129 lines
4.4 KiB
C++
129 lines
4.4 KiB
C++
#include <algorithm>
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#include <bit>
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#include <cstdint>
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#include <iomanip>
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#include <iostream>
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#include <sstream>
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#include <vector>
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const uint32_t INITIAL_A = 0x67452301;
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const uint32_t INITIAL_B = static_cast<uint32_t>(0xEFCDAB89L);
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const uint32_t INITIAL_C = static_cast<uint32_t>(0x98BADCFEL);
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const uint32_t INITIAL_D = 0x10325476;
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const std::vector<uint32_t> SHIFT_AMOUNTS = { 7, 12, 17, 22, 5, 9, 14, 20, 4, 11, 16, 23, 6, 10, 15, 21 };
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const std::vector<uint32_t> K = { 0xd76aa478, 0xe8c7b756, 0x242070db, 0xc1bdceee,
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0xf57c0faf, 0x4787c62a, 0xa8304613, 0xfd469501,
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0x698098d8, 0x8b44f7af, 0xffff5bb1, 0x895cd7be,
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0x6b901122, 0xfd987193, 0xa679438e, 0x49b40821,
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0xf61e2562, 0xc040b340, 0x265e5a51, 0xe9b6c7aa,
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0xd62f105d, 0x02441453, 0xd8a1e681, 0xe7d3fbc8,
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0x21e1cde6, 0xc33707d6, 0xf4d50d87, 0x455a14ed,
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0xa9e3e905, 0xfcefa3f8, 0x676f02d9, 0x8d2a4c8a,
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0xfffa3942, 0x8771f681, 0x6d9d6122, 0xfde5380c,
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0xa4beea44, 0x4bdecfa9, 0xf6bb4b60, 0xbebfbc70,
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0x289b7ec6, 0xeaa127fa, 0xd4ef3085, 0x04881d05,
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0xd9d4d039, 0xe6db99e5, 0x1fa27cf8, 0xc4ac5665,
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0xf4292244, 0x432aff97, 0xab9423a7, 0xfc93a039,
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0x655b59c3, 0x8f0ccc92, 0xffeff47d, 0x85845dd1,
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0x6fa87e4f, 0xfe2ce6e0, 0xa3014314, 0x4e0811a1,
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0xf7537e82, 0xbd3af235, 0x2ad7d2bb, 0xeb86d391 };
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std::string to_hex_string(const std::vector<int8_t>& bytes) {
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std::string hex_string = "";
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std::stringstream stream;
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for ( const int8_t& bb : bytes ) {
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stream << std::setfill('0') << std::setw(2) << std::hex << ( bb & 0xff );
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hex_string += stream.str();
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stream.str("");
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}
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return hex_string;
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}
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std::vector<int8_t> to_byte_vector(const std::string& text) {
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std::vector<int8_t> bytes;
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bytes.reserve(text.size());
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std::transform(text.begin(), text.end(),
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std::back_inserter(bytes), [](char ch){ return static_cast<int8_t>(ch); });
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return bytes;
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}
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std::vector<int8_t> computeMD5(const std::vector<int8_t>& message) {
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uint64_t message_length_bytes = message.size();
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uint32_t number_blocks = ( ( message_length_bytes + 8 ) >> 6 ) + 1;
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uint32_t total_length = number_blocks << 6;
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std::vector<int8_t> padding_bytes(total_length - message_length_bytes);
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padding_bytes[0] = static_cast<int8_t>(0x80);
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uint64_t message_length_bits = message_length_bytes << 3;
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for ( uint32_t i = 0; i < 8; ++i ) {
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padding_bytes[padding_bytes.size() - 8 + i] = static_cast<int8_t>(message_length_bits);
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message_length_bits >>= 8;
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}
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uint32_t a = INITIAL_A;
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uint32_t b = INITIAL_B;
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uint32_t c = INITIAL_C;
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uint32_t d = INITIAL_D;
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std::vector<uint32_t> buffer(16);
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for ( uint32_t i = 0; i < number_blocks; ++i ) {
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uint32_t index = i << 6;
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for ( uint32_t j = 0; j < 64; index++, ++j ) {
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buffer[j >> 2] = ( static_cast<uint32_t>( ( index < message_length_bytes ) ? message[index]
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: padding_bytes[index - message_length_bytes] ) << 24 ) | ( buffer[j >> 2] >> 8 );
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}
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uint32_t original_A = a;
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uint32_t original_B = b;
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uint32_t original_C = c;
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uint32_t original_D = d;
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for ( uint32_t j = 0; j < 64; ++j ) {
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uint32_t div16 = j >> 4;
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uint32_t f = 0;
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uint32_t buffer_index = j;
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switch ( div16 ) {
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case 0: f = ( b & c ) | ( ~b & d ); break;
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case 1: f = ( b & d ) | ( c & ~d ); buffer_index = ( buffer_index * 5 + 1 ) & 0x0F; break;
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case 2: f = b ^ c ^ d; buffer_index = ( buffer_index * 3 + 5 ) & 0x0F; break;
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case 3: f = c ^ ( b | ~d ); buffer_index = ( buffer_index * 7 ) & 0x0F; break;
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}
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uint32_t temp = b + std::rotl(
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a + f + buffer[buffer_index] + K[j], SHIFT_AMOUNTS[( div16 << 2 ) | ( j & 3 )]);
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a = d;
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d = c;
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c = b;
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b = temp;
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}
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a += original_A;
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b += original_B;
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c += original_C;
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d += original_D;
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}
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std::vector<int8_t> md5(16);
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uint32_t count = 0;
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for ( uint32_t i = 0; i < 4; ++i ) {
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uint32_t n = ( i == 0 ) ? a : ( ( i == 1 ) ? b : ( ( i == 2 ) ? c : d ) );
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for ( uint32_t j = 0; j < 4; ++j ) {
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md5[count++] = static_cast<int8_t>(n);
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n >>= 8;
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}
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}
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return md5;
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}
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int main() {
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const std::vector<std::string> tests = { "", "a", "abc", "message digest", "abcdefghijklmnopqrstuvwxyz",
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"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789",
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"12345678901234567890123456789012345678901234567890123456789012345678901234567890" };
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for ( const std::string& test : tests ) {
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std::cout << to_hex_string(computeMD5(to_byte_vector(test))) << " <== \"" + test + "\"" << "\n";
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}
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}
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