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99 lines
2.7 KiB
99 lines
2.7 KiB
#include "md5.h"
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#include <cstring>
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using md5::MD5;
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using md5::value::K;
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using md5::value::S;
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using md5::value::T;
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#define R1 A, B, C, D
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#define R2 D, A, B, C
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#define R3 C, D, A, B
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#define R4 B, C, D, A
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#define F(x, y, z) (z ^ (x & (y ^ z)))
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#define G(x, y, z) (y ^ (z & (x ^ y)))
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#define H(x, y, z) (x ^ y ^ z)
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#define I(x, y, z) (y ^ (x | ~z))
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#define MD5_ROUND(i, f, a, b, c, d) \
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do { \
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a += f(b, c, d) + block[K(i)] + T(i); \
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a = a << S(i) | a >> (32 - S(i)); \
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a += b; \
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} while (0)
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#ifdef _MSC_VER
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#define EXPAND(...) __VA_ARGS__
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#define ROUND(...) EXPAND(MD5_ROUND(__VA_ARGS__))
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#else
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#define ROUND MD5_ROUND
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#endif
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#define FF(i, ...) ROUND(i | 0x00, F, __VA_ARGS__)
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#define GG(i, ...) ROUND(i | 0x10, G, __VA_ARGS__)
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#define HH(i, ...) ROUND(i | 0x20, H, __VA_ARGS__)
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#define II(i, ...) ROUND(i | 0x30, I, __VA_ARGS__)
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#define MD5_UPDATE(OP) \
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OP(0x0, R1); OP(0x1, R2); OP(0x2, R3); OP(0x3, R4); \
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OP(0x4, R1); OP(0x5, R2); OP(0x6, R3); OP(0x7, R4); \
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OP(0x8, R1); OP(0x9, R2); OP(0xa, R3); OP(0xb, R4); \
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OP(0xc, R1); OP(0xd, R2); OP(0xe, R3); OP(0xf, R4);
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static constexpr unsigned char Padding[64] { 0x80, /* 0x00, ... */ };
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const void* MD5::UpdateImpl(const void *data, size_t len) {
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len &= ~static_cast<size_t>(0b111111); // len -> n * 64
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auto *block = static_cast<const uint32_t *>(data);
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auto *limit = block + (len >> 2);
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auto A = ctx_.A;
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auto B = ctx_.B;
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auto C = ctx_.C;
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auto D = ctx_.D;
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while (block < limit) {
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const auto A_ = A;
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const auto B_ = B;
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const auto C_ = C;
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const auto D_ = D;
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MD5_UPDATE(FF)
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MD5_UPDATE(GG)
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MD5_UPDATE(HH)
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MD5_UPDATE(II)
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A += A_;
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B += B_;
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C += C_;
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D += D_;
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block += 16; // move to next block
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}
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ctx_.A = A;
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ctx_.B = B;
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ctx_.C = C;
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ctx_.D = D;
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ctx_.size += len;
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return limit;
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}
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void MD5::FinalImpl(const void *data, size_t len) {
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if (len >= 120) { // len -> [64 + 56, INF)
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data = UpdateImpl(data, len);
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len &= 0b111111; // len -> [0, 64)
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}
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unsigned char buffer[128]; // 2 blocks
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std::memcpy(buffer, data, len);
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const uint64_t total = (ctx_.size + len) << 3; // total number in bit
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if (len < 56) { // len -> [0, 56)
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std::memcpy(buffer + len, Padding, 56 - len);
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std::memcpy(buffer + 56, &total, 8);
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UpdateImpl(buffer, 64); // update 1 block
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} else { // len -> [56, 64 + 56)
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std::memcpy(buffer + len, Padding, 120 - len);
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std::memcpy(buffer + 120, &total, 8);
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UpdateImpl(buffer, 128); // update 2 blocks
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}
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}
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