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https://github.com/RGBCube/serenity
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LibCrypto: Move all elliptic curve private methods into .cpp
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
Ali Mohammad Pur
parent
596391a4ee
commit
e07ec02470
6 changed files with 171 additions and 220 deletions
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@ -11,19 +11,24 @@
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namespace Crypto::Curves {
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void X25519::import_state(u32* state, ReadonlyBytes data)
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static constexpr u8 BITS = 255;
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static constexpr u8 BYTES = 32;
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static constexpr u8 WORDS = 8;
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static constexpr u32 A24 = 121666;
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static void import_state(u32* state, ReadonlyBytes data)
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{
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for (auto i = 0; i < X25519::WORDS; i++) {
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for (auto i = 0; i < WORDS; i++) {
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u32 value = ByteReader::load32(data.offset_pointer(sizeof(u32) * i));
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state[i] = AK::convert_between_host_and_little_endian(value);
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}
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}
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ErrorOr<ByteBuffer> X25519::export_state(u32* data)
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static ErrorOr<ByteBuffer> export_state(u32* data)
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{
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auto buffer = TRY(ByteBuffer::create_uninitialized(X25519::BYTES));
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auto buffer = TRY(ByteBuffer::create_uninitialized(BYTES));
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for (auto i = 0; i < X25519::WORDS; i++) {
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for (auto i = 0; i < WORDS; i++) {
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u32 value = AK::convert_between_host_and_little_endian(data[i]);
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ByteReader::store(buffer.offset_pointer(sizeof(u32) * i), value);
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}
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@ -31,49 +36,68 @@ ErrorOr<ByteBuffer> X25519::export_state(u32* data)
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return buffer;
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}
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void X25519::select(u32* state, u32* a, u32* b, u32 condition)
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static void select(u32* state, u32* a, u32* b, u32 condition)
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{
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// If B < (2^255 - 19) then R = B, else R = A
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u32 mask = condition - 1;
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for (auto i = 0; i < X25519::WORDS; i++) {
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for (auto i = 0; i < WORDS; i++) {
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state[i] = (a[i] & mask) | (b[i] & ~mask);
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}
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}
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void X25519::set(u32* state, u32 value)
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static void set(u32* state, u32 value)
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{
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state[0] = value;
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for (auto i = 1; i < X25519::WORDS; i++) {
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for (auto i = 1; i < WORDS; i++) {
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state[i] = 0;
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}
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}
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void X25519::copy(u32* state, u32* value)
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static void copy(u32* state, u32* value)
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{
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for (auto i = 0; i < X25519::WORDS; i++) {
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for (auto i = 0; i < WORDS; i++) {
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state[i] = value[i];
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}
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}
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void X25519::conditional_swap(u32* first, u32* second, u32 condition)
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static void conditional_swap(u32* first, u32* second, u32 condition)
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{
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u32 mask = ~condition + 1;
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for (auto i = 0; i < X25519::WORDS; i++) {
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for (auto i = 0; i < WORDS; i++) {
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u32 temp = mask & (first[i] ^ second[i]);
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first[i] ^= temp;
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second[i] ^= temp;
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}
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}
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void X25519::modular_multiply_single(u32* state, u32* first, u32 second)
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static void modular_reduce(u32* state, u32* data)
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{
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// R = A mod p
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u64 temp = 19;
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u32 other[WORDS];
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for (auto i = 0; i < WORDS; i++) {
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temp += data[i];
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other[i] = temp & 0xFFFFFFFF;
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temp >>= 32;
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}
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// Compute B = A - (2^255 - 19)
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other[7] -= 0x80000000;
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u32 mask = (other[7] & 0x80000000) >> 31;
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select(state, other, data, mask);
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}
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static void modular_multiply_single(u32* state, u32* first, u32 second)
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{
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// Compute R = (A * B) mod p
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u64 temp = 0;
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u32 output[X25519::WORDS];
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u32 output[WORDS];
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for (auto i = 0; i < X25519::WORDS; i++) {
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for (auto i = 0; i < WORDS; i++) {
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temp += (u64)first[i] * second;
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output[i] = temp & 0xFFFFFFFF;
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temp >>= 32;
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@ -87,7 +111,7 @@ void X25519::modular_multiply_single(u32* state, u32* first, u32 second)
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output[7] &= 0x7FFFFFFF;
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// Fast modular reduction
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for (auto i = 0; i < X25519::WORDS; i++) {
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for (auto i = 0; i < WORDS; i++) {
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temp += output[i];
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output[i] = temp & 0xFFFFFFFF;
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temp >>= 32;
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@ -96,29 +120,23 @@ void X25519::modular_multiply_single(u32* state, u32* first, u32 second)
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modular_reduce(state, output);
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}
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void X25519::modular_square(u32* state, u32* value)
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{
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// Compute R = (A ^ 2) mod p
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modular_multiply(state, value, value);
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}
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void X25519::modular_multiply(u32* state, u32* first, u32* second)
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static void modular_multiply(u32* state, u32* first, u32* second)
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{
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// Compute R = (A * B) mod p
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u64 temp = 0;
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u64 carry = 0;
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u32 output[X25519::WORDS * 2];
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u32 output[WORDS * 2];
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// Comba's method
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for (auto i = 0; i < 16; i++) {
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if (i < X25519::WORDS) {
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if (i < WORDS) {
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for (auto j = 0; j <= i; j++) {
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temp += (u64)first[j] * second[i - j];
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carry += temp >> 32;
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temp &= 0xFFFFFFFF;
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}
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} else {
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for (auto j = i - 7; j < X25519::WORDS; j++) {
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for (auto j = i - 7; j < WORDS; j++) {
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temp += (u64)first[j] * second[i - j];
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carry += temp >> 32;
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temp &= 0xFFFFFFFF;
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@ -136,7 +154,7 @@ void X25519::modular_multiply(u32* state, u32* first, u32* second)
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output[7] &= 0x7FFFFFFF;
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// Fast modular reduction 1st pass
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for (auto i = 0; i < X25519::WORDS; i++) {
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for (auto i = 0; i < WORDS; i++) {
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temp += output[i];
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temp += (u64)output[i + 8] * 38;
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output[i] = temp & 0xFFFFFFFF;
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@ -151,7 +169,7 @@ void X25519::modular_multiply(u32* state, u32* first, u32* second)
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output[7] &= 0x7FFFFFFF;
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// Fast modular reduction 2nd pass
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for (auto i = 0; i < X25519::WORDS; i++) {
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for (auto i = 0; i < WORDS; i++) {
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temp += output[i];
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output[i] = temp & 0xFFFFFFFF;
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temp >>= 32;
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@ -160,11 +178,17 @@ void X25519::modular_multiply(u32* state, u32* first, u32* second)
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modular_reduce(state, output);
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}
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void X25519::modular_add(u32* state, u32* first, u32* second)
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static void modular_square(u32* state, u32* value)
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{
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// Compute R = (A ^ 2) mod p
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modular_multiply(state, value, value);
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}
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static void modular_add(u32* state, u32* first, u32* second)
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{
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// R = (A + B) mod p
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u64 temp = 0;
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for (auto i = 0; i < X25519::WORDS; i++) {
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for (auto i = 0; i < WORDS; i++) {
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temp += first[i];
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temp += second[i];
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state[i] = temp & 0xFFFFFFFF;
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@ -174,11 +198,11 @@ void X25519::modular_add(u32* state, u32* first, u32* second)
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modular_reduce(state, state);
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}
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void X25519::modular_subtract(u32* state, u32* first, u32* second)
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static void modular_subtract(u32* state, u32* first, u32* second)
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{
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// R = (A - B) mod p
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i64 temp = -19;
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for (auto i = 0; i < X25519::WORDS; i++) {
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for (auto i = 0; i < WORDS; i++) {
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temp += first[i];
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temp -= second[i];
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state[i] = temp & 0xFFFFFFFF;
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@ -191,26 +215,7 @@ void X25519::modular_subtract(u32* state, u32* first, u32* second)
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modular_reduce(state, state);
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}
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void X25519::modular_reduce(u32* state, u32* data)
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{
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// R = A mod p
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u64 temp = 19;
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u32 other[X25519::WORDS];
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for (auto i = 0; i < X25519::WORDS; i++) {
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temp += data[i];
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other[i] = temp & 0xFFFFFFFF;
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temp >>= 32;
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}
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// Compute B = A - (2^255 - 19)
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other[7] -= 0x80000000;
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u32 mask = (other[7] & 0x80000000) >> 31;
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select(state, other, data, mask);
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}
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void X25519::to_power_of_2n(u32* state, u32* value, u8 n)
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static void to_power_of_2n(u32* state, u32* value, u8 n)
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{
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// compute R = (A ^ (2^n)) mod p
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modular_square(state, value);
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@ -219,11 +224,11 @@ void X25519::to_power_of_2n(u32* state, u32* value, u8 n)
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}
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}
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void X25519::modular_multiply_inverse(u32* state, u32* value)
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static void modular_multiply_inverse(u32* state, u32* value)
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{
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// Compute R = A^-1 mod p
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u32 u[X25519::WORDS];
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u32 v[X25519::WORDS];
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u32 u[WORDS];
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u32 v[WORDS];
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// Fermat's little theorem
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modular_square(u, value);
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@ -276,14 +281,14 @@ ErrorOr<ByteBuffer> X25519::generate_public_key(ReadonlyBytes a)
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// https://datatracker.ietf.org/doc/html/rfc7748#section-5
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ErrorOr<ByteBuffer> X25519::compute_coordinate(ReadonlyBytes input_k, ReadonlyBytes input_u)
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{
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u32 k[X25519::WORDS] {};
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u32 u[X25519::WORDS] {};
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u32 x1[X25519::WORDS] {};
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u32 x2[X25519::WORDS] {};
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u32 z1[X25519::WORDS] {};
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u32 z2[X25519::WORDS] {};
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u32 t1[X25519::WORDS] {};
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u32 t2[X25519::WORDS] {};
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u32 k[WORDS] {};
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u32 u[WORDS] {};
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u32 x1[WORDS] {};
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u32 x2[WORDS] {};
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u32 z1[WORDS] {};
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u32 z2[WORDS] {};
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u32 t1[WORDS] {};
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u32 t2[WORDS] {};
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// Copy input to internal state
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import_state(k, input_k);
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@ -310,8 +315,8 @@ ErrorOr<ByteBuffer> X25519::compute_coordinate(ReadonlyBytes input_k, ReadonlyBy
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// Montgomery ladder
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u32 swap = 0;
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for (auto i = X25519::BITS - 1; i >= 0; i--) {
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u32 b = (k[i / X25519::BYTES] >> (i % X25519::BYTES)) & 1;
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for (auto i = BITS - 1; i >= 0; i--) {
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u32 b = (k[i / BYTES] >> (i % BYTES)) & 1;
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conditional_swap(x1, x2, swap ^ b);
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conditional_swap(z1, z2, swap ^ b);
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