/* Copyright (c) 1998 Apple Computer, Inc.  All rights reserved.
 *
 * NOTICE: USE OF THE MATERIALS ACCOMPANYING THIS NOTICE IS SUBJECT
 * TO THE TERMS OF THE SIGNED "FAST ELLIPTIC ENCRYPTION (FEE) REFERENCE
 * SOURCE CODE EVALUATION AGREEMENT" BETWEEN APPLE COMPUTER, INC. AND THE
 * ORIGINAL LICENSEE THAT OBTAINED THESE MATERIALS FROM APPLE COMPUTER,
 * INC.  ANY USE OF THESE MATERIALS NOT PERMITTED BY SUCH AGREEMENT WILL
 * EXPOSE YOU TO LIABILITY.
 ***************************************************************************
 *
 * SHA1_priv.c - low-level SHA-1 hash algorithm.
 *
 * Revision History
 * ----------------
 * 05 Jan 1998	Doug Mitchell at Apple
 *	Created, based on source by Peter C. Gutmann.
 *	Mods: made reentrant, added NIST fix to expand(), eliminated
 *	unnecessary copy to local W[] array.
 */


/* NIST proposed Secure Hash Standard.

   Written 2 September 1992, Peter C. Gutmann.
   This implementation placed in the public domain.

   Comments to pgut1@cs.aukuni.ac.nz */


#include "SHA1_priv.h"
#include <string.h>

/* The SHS f()-functions */

#define f1(x,y,z)   ( ( x & y ) | ( ~x & z ) )              /* Rounds  0-19 */
#define f2(x,y,z)   ( x ^ y ^ z )                           /* Rounds 20-39 */
#define f3(x,y,z)   ( ( x & y ) | ( x & z ) | ( y & z ) )   /* Rounds 40-59 */
#define f4(x,y,z)   ( x ^ y ^ z )                           /* Rounds 60-79 */

/* The SHS Mysterious Constants */

#define K1  0x5A827999L     /* Rounds  0-19 */
#define K2  0x6ED9EBA1L     /* Rounds 20-39 */
#define K3  0x8F1BBCDCL     /* Rounds 40-59 */
#define K4  0xCA62C1D6L     /* Rounds 60-79 */

/* SHS initial values */

#define h0init  0x67452301L
#define h1init  0xEFCDAB89L
#define h2init  0x98BADCFEL
#define h3init  0x10325476L
#define h4init  0xC3D2E1F0L

/* 32-bit rotate - kludged with shifts */

#define S(n,X)  ( ( X << n ) | ( X >> ( 32 - n ) ) )

/* The initial expanding function */

/*
 * 06 Jan 1998. Added left circular shift per NIST FIPS-180-1 (at
 * http://www.nist.gov/itl/div897/pubs/fip180-1.htm). Also see
 * B. Schneier, Applied Cryptography, Second Edition, section 18.7
 * for info on this addenda to the original NIST spec.
 */
#define expand(count) {	\
    W[count] = W[count - 3] ^ W[count - 8] ^ W[count - 14] ^ W[count - 16]; \
    W[count] = S(1, W[count]); \
}

/* The four SHS sub-rounds */

#define subRound1(count)    \
    { \
    temp = S( 5, A ) + f1( B, C, D ) + E + W[ count ] + K1; \
    E = D; \
    D = C; \
    C = S( 30, B ); \
    B = A; \
    A = temp; \
    }

#define subRound2(count)    \
    { \
    temp = S( 5, A ) + f2( B, C, D ) + E + W[ count ] + K2; \
    E = D; \
    D = C; \
    C = S( 30, B ); \
    B = A; \
    A = temp; \
    }

#define subRound3(count)    \
    { \
    temp = S( 5, A ) + f3( B, C, D ) + E + W[ count ] + K3; \
    E = D; \
    D = C; \
    C = S( 30, B ); \
    B = A; \
    A = temp; \
    }

#define subRound4(count)    \
    { \
    temp = S( 5, A ) + f4( B, C, D ) + E + W[ count ] + K4; \
    E = D; \
    D = C; \
    C = S( 30, B ); \
    B = A; \
    A = temp; \
    }

/* Initialize the SHS values */

void shsInit( SHS_INFO *shsInfo )
    {
    /* Set the h-vars to their initial values */
    shsInfo->digest[ 0 ] = h0init;
    shsInfo->digest[ 1 ] = h1init;
    shsInfo->digest[ 2 ] = h2init;
    shsInfo->digest[ 3 ] = h3init;
    shsInfo->digest[ 4 ] = h4init;

    /* Initialise bit count */
    shsInfo->countLo = shsInfo->countHi = 0L;
    }

/* Perform the SHS transformation.  Note that this code, like MD5, seems to
   break some optimizing compilers - it may be necessary to split it into
   sections, eg based on the four subrounds */

static void shsTransform( SHS_INFO *shsInfo )
{
    LONG *W, temp;
    LONG A, B, C, D, E;

    /* Step A.  Copy the data buffer into the local work buffer. */
    /* 07 Jan 1998, dmitch: skip this bogus move, and let the caller
     * copy data directly into the W[] array. To minimize changes,
     * we'll just increase the size of shsInfo->data[] and make W
     * a pointer here.
     */
    W = shsInfo->data;

    /* Step B.  Expand the 16 words into 64 temporary data words */

    /*
     * Note: I tried optimizing this via a for loop, and for some reason,
     * the "optimized" version ran slower on PPC than the original
     * unrolled version. The optimized version does run faster on i486 than
     * the unrolled version.
     *
     * Similarly, the set of subRounds, below, runs slower on i486 when
     * optimized via 4 'for' loops. The "optimized" version of that is
     * a wash on PPC.
     *
     * Conclusion: leave both of 'em unrolled. We could ifdef per machine,
     * but this would get messy once we had more than two architectures.
     * We may want to revisit this.  --dpm
     */
    expand( 16 ); expand( 17 ); expand( 18 ); expand( 19 ); expand( 20 );
    expand( 21 ); expand( 22 ); expand( 23 ); expand( 24 ); expand( 25 );
    expand( 26 ); expand( 27 ); expand( 28 ); expand( 29 ); expand( 30 );
    expand( 31 ); expand( 32 ); expand( 33 ); expand( 34 ); expand( 35 );
    expand( 36 ); expand( 37 ); expand( 38 ); expand( 39 ); expand( 40 );
    expand( 41 ); expand( 42 ); expand( 43 ); expand( 44 ); expand( 45 );
    expand( 46 ); expand( 47 ); expand( 48 ); expand( 49 ); expand( 50 );
    expand( 51 ); expand( 52 ); expand( 53 ); expand( 54 ); expand( 55 );
    expand( 56 ); expand( 57 ); expand( 58 ); expand( 59 ); expand( 60 );
    expand( 61 ); expand( 62 ); expand( 63 ); expand( 64 ); expand( 65 );
    expand( 66 ); expand( 67 ); expand( 68 ); expand( 69 ); expand( 70 );
    expand( 71 ); expand( 72 ); expand( 73 ); expand( 74 ); expand( 75 );
    expand( 76 ); expand( 77 ); expand( 78 ); expand( 79 );

    /* Step C.  Set up first buffer */
    A = shsInfo->digest[ 0 ];
    B = shsInfo->digest[ 1 ];
    C = shsInfo->digest[ 2 ];
    D = shsInfo->digest[ 3 ];
    E = shsInfo->digest[ 4 ];

    /* Step D.  Serious mangling, divided into four sub-rounds */
    subRound1( 0 ); subRound1( 1 ); subRound1( 2 ); subRound1( 3 );
    subRound1( 4 ); subRound1( 5 ); subRound1( 6 ); subRound1( 7 );
    subRound1( 8 ); subRound1( 9 ); subRound1( 10 ); subRound1( 11 );
    subRound1( 12 ); subRound1( 13 ); subRound1( 14 ); subRound1( 15 );
    subRound1( 16 ); subRound1( 17 ); subRound1( 18 ); subRound1( 19 );
    subRound2( 20 ); subRound2( 21 ); subRound2( 22 ); subRound2( 23 );
    subRound2( 24 ); subRound2( 25 ); subRound2( 26 ); subRound2( 27 );
    subRound2( 28 ); subRound2( 29 ); subRound2( 30 ); subRound2( 31 );
    subRound2( 32 ); subRound2( 33 ); subRound2( 34 ); subRound2( 35 );
    subRound2( 36 ); subRound2( 37 ); subRound2( 38 ); subRound2( 39 );
    subRound3( 40 ); subRound3( 41 ); subRound3( 42 ); subRound3( 43 );
    subRound3( 44 ); subRound3( 45 ); subRound3( 46 ); subRound3( 47 );
    subRound3( 48 ); subRound3( 49 ); subRound3( 50 ); subRound3( 51 );
    subRound3( 52 ); subRound3( 53 ); subRound3( 54 ); subRound3( 55 );
    subRound3( 56 ); subRound3( 57 ); subRound3( 58 ); subRound3( 59 );
    subRound4( 60 ); subRound4( 61 ); subRound4( 62 ); subRound4( 63 );
    subRound4( 64 ); subRound4( 65 ); subRound4( 66 ); subRound4( 67 );
    subRound4( 68 ); subRound4( 69 ); subRound4( 70 ); subRound4( 71 );
    subRound4( 72 ); subRound4( 73 ); subRound4( 74 ); subRound4( 75 );
    subRound4( 76 ); subRound4( 77 ); subRound4( 78 ); subRound4( 79 );

    /* Step E.  Build message digest */
    shsInfo->digest[ 0 ] += A;
    shsInfo->digest[ 1 ] += B;
    shsInfo->digest[ 2 ] += C;
    shsInfo->digest[ 3 ] += D;
    shsInfo->digest[ 4 ] += E;
}

/* __LITTLE_ENDIAN__ is in fact #defined on OS X on  PPC.... */
//#ifdef __LITTLE_ENDIAN__
#if 0

/* When run on a little-endian CPU we need to perform byte reversal on an
   array of longwords.  It is possible to make the code endianness-
   independant by fiddling around with data at the byte level, but this
   makes for very slow code, so we rely on the user to sort out endianness
   at compile time */

static void byteReverse( buffer, byteCount )
  LONG *buffer;
  int byteCount;

    {
    LONG value;
    int count;

    byteCount /= sizeof( LONG );
    for( count = 0; count < byteCount; count++ )
	{
	value = ( buffer[ count ] << 16 ) | ( buffer[ count ] >> 16 );
	buffer[ count ] = ( ( value & 0xFF00FF00L ) >> 8 ) | ( ( value & 0x00FF00FFL ) << 8 );
	}
    }

#else	/* __LITTLE_ENDIAN__ */

/*
 * Nop for big-endian machines
 */
#define byteReverse( buffer, byteCount )

#endif /* __LITTLE_ENDIAN__ */


/* Update SHS for a block of data.  This code assumes that the buffer size
   is a multiple of SHS_BLOCKSIZE bytes long, which makes the code a lot
   more efficient since it does away with the need to handle partial blocks
   between calls to shsUpdate() */

void shsUpdate(
  SHS_INFO *shsInfo,
  const BYTE *buffer,
  int count)

    {
    /* Update bitcount */
    if( ( shsInfo->countLo + ( ( LONG ) count << 3 ) ) < shsInfo->countLo )
	shsInfo->countHi++; /* Carry from low to high bitCount */
    shsInfo->countLo += ( ( LONG ) count << 3 );
    shsInfo->countHi += ( ( LONG ) count >> 29 );

    /* Process data in SHS_BLOCKSIZE chunks */
    while( count >= SHS_BLOCKSIZE )
	{
	memcpy( shsInfo->data, buffer, SHS_BLOCKSIZE );
	byteReverse( shsInfo->data, SHS_BLOCKSIZE );
	shsTransform( shsInfo );
	buffer += SHS_BLOCKSIZE;
	count -= SHS_BLOCKSIZE;
	}

    /* Handle any remaining bytes of data.  This should only happen once
       on the final lot of data */
    memcpy( shsInfo->data, buffer, count );
    }

void shsFinal(SHS_INFO *shsInfo)
    {
    int count;
    LONG lowBitcount = shsInfo->countLo, highBitcount = shsInfo->countHi;

    /* Compute number of bytes mod 64 */
    count = ( int ) ( ( shsInfo->countLo >> 3 ) & 0x3F );

    /* Set the first char of padding to 0x80.  This is safe since there is
       always at least one byte free */
    ( ( BYTE * ) shsInfo->data )[ count++ ] = 0x80;

    /* Pad out to 56 mod 64 */
    if( count > 56 )
	{
	/* Two lots of padding:  Pad the first block to 64 bytes */
	memset( ( BYTE * ) &shsInfo->data + count, 0, 64 - count );
	byteReverse( shsInfo->data, SHS_BLOCKSIZE );
	shsTransform( shsInfo );

	/* Now fill the next block with 56 bytes */
	memset( &shsInfo->data, 0, 56 );
	}
    else
	/* Pad block to 56 bytes */
	memset( ( BYTE * ) &shsInfo->data + count, 0, 56 - count );
	byteReverse( shsInfo->data, SHS_BLOCKSIZE );

    /* Append length in bits and transform */
    shsInfo->data[ 14 ] = highBitcount;
    shsInfo->data[ 15 ] = lowBitcount;

    shsTransform( shsInfo );
    byteReverse( shsInfo->data, SHS_DIGESTSIZE );
    }
