/*
 *  NkArc
 *  Copyright (C) 2023 A1ive
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <grub/types.h>
#include <grub/crypto.h>
#include <grub/misc.h>
#include "gcry_wrap.h"

/* A macro to test whether P is properly aligned for an u32 type.
   Note that config.h provides a suitable replacement for uintptr_t if
   it does not exist in stdint.h.  */
   /* #if __GNUC__ >= 2 */
   /* # define U32_ALIGNED_P(p) (!(((uintptr_t)p) % __alignof__ (u32))) */
   /* #else */
   /* # define U32_ALIGNED_P(p) (!(((uintptr_t)p) % sizeof (u32))) */
   /* #endif */

#define TRANSFORM(x,d,n) transform ((x), (d), (n))

typedef struct
{
	u32           h0, h1, h2, h3, h4;
	u32           nblocks;
	unsigned char buf[64];
	int           count;
} SHA1_CONTEXT;

static void
sha1_init(void* context)
{
	SHA1_CONTEXT* hd = context;

	hd->h0 = 0x67452301;
	hd->h1 = 0xefcdab89;
	hd->h2 = 0x98badcfe;
	hd->h3 = 0x10325476;
	hd->h4 = 0xc3d2e1f0;
	hd->nblocks = 0;
	hd->count = 0;
}


/* Round function macros. */
#define K1  0x5A827999L
#define K2  0x6ED9EBA1L
#define K3  0x8F1BBCDCL
#define K4  0xCA62C1D6L
#define F1(x,y,z)   ( z ^ ( x & ( y ^ z ) ) )
#define F2(x,y,z)   ( x ^ y ^ z )
#define F3(x,y,z)   ( ( x & y ) | ( z & ( x | y ) ) )
#define F4(x,y,z)   ( x ^ y ^ z )
#define M(i) ( tm =    x[ i    &0x0f]  \
					 ^ x[(i-14)&0x0f]  \
			 ^ x[(i-8) &0x0f]  \
					 ^ x[(i-3) &0x0f], \
					 (x[i&0x0f] = rol(tm, 1)))
#define R(a,b,c,d,e,f,k,m)  do { e += rol( a, 5 )     \
								  + f( b, c, d )  \
					  + k	      \
					  + m;	      \
				 b = rol( b, 30 );    \
				   } while(0)


/*
 * Transform NBLOCKS of each 64 bytes (16 32-bit words) at DATA.
 */
static void
transform(SHA1_CONTEXT* hd, const unsigned char* data, grub_size_t nblocks)
{
	register u32 a, b, c, d, e; /* Local copies of the chaining variables.  */
	register u32 tm;            /* Helper.  */
	u32 x[16];                  /* The array we work on. */

	/* Loop over all blocks.  */
	for (; nblocks; nblocks--)
	{
#ifdef WORDS_BIGENDIAN
		memcpy(x, data, 64);
		data += 64;
#else
		{
			int i;
			unsigned char* p;

			for (i = 0, p = (unsigned char*)x; i < 16; i++, p += 4)
			{
				p[3] = *data++;
				p[2] = *data++;
				p[1] = *data++;
				p[0] = *data++;
			}
		}
#endif
		/* Get the values of the chaining variables. */
		a = hd->h0;
		b = hd->h1;
		c = hd->h2;
		d = hd->h3;
		e = hd->h4;

		/* Transform. */
		R(a, b, c, d, e, F1, K1, x[0]);
		R(e, a, b, c, d, F1, K1, x[1]);
		R(d, e, a, b, c, F1, K1, x[2]);
		R(c, d, e, a, b, F1, K1, x[3]);
		R(b, c, d, e, a, F1, K1, x[4]);
		R(a, b, c, d, e, F1, K1, x[5]);
		R(e, a, b, c, d, F1, K1, x[6]);
		R(d, e, a, b, c, F1, K1, x[7]);
		R(c, d, e, a, b, F1, K1, x[8]);
		R(b, c, d, e, a, F1, K1, x[9]);
		R(a, b, c, d, e, F1, K1, x[10]);
		R(e, a, b, c, d, F1, K1, x[11]);
		R(d, e, a, b, c, F1, K1, x[12]);
		R(c, d, e, a, b, F1, K1, x[13]);
		R(b, c, d, e, a, F1, K1, x[14]);
		R(a, b, c, d, e, F1, K1, x[15]);
		R(e, a, b, c, d, F1, K1, M(16));
		R(d, e, a, b, c, F1, K1, M(17));
		R(c, d, e, a, b, F1, K1, M(18));
		R(b, c, d, e, a, F1, K1, M(19));
		R(a, b, c, d, e, F2, K2, M(20));
		R(e, a, b, c, d, F2, K2, M(21));
		R(d, e, a, b, c, F2, K2, M(22));
		R(c, d, e, a, b, F2, K2, M(23));
		R(b, c, d, e, a, F2, K2, M(24));
		R(a, b, c, d, e, F2, K2, M(25));
		R(e, a, b, c, d, F2, K2, M(26));
		R(d, e, a, b, c, F2, K2, M(27));
		R(c, d, e, a, b, F2, K2, M(28));
		R(b, c, d, e, a, F2, K2, M(29));
		R(a, b, c, d, e, F2, K2, M(30));
		R(e, a, b, c, d, F2, K2, M(31));
		R(d, e, a, b, c, F2, K2, M(32));
		R(c, d, e, a, b, F2, K2, M(33));
		R(b, c, d, e, a, F2, K2, M(34));
		R(a, b, c, d, e, F2, K2, M(35));
		R(e, a, b, c, d, F2, K2, M(36));
		R(d, e, a, b, c, F2, K2, M(37));
		R(c, d, e, a, b, F2, K2, M(38));
		R(b, c, d, e, a, F2, K2, M(39));
		R(a, b, c, d, e, F3, K3, M(40));
		R(e, a, b, c, d, F3, K3, M(41));
		R(d, e, a, b, c, F3, K3, M(42));
		R(c, d, e, a, b, F3, K3, M(43));
		R(b, c, d, e, a, F3, K3, M(44));
		R(a, b, c, d, e, F3, K3, M(45));
		R(e, a, b, c, d, F3, K3, M(46));
		R(d, e, a, b, c, F3, K3, M(47));
		R(c, d, e, a, b, F3, K3, M(48));
		R(b, c, d, e, a, F3, K3, M(49));
		R(a, b, c, d, e, F3, K3, M(50));
		R(e, a, b, c, d, F3, K3, M(51));
		R(d, e, a, b, c, F3, K3, M(52));
		R(c, d, e, a, b, F3, K3, M(53));
		R(b, c, d, e, a, F3, K3, M(54));
		R(a, b, c, d, e, F3, K3, M(55));
		R(e, a, b, c, d, F3, K3, M(56));
		R(d, e, a, b, c, F3, K3, M(57));
		R(c, d, e, a, b, F3, K3, M(58));
		R(b, c, d, e, a, F3, K3, M(59));
		R(a, b, c, d, e, F4, K4, M(60));
		R(e, a, b, c, d, F4, K4, M(61));
		R(d, e, a, b, c, F4, K4, M(62));
		R(c, d, e, a, b, F4, K4, M(63));
		R(b, c, d, e, a, F4, K4, M(64));
		R(a, b, c, d, e, F4, K4, M(65));
		R(e, a, b, c, d, F4, K4, M(66));
		R(d, e, a, b, c, F4, K4, M(67));
		R(c, d, e, a, b, F4, K4, M(68));
		R(b, c, d, e, a, F4, K4, M(69));
		R(a, b, c, d, e, F4, K4, M(70));
		R(e, a, b, c, d, F4, K4, M(71));
		R(d, e, a, b, c, F4, K4, M(72));
		R(c, d, e, a, b, F4, K4, M(73));
		R(b, c, d, e, a, F4, K4, M(74));
		R(a, b, c, d, e, F4, K4, M(75));
		R(e, a, b, c, d, F4, K4, M(76));
		R(d, e, a, b, c, F4, K4, M(77));
		R(c, d, e, a, b, F4, K4, M(78));
		R(b, c, d, e, a, F4, K4, M(79));

		/* Update the chaining variables. */
		hd->h0 += a;
		hd->h1 += b;
		hd->h2 += c;
		hd->h3 += d;
		hd->h4 += e;
	}
}


/* Update the message digest with the contents
 * of INBUF with length INLEN.
 */
static void
sha1_write(void* context, const void* inbuf_arg, grub_size_t inlen)
{
	const unsigned char* inbuf = inbuf_arg;
	SHA1_CONTEXT* hd = context;
	grub_size_t nblocks;

	if (hd->count == 64)  /* Flush the buffer. */
	{
		TRANSFORM(hd, hd->buf, 1);
		_gcry_burn_stack(88 + 4 * sizeof(void*));
		hd->count = 0;
		hd->nblocks++;
	}
	if (!inbuf)
		return;

	if (hd->count)
	{
		for (; inlen && hd->count < 64; inlen--)
			hd->buf[hd->count++] = *inbuf++;
		sha1_write(hd, NULL, 0);
		if (!inlen)
			return;
	}

	nblocks = inlen / 64;
	if (nblocks)
	{
		TRANSFORM(hd, inbuf, nblocks);
		hd->count = 0;
		hd->nblocks += (u32) nblocks;
		inlen -= nblocks * 64;
		inbuf += nblocks * 64;
	}
	_gcry_burn_stack(88 + 4 * sizeof(void*));

	/* Save remaining bytes.  */
	for (; inlen && hd->count < 64; inlen--)
		hd->buf[hd->count++] = *inbuf++;
}


/* The routine final terminates the computation and
 * returns the digest.
 * The handle is prepared for a new cycle, but adding bytes to the
 * handle will the destroy the returned buffer.
 * Returns: 20 bytes representing the digest.
 */

static void
sha1_final(void* context)
{
	SHA1_CONTEXT* hd = context;

	u32 t, msb, lsb;
	unsigned char* p;

	sha1_write(hd, NULL, 0); /* flush */;

	t = hd->nblocks;
	/* multiply by 64 to make a byte count */
	lsb = t << 6;
	msb = t >> 26;
	/* add the count */
	t = lsb;
	if ((lsb += hd->count) < t)
		msb++;
	/* multiply by 8 to make a bit count */
	t = lsb;
	lsb <<= 3;
	msb <<= 3;
	msb |= t >> 29;

	if (hd->count < 56) /* enough room */
	{
		hd->buf[hd->count++] = 0x80; /* pad */
		while (hd->count < 56)
			hd->buf[hd->count++] = 0;  /* pad */
	}
	else  /* need one extra block */
	{
		hd->buf[hd->count++] = 0x80; /* pad character */
		while (hd->count < 64)
			hd->buf[hd->count++] = 0;
		sha1_write(hd, NULL, 0);  /* flush */;
		grub_memset(hd->buf, 0, 56); /* fill next block with zeroes */
	}
	/* append the 64 bit count */
	hd->buf[56] = msb >> 24;
	hd->buf[57] = msb >> 16;
	hd->buf[58] = msb >> 8;
	hd->buf[59] = msb;
	hd->buf[60] = lsb >> 24;
	hd->buf[61] = lsb >> 16;
	hd->buf[62] = lsb >> 8;
	hd->buf[63] = lsb;
	TRANSFORM(hd, hd->buf, 1);
	_gcry_burn_stack(88 + 4 * sizeof(void*));

	p = hd->buf;
#ifdef WORDS_BIGENDIAN
#define X(a) do { *(u32*)p = hd->h##a ; p += 4; } while(0)
#else /* little endian */
#define X(a) do { *p++ = hd->h##a >> 24; *p++ = hd->h##a >> 16;	 \
				  *p++ = hd->h##a >> 8; *p++ = hd->h##a; } while(0)
#endif
	X(0);
	X(1);
	X(2);
	X(3);
	X(4);
#undef X

}

static unsigned char*
sha1_read(void* context)
{
	SHA1_CONTEXT* hd = context;

	return hd->buf;
}

/****************
 * Shortcut functions which puts the hash value of the supplied buffer
 * into outbuf which must have a size of 20 bytes.
 */
#if 0
void
_gcry_sha1_hash_buffer(void* outbuf, const void* buffer, grub_size_t length)
{
	SHA1_CONTEXT hd;

	sha1_init(&hd);
	sha1_write(&hd, buffer, length);
	sha1_final(&hd);
	memcpy(outbuf, hd.buf, 20);
}
#endif

static unsigned char asn[15] = /* Object ID is 1.3.14.3.2.26 */
{
  0x30, 0x21, 0x30, 0x09, 0x06, 0x05, 0x2b, 0x0e, 0x03,
  0x02, 0x1a, 0x05, 0x00, 0x04, 0x14
};

static gcry_md_oid_spec_t oid_spec_sha1[] =
{
	/* iso.member-body.us.rsadsi.pkcs.pkcs-1.5 (sha1WithRSAEncryption) */
	{ "1.2.840.113549.1.1.5" },
	/* iso.member-body.us.x9-57.x9cm.3 (dsaWithSha1)*/
	{ "1.2.840.10040.4.3" },
	/* from NIST's OIW  (sha1) */
	{ "1.3.14.3.2.26" },
	/* from NIST OIW (sha-1WithRSAEncryption) */
	{ "1.3.14.3.2.29" },
	/* iso.member-body.us.ansi-x9-62.signatures.ecdsa-with-sha1 */
	{ "1.2.840.10045.4.1" },
	{ NULL },
};

gcry_md_spec_t _gcry_digest_spec_sha1 =
{
	"SHA1", asn, DIM(asn), oid_spec_sha1, 20,
	sha1_init, sha1_write, sha1_final, sha1_read,
	sizeof(SHA1_CONTEXT)
};
