SHA256ハッシュを算出する

my_sha256.cpp

/*
	http://www.ouah.org/ogay/sha2/
	から SHA-256 部分だけを抜き出してテキトーに書き換えたもの。BSDライセンス
*/
/*
 * FIPS 180-2 SHA-224/256/384/512 implementation
 * Last update: 02/02/2007
 * Issue date:  04/30/2005
 *
 * Copyright (C) 2005, 2007 Olivier Gay <olivier.gay@a3.epfl.ch>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the project nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */
#include <string.h>
#define SHA256_DIGEST_SIZE ( 256 / 8)
#define SHA256_BLOCK_SIZE  ( 512 / 8)

#define SHFR(x, n)    (x >> n)
#define ROTR(x, n)   ((x >> n) | (x << ((sizeof(x) << 3) - n)))
#define ROTL(x, n)   ((x << n) | (x >> ((sizeof(x) << 3) - n)))
#define CH(x, y, z)  ((x & y) ^ (~x & z))
#define MAJ(x, y, z) ((x & y) ^ (x & z) ^ (y & z))

#define SHA256_F1(x) (ROTR(x,  2) ^ ROTR(x, 13) ^ ROTR(x, 22))
#define SHA256_F2(x) (ROTR(x,  6) ^ ROTR(x, 11) ^ ROTR(x, 25))
#define SHA256_F3(x) (ROTR(x,  7) ^ ROTR(x, 18) ^ SHFR(x,  3))
#define SHA256_F4(x) (ROTR(x, 17) ^ ROTR(x, 19) ^ SHFR(x, 10))

Sha256::Sha256() {
	clear();
}

void Sha256::getDigest(Digest* digest) const {
	memcpy(digest->bytes, this->digest, sizeof(digest->bytes));
}

void Sha256::clear() {
	static const u32 sha256_h0[8] = {
		0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a,
		0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19
	};
	memcpy(&h[0], &sha256_h0[0], sizeof(h));
	tot_len = 0;
	len = 0;
}

void Sha256::update(const void* message, unsigned int len) {
	if(len) {
		unsigned int tmp_len = SHA256_BLOCK_SIZE - this->len;
		unsigned int rem_len = len < tmp_len ? len : tmp_len;
		memcpy(&this->block[this->len], message, rem_len);

		if(this->len + len < SHA256_BLOCK_SIZE) {
			this->len += len;
		} else {
			unsigned int new_len = len - rem_len;
			unsigned int block_nb = new_len / SHA256_BLOCK_SIZE;

			const unsigned char* shifted_message = static_cast<const unsigned char*>(message) + rem_len;

			transf(this->block, 1);
			transf(shifted_message, block_nb);

			rem_len = new_len % SHA256_BLOCK_SIZE;

			memcpy(this->block, &shifted_message[block_nb << 6], rem_len);

			this->len = rem_len;
			this->tot_len += (block_nb + 1) << 6;
		}
	}
}

static void storeBigendianU32(Sha256::u32 x, void* p) {
	unsigned char* str = static_cast<unsigned char*>(p);
	*((str) + 3) = (unsigned char) ((x)      );
	*((str) + 2) = (unsigned char) ((x) >>  8);
	*((str) + 1) = (unsigned char) ((x) >> 16);
	*((str) + 0) = (unsigned char) ((x) >> 24);
}

void Sha256::final() {
	unsigned int block_nb = (1 + ((SHA256_BLOCK_SIZE - 9) < (this->len % SHA256_BLOCK_SIZE)));
	unsigned int len_b = (this->tot_len + this->len) << 3;
	unsigned int pm_len = block_nb << 6;

    memset(this->block + this->len, 0, pm_len - this->len);
    this->block[this->len] = 0x80;
	storeBigendianU32(len_b, this->block + pm_len - 4);

	transf(this->block, block_nb);

	for (int i = 0 ; i < 8; i++) {
		storeBigendianU32(this->h[i], &digest[i << 2]);
	}
}

void Sha256::transf(const void* msg, unsigned int block_nb) {
	const unsigned char* message = static_cast<const unsigned char*>(msg);

	static const u32 sha256_k[64] = {
		0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5,
		0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
		0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
		0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
		0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc,
		0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
		0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,
		0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
		0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
		0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
		0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3,
		0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
		0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5,
		0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
		0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
		0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2
	};

	for (int i = 0; i < (int) block_nb; i++) {
		const unsigned char *sub_block = message + (i << 6);

		u32 w[64];
		u32 wv[8];

		for (int j = 0; j < 16; j++) {
			const unsigned char* str = &sub_block[j << 2];
			w[j] =    ((u32) *((str) + 3)      )
					| ((u32) *((str) + 2) <<  8)
					| ((u32) *((str) + 1) << 16)
					| ((u32) *((str) + 0) << 24);
        }

        for (int j = 16; j < 64; j++) {
			w[j] = SHA256_F4(w[j -  2]) + w[j -  7] + SHA256_F3(w[j - 15]) + w[j - 16];
        }

        for (int j = 0; j < 8; j++) {
            wv[j] = this->h[j];
        }

        for (int j = 0; j < 64; j++) {
			u32 t1, t2;
            t1 = wv[7] + SHA256_F2(wv[4]) + CH(wv[4], wv[5], wv[6]) + sha256_k[j] + w[j];
            t2 = SHA256_F1(wv[0]) + MAJ(wv[0], wv[1], wv[2]);
            wv[7] = wv[6];
            wv[6] = wv[5];
            wv[5] = wv[4];
            wv[4] = wv[3] + t1;
            wv[3] = wv[2];
            wv[2] = wv[1];
            wv[1] = wv[0];
            wv[0] = t1 + t2;
        }

        for (int j = 0; j < 8; j++) {
            this->h[j] += wv[j];
        }
    }
}


#if defined(MY_SHA256_EXAMPLE)
#include <stdio.h>
#include <vector>

int main(int argc, const char* argv[]) {
	if(argc > 1) {
		const char* filename = argv[1];
		FILE* fp = fopen(filename, "rb");
		if(fp) {
			Sha256 s;
			std::vector<char> f(1024*1024);
			size_t r = 0;
			do {
				r = fread(&f[0], sizeof(f[0]), f.size(), fp);
				s.update(&f[0], r);
			} while(r == f.size());
			s.final();
			fclose(fp);

			Sha256::Digest d;
			s.getDigest(&d);

			printf("%s\nSHA256 ", filename);
			for(int i = 0; i < sizeof(d.bytes); ++i) {
				printf("%02x", d.bytes[i]);
			}
		}
	}
	return 0;
}
#endif

my_sha256.h

//	http://www.ouah.org/ogay/sha2/
//	から SHA-256 部分だけを抜き出してテキトーに書き換えたもの。本体のコードは BSD ライセンス
class Sha256 {
public:
	typedef unsigned int u32;
	struct Digest {
		unsigned char bytes[256/8];
	};

	Sha256();
	~Sha256() {}

	void getDigest(Digest* digest) const;
	void clear();
	void update(const void* message, unsigned int len);
	void final();

	static void getDigest(Digest* digest, const void* message, unsigned int len) {
		Sha256 s;
		s.update(message, len);
		s.final();
		s.getDigest(digest);
	}

protected:
	void transf(const void* message, unsigned int block_nb);

	u32				h[8];
	unsigned int	tot_len;
	unsigned int	len;
	unsigned char	block[2 * 512 / 8];
	unsigned char	digest[256/8];
};