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LibCrypto+LibTLS: Generalize the elliptic curve interface

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These changes generalize the interface with an elliptic curve
implementation. This allows LibTLS to support elliptic curves generally
without needing the specifics of elliptic curve implementations.

This should allow for easier addition of other elliptic curves.
This commit is contained in:
Michiel Visser 2022-03-05 18:13:39 +01:00 • committed by Ali Mohammad Pur
parent 21bbff0349
commit c1b041e761
10 changed files with 133 additions and 122 deletions
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24
Userland/Libraries/LibCrypto/Curves/EllipticCurve.h Normal file
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@ -0,0 +1,24 @@
/*
* Copyright (c) 2022, Michiel Visser <opensource@webmichiel.nl>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/ByteBuffer.h>
namespace Crypto::Curves {
class EllipticCurve {
public:
virtual size_t key_size() = 0;
virtual ErrorOr<ByteBuffer> generate_private_key() = 0;
virtual ErrorOr<ByteBuffer> generate_public_key(ReadonlyBytes a) = 0;
virtual ErrorOr<ByteBuffer> compute_coordinate(ReadonlyBytes scalar_bytes, ReadonlyBytes point_bytes) = 0;
virtual ErrorOr<ByteBuffer> derive_premaster_key(ReadonlyBytes shared_point) = 0;
virtual ~EllipticCurve() = default;
};
}

22
Userland/Libraries/LibCrypto/Curves/X25519.cpp
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@ -6,6 +6,7 @@
#include <AK/ByteReader.h>
#include <AK/Endian.h>
#include <AK/Random.h>
#include <LibCrypto/Curves/X25519.h>
namespace Crypto::Curves {
@ -259,6 +260,19 @@ void X25519::modular_multiply_inverse(u32* state, u32* value)
modular_multiply(state, u, value);
}
ErrorOr<ByteBuffer> X25519::generate_private_key()
{
auto buffer = TRY(ByteBuffer::create_uninitialized(BYTES));
fill_with_random(buffer.data(), buffer.size());
return buffer;
}
ErrorOr<ByteBuffer> X25519::generate_public_key(ReadonlyBytes a)
{
u8 generator[BYTES] { 9 };
return compute_coordinate(a, { generator, BYTES });
}
// https://datatracker.ietf.org/doc/html/rfc7748#section-5
ErrorOr<ByteBuffer> X25519::compute_coordinate(ReadonlyBytes input_k, ReadonlyBytes input_u)
{
@ -334,4 +348,12 @@ ErrorOr<ByteBuffer> X25519::compute_coordinate(ReadonlyBytes input_k, ReadonlyBy
// Encode state for export
return export_state(u);
}
ErrorOr<ByteBuffer> X25519::derive_premaster_key(ReadonlyBytes shared_point)
{
VERIFY(shared_point.size() == BYTES);
ByteBuffer premaster_key = TRY(ByteBuffer::copy(shared_point));
return premaster_key;
}
}

9
Userland/Libraries/LibCrypto/Curves/X25519.h
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@ -7,10 +7,11 @@
#pragma once
#include <AK/ByteBuffer.h>
#include <LibCrypto/Curves/EllipticCurve.h>
namespace Crypto::Curves {
class X25519 {
class X25519 : public EllipticCurve {
static constexpr u8 BITS = 255;
static constexpr u8 BYTES = 32;
@ -18,7 +19,11 @@ class X25519 {
static constexpr u32 A24 = 121666;
public:
static ErrorOr<ByteBuffer> compute_coordinate(ReadonlyBytes a, ReadonlyBytes b);
size_t key_size() override { return BYTES; }
ErrorOr<ByteBuffer> generate_private_key() override;
ErrorOr<ByteBuffer> generate_public_key(ReadonlyBytes a) override;
ErrorOr<ByteBuffer> compute_coordinate(ReadonlyBytes a, ReadonlyBytes b) override;
ErrorOr<ByteBuffer> derive_premaster_key(ReadonlyBytes shared_point) override;
private:
static void import_state(u32* state, ReadonlyBytes data);

22
Userland/Libraries/LibCrypto/Curves/X448.cpp
View file

@ -6,6 +6,7 @@
#include <AK/ByteReader.h>
#include <AK/Endian.h>
#include <AK/Random.h>
#include <LibCrypto/Curves/X448.h>
namespace Crypto::Curves {
@ -282,6 +283,19 @@ void X448::modular_multiply_inverse(u32* state, u32* value)
modular_multiply(state, u, value);
}
ErrorOr<ByteBuffer> X448::generate_private_key()
{
auto buffer = TRY(ByteBuffer::create_uninitialized(BYTES));
fill_with_random(buffer.data(), buffer.size());
return buffer;
}
ErrorOr<ByteBuffer> X448::generate_public_key(ReadonlyBytes a)
{
u8 generator[BYTES] { 5 };
return compute_coordinate(a, { generator, BYTES });
}
// https://datatracker.ietf.org/doc/html/rfc7748#section-5
ErrorOr<ByteBuffer> X448::compute_coordinate(ReadonlyBytes input_k, ReadonlyBytes input_u)
{
@ -353,4 +367,12 @@ ErrorOr<ByteBuffer> X448::compute_coordinate(ReadonlyBytes input_k, ReadonlyByte
// Encode state for export
return export_state(u);
}
ErrorOr<ByteBuffer> X448::derive_premaster_key(ReadonlyBytes shared_point)
{
VERIFY(shared_point.size() == BYTES);
ByteBuffer premaster_key = TRY(ByteBuffer::copy(shared_point));
return premaster_key;
}
}

9
Userland/Libraries/LibCrypto/Curves/X448.h
View file

@ -7,10 +7,11 @@
#pragma once
#include <AK/ByteBuffer.h>
#include <LibCrypto/Curves/EllipticCurve.h>
namespace Crypto::Curves {
class X448 {
class X448 : public EllipticCurve {
static constexpr u16 BITS = 448;
static constexpr u8 BYTES = 56;
@ -18,7 +19,11 @@ class X448 {
static constexpr u32 A24 = 39082;
public:
static ErrorOr<ByteBuffer> compute_coordinate(ReadonlyBytes a, ReadonlyBytes b);
size_t key_size() override { return BYTES; }
ErrorOr<ByteBuffer> generate_private_key() override;
ErrorOr<ByteBuffer> generate_public_key(ReadonlyBytes a) override;
ErrorOr<ByteBuffer> compute_coordinate(ReadonlyBytes a, ReadonlyBytes b) override;
ErrorOr<ByteBuffer> derive_premaster_key(ReadonlyBytes shared_point) override;
private:
static void import_state(u32* state, ReadonlyBytes data);