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559a6585ef
byuu says:
First 32 instructions implemented in the TLCS900H disassembler. Only 992
to go!
I removed the use of anonymous namespaces in nall. It was something I
rarely used, because it rarely did what I wanted.
I updated all nested namespaces to use C++17-style namespace Foo::Bar {}
syntax instead of classic C++-style namespace Foo { namespace Bar {}}.
I updated ruby::Video::acquire() to return a struct, so we can use C++17
structured bindings. Long term, I want to get away from all functions
that take references for output only. Even though C++ botched structured
bindings by not allowing you to bind to existing variables, it's even
worse to have function calls that take arguments by reference and then
write to them. From the caller side, you can't tell the value is being
written, nor that the value passed in doesn't matter, which is terrible.
85 lines
2.4 KiB
C++
85 lines
2.4 KiB
C++
#pragma once
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//warning: this implementation leaks side-channel information
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//use modulo25519-optimized.hpp in production
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#include <nall/arithmetic/barrett.hpp>
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namespace nall::EllipticCurve {
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static const uint256_t P = (1_u256 << 255) - 19;
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struct Modulo25519 {
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inline Modulo25519() = default;
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inline Modulo25519(const Modulo25519& source) : value(source.value) {}
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template<typename T> inline Modulo25519(const T& value) : value(value) {}
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inline explicit operator bool() const { return (bool)value; }
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inline auto operator()() const -> uint256_t { return value; }
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private:
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uint256_t value;
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};
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inline auto operator-(const Modulo25519& lhs) -> Modulo25519 {
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return P - lhs();
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}
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inline auto operator+(const Modulo25519& lhs, const Modulo25519& rhs) -> Modulo25519 {
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uint512_t value = (uint512_t)lhs() + rhs();
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if(value >= P) value -= P;
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return value;
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}
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inline auto operator-(const Modulo25519& lhs, const Modulo25519& rhs) -> Modulo25519 {
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uint512_t value = (uint512_t)lhs();
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if(value < rhs()) value += P;
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return uint256_t(value - rhs());
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}
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inline auto operator*(const Modulo25519& lhs, const Modulo25519& rhs) -> Modulo25519 {
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static const BarrettReduction<256> P{EllipticCurve::P};
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uint256_t hi, lo;
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mul(lhs(), rhs(), hi, lo);
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return uint512_t{hi, lo} % P;
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}
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inline auto operator&(const Modulo25519& lhs, uint256_t rhs) -> uint256_t {
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return lhs() & rhs;
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}
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inline auto square(const Modulo25519& lhs) -> Modulo25519 {
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static const BarrettReduction<256> P{EllipticCurve::P};
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uint256_t hi, lo;
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square(lhs(), hi, lo);
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return uint512_t{hi, lo} % P;
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}
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inline auto exponentiate(const Modulo25519& lhs, uint256_t exponent) -> Modulo25519 {
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if(exponent == 0) return 1;
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Modulo25519 value = square(exponentiate(lhs, exponent >> 1));
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if(exponent & 1) value = value * lhs;
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return value;
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}
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inline auto reciprocal(const Modulo25519& lhs) -> Modulo25519 {
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return exponentiate(lhs, P - 2);
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}
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inline auto squareRoot(const Modulo25519& lhs) -> Modulo25519 {
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static const Modulo25519 I = exponentiate(Modulo25519(2), P - 1 >> 2); //I = sqrt(-1)
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Modulo25519 value = exponentiate(lhs, P + 3 >> 3);
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if(square(value) - lhs) value = value * I;
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if(value & 1) value = -value;
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return value;
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}
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inline auto cmove(bool condition, Modulo25519& lhs, const Modulo25519& rhs) -> void {
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if(condition) lhs = rhs;
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}
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inline auto cswap(bool condition, Modulo25519& lhs, Modulo25519& rhs) -> void {
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if(condition) swap(lhs, rhs);
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}
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}
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