packet::<lmp::EncapsulatedHeaderPacket>().await.get_payload_length().into();
		let mut key = PublicKey::generate(key_size).unwrap();
		let mut key = PublicKey::new(key_size).unwrap();

		ctx.send_lmp_packet(
		lmp::AcceptedBuilder { transaction_id, accepted_opcode: lmp::Opcode::EncapsulatedHeader }
		@@ -420,15 +382,20 @@ pub async fn initiate(ctx: &impl Context) -> Result<(), ()> {
		};

		// Public Key Exchange
		let peer_public_key = {
		let dh_key = {
		use hci::LMPFeaturesPage1Bits::SecureConnectionsHostSupport;
		let key = if features::supported_on_both_page1(ctx, SecureConnectionsHostSupport).await {
		PublicKey::generate(P256_PUBLIC_KEY_SIZE).unwrap()

		let private_key =
		if features::supported_on_both_page1(ctx, SecureConnectionsHostSupport).await {
		PrivateKey::generate_p256()
		} else {
		PublicKey::generate(P192_PUBLIC_KEY_SIZE).unwrap()
		PrivateKey::generate_p192()
		};
		send_public_key(ctx, 0, key).await;
		receive_public_key(ctx, 0).await
		ctx.set_private_key(&private_key);
		let local_public_key = private_key.derive();
		send_public_key(ctx, 0, local_public_key).await;
		let peer_public_key = receive_public_key(ctx, 0).await;
		private_key.shared_secret(peer_public_key)
		};

		// Authentication Stage 1
		@@ -534,7 +501,7 @@ pub async fn initiate(ctx: &impl Context) -> Result<(), ()> {
		ctx.send_hci_event(
		hci::LinkKeyNotificationBuilder {
		bd_addr: ctx.peer_address(),
		key_type: link_key_type(auth_method, peer_public_key),
		key_type: link_key_type(auth_method, dh_key),
		link_key,
		}
		.build(),
		@@ -597,11 +564,16 @@ pub async fn respond(ctx: &impl Context, request: lmp::IoCapabilityReqPacket) ->
		};

		// Public Key Exchange
		let peer_public_key = {
		let dh_key = {
		let peer_public_key = receive_public_key(ctx, 0).await;
		let public_key = PublicKey::generate(peer_public_key.get_size()).unwrap();
		send_public_key(ctx, 0, public_key).await;
		peer_public_key
		let private_key = match peer_public_key {
		PublicKey::P192(_) => PrivateKey::generate_p192(),
		PublicKey::P256(_) => PrivateKey::generate_p256(),
		};
		ctx.set_private_key(&private_key);
		let local_public_key = private_key.derive();
		send_public_key(ctx, 0, local_public_key).await;
		private_key.shared_secret(peer_public_key)
		};

		// Authentication Stage 1
		@@ -712,7 +684,7 @@ pub async fn respond(ctx: &impl Context, request: lmp::IoCapabilityReqPacket) ->
		ctx.send_hci_event(
		hci::LinkKeyNotificationBuilder {
		bd_addr: ctx.peer_address(),
		key_type: link_key_type(auth_method, peer_public_key),
		key_type: link_key_type(auth_method, dh_key),
		link_key,
		}
		.build(),
		@@ -723,12 +695,32 @@ pub async fn respond(ctx: &impl Context, request: lmp::IoCapabilityReqPacket) ->

		#[cfg(test)]
		mod tests {
		use crate::ec::PrivateKey;
		use crate::procedure::Context;
		use crate::test::{sequence, TestContext};
		// simple pairing is part of authentication procedure
		use super::super::authentication::initiate;
		use super::super::authentication::respond;

		fn local_p192_public_key(context: &crate::test::TestContext) -> [[u8; 16]; 3] {
		let mut buf = [[0; 16], [0; 16], [0; 16]];
		if let Some(key) = context.get_private_key() {
		for (dst, src) in buf.iter_mut().zip(key.derive().as_slice().chunks(16)) {
		dst.copy_from_slice(src);
		}
		}
		buf
		}

		fn peer_p192_public_key() -> [[u8; 16]; 3] {
		let mut buf = [[0; 16], [0; 16], [0; 16]];
		let key = PrivateKey::generate_p192().derive();
		for (dst, src) in buf.iter_mut().zip(key.as_slice().chunks(16)) {
		dst.copy_from_slice(src);
		}
		buf
		}

		#[test]
		fn initiate_size() {
		let context = crate::test::TestContext::new();