No puede seleccionar más de 25 temas
Los temas deben comenzar con una letra o número, pueden incluir guiones ('-') y pueden tener hasta 35 caracteres de largo.
142 líneas
2.9 KiB
142 líneas
2.9 KiB
#pragma once
|
|
#include <stdint.h>
|
|
#include <stddef.h>
|
|
#include <gp/integer_math.hpp>
|
|
#include <algorithm>
|
|
#include <array>
|
|
// BUG: A proper investigation is required to fix this file so that it gives the correct output.
|
|
|
|
|
|
template<typename word_t = uint32_t, size_t r = 20, size_t b = 128, word_t P = 0xb7e15163L, word_t Q = 0x9e3779b9L>
|
|
class RC6 {
|
|
static constexpr size_t word_size = 8*sizeof(word_t);
|
|
|
|
constexpr static word_t r_l(const word_t& w, size_t v) {
|
|
return (w << v) | ( w >> (word_size-v));
|
|
}
|
|
|
|
constexpr static word_t r_r(const word_t& w, size_t v) {
|
|
return (w >> v) | ( w << (word_size-v));
|
|
}
|
|
|
|
|
|
class RC6_KeySched {
|
|
using sched_t = std::array<word_t, 2*r+4>;
|
|
public:
|
|
static constexpr size_t c = (b+word_size-1)/word_size;
|
|
static constexpr size_t v_3 = std::max(c, 2*r+4);
|
|
static constexpr size_t v = v_3*3;
|
|
private:
|
|
sched_t S;
|
|
public:
|
|
constexpr RC6_KeySched(std::array<word_t, c> L)
|
|
{
|
|
assert(r_l(r_r(13,13),13) == 13);
|
|
|
|
auto it = S.begin();
|
|
*(it++) = P;
|
|
for(; it != S.end(); ++it)
|
|
{
|
|
*it = *(it-1) + Q;
|
|
}
|
|
word_t A = 0;
|
|
word_t B = 0;
|
|
word_t i = 0;
|
|
word_t j = 0;
|
|
|
|
for(size_t s = 0; s < v; ++s)
|
|
{
|
|
A = S[i] = r_l( S[i] + A + B, 3 );
|
|
B = L[j] = r_l( L[j] + A + B, (A + B)%(word_size));
|
|
|
|
i = s % S.size();
|
|
j = s % L.size();
|
|
}
|
|
}
|
|
|
|
const auto cbegin()
|
|
{
|
|
return S.cbegin();
|
|
}
|
|
|
|
const auto cend()
|
|
{
|
|
return S.cend();
|
|
}
|
|
|
|
const auto crbegin()
|
|
{
|
|
return S.crbegin();
|
|
}
|
|
|
|
const auto crend()
|
|
{
|
|
return S.crend();
|
|
}
|
|
};
|
|
|
|
RC6_KeySched S;
|
|
|
|
public:
|
|
|
|
typedef std::array<word_t, RC6_KeySched::c> key_type;
|
|
typedef std::array<word_t, 4> block_type;
|
|
|
|
constexpr RC6(const key_type& key)
|
|
: S(key)
|
|
{}
|
|
|
|
constexpr block_type encrypt(block_type plaintext) {
|
|
using namespace gp::math;
|
|
auto& A = plaintext[0];
|
|
auto& B = plaintext[1];
|
|
auto& C = plaintext[2];
|
|
auto& D = plaintext[3];
|
|
|
|
auto it = S.cbegin();
|
|
|
|
B += *(it++);
|
|
D += *(it++);
|
|
|
|
for(size_t i = 0; i < r; ++i)
|
|
{
|
|
auto u = r_l( D * ( 2 * D + 1 ), msb(word_size));
|
|
auto t = r_l( B * ( 2 * B + 1 ), msb(word_size));
|
|
A = r_l((A ^ t), u % word_size) + *(it++);
|
|
C = r_l((C ^ u), t % word_size) + *(it++);
|
|
std::rotate(plaintext.begin(), plaintext.begin()+1, plaintext.end());
|
|
}
|
|
|
|
A += *(it++);
|
|
C += *(it++);
|
|
assert(it == S.cend());
|
|
return plaintext;
|
|
}
|
|
|
|
constexpr block_type decrypt(block_type plaintext) {
|
|
using namespace gp::math;
|
|
auto& A = plaintext[0];
|
|
auto& B = plaintext[1];
|
|
auto& C = plaintext[2];
|
|
auto& D = plaintext[3];
|
|
auto it = S.crbegin();
|
|
|
|
C -= *(it++);
|
|
A -= *(it++);
|
|
|
|
for(size_t i = 0; i < r; ++i)
|
|
{
|
|
std::rotate(plaintext.begin(), plaintext.end()-1, plaintext.end());
|
|
auto u = r_l( D * ( 2 * D + 1 ), msb(word_size));
|
|
auto t = r_l( B * ( 2 * B + 1 ), msb(word_size));
|
|
C = r_r( (C - *(it++)) , t % word_size) ^ u ;
|
|
A = r_r( (A - *(it++)) , u % word_size) ^ t ;
|
|
}
|
|
|
|
D -= *(it++);
|
|
B -= *(it++);
|
|
assert(it == S.crend());
|
|
return plaintext;
|
|
}
|
|
|
|
};
|