ハッシュ関数をつくってみた (適当

今回は、MD5, SHA-1 などのハッシュ関数と呼ばれるものを作ってみました。
ハッシュ関数の詳細はググってください。

今回作ったものは、適当なのであまりいい特性ではないかもしれません。

コード↓

#include <iostream>
#include <cstring>
#include <fstream>
using namespace std;

const int BIT = 8;
const int  prime[BIT] = { 11, 13, 17, 19, 23, 29, 31, 37};

class HD
{
private:

public:
	int hash(char [], int, unsigned int[]);
	int shash(char []);
	void operator = (char *ch)
	{
		shash(ch);
	}
	char str[33];
};


int HD::hash(char word1[],int wordsz1, unsigned int data[])
{
	unsigned int i=0, j=0, k = 2166136261, l = 0, data2[BIT] = {0};
	char word[32] = { 0 };

	unsigned long A, B, C, D, E, F, G, H;
	memset(data,0,BIT);

	for(l = 0; l < 2; l++)
	{
		for(i = 0; i < BIT; i++)
		{
			word[i % 32] |= k << 2;
			word[i % 32] += word1[i];
			word[i % 32] ^= word1[i] * k;
		}
	}

	for(i = 0; word1[i] != 0; i++)
	{
		k = (k * 16777931) + word1[i]  + word[i % 32];
		data[i % BIT] += k;
	}

	for(i = 0; i < BIT; i++)
	{
		k = (k * 16777931) + data[i];
		data[i] ^= prime[i] * k;
		data[i] &= prime[i] + k;
		data[i] += prime[i];
		data[i] += (data[i] & k) ^ ~k; 
	}

	data2[0] = data[0];  A = data2[7];
	data2[1] = data[1];	 B = data2[0];
	data2[2] = data[2];	 C = data2[1];
	data2[3] = data[3];	 D = data2[2];
	data2[4] = data[4];	 E = data2[3];
	data2[5] = data[5];	 F = data2[4];
	data2[6] = data[6];	 G = data2[5];
	data2[7] = data[7];	 H = data2[6];

	memset(data, 0, BIT);

	for(j = 0; j < 64; j++)
	{
		
		A = (A = A ^ H * ~k) * (A = A ^ (k * A) ^ ~H);
		B = (B = B ^ G * ~k) * (B = B ^ (k * B) ^ ~G);
		C = (C = C ^ F * ~k) * (C = C ^ (k * C) ^ ~F);
		D = (D = D ^ E * ~k) * (D = D ^ (k * D) ^ ~E);
		E = (E = E ^ D * ~k) * (E = E ^ (k * E) ^ ~D);
		F = (F = F ^ C * ~k) * (F = F ^ (k * F) ^ ~C);
		G = (G = G ^ B * ~k) * (G = G ^ (k * G) ^ ~B);
		H = (H = H ^ A * ~k) * (H = H ^ (k * H) ^ ~A);

		A = ((A = A ^ (A * (A % k))) % (k * A)) ^ (k + H) ^ (~A);
		B = ((B = B ^ (B * (B % k))) % (k * B)) ^ (k + G) ^ (~B);
		C = ((C = C ^ (C * (C % k))) % (k * C)) ^ (k + F) ^ (~C);
		D = ((D = D ^ (D * (D % k))) % (k * D)) ^ (k + E) ^ (~D);
		E = ((E = E ^ (E * (E % k))) % (k * E)) ^ (k + D) ^ (~E);
		F = ((F = F ^ (F * (F % k))) % (k * F)) ^ (k + C) ^ (~F);
		G = ((G = G ^ (G * (G % k))) % (k * G)) ^ (k + B) ^ (~G);
		H = ((H = H ^ (H * (H % k))) % (k * H)) ^ (k + A) ^ (~H);
		
		data2[0] = A; A = data2[7];
		data2[1] = B; B = data2[0];
		data2[2] = C; C = data2[1];
		data2[3] = D; D = data2[2];
		data2[4] = E; E = data2[3];
		data2[5] = F; F = data2[4];
		data2[6] = G; G = data2[5];
		data2[7] = H; H = data2[6];
		
	}
	{
		data[0] = A;
		data[1] = B;
		data[2] = C;
		data[3] = D;
		data[4] = E;
		data[5] = F;
		data[6] = G;
		data[7] = H;
	}

	for(i = 0; i < BIT; i++)
	{
		data[i] %= 65535;
		if(data[i] < 0) data[i] = -data[i];
	}

	return 0;
}

int HD::shash(char word[])
{
	unsigned int data[BIT] = { 0 },i = 0, wordsz = 0;
	wordsz = (unsigned int)strlen(word);
	hash(word,wordsz,data);
	memset(str, 0, 33);
	for(i = 0; i < BIT; i++)
	{
		sprintf(str, "%s%04x", str, data[i]);
	}
	return 0;
}


int main()
{
	HD hash;// Hash Digest object

	hash = "";
	cout << hash.str << endl;

	hash = "The quick brown fox jumps lazy dog";// ハッシュ化したい文字列を代入 (operator =)
	cout << hash.str << endl;// HD::str はハッシュ後の文字列(char str[33])
}