/*
 * MD4 (RFC-1320) message digest.
 * Modified from MD5 code by Andrey Panin <pazke@donpac.ru>
 *
 * Written by Solar Designer <solar@openwall.com> in 2001, and placed in
 * the public domain.  There's absolutely no warranty.
 *
 * This differs from Colin Plumb's older public domain implementation in
 * that no 32-bit integer data type is required, there's no compile-time
 * endianness configuration, and the function prototypes match OpenSSL's.
 * The primary goals are portability and ease of use.
 *
 * This implementation is meant to be fast, but not as fast as possible.
 * Some known optimizations are not included to reduce source code size
 * and avoid compile-time configuration.
 */

#include <stdlib.h>
#include <string.h>

#include "md4lib.h"

/*
 * The basic MD4 functions.
 */
#define F( x, y, z )  ( ( z ) ^ ( ( x ) & ( ( y ) ^ ( z ) ) ) )
#define G( x, y, z )  ( ( ( x ) & ( y ) ) | ( ( x ) & ( z ) ) | ( ( y ) & ( z ) ) )
#define H( x, y, z )  ( ( x ) ^ ( y ) ^ ( z ) )

/*
 * The MD4 transformation for all four rounds.
 */
#define STEP( f, a, b, c, d, x, s )	\
	( a ) += f( ( b ), ( c ), ( d ) ) + ( x );	 \
	( a ) = ( ( a ) << ( s ) ) | ( ( a ) >> ( 32 - ( s ) ) )


/*
 * SET reads 4 input bytes in little-endian byte order and stores them
 * in a properly aligned word in host byte order.
 *
 * The check for little-endian architectures which tolerate unaligned
 * memory accesses is just an optimization.  Nothing will break if it
 * doesn't work.
 */
#if defined( __i386__ ) || defined( __x86_64__ ) || defined( __vax__ )
#define SET( n ) \
	( *(const uint_fast32_t *)&ptr[( n ) * 4] )
#define GET( n ) \
	SET( n )
#else
#define SET( n ) \
	( ctx->block[( n )] = \
		  (uint_fast32_t)ptr[( n ) * 4] | \
		  ( (uint_fast32_t)ptr[( n ) * 4 + 1] << 8 ) | \
		  ( (uint_fast32_t)ptr[( n ) * 4 + 2] << 16 ) |	\
		  ( (uint_fast32_t)ptr[( n ) * 4 + 3] << 24 ) )
#define GET( n ) \
	( ctx->block[( n )] )
#endif

/*
 * This processes one or more 64-byte data blocks, but does NOT update
 * the bit counters.  There're no alignment requirements.
 */
static const void *body( struct md4_context *ctx, const void *data, size_t size ){
	const unsigned char *ptr;
	uint32_t a, b, c, d;
	uint32_t saved_a, saved_b, saved_c, saved_d;

	ptr = data;

	a = ctx->a;
	b = ctx->b;
	c = ctx->c;
	d = ctx->d;

	do {
		saved_a = a;
		saved_b = b;
		saved_c = c;
		saved_d = d;

/* Round 1 */
		STEP( F, a, b, c, d, SET( 0 ),  3 );
		STEP( F, d, a, b, c, SET( 1 ),  7 );
		STEP( F, c, d, a, b, SET( 2 ), 11 );
		STEP( F, b, c, d, a, SET( 3 ), 19 );

		STEP( F, a, b, c, d, SET( 4 ),  3 );
		STEP( F, d, a, b, c, SET( 5 ),  7 );
		STEP( F, c, d, a, b, SET( 6 ), 11 );
		STEP( F, b, c, d, a, SET( 7 ), 19 );

		STEP( F, a, b, c, d, SET( 8 ),  3 );
		STEP( F, d, a, b, c, SET( 9 ),  7 );
		STEP( F, c, d, a, b, SET( 10 ), 11 );
		STEP( F, b, c, d, a, SET( 11 ), 19 );

		STEP( F, a, b, c, d, SET( 12 ),  3 );
		STEP( F, d, a, b, c, SET( 13 ),  7 );
		STEP( F, c, d, a, b, SET( 14 ), 11 );
		STEP( F, b, c, d, a, SET( 15 ), 19 );
/* Round 2 */
		STEP( G, a, b, c, d, GET( 0 ) + 0x5A827999,  3 );
		STEP( G, d, a, b, c, GET( 4 ) + 0x5A827999,  5 );
		STEP( G, c, d, a, b, GET( 8 ) + 0x5A827999,  9 );
		STEP( G, b, c, d, a, GET( 12 ) + 0x5A827999, 13 );

		STEP( G, a, b, c, d, GET( 1 ) + 0x5A827999,  3 );
		STEP( G, d, a, b, c, GET( 5 ) + 0x5A827999,  5 );
		STEP( G, c, d, a, b, GET( 9 ) + 0x5A827999,  9 );
		STEP( G, b, c, d, a, GET( 13 ) + 0x5A827999, 13 );

		STEP( G, a, b, c, d, GET( 2 ) + 0x5A827999,  3 );
		STEP( G, d, a, b, c, GET( 6 ) + 0x5A827999,  5 );
		STEP( G, c, d, a, b, GET( 10 ) + 0x5A827999,  9 );
		STEP( G, b, c, d, a, GET( 14 ) + 0x5A827999, 13 );

		STEP( G, a, b, c, d, GET( 3 ) + 0x5A827999,  3 );
		STEP( G, d, a, b, c, GET( 7 ) + 0x5A827999,  5 );
		STEP( G, c, d, a, b, GET( 11 ) + 0x5A827999,  9 );
		STEP( G, b, c, d, a, GET( 15 ) + 0x5A827999, 13 );
/* Round 3 */
		STEP( H, a, b, c, d, GET( 0 ) + 0x6ED9EBA1,  3 );
		STEP( H, d, a, b, c, GET( 8 ) + 0x6ED9EBA1,  9 );
		STEP( H, c, d, a, b, GET( 4 ) + 0x6ED9EBA1, 11 );
		STEP( H, b, c, d, a, GET( 12 ) + 0x6ED9EBA1, 15 );

		STEP( H, a, b, c, d, GET( 2 ) + 0x6ED9EBA1,  3 );
		STEP( H, d, a, b, c, GET( 10 ) + 0x6ED9EBA1,  9 );
		STEP( H, c, d, a, b, GET( 6 ) + 0x6ED9EBA1, 11 );
		STEP( H, b, c, d, a, GET( 14 ) + 0x6ED9EBA1, 15 );

		STEP( H, a, b, c, d, GET( 1 ) + 0x6ED9EBA1,  3 );
		STEP( H, d, a, b, c, GET( 9 ) + 0x6ED9EBA1,  9 );
		STEP( H, c, d, a, b, GET( 5 ) + 0x6ED9EBA1, 11 );
		STEP( H, b, c, d, a, GET( 13 ) + 0x6ED9EBA1, 15 );

		STEP( H, a, b, c, d, GET( 3 ) + 0x6ED9EBA1,  3 );
		STEP( H, d, a, b, c, GET( 11 ) + 0x6ED9EBA1,  9 );
		STEP( H, c, d, a, b, GET( 7 ) + 0x6ED9EBA1, 11 );
		STEP( H, b, c, d, a, GET( 15 ) + 0x6ED9EBA1, 15 );

		a += saved_a;
		b += saved_b;
		c += saved_c;
		d += saved_d;

		ptr += 64;
	} while ( size -= 64 );

	ctx->a = a;
	ctx->b = b;
	ctx->c = c;
	ctx->d = d;

	return ptr;
}

void md4_init( struct md4_context *ctx ){
	ctx->a = 0x67452301;
	ctx->b = 0xefcdab89;
	ctx->c = 0x98badcfe;
	ctx->d = 0x10325476;

	ctx->lo = 0;
	ctx->hi = 0;
}

void md4_update( struct md4_context *ctx, const void *data, size_t size ){
	/* @UNSAFE */
	uint_fast32_t saved_lo;
	unsigned long used, free;

	saved_lo = ctx->lo;
	if ( ( ctx->lo = ( saved_lo + size ) & 0x1fffffff ) < saved_lo ) {
		ctx->hi++;
	}
	ctx->hi += size >> 29;

	used = saved_lo & 0x3f;

	if ( used ) {
		free = 64 - used;

		if ( size < free ) {
			memcpy( &ctx->buffer[used], data, size );
			return;
		}

		memcpy( &ctx->buffer[used], data, free );
		data = (const unsigned char *) data + free;
		size -= free;
		body( ctx, ctx->buffer, 64 );
	}

	if ( size >= 64 ) {
		data = body( ctx, data, size & ~(unsigned long)0x3f );
		size &= 0x3f;
	}

	memcpy( ctx->buffer, data, size );
}

void md4_final( struct md4_context *ctx, unsigned char result[MD4_RESULTLEN] ){
	/* @UNSAFE */
	unsigned long used, free;

	used = ctx->lo & 0x3f;

	ctx->buffer[used++] = 0x80;

	free = 64 - used;

	if ( free < 8 ) {
		memset( &ctx->buffer[used], 0, free );
		body( ctx, ctx->buffer, 64 );
		used = 0;
		free = 64;
	}

	memset( &ctx->buffer[used], 0, free - 8 );

	ctx->lo <<= 3;
	ctx->buffer[56] = ctx->lo;
	ctx->buffer[57] = ctx->lo >> 8;
	ctx->buffer[58] = ctx->lo >> 16;
	ctx->buffer[59] = ctx->lo >> 24;
	ctx->buffer[60] = ctx->hi;
	ctx->buffer[61] = ctx->hi >> 8;
	ctx->buffer[62] = ctx->hi >> 16;
	ctx->buffer[63] = ctx->hi >> 24;

	body( ctx, ctx->buffer, 64 );

	result[0] = ctx->a;
	result[1] = ctx->a >> 8;
	result[2] = ctx->a >> 16;
	result[3] = ctx->a >> 24;
	result[4] = ctx->b;
	result[5] = ctx->b >> 8;
	result[6] = ctx->b >> 16;
	result[7] = ctx->b >> 24;
	result[8] = ctx->c;
	result[9] = ctx->c >> 8;
	result[10] = ctx->c >> 16;
	result[11] = ctx->c >> 24;
	result[12] = ctx->d;
	result[13] = ctx->d >> 8;
	result[14] = ctx->d >> 16;
	result[15] = ctx->d >> 24;

	memset( ctx, 0, sizeof( *ctx ) );
}

void md4_get_digest( const void *data, size_t size,
					 unsigned char result[MD4_RESULTLEN] ){
	struct md4_context ctx;

	md4_init( &ctx );
	md4_update( &ctx, data, size );
	md4_final( &ctx, result );
}

static void hash_method_init_md4( void *context ){
	md4_init( context );
}
static void hash_method_loop_md4( void *context, const void *data, size_t size ){
	md4_update( context, data, size );
}

static void hash_method_result_md4( void *context, unsigned char *result_r ){
	md4_final( context, result_r );
}

const struct hash_method hash_method_md4 = {
	"md4",
	sizeof( struct md4_context ),
	MD4_RESULTLEN,

	hash_method_init_md4,
	hash_method_loop_md4,
	hash_method_result_md4
};
