/*
 * $Id: sha1.c,v 1.3 2004/10/26 19:33:50 rmanfredi Exp $
 *
 * This file comes from RFC 3174. Inclusion in gtk-gnutella is:
 *
 *   Copyright (c) 2002-2003, Raphael Manfredi
 *
 *----------------------------------------------------------------------
 * This file is part of gtk-gnutella.
 *
 *  gtk-gnutella 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 2 of the License, or
 *  (at your option) any later version.
 *
 *  gtk-gnutella 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 gtk-gnutella; if not, write to the Free Software
 *  Foundation, Inc.:
 *      59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *----------------------------------------------------------------------
 */

/*
 *  sha1.c
 *
 *  Description:
 *      This file implements the Secure Hashing Algorithm 1 as
 *      defined in FIPS PUB 180-1 published April 17, 1995.
 *
 *      The SHA-1, produces a 160-bit message digest for a given
 *      data stream.  It should take about 2**n steps to find a
 *      message with the same digest as a given message and
 *      2**(n/2) to find any two messages with the same digest,
 *      when n is the digest size in bits.  Therefore, this
 *      algorithm can serve as a means of providing a
 *      "fingerprint" for a message.
 *
 *  Portability Issues:
 *      SHA-1 is defined in terms of 32-bit "words".  This code
 *      uses <stdint.h> (included via "sha1.h" to define 32 and 8
 *      bit unsigned integer types.  If your C compiler does not
 *      support 32 bit unsigned integers, this code is not
 *      appropriate.
 *
 *  Caveats:
 *      SHA-1 is designed to work with messages less than 2^64 bits
 *      long.  Although SHA-1 allows a message digest to be generated
 *      for messages of any number of bits less than 2^64, this
 *      implementation only works with messages with a length that is
 *      a multiple of the size of an 8-bit character.
 *
 */

#include "common.h"
#include "sha1.h"
#include "misc.h"		/* For RCSID */
#include "override.h"		/* Must be the last header included */

RCSID("$Id: sha1.c,v 1.3 2004/10/26 19:33:50 rmanfredi Exp $");

/*
 *  Define the SHA1 circular left shift macro
 */
#define SHA1CircularShift(bits,word) \
                (((word) << (bits)) | ((word) >> (32-(bits))))

/* Local Function Prototyptes */
void SHA1PadMessage(SHA1Context *);
void SHA1ProcessMessageBlock(SHA1Context *);

/*
 *  SHA1Reset
 *
 *  Description:
 *      This function will initialize the SHA1Context in preparation
 *      for computing a new SHA1 message digest.
 *
 *  Parameters:
 *      context: [in/out]
 *          The context to reset.
 *
 *  Returns:
 *      sha Error Code.
 *
 */
int SHA1Reset(SHA1Context *context)
{
    if (!context)
    {
        return shaNull;
    }

    context->Length_Low             = 0;
    context->Length_High            = 0;
    context->Message_Block_Index    = 0;

    context->Intermediate_Hash[0]   = 0x67452301;
    context->Intermediate_Hash[1]   = 0xEFCDAB89;
    context->Intermediate_Hash[2]   = 0x98BADCFE;
    context->Intermediate_Hash[3]   = 0x10325476;
    context->Intermediate_Hash[4]   = 0xC3D2E1F0;

    context->Computed   = 0;
    context->Corrupted  = 0;

    return shaSuccess;
}

/*
 *  SHA1Result
 *
 *  Description:
 *      This function will return the 160-bit message digest into the
 *      Message_Digest array  provided by the caller.
 *      NOTE: The first octet of hash is stored in the 0th element,
 *            the last octet of hash in the 19th element.
 *
 *  Parameters:
 *      context: [in/out]
 *          The context to use to calculate the SHA-1 hash.
 *      Message_Digest: [out]
 *          Where the digest is returned.
 *
 *  Returns:
 *      sha Error Code.
 *
 */
int SHA1Result( SHA1Context *context,
                guint8 Message_Digest[SHA1HashSize])
{
    int i;

    if (!context || !Message_Digest)
    {
        return shaNull;
    }

    if (context->Corrupted)
    {
        return context->Corrupted;
    }

    if (!context->Computed)
    {
        SHA1PadMessage(context);
        for(i=0; i<64; ++i)
        {
            /* message may be sensitive, clear it out */
            context->Message_Block[i] = 0;
        }
        context->Length_Low = 0;    /* and clear length */
        context->Length_High = 0;
        context->Computed = 1;
    }

    for(i = 0; i < SHA1HashSize; ++i)
    {
        Message_Digest[i] = context->Intermediate_Hash[i>>2]
                            >> 8 * ( 3 - ( i & 0x03 ) );
    }

    return shaSuccess;
}

/*
 *  SHA1Input
 *
 *  Description:
 *      This function accepts an array of octets as the next portion
 *      of the message.
 *
 *  Parameters:
 *      context: [in/out]
 *          The SHA context to update
 *      message_array: [in]
 *          An array of characters representing the next portion of
 *          the message.
 *      length: [in]
 *          The length of the message in message_array
 *
 *  Returns:
 *      sha Error Code.
 *
 */
int SHA1Input(    SHA1Context    *context,
                  const guint8  *message_array,
                  unsigned       length)
{
    if (!length)
    {
        return shaSuccess;
    }

    if (!context || !message_array)
    {
        return shaNull;
    }

    if (context->Computed)
    {
        context->Corrupted = shaStateError;
        return shaStateError;
    }

    if (context->Corrupted)
    {
         return context->Corrupted;
    }
    while(length-- && !context->Corrupted)
    {
    context->Message_Block[context->Message_Block_Index++] =
                    (*message_array & 0xFF);

    context->Length_Low += 8;
    if (context->Length_Low == 0)
    {
        context->Length_High++;
        if (context->Length_High == 0)
        {
            /* Message is too long */
            context->Corrupted = 1;
        }
    }

    if (context->Message_Block_Index == 64)
    {
        SHA1ProcessMessageBlock(context);
    }

    message_array++;
    }

    return shaSuccess;
}

/*
 *  SHA1ProcessMessageBlock
 *
 *  Description:
 *      This function will process the next 512 bits of the message
 *      stored in the Message_Block array.
 *
 *  Parameters:
 *      None.
 *
 *  Returns:
 *      Nothing.
 *
 *  Comments:
 *      Many of the variable names in this code, especially the
 *      single character names, were used because those were the
 *      names used in the publication.
 *
 *
 */
void SHA1ProcessMessageBlock(SHA1Context *context)
{
    const guint32 K[] =    {       /* Constants defined in SHA-1   */
                            0x5A827999,
                            0x6ED9EBA1,
                            0x8F1BBCDC,
                            0xCA62C1D6
                            };
    int           t;                /* Loop counter                */
    guint32      temp;              /* Temporary word value        */
    guint32      W[80];             /* Word sequence               */
    guint32      A, B, C, D, E;     /* Word buffers                */
    guint32      *wp;               /* Pointer in word sequence    */

    /*
     *  Initialize the first 16 words in the array W
     */

#define INIT(x) \
        W[x] = (context->Message_Block[(x) * 4] << 24) | \
        	(context->Message_Block[(x) * 4 + 1] << 16) | \
        	(context->Message_Block[(x) * 4 +2] << 8) | \
        	(context->Message_Block[(x) * 4 +3])

	/* Unrolling this loop saves time */
	INIT(0);  INIT(1);  INIT(2);  INIT(3);
	INIT(4);  INIT(5);  INIT(6);  INIT(7);
	INIT(8);  INIT(9);  INIT(10); INIT(11);
	INIT(12); INIT(13); INIT(14); INIT(15);

#define CRUNCH \
       *wp = SHA1CircularShift(1,wp[-3] ^ wp[-8] ^ wp[-14] ^ wp[-16])

	wp = &W[16];
	CRUNCH; wp++;		/* 16 */
	CRUNCH; wp++;		/* 17 */
	CRUNCH; wp++;		/* 18 */
	CRUNCH; wp++;		/* 19 */

	/* Fully unrolling this loop does NOT save time due to I-cache misses */
    for (t = 20; t < 80; t += 10) {
		CRUNCH; wp++;		/* t+0 */
		CRUNCH; wp++;		/* t+1 */
		CRUNCH; wp++;		/* t+2 */
		CRUNCH; wp++;		/* t+3 */
		CRUNCH; wp++;		/* t+4 */
		CRUNCH; wp++;		/* t+5 */
		CRUNCH; wp++;		/* t+6 */
		CRUNCH; wp++;		/* t+7 */
		CRUNCH; wp++;		/* t+8 */
		CRUNCH; wp++;		/* t+9 */
    }

    A = context->Intermediate_Hash[0];
    B = context->Intermediate_Hash[1];
    C = context->Intermediate_Hash[2];
    D = context->Intermediate_Hash[3];
    E = context->Intermediate_Hash[4];

	wp = &W[0];

#define ROTATE(k, mix) \
	temp = SHA1CircularShift(5,A) + (mix) + E + *wp++ + K[k]; \
	E = D; D = C; \
	C = SHA1CircularShift(30,B); \
	B = A; A = temp

	/* Optimizing "(B & C) | (~B & D)" into "D ^ (B & (C ^ D))" */
	ROTATE(0, D ^ (B & (C ^ D)));
	ROTATE(0, D ^ (B & (C ^ D)));
	ROTATE(0, D ^ (B & (C ^ D)));
	ROTATE(0, D ^ (B & (C ^ D)));
	ROTATE(0, D ^ (B & (C ^ D)));
	ROTATE(0, D ^ (B & (C ^ D)));
	ROTATE(0, D ^ (B & (C ^ D)));
	ROTATE(0, D ^ (B & (C ^ D)));
	ROTATE(0, D ^ (B & (C ^ D)));
	ROTATE(0, D ^ (B & (C ^ D)));
	ROTATE(0, D ^ (B & (C ^ D)));
	ROTATE(0, D ^ (B & (C ^ D)));
	ROTATE(0, D ^ (B & (C ^ D)));
	ROTATE(0, D ^ (B & (C ^ D)));
	ROTATE(0, D ^ (B & (C ^ D)));
	ROTATE(0, D ^ (B & (C ^ D)));
	ROTATE(0, D ^ (B & (C ^ D)));
	ROTATE(0, D ^ (B & (C ^ D)));
	ROTATE(0, D ^ (B & (C ^ D)));
	ROTATE(0, D ^ (B & (C ^ D)));

	ROTATE(1, B ^ C ^ D);
	ROTATE(1, B ^ C ^ D);
	ROTATE(1, B ^ C ^ D);
	ROTATE(1, B ^ C ^ D);
	ROTATE(1, B ^ C ^ D);
	ROTATE(1, B ^ C ^ D);
	ROTATE(1, B ^ C ^ D);
	ROTATE(1, B ^ C ^ D);
	ROTATE(1, B ^ C ^ D);
	ROTATE(1, B ^ C ^ D);
	ROTATE(1, B ^ C ^ D);
	ROTATE(1, B ^ C ^ D);
	ROTATE(1, B ^ C ^ D);
	ROTATE(1, B ^ C ^ D);
	ROTATE(1, B ^ C ^ D);
	ROTATE(1, B ^ C ^ D);
	ROTATE(1, B ^ C ^ D);
	ROTATE(1, B ^ C ^ D);
	ROTATE(1, B ^ C ^ D);
	ROTATE(1, B ^ C ^ D);

	/* Optimizing "(B & C) | (B & D)" into "B & (C | D)" */
	ROTATE(2, (B & (C | D)) | (C & D));
	ROTATE(2, (B & (C | D)) | (C & D));
	ROTATE(2, (B & (C | D)) | (C & D));
	ROTATE(2, (B & (C | D)) | (C & D));
	ROTATE(2, (B & (C | D)) | (C & D));
	ROTATE(2, (B & (C | D)) | (C & D));
	ROTATE(2, (B & (C | D)) | (C & D));
	ROTATE(2, (B & (C | D)) | (C & D));
	ROTATE(2, (B & (C | D)) | (C & D));
	ROTATE(2, (B & (C | D)) | (C & D));
	ROTATE(2, (B & (C | D)) | (C & D));
	ROTATE(2, (B & (C | D)) | (C & D));
	ROTATE(2, (B & (C | D)) | (C & D));
	ROTATE(2, (B & (C | D)) | (C & D));
	ROTATE(2, (B & (C | D)) | (C & D));
	ROTATE(2, (B & (C | D)) | (C & D));
	ROTATE(2, (B & (C | D)) | (C & D));
	ROTATE(2, (B & (C | D)) | (C & D));
	ROTATE(2, (B & (C | D)) | (C & D));
	ROTATE(2, (B & (C | D)) | (C & D));

	ROTATE(3, B ^ C ^ D);
	ROTATE(3, B ^ C ^ D);
	ROTATE(3, B ^ C ^ D);
	ROTATE(3, B ^ C ^ D);
	ROTATE(3, B ^ C ^ D);
	ROTATE(3, B ^ C ^ D);
	ROTATE(3, B ^ C ^ D);
	ROTATE(3, B ^ C ^ D);
	ROTATE(3, B ^ C ^ D);
	ROTATE(3, B ^ C ^ D);
	ROTATE(3, B ^ C ^ D);
	ROTATE(3, B ^ C ^ D);
	ROTATE(3, B ^ C ^ D);
	ROTATE(3, B ^ C ^ D);
	ROTATE(3, B ^ C ^ D);
	ROTATE(3, B ^ C ^ D);
	ROTATE(3, B ^ C ^ D);
	ROTATE(3, B ^ C ^ D);
	ROTATE(3, B ^ C ^ D);
	ROTATE(3, B ^ C ^ D);

    context->Intermediate_Hash[0] += A;
    context->Intermediate_Hash[1] += B;
    context->Intermediate_Hash[2] += C;
    context->Intermediate_Hash[3] += D;
    context->Intermediate_Hash[4] += E;

    context->Message_Block_Index = 0;
}


/*
 *  SHA1PadMessage
 *
 *  Description:
 *      According to the standard, the message must be padded to an even
 *      512 bits.  The first padding bit must be a '1'.  The last 64
 *      bits represent the length of the original message.  All bits in
 *      between should be 0.  This function will pad the message
 *      according to those rules by filling the Message_Block array
 *      accordingly.  It will also call the ProcessMessageBlock function
 *      provided appropriately.  When it returns, it can be assumed that
 *      the message digest has been computed.
 *
 *  Parameters:
 *      context: [in/out]
 *          The context to pad
 *      ProcessMessageBlock: [in]
 *          The appropriate SHA*ProcessMessageBlock function
 *  Returns:
 *      Nothing.
 *
 */

void SHA1PadMessage(SHA1Context *context)
{
    /*
     *  Check to see if the current message block is too small to hold
     *  the initial padding bits and length.  If so, we will pad the
     *  block, process it, and then continue padding into a second
     *  block.
     */
    if (context->Message_Block_Index > 55)
    {
        context->Message_Block[context->Message_Block_Index++] = 0x80;
        while(context->Message_Block_Index < 64)
        {
            context->Message_Block[context->Message_Block_Index++] = 0;
        }

        SHA1ProcessMessageBlock(context);

        while(context->Message_Block_Index < 56)
        {
            context->Message_Block[context->Message_Block_Index++] = 0;
        }
    }
    else
    {
        context->Message_Block[context->Message_Block_Index++] = 0x80;
        while(context->Message_Block_Index < 56)
        {
            context->Message_Block[context->Message_Block_Index++] = 0;
        }
    }

    /*
     *  Store the message length as the last 8 octets
     */
    context->Message_Block[56] = context->Length_High >> 24;
    context->Message_Block[57] = context->Length_High >> 16;
    context->Message_Block[58] = context->Length_High >> 8;
    context->Message_Block[59] = context->Length_High;
    context->Message_Block[60] = context->Length_Low >> 24;
    context->Message_Block[61] = context->Length_Low >> 16;
    context->Message_Block[62] = context->Length_Low >> 8;
    context->Message_Block[63] = context->Length_Low;

    SHA1ProcessMessageBlock(context);
}
