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refactor: Improve encapsulation between MuHash3072 and Num3072

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Also fixes a typo.
This commit is contained in:
Fabian Jahr 2021-01-14 01:27:37 +01:00
parent cb2c578451
commit a1fcceac69
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2 changed files with 29 additions and 20 deletions
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42
src/crypto/muhash.cpp
View file

@ -17,7 +17,6 @@ namespace {
using limb_t = Num3072::limb_t;
using double_limb_t = Num3072::double_limb_t;
constexpr int LIMB_SIZE = Num3072::LIMB_SIZE;
constexpr int LIMBS = Num3072::LIMBS;
/** 2^3072 - 1103717, the largest 3072-bit safe prime number, is used as the modulus. */
constexpr limb_t MAX_PRIME_DIFF = 1103717;
@ -123,7 +122,7 @@ inline void square_n_mul(Num3072& in_out, const int sq, const Num3072& mul)
} // namespace
/** Indicates wether d is larger than the modulus. */
/** Indicates whether d is larger than the modulus. */
bool Num3072::IsOverflow() const
{
if (this->limbs[0] <= std::numeric_limits<limb_t>::max() - MAX_PRIME_DIFF) return false;
@ -276,18 +275,33 @@ void Num3072::Divide(const Num3072& a)
if (this->IsOverflow()) this->FullReduce();
}
Num3072 MuHash3072::ToNum3072(Span<const unsigned char> in) {
Num3072 out{};
uint256 hashed_in = (CHashWriter(SER_DISK, 0) << in).GetSHA256();
unsigned char tmp[BYTE_SIZE];
ChaCha20(hashed_in.data(), hashed_in.size()).Keystream(tmp, BYTE_SIZE);
Num3072::Num3072(const unsigned char (&data)[BYTE_SIZE]) {
for (int i = 0; i < LIMBS; ++i) {
if (sizeof(limb_t) == 4) {
out.limbs[i] = ReadLE32(tmp + 4 * i);
this->limbs[i] = ReadLE32(data + 4 * i);
} else if (sizeof(limb_t) == 8) {
out.limbs[i] = ReadLE64(tmp + 8 * i);
this->limbs[i] = ReadLE64(data + 8 * i);
}
}
}
void Num3072::ToBytes(unsigned char (&out)[BYTE_SIZE]) {
for (int i = 0; i < LIMBS; ++i) {
if (sizeof(limb_t) == 4) {
WriteLE32(out + i * 4, this->limbs[i]);
} else if (sizeof(limb_t) == 8) {
WriteLE64(out + i * 8, this->limbs[i]);
}
}
}
Num3072 MuHash3072::ToNum3072(Span<const unsigned char> in) {
unsigned char tmp[Num3072::BYTE_SIZE];
uint256 hashed_in = (CHashWriter(SER_DISK, 0) << in).GetSHA256();
ChaCha20(hashed_in.data(), hashed_in.size()).Keystream(tmp, Num3072::BYTE_SIZE);
Num3072 out{tmp};
return out;
}
@ -301,14 +315,8 @@ void MuHash3072::Finalize(uint256& out) noexcept
m_numerator.Divide(m_denominator);
m_denominator.SetToOne(); // Needed to keep the MuHash object valid
unsigned char data[384];
for (int i = 0; i < LIMBS; ++i) {
if (sizeof(limb_t) == 4) {
WriteLE32(data + i * 4, m_numerator.limbs[i]);
} else if (sizeof(limb_t) == 8) {
WriteLE64(data + i * 8, m_numerator.limbs[i]);
}
}
unsigned char data[Num3072::BYTE_SIZE];
m_numerator.ToBytes(data);
out = (CHashWriter(SER_DISK, 0) << data).GetSHA256();
}

7
src/crypto/muhash.h
View file

@ -22,6 +22,7 @@ private:
Num3072 GetInverse() const;
public:
static constexpr size_t BYTE_SIZE = 384;
#ifdef HAVE___INT128
typedef unsigned __int128 double_limb_t;
@ -48,8 +49,10 @@ public:
void Divide(const Num3072& a);
void SetToOne();
void Square();
void ToBytes(unsigned char (&out)[BYTE_SIZE]);
Num3072() { this->SetToOne(); };
Num3072(const unsigned char (&data)[BYTE_SIZE]);
SERIALIZE_METHODS(Num3072, obj)
{
@ -78,7 +81,7 @@ public:
* arbitrary subset of the update operations, allowing them to be
* efficiently combined later.
*
* Muhash does not support checking if an element is already part of the
* MuHash does not support checking if an element is already part of the
* set. That is why this class does not enforce the use of a set as the
* data it represents because there is no efficient way to do so.
* It is possible to add elements more than once and also to remove
@ -91,8 +94,6 @@ public:
class MuHash3072
{
private:
static constexpr size_t BYTE_SIZE = 384;
Num3072 m_numerator;
Num3072 m_denominator;