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LibCrypto: Move all elliptic curve private methods into .cpp

Browse source 
All the elliptic curve implementations had a long list of private
methods which were all stored in a single .cpp file. Now we simply use
static methods instead.
This commit is contained in:
Michiel Visser 2022-03-18 19:18:29 +01:00 • committed by Ali Mohammad Pur
parent 596391a4ee
commit e07ec02470
6 changed files with 171 additions and 220 deletions
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34
Userland/Libraries/LibCrypto/Curves/SECP256r1.cpp
View file

@ -14,6 +14,14 @@
namespace Crypto::Curves { namespace Crypto::Curves {
static constexpr u256 REDUCE_PRIME { u128 { 0x0000000000000001ull, 0xffffffff00000000ull }, u128 { 0xffffffffffffffffull, 0x00000000fffffffe } };
static constexpr u256 REDUCE_ORDER { u128 { 0x0c46353d039cdaafull, 0x4319055258e8617bull }, u128 { 0x0000000000000000ull, 0x00000000ffffffff } };
static constexpr u256 PRIME_INVERSE_MOD_R { u128 { 0x0000000000000001ull, 0x0000000100000000ull }, u128 { 0x0000000000000000ull, 0xffffffff00000002ull } };
static constexpr u256 PRIME { u128 { 0xffffffffffffffffull, 0x00000000ffffffffull }, u128 { 0x0000000000000000ull, 0xffffffff00000001ull } };
static constexpr u256 R2_MOD_PRIME { u128 { 0x0000000000000003ull, 0xfffffffbffffffffull }, u128 { 0xfffffffffffffffeull, 0x00000004fffffffdull } };
static constexpr u256 ONE { 1u };
static constexpr u256 B_MONTGOMERY { u128 { 0xd89cdf6229c4bddfull, 0xacf005cd78843090ull }, u128 { 0xe5a220abf7212ed6ull, 0xdc30061d04874834ull } };
static u256 import_big_endian(ReadonlyBytes data) static u256 import_big_endian(ReadonlyBytes data)
{ {
VERIFY(data.size() == 32); VERIFY(data.size() == 32);
@ -53,7 +61,7 @@ static u512 multiply(u256 const& left, u256 const& right)
return { result.low, result.high }; return { result.low, result.high };
} }
u256 SECP256r1::modular_reduce(u256 const& value) static u256 modular_reduce(u256 const& value)
{ {
// Add -prime % 2^256 = 2^224-2^192-2^96+1 // Add -prime % 2^256 = 2^224-2^192-2^96+1
bool carry = false; bool carry = false;
@ -63,7 +71,7 @@ u256 SECP256r1::modular_reduce(u256 const& value)
return select(value, other, carry); return select(value, other, carry);
} }
u256 SECP256r1::modular_reduce_order(u256 const& value) static u256 modular_reduce_order(u256 const& value)
{ {
// Add -order % 2^256 // Add -order % 2^256
bool carry = false; bool carry = false;
@ -73,7 +81,7 @@ u256 SECP256r1::modular_reduce_order(u256 const& value)
return select(value, other, carry); return select(value, other, carry);
} }
u256 SECP256r1::modular_add(u256 const& left, u256 const& right, bool carry_in) static u256 modular_add(u256 const& left, u256 const& right, bool carry_in = false)
{ {
bool carry = carry_in; bool carry = carry_in;
u256 output = left.addc(right, carry); u256 output = left.addc(right, carry);
@ -90,7 +98,7 @@ u256 SECP256r1::modular_add(u256 const& left, u256 const& right, bool carry_in)
return output + addend; return output + addend;
} }
u256 SECP256r1::modular_sub(u256 const& left, u256 const& right) static u256 modular_sub(u256 const& left, u256 const& right)
{ {
bool borrow = false; bool borrow = false;
u256 output = left.subc(right, borrow); u256 output = left.subc(right, borrow);
@ -107,7 +115,7 @@ u256 SECP256r1::modular_sub(u256 const& left, u256 const& right)
return output - sub; return output - sub;
} }
u256 SECP256r1::modular_multiply(u256 const& left, u256 const& right) static u256 modular_multiply(u256 const& left, u256 const& right)
{ {
// Modular multiplication using the Montgomery method: https://en.wikipedia.org/wiki/Montgomery_modular_multiplication // Modular multiplication using the Montgomery method: https://en.wikipedia.org/wiki/Montgomery_modular_multiplication
// This requires that the inputs to this function are in Montgomery form. // This requires that the inputs to this function are in Montgomery form.
@ -129,22 +137,22 @@ u256 SECP256r1::modular_multiply(u256 const& left, u256 const& right)
return modular_add(mult.high(), mp.high(), carry); return modular_add(mult.high(), mp.high(), carry);
} }
u256 SECP256r1::modular_square(u256 const& value) static u256 modular_square(u256 const& value)
{ {
return modular_multiply(value, value); return modular_multiply(value, value);
} }
u256 SECP256r1::to_montgomery(u256 const& value) static u256 to_montgomery(u256 const& value)
{ {
return modular_multiply(value, R2_MOD_PRIME); return modular_multiply(value, R2_MOD_PRIME);
} }
u256 SECP256r1::from_montgomery(u256 const& value) static u256 from_montgomery(u256 const& value)
{ {
return modular_multiply(value, ONE); return modular_multiply(value, ONE);
} }
u256 SECP256r1::modular_inverse(u256 const& value) static u256 modular_inverse(u256 const& value)
{ {
// Modular inverse modulo the curve prime can be computed using Fermat's little theorem: a^(p-2) mod p = a^-1 mod p. // Modular inverse modulo the curve prime can be computed using Fermat's little theorem: a^(p-2) mod p = a^-1 mod p.
// Calculating a^(p-2) mod p can be done using the square-and-multiply exponentiation method, as p-2 is constant. // Calculating a^(p-2) mod p can be done using the square-and-multiply exponentiation method, as p-2 is constant.
@ -193,7 +201,7 @@ u256 SECP256r1::modular_inverse(u256 const& value)
return result; return result;
} }
void SECP256r1::point_double(JacobianPoint& output_point, JacobianPoint const& point) static void point_double(JacobianPoint& output_point, JacobianPoint const& point)
{ {
// Based on "Point Doubling" from http://point-at-infinity.org/ecc/Prime_Curve_Jacobian_Coordinates.html // Based on "Point Doubling" from http://point-at-infinity.org/ecc/Prime_Curve_Jacobian_Coordinates.html
@ -247,7 +255,7 @@ void SECP256r1::point_double(JacobianPoint& output_point, JacobianPoint const& p
output_point.z = zp; output_point.z = zp;
} }
void SECP256r1::point_add(JacobianPoint& output_point, JacobianPoint const& point_a, JacobianPoint const& point_b) static void point_add(JacobianPoint& output_point, JacobianPoint const& point_a, JacobianPoint const& point_b)
{ {
// Based on "Point Addition" from http://point-at-infinity.org/ecc/Prime_Curve_Jacobian_Coordinates.html // Based on "Point Addition" from http://point-at-infinity.org/ecc/Prime_Curve_Jacobian_Coordinates.html
if (point_a.x.is_zero_constant_time() && point_a.y.is_zero_constant_time() && point_a.z.is_zero_constant_time()) { if (point_a.x.is_zero_constant_time() && point_a.y.is_zero_constant_time() && point_a.z.is_zero_constant_time()) {
@ -314,7 +322,7 @@ void SECP256r1::point_add(JacobianPoint& output_point, JacobianPoint const& poin
output_point.z = z3; output_point.z = z3;
} }
void SECP256r1::convert_jacobian_to_affine(JacobianPoint& point) static void convert_jacobian_to_affine(JacobianPoint& point)
{ {
u256 temp; u256 temp;
// X' = X/Z^2 // X' = X/Z^2
@ -328,7 +336,7 @@ void SECP256r1::convert_jacobian_to_affine(JacobianPoint& point)
point.y = modular_multiply(point.y, temp); point.y = modular_multiply(point.y, temp);
} }
bool SECP256r1::is_point_on_curve(JacobianPoint const& point) static bool is_point_on_curve(JacobianPoint const& point)
{ {
// This check requires the point to be in Montgomery form, with Z=1 // This check requires the point to be in Montgomery form, with Z=1
u256 temp, temp2; u256 temp, temp2;

23
Userland/Libraries/LibCrypto/Curves/SECP256r1.h
View file

@ -25,29 +25,6 @@ public:
ErrorOr<ByteBuffer> generate_public_key(ReadonlyBytes a) override; ErrorOr<ByteBuffer> generate_public_key(ReadonlyBytes a) override;
ErrorOr<ByteBuffer> compute_coordinate(ReadonlyBytes scalar_bytes, ReadonlyBytes point_bytes) override; ErrorOr<ByteBuffer> compute_coordinate(ReadonlyBytes scalar_bytes, ReadonlyBytes point_bytes) override;
ErrorOr<ByteBuffer> derive_premaster_key(ReadonlyBytes shared_point) override; ErrorOr<ByteBuffer> derive_premaster_key(ReadonlyBytes shared_point) override;
private:
static u256 modular_reduce(u256 const& value);
static u256 modular_reduce_order(u256 const& value);
static u256 modular_add(u256 const& left, u256 const& right, bool carry_in = false);
static u256 modular_sub(u256 const& left, u256 const& right);
static u256 modular_multiply(u256 const& left, u256 const& right);
static u256 modular_square(u256 const& value);
static u256 to_montgomery(u256 const& value);
static u256 from_montgomery(u256 const& value);
static u256 modular_inverse(u256 const& value);
static void point_double(JacobianPoint& output_point, JacobianPoint const& point);
static void point_add(JacobianPoint& output_point, JacobianPoint const& point_a, JacobianPoint const& point_b);
static void convert_jacobian_to_affine(JacobianPoint& point);
static bool is_point_on_curve(JacobianPoint const& point);
static constexpr u256 REDUCE_PRIME { u128 { 0x0000000000000001ull, 0xffffffff00000000ull }, u128 { 0xffffffffffffffffull, 0x00000000fffffffe } };
static constexpr u256 REDUCE_ORDER { u128 { 0x0c46353d039cdaafull, 0x4319055258e8617bull }, u128 { 0x0000000000000000ull, 0x00000000ffffffff } };
static constexpr u256 PRIME_INVERSE_MOD_R { u128 { 0x0000000000000001ull, 0x0000000100000000ull }, u128 { 0x0000000000000000ull, 0xffffffff00000002ull } };
static constexpr u256 PRIME { u128 { 0xffffffffffffffffull, 0x00000000ffffffffull }, u128 { 0x0000000000000000ull, 0xffffffff00000001ull } };
static constexpr u256 R2_MOD_PRIME { u128 { 0x0000000000000003ull, 0xfffffffbffffffffull }, u128 { 0xfffffffffffffffeull, 0x00000004fffffffdull } };
static constexpr u256 ONE { 1u };
static constexpr u256 B_MONTGOMERY { u128 { 0xd89cdf6229c4bddfull, 0xacf005cd78843090ull }, u128 { 0xe5a220abf7212ed6ull, 0xdc30061d04874834ull } };
}; };
} }

137
Userland/Libraries/LibCrypto/Curves/X25519.cpp
View file

@ -11,19 +11,24 @@
namespace Crypto::Curves { namespace Crypto::Curves {
void X25519::import_state(u32* state, ReadonlyBytes data) static constexpr u8 BITS = 255;
static constexpr u8 BYTES = 32;
static constexpr u8 WORDS = 8;
static constexpr u32 A24 = 121666;
static void import_state(u32* state, ReadonlyBytes data)
{ {
for (auto i = 0; i < X25519::WORDS; i++) { for (auto i = 0; i < WORDS; i++) {
u32 value = ByteReader::load32(data.offset_pointer(sizeof(u32) * i)); u32 value = ByteReader::load32(data.offset_pointer(sizeof(u32) * i));
state[i] = AK::convert_between_host_and_little_endian(value); state[i] = AK::convert_between_host_and_little_endian(value);
} }
} }
ErrorOr<ByteBuffer> X25519::export_state(u32* data) static ErrorOr<ByteBuffer> export_state(u32* data)
{ {
auto buffer = TRY(ByteBuffer::create_uninitialized(X25519::BYTES)); auto buffer = TRY(ByteBuffer::create_uninitialized(BYTES));
for (auto i = 0; i < X25519::WORDS; i++) { for (auto i = 0; i < WORDS; i++) {
u32 value = AK::convert_between_host_and_little_endian(data[i]); u32 value = AK::convert_between_host_and_little_endian(data[i]);
ByteReader::store(buffer.offset_pointer(sizeof(u32) * i), value); ByteReader::store(buffer.offset_pointer(sizeof(u32) * i), value);
} }
@ -31,49 +36,68 @@ ErrorOr<ByteBuffer> X25519::export_state(u32* data)
return buffer; return buffer;
} }
void X25519::select(u32* state, u32* a, u32* b, u32 condition) static void select(u32* state, u32* a, u32* b, u32 condition)
{ {
// If B < (2^255 - 19) then R = B, else R = A // If B < (2^255 - 19) then R = B, else R = A
u32 mask = condition - 1; u32 mask = condition - 1;
for (auto i = 0; i < X25519::WORDS; i++) { for (auto i = 0; i < WORDS; i++) {
state[i] = (a[i] & mask) | (b[i] & ~mask); state[i] = (a[i] & mask) | (b[i] & ~mask);
} }
} }
void X25519::set(u32* state, u32 value) static void set(u32* state, u32 value)
{ {
state[0] = value; state[0] = value;
for (auto i = 1; i < X25519::WORDS; i++) { for (auto i = 1; i < WORDS; i++) {
state[i] = 0; state[i] = 0;
} }
} }
void X25519::copy(u32* state, u32* value) static void copy(u32* state, u32* value)
{ {
for (auto i = 0; i < X25519::WORDS; i++) { for (auto i = 0; i < WORDS; i++) {
state[i] = value[i]; state[i] = value[i];
} }
} }
void X25519::conditional_swap(u32* first, u32* second, u32 condition) static void conditional_swap(u32* first, u32* second, u32 condition)
{ {
u32 mask = ~condition + 1; u32 mask = ~condition + 1;
for (auto i = 0; i < X25519::WORDS; i++) { for (auto i = 0; i < WORDS; i++) {
u32 temp = mask & (first[i] ^ second[i]); u32 temp = mask & (first[i] ^ second[i]);
first[i] ^= temp; first[i] ^= temp;
second[i] ^= temp; second[i] ^= temp;
} }
} }
void X25519::modular_multiply_single(u32* state, u32* first, u32 second) static void modular_reduce(u32* state, u32* data)
{
// R = A mod p
u64 temp = 19;
u32 other[WORDS];
for (auto i = 0; i < WORDS; i++) {
temp += data[i];
other[i] = temp & 0xFFFFFFFF;
temp >>= 32;
}
// Compute B = A - (2^255 - 19)
other[7] -= 0x80000000;
u32 mask = (other[7] & 0x80000000) >> 31;
select(state, other, data, mask);
}
static void modular_multiply_single(u32* state, u32* first, u32 second)
{ {
// Compute R = (A * B) mod p // Compute R = (A * B) mod p
u64 temp = 0; u64 temp = 0;
u32 output[X25519::WORDS]; u32 output[WORDS];
for (auto i = 0; i < X25519::WORDS; i++) { for (auto i = 0; i < WORDS; i++) {
temp += (u64)first[i] * second; temp += (u64)first[i] * second;
output[i] = temp & 0xFFFFFFFF; output[i] = temp & 0xFFFFFFFF;
temp >>= 32; temp >>= 32;
@ -87,7 +111,7 @@ void X25519::modular_multiply_single(u32* state, u32* first, u32 second)
output[7] &= 0x7FFFFFFF; output[7] &= 0x7FFFFFFF;
// Fast modular reduction // Fast modular reduction
for (auto i = 0; i < X25519::WORDS; i++) { for (auto i = 0; i < WORDS; i++) {
temp += output[i]; temp += output[i];
output[i] = temp & 0xFFFFFFFF; output[i] = temp & 0xFFFFFFFF;
temp >>= 32; temp >>= 32;
@ -96,29 +120,23 @@ void X25519::modular_multiply_single(u32* state, u32* first, u32 second)
modular_reduce(state, output); modular_reduce(state, output);
} }
void X25519::modular_square(u32* state, u32* value) static void modular_multiply(u32* state, u32* first, u32* second)
{
// Compute R = (A ^ 2) mod p
modular_multiply(state, value, value);
}
void X25519::modular_multiply(u32* state, u32* first, u32* second)
{ {
// Compute R = (A * B) mod p // Compute R = (A * B) mod p
u64 temp = 0; u64 temp = 0;
u64 carry = 0; u64 carry = 0;
u32 output[X25519::WORDS * 2]; u32 output[WORDS * 2];
// Comba's method // Comba's method
for (auto i = 0; i < 16; i++) { for (auto i = 0; i < 16; i++) {
if (i < X25519::WORDS) { if (i < WORDS) {
for (auto j = 0; j <= i; j++) { for (auto j = 0; j <= i; j++) {
temp += (u64)first[j] * second[i - j]; temp += (u64)first[j] * second[i - j];
carry += temp >> 32; carry += temp >> 32;
temp &= 0xFFFFFFFF; temp &= 0xFFFFFFFF;
} }
} else { } else {
for (auto j = i - 7; j < X25519::WORDS; j++) { for (auto j = i - 7; j < WORDS; j++) {
temp += (u64)first[j] * second[i - j]; temp += (u64)first[j] * second[i - j];
carry += temp >> 32; carry += temp >> 32;
temp &= 0xFFFFFFFF; temp &= 0xFFFFFFFF;
@ -136,7 +154,7 @@ void X25519::modular_multiply(u32* state, u32* first, u32* second)
output[7] &= 0x7FFFFFFF; output[7] &= 0x7FFFFFFF;
// Fast modular reduction 1st pass // Fast modular reduction 1st pass
for (auto i = 0; i < X25519::WORDS; i++) { for (auto i = 0; i < WORDS; i++) {
temp += output[i]; temp += output[i];
temp += (u64)output[i + 8] * 38; temp += (u64)output[i + 8] * 38;
output[i] = temp & 0xFFFFFFFF; output[i] = temp & 0xFFFFFFFF;
@ -151,7 +169,7 @@ void X25519::modular_multiply(u32* state, u32* first, u32* second)
output[7] &= 0x7FFFFFFF; output[7] &= 0x7FFFFFFF;
// Fast modular reduction 2nd pass // Fast modular reduction 2nd pass
for (auto i = 0; i < X25519::WORDS; i++) { for (auto i = 0; i < WORDS; i++) {
temp += output[i]; temp += output[i];
output[i] = temp & 0xFFFFFFFF; output[i] = temp & 0xFFFFFFFF;
temp >>= 32; temp >>= 32;
@ -160,11 +178,17 @@ void X25519::modular_multiply(u32* state, u32* first, u32* second)
modular_reduce(state, output); modular_reduce(state, output);
} }
void X25519::modular_add(u32* state, u32* first, u32* second) static void modular_square(u32* state, u32* value)
{
// Compute R = (A ^ 2) mod p
modular_multiply(state, value, value);
}
static void modular_add(u32* state, u32* first, u32* second)
{ {
// R = (A + B) mod p // R = (A + B) mod p
u64 temp = 0; u64 temp = 0;
for (auto i = 0; i < X25519::WORDS; i++) { for (auto i = 0; i < WORDS; i++) {
temp += first[i]; temp += first[i];
temp += second[i]; temp += second[i];
state[i] = temp & 0xFFFFFFFF; state[i] = temp & 0xFFFFFFFF;
@ -174,11 +198,11 @@ void X25519::modular_add(u32* state, u32* first, u32* second)
modular_reduce(state, state); modular_reduce(state, state);
} }
void X25519::modular_subtract(u32* state, u32* first, u32* second) static void modular_subtract(u32* state, u32* first, u32* second)
{ {
// R = (A - B) mod p // R = (A - B) mod p
i64 temp = -19; i64 temp = -19;
for (auto i = 0; i < X25519::WORDS; i++) { for (auto i = 0; i < WORDS; i++) {
temp += first[i]; temp += first[i];
temp -= second[i]; temp -= second[i];
state[i] = temp & 0xFFFFFFFF; state[i] = temp & 0xFFFFFFFF;
@ -191,26 +215,7 @@ void X25519::modular_subtract(u32* state, u32* first, u32* second)
modular_reduce(state, state); modular_reduce(state, state);
} }
void X25519::modular_reduce(u32* state, u32* data) static void to_power_of_2n(u32* state, u32* value, u8 n)
{
// R = A mod p
u64 temp = 19;
u32 other[X25519::WORDS];
for (auto i = 0; i < X25519::WORDS; i++) {
temp += data[i];
other[i] = temp & 0xFFFFFFFF;
temp >>= 32;
}
// Compute B = A - (2^255 - 19)
other[7] -= 0x80000000;
u32 mask = (other[7] & 0x80000000) >> 31;
select(state, other, data, mask);
}
void X25519::to_power_of_2n(u32* state, u32* value, u8 n)
{ {
// compute R = (A ^ (2^n)) mod p // compute R = (A ^ (2^n)) mod p
modular_square(state, value); modular_square(state, value);
@ -219,11 +224,11 @@ void X25519::to_power_of_2n(u32* state, u32* value, u8 n)
} }
} }
void X25519::modular_multiply_inverse(u32* state, u32* value) static void modular_multiply_inverse(u32* state, u32* value)
{ {
// Compute R = A^-1 mod p // Compute R = A^-1 mod p
u32 u[X25519::WORDS]; u32 u[WORDS];
u32 v[X25519::WORDS]; u32 v[WORDS];
// Fermat's little theorem // Fermat's little theorem
modular_square(u, value); modular_square(u, value);
@ -276,14 +281,14 @@ ErrorOr<ByteBuffer> X25519::generate_public_key(ReadonlyBytes a)
// https://datatracker.ietf.org/doc/html/rfc7748#section-5 // https://datatracker.ietf.org/doc/html/rfc7748#section-5
ErrorOr<ByteBuffer> X25519::compute_coordinate(ReadonlyBytes input_k, ReadonlyBytes input_u) ErrorOr<ByteBuffer> X25519::compute_coordinate(ReadonlyBytes input_k, ReadonlyBytes input_u)
{ {
u32 k[X25519::WORDS] {}; u32 k[WORDS] {};
u32 u[X25519::WORDS] {}; u32 u[WORDS] {};
u32 x1[X25519::WORDS] {}; u32 x1[WORDS] {};
u32 x2[X25519::WORDS] {}; u32 x2[WORDS] {};
u32 z1[X25519::WORDS] {}; u32 z1[WORDS] {};
u32 z2[X25519::WORDS] {}; u32 z2[WORDS] {};
u32 t1[X25519::WORDS] {}; u32 t1[WORDS] {};
u32 t2[X25519::WORDS] {}; u32 t2[WORDS] {};
// Copy input to internal state // Copy input to internal state
import_state(k, input_k); import_state(k, input_k);
@ -310,8 +315,8 @@ ErrorOr<ByteBuffer> X25519::compute_coordinate(ReadonlyBytes input_k, ReadonlyBy
// Montgomery ladder // Montgomery ladder
u32 swap = 0; u32 swap = 0;
for (auto i = X25519::BITS - 1; i >= 0; i--) { for (auto i = BITS - 1; i >= 0; i--) {
u32 b = (k[i / X25519::BYTES] >> (i % X25519::BYTES)) & 1; u32 b = (k[i / BYTES] >> (i % BYTES)) & 1;
conditional_swap(x1, x2, swap ^ b); conditional_swap(x1, x2, swap ^ b);
conditional_swap(z1, z2, swap ^ b); conditional_swap(z1, z2, swap ^ b);

24
Userland/Libraries/LibCrypto/Curves/X25519.h
View file

@ -12,34 +12,12 @@
namespace Crypto::Curves { namespace Crypto::Curves {
class X25519 : public EllipticCurve { class X25519 : public EllipticCurve {
static constexpr u8 BITS = 255;
static constexpr u8 BYTES = 32;
static constexpr u8 WORDS = 8;
static constexpr u32 A24 = 121666;
public: public:
size_t key_size() override { return BYTES; } size_t key_size() override { return 32; }
ErrorOr<ByteBuffer> generate_private_key() override; ErrorOr<ByteBuffer> generate_private_key() override;
ErrorOr<ByteBuffer> generate_public_key(ReadonlyBytes a) override; ErrorOr<ByteBuffer> generate_public_key(ReadonlyBytes a) override;
ErrorOr<ByteBuffer> compute_coordinate(ReadonlyBytes a, ReadonlyBytes b) override; ErrorOr<ByteBuffer> compute_coordinate(ReadonlyBytes a, ReadonlyBytes b) override;
ErrorOr<ByteBuffer> derive_premaster_key(ReadonlyBytes shared_point) override; ErrorOr<ByteBuffer> derive_premaster_key(ReadonlyBytes shared_point) override;
private:
static void import_state(u32* state, ReadonlyBytes data);
static ErrorOr<ByteBuffer> export_state(u32* data);
static void select(u32* state, u32* a, u32* b, u32 condition);
static void set(u32* state, u32 value);
static void copy(u32* state, u32* value);
static void conditional_swap(u32* first, u32* second, u32 condition);
static void modular_multiply_single(u32* state, u32* first, u32 second);
static void modular_square(u32* state, u32* value);
static void modular_multiply(u32* state, u32* first, u32* second);
static void modular_add(u32* state, u32* first, u32* second);
static void modular_subtract(u32* state, u32* first, u32* second);
static void modular_reduce(u32* state, u32* data);
static void to_power_of_2n(u32* state, u32* value, u8 n);
static void modular_multiply_inverse(u32* state, u32* value);
}; };
} }

149
Userland/Libraries/LibCrypto/Curves/X448.cpp
View file

@ -11,19 +11,24 @@
namespace Crypto::Curves { namespace Crypto::Curves {
void X448::import_state(u32* state, ReadonlyBytes data) static constexpr u16 BITS = 448;
static constexpr u8 BYTES = 56;
static constexpr u8 WORDS = 14;
static constexpr u32 A24 = 39082;
static void import_state(u32* state, ReadonlyBytes data)
{ {
for (auto i = 0; i < X448::WORDS; i++) { for (auto i = 0; i < WORDS; i++) {
u32 value = ByteReader::load32(data.offset_pointer(sizeof(u32) * i)); u32 value = ByteReader::load32(data.offset_pointer(sizeof(u32) * i));
state[i] = AK::convert_between_host_and_little_endian(value); state[i] = AK::convert_between_host_and_little_endian(value);
} }
} }
ErrorOr<ByteBuffer> X448::export_state(u32* data) static ErrorOr<ByteBuffer> export_state(u32* data)
{ {
auto buffer = TRY(ByteBuffer::create_uninitialized(X448::BYTES)); auto buffer = TRY(ByteBuffer::create_uninitialized(BYTES));
for (auto i = 0; i < X448::WORDS; i++) { for (auto i = 0; i < WORDS; i++) {
u32 value = AK::convert_between_host_and_little_endian(data[i]); u32 value = AK::convert_between_host_and_little_endian(data[i]);
ByteReader::store(buffer.offset_pointer(sizeof(u32) * i), value); ByteReader::store(buffer.offset_pointer(sizeof(u32) * i), value);
} }
@ -31,50 +36,74 @@ ErrorOr<ByteBuffer> X448::export_state(u32* data)
return buffer; return buffer;
} }
void X448::select(u32* state, u32* a, u32* b, u32 condition) static void select(u32* state, u32* a, u32* b, u32 condition)
{ {
// If B < (2^448 - 2^224 + 1) then R = B, else R = A // If B < (2^448 - 2^224 + 1) then R = B, else R = A
u32 mask = condition - 1; u32 mask = condition - 1;
for (auto i = 0; i < X448::WORDS; i++) { for (auto i = 0; i < WORDS; i++) {
state[i] = (a[i] & mask) | (b[i] & ~mask); state[i] = (a[i] & mask) | (b[i] & ~mask);
} }
} }
void X448::set(u32* state, u32 value) static void set(u32* state, u32 value)
{ {
state[0] = value; state[0] = value;
for (auto i = 1; i < X448::WORDS; i++) { for (auto i = 1; i < WORDS; i++) {
state[i] = 0; state[i] = 0;
} }
} }
void X448::copy(u32* state, u32* value) static void copy(u32* state, u32* value)
{ {
for (auto i = 0; i < X448::WORDS; i++) { for (auto i = 0; i < WORDS; i++) {
state[i] = value[i]; state[i] = value[i];
} }
} }
void X448::conditional_swap(u32* first, u32* second, u32 condition) static void conditional_swap(u32* first, u32* second, u32 condition)
{ {
u32 mask = ~condition + 1; u32 mask = ~condition + 1;
for (auto i = 0; i < X448::WORDS; i++) { for (auto i = 0; i < WORDS; i++) {
u32 temp = mask & (first[i] ^ second[i]); u32 temp = mask & (first[i] ^ second[i]);
first[i] ^= temp; first[i] ^= temp;
second[i] ^= temp; second[i] ^= temp;
} }
} }
void X448::modular_multiply_single(u32* state, u32* first, u32 second) static void modular_reduce(u32* state, u32* data, u32 a_high)
{
u64 temp = 1;
u32 other[WORDS];
// Compute B = A - (2^448 - 2^224 - 1)
for (auto i = 0; i < WORDS / 2; i++) {
temp += data[i];
other[i] = temp & 0xFFFFFFFF;
temp >>= 32;
}
temp += 1;
for (auto i = 7; i < WORDS; i++) {
temp += data[i];
other[i] = temp & 0xFFFFFFFF;
temp >>= 32;
}
auto condition = (a_high + (u32)temp - 1) & 1;
select(state, other, data, condition);
}
static void modular_multiply_single(u32* state, u32* first, u32 second)
{ {
// Compute R = (A * B) mod p // Compute R = (A * B) mod p
u64 temp = 0; u64 temp = 0;
u64 carry = 0; u64 carry = 0;
u32 output[X448::WORDS]; u32 output[WORDS];
for (auto i = 0; i < X448::WORDS; i++) { for (auto i = 0; i < WORDS; i++) {
temp += (u64)first[i] * second; temp += (u64)first[i] * second;
output[i] = temp & 0xFFFFFFFF; output[i] = temp & 0xFFFFFFFF;
temp >>= 32; temp >>= 32;
@ -82,14 +111,14 @@ void X448::modular_multiply_single(u32* state, u32* first, u32 second)
// Fast modular reduction // Fast modular reduction
carry = temp; carry = temp;
for (auto i = 0; i < X448::WORDS / 2; i++) { for (auto i = 0; i < WORDS / 2; i++) {
temp += output[i]; temp += output[i];
output[i] = temp & 0xFFFFFFFF; output[i] = temp & 0xFFFFFFFF;
temp >>= 32; temp >>= 32;
} }
temp += carry; temp += carry;
for (auto i = X448::WORDS / 2; i < X448::WORDS; i++) { for (auto i = WORDS / 2; i < WORDS; i++) {
temp += output[i]; temp += output[i];
output[i] = temp & 0xFFFFFFFF; output[i] = temp & 0xFFFFFFFF;
temp >>= 32; temp >>= 32;
@ -98,22 +127,16 @@ void X448::modular_multiply_single(u32* state, u32* first, u32 second)
modular_reduce(state, output, (u32)temp); modular_reduce(state, output, (u32)temp);
} }
void X448::modular_square(u32* state, u32* value) static void modular_multiply(u32* state, u32* first, u32* second)
{
// Compute R = (A ^ 2) mod p
modular_multiply(state, value, value);
}
void X448::modular_multiply(u32* state, u32* first, u32* second)
{ {
// Compute R = (A * B) mod p // Compute R = (A * B) mod p
u64 temp = 0; u64 temp = 0;
u64 carry = 0; u64 carry = 0;
u32 output[X448::WORDS * 2]; u32 output[WORDS * 2];
// Comba's method // Comba's method
for (auto i = 0; i < X448::WORDS * 2; i++) { for (auto i = 0; i < WORDS * 2; i++) {
if (i < 14) { if (i < 14) {
for (auto j = 0; j <= i; j++) { for (auto j = 0; j <= i; j++) {
temp += (u64)first[j] * second[i - j]; temp += (u64)first[j] * second[i - j];
@ -121,7 +144,7 @@ void X448::modular_multiply(u32* state, u32* first, u32* second)
temp &= 0xFFFFFFFF; temp &= 0xFFFFFFFF;
} }
} else { } else {
for (auto j = i - 13; j < X448::WORDS; j++) { for (auto j = i - 13; j < WORDS; j++) {
temp += (u64)first[j] * second[i - j]; temp += (u64)first[j] * second[i - j];
carry += temp >> 32; carry += temp >> 32;
temp &= 0xFFFFFFFF; temp &= 0xFFFFFFFF;
@ -135,7 +158,7 @@ void X448::modular_multiply(u32* state, u32* first, u32* second)
// Fast modular reduction (first pass) // Fast modular reduction (first pass)
temp = 0; temp = 0;
for (auto i = 0; i < X448::WORDS / 2; i++) { for (auto i = 0; i < WORDS / 2; i++) {
temp += output[i]; temp += output[i];
temp += output[i + 14]; temp += output[i + 14];
temp += output[i + 21]; temp += output[i + 21];
@ -143,7 +166,7 @@ void X448::modular_multiply(u32* state, u32* first, u32* second)
temp >>= 32; temp >>= 32;
} }
for (auto i = X448::WORDS / 2; i < X448::WORDS; i++) { for (auto i = WORDS / 2; i < WORDS; i++) {
temp += output[i]; temp += output[i];
temp += output[i + 7]; temp += output[i + 7];
temp += output[i + 14]; temp += output[i + 14];
@ -154,14 +177,14 @@ void X448::modular_multiply(u32* state, u32* first, u32* second)
// Fast modular reduction (second pass) // Fast modular reduction (second pass)
carry = temp; carry = temp;
for (auto i = 0; i < X448::WORDS / 2; i++) { for (auto i = 0; i < WORDS / 2; i++) {
temp += output[i]; temp += output[i];
output[i] = temp & 0xFFFFFFFF; output[i] = temp & 0xFFFFFFFF;
temp >>= 32; temp >>= 32;
} }
temp += carry; temp += carry;
for (auto i = X448::WORDS / 2; i < X448::WORDS; i++) { for (auto i = WORDS / 2; i < WORDS; i++) {
temp += output[i]; temp += output[i];
output[i] = temp & 0xFFFFFFFF; output[i] = temp & 0xFFFFFFFF;
temp >>= 32; temp >>= 32;
@ -170,12 +193,18 @@ void X448::modular_multiply(u32* state, u32* first, u32* second)
modular_reduce(state, output, (u32)temp); modular_reduce(state, output, (u32)temp);
} }
void X448::modular_add(u32* state, u32* first, u32* second) static void modular_square(u32* state, u32* value)
{
// Compute R = (A ^ 2) mod p
modular_multiply(state, value, value);
}
static void modular_add(u32* state, u32* first, u32* second)
{ {
u64 temp = 0; u64 temp = 0;
// Compute R = A + B // Compute R = A + B
for (auto i = 0; i < X448::WORDS; i++) { for (auto i = 0; i < WORDS; i++) {
temp += first[i]; temp += first[i];
temp += second[i]; temp += second[i];
state[i] = temp & 0xFFFFFFFF; state[i] = temp & 0xFFFFFFFF;
@ -185,7 +214,7 @@ void X448::modular_add(u32* state, u32* first, u32* second)
modular_reduce(state, state, (u32)temp); modular_reduce(state, state, (u32)temp);
} }
void X448::modular_subtract(u32* state, u32* first, u32* second) static void modular_subtract(u32* state, u32* first, u32* second)
{ {
i64 temp = -1; i64 temp = -1;
@ -211,31 +240,7 @@ void X448::modular_subtract(u32* state, u32* first, u32* second)
modular_reduce(state, state, (u32)temp); modular_reduce(state, state, (u32)temp);
} }
void X448::modular_reduce(u32* state, u32* data, u32 a_high) static void to_power_of_2n(u32* state, u32* value, u8 n)
{
u64 temp = 1;
u32 other[X448::WORDS];
// Compute B = A - (2^448 - 2^224 - 1)
for (auto i = 0; i < X448::WORDS / 2; i++) {
temp += data[i];
other[i] = temp & 0xFFFFFFFF;
temp >>= 32;
}
temp += 1;
for (auto i = 7; i < X448::WORDS; i++) {
temp += data[i];
other[i] = temp & 0xFFFFFFFF;
temp >>= 32;
}
auto condition = (a_high + (u32)temp - 1) & 1;
select(state, other, data, condition);
}
void X448::to_power_of_2n(u32* state, u32* value, u8 n)
{ {
// Compute R = (A ^ (2^n)) mod p // Compute R = (A ^ (2^n)) mod p
modular_square(state, value); modular_square(state, value);
@ -244,11 +249,11 @@ void X448::to_power_of_2n(u32* state, u32* value, u8 n)
} }
} }
void X448::modular_multiply_inverse(u32* state, u32* value) static void modular_multiply_inverse(u32* state, u32* value)
{ {
// Compute R = A^-1 mod p // Compute R = A^-1 mod p
u32 u[X448::WORDS]; u32 u[WORDS];
u32 v[X448::WORDS]; u32 v[WORDS];
modular_square(u, value); modular_square(u, value);
modular_multiply(u, u, value); modular_multiply(u, u, value);
@ -299,14 +304,14 @@ ErrorOr<ByteBuffer> X448::generate_public_key(ReadonlyBytes a)
// https://datatracker.ietf.org/doc/html/rfc7748#section-5 // https://datatracker.ietf.org/doc/html/rfc7748#section-5
ErrorOr<ByteBuffer> X448::compute_coordinate(ReadonlyBytes input_k, ReadonlyBytes input_u) ErrorOr<ByteBuffer> X448::compute_coordinate(ReadonlyBytes input_k, ReadonlyBytes input_u)
{ {
u32 k[X448::WORDS] {}; u32 k[WORDS] {};
u32 u[X448::WORDS] {}; u32 u[WORDS] {};
u32 x1[X448::WORDS] {}; u32 x1[WORDS] {};
u32 x2[X448::WORDS] {}; u32 x2[WORDS] {};
u32 z1[X448::WORDS] {}; u32 z1[WORDS] {};
u32 z2[X448::WORDS] {}; u32 z2[WORDS] {};
u32 t1[X448::WORDS] {}; u32 t1[WORDS] {};
u32 t2[X448::WORDS] {}; u32 t2[WORDS] {};
// Copy input to internal state // Copy input to internal state
import_state(k, input_k); import_state(k, input_k);
@ -329,7 +334,7 @@ ErrorOr<ByteBuffer> X448::compute_coordinate(ReadonlyBytes input_k, ReadonlyByte
// Montgomery ladder // Montgomery ladder
u32 swap = 0; u32 swap = 0;
for (auto i = X448::BITS - 1; i >= 0; i--) { for (auto i = BITS - 1; i >= 0; i--) {
u32 b = (k[i / 32] >> (i % 32)) & 1; u32 b = (k[i / 32] >> (i % 32)) & 1;
conditional_swap(x1, x2, swap ^ b); conditional_swap(x1, x2, swap ^ b);

24
Userland/Libraries/LibCrypto/Curves/X448.h
View file

@ -12,34 +12,12 @@
namespace Crypto::Curves { namespace Crypto::Curves {
class X448 : public EllipticCurve { class X448 : public EllipticCurve {
static constexpr u16 BITS = 448;
static constexpr u8 BYTES = 56;
static constexpr u8 WORDS = 14;
static constexpr u32 A24 = 39082;
public: public:
size_t key_size() override { return BYTES; } size_t key_size() override { return 56; }
ErrorOr<ByteBuffer> generate_private_key() override; ErrorOr<ByteBuffer> generate_private_key() override;
ErrorOr<ByteBuffer> generate_public_key(ReadonlyBytes a) override; ErrorOr<ByteBuffer> generate_public_key(ReadonlyBytes a) override;
ErrorOr<ByteBuffer> compute_coordinate(ReadonlyBytes a, ReadonlyBytes b) override; ErrorOr<ByteBuffer> compute_coordinate(ReadonlyBytes a, ReadonlyBytes b) override;
ErrorOr<ByteBuffer> derive_premaster_key(ReadonlyBytes shared_point) override; ErrorOr<ByteBuffer> derive_premaster_key(ReadonlyBytes shared_point) override;
private:
static void import_state(u32* state, ReadonlyBytes data);
static ErrorOr<ByteBuffer> export_state(u32* data);
static void select(u32* state, u32* a, u32* b, u32 condition);
static void set(u32* state, u32 value);
static void copy(u32* state, u32* value);
static void conditional_swap(u32* first, u32* second, u32 condition);
static void modular_multiply_single(u32* state, u32* first, u32 second);
static void modular_square(u32* state, u32* value);
static void modular_multiply(u32* state, u32* first, u32* second);
static void modular_add(u32* state, u32* first, u32* second);
static void modular_subtract(u32* state, u32* first, u32* second);
static void modular_reduce(u32* state, u32* data, u32 data_high);
static void to_power_of_2n(u32* state, u32* value, u8 n);
static void modular_multiply_inverse(u32* state, u32* value);
}; };
} }