/* Implementation of NIST's Secure Hash Algorithm (FIPS 180)
 * Lightly bummed for execution efficiency.
 *
 * Jim Gillogly 3 May 1993
 *
 * 27 Aug 93: imported SHA_LITTLE_ENDIAN mods from Peter Gutmann's implementation
 * 5 Jul 94: Modified for NSA fix
 *
 * Compile: cc -O -o sha sha.c
 *
 * To remove the test wrapper and use just the nist_hash() routine,
 *      compile with -DONT_WRAP
 *
 * To reverse byte order for little-endian machines, use -DSHA_LITTLE_ENDIAN
 *
 * To get the original SHA definition before the 1994 fix, use -DVERSION_0
 *
 * Usage: sha [-vt] [filename ...]
 *
 *      -v switch: output the filename as well
 *      -t switch: suppress spaces between 32-bit blocks
 *
 *      If no input files are specified, process standard input.
 *
 * Output: 40-hex-digit digest of each file specified (160 bits)
 *
 * Synopsis of the function calls:
 *
 *   sha_file(char *filename, uint32 *buffer)
 *      Filename is a file to be opened and processed.
 *      buffer is a user-supplied array of 5 or more longs.
 *      The 5-word buffer is filled with 160 bits of non-terminated hash.
 *      Returns 0 if successful, non-zero if bad file.
 *
 *   void sha_stream(FILE *stream, uint32 *buffer)
 *      Input is from already-opened stream, not file.
 *
 *   void sha_memory(char *mem, int32 length, uint32 *buffer)
 *      Input is a memory block "length" bytes long.
 *
 * Caveat:
 *      Not tested for case that requires the high word of the length,
 *      which would be files larger than 1/2 gig or so.
 *
 * Limitation:
 *      sha_memory (the memory block function) will deal with blocks no longer
 *      than 4 gigabytes; for longer samples, the stream version will
 *      probably be most convenient (e.g. perl moby_data.pl | sha).
 *
 * Bugs:
 *      The standard is defined for bit strings; I assume bytes.
 *
 * Copyright 1993, Dr. James J. Gillogly
 * This code may be freely used in any application.
 */

/* #define VERSION_0 */  /* Define this to get the original SHA definition */

#include <stdio.h>
#include <memory.h>
#include "sha.h"

#ifdef MSDOS
# define SHA_LITTLE_ENDIAN
#endif

#define VERBOSE

#define TRUE  1
#define FALSE 0

#define FFFTP_SUCCESS 0
#define FAILURE -1

int sha_file();                         /* External entries */
void sha_stream(), sha_memory();

static void nist_guts();

#ifdef SHA_TEST_WRAP        /* make a test program */

#define HASH_SIZE 5     /* Produces 160-bit digest of the message */

main(argc, argv)
int argc;
char **argv;
{
    uint32 hbuf[HASH_SIZE];
    char *s;
    int file_args = FALSE;  /* If no files, take it from stdin */
    int verbose = FALSE;
    int terse = FALSE;

#ifdef MEMTEST
    sha_memory("abc", 3l, hbuf);         /* NIST test value from appendix A */
    if (verbose) printf("Memory:");
    if (terse) printf("%08lx%08lx%08lx%08lx%08lx\n",
	hbuf[0], hbuf[1], hbuf[2], hbuf[3], hbuf[4]);
    else printf("%08lx %08lx %08lx %08lx %08lx\n",
	hbuf[0], hbuf[1], hbuf[2], hbuf[3], hbuf[4]);
#endif

    for (++argv; --argc; ++argv)           /* March down the arg list */
    {
	if (**argv == '-')                 /* Process one or more flags */
	    for (s = &(*argv)[1]; *s; s++) /* Obfuscated C contest entry */
		switch(*s)
		{
		    case 'v': case 'V':
			verbose = TRUE;
			break;
		    case 't': case 'T':
			terse = TRUE;
			break;
		    default:
			fprintf(stderr, "Unrecognized flag: %c\n", *s);
			return FALSE;
		}
	else                            /* Process a file */
	{
	    if (verbose) printf("%s:", *argv);
	    file_args = TRUE;           /* Whether or not we could read it */

	    if (sha_file(*argv, hbuf) == FAILURE)
		printf("Can't open file %s.\n", *argv);
	    else
		if (terse) printf("%08lx%08lx%08lx%08lx%08lx\n",
		    hbuf[0], hbuf[1], hbuf[2], hbuf[3], hbuf[4]);
		else printf("%08lx %08lx %08lx %08lx %08lx\n",
		    hbuf[0], hbuf[1], hbuf[2], hbuf[3], hbuf[4]);
	}
    }
    if (! file_args)    /* No file specified */
    {
	if (verbose) printf("%s:", *argv);
	sha_stream(stdin, hbuf);

	if (terse) printf("%08lx%08lx%08lx%08lx%08lx\n",
	    hbuf[0], hbuf[1], hbuf[2], hbuf[3], hbuf[4]);
	else printf("%08lx %08lx %08lx %08lx %08lx\n",
	    hbuf[0], hbuf[1], hbuf[2], hbuf[3], hbuf[4]);
    }
    return TRUE;
}

#endif ONT_WRAP

#ifdef SHA_LITTLE_ENDIAN    /* Imported from Peter Gutmann's implementation */

/* 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( uint32 *buffer, int byteCount )
    {
    uint32 value;
    int count;

    byteCount /= sizeof( uint32 );
    for( count = 0; count < byteCount; count++ )
	{
	value = ( buffer[ count ] << 16 ) | ( buffer[ count ] >> 16 );
	buffer[ count ] = ( ( value & 0xFF00FF00L ) >> 8 ) | ( ( value & 0x00FF00FFL ) << 8 );
	}
    }
#endif /* SHA_LITTLE_ENDIAN */



union longbyte
{
    uint32 W[80];        /* Process 16 32-bit words at a time */
    char B[320];                /* But read them as bytes for counting */
};

sha_file(filename, buffer)      /* Hash a file */
char *filename;
uint32 *buffer;
{
    FILE *infile;

    if ((infile = fopen(filename, "rb")) == NULL)
    {
	int i;

	for (i = 0; i < 5; i++)
	    buffer[i] = 0xdeadbeef;
	return FAILURE;
    }
    (void) sha_stream(infile, buffer);
    fclose(infile);
    return FFFTP_SUCCESS;
}

void sha_memory(mem, length, buffer)    /* Hash a memory block */
char *mem;
uint32 length;
uint32 *buffer;
{
    nist_guts(FALSE, (FILE *) NULL, mem, length, buffer);
}

void sha_stream(stream, buffer)
FILE *stream;
uint32 *buffer;
{
    nist_guts(TRUE, stream, (char *) NULL, 0l, buffer);
}

#define f0(x,y,z) (z ^ (x & (y ^ z)))           /* Magic functions */
#define f1(x,y,z) (x ^ y ^ z)
#define f2(x,y,z) ((x & y) | (z & (x | y)))
#define f3(x,y,z) (x ^ y ^ z)

#define K0 0x5a827999                           /* Magic constants */
#define K1 0x6ed9eba1
#define K2 0x8f1bbcdc
#define K3 0xca62c1d6

#define S(n, X) ((X << n) | (X >> (32 - n)))    /* Barrel roll */

#define r0(f, K) \
    temp = S(5, A) + f(B, C, D) + E + *p0++ + K; \
    E = D;  \
    D = C;  \
    C = S(30, B); \
    B = A;  \
    A = temp

#ifdef VERSION_0
#define r1(f, K) \
    temp = S(5, A) + f(B, C, D) + E + \
	   (*p0++ = *p1++ ^ *p2++ ^ *p3++ ^ *p4++) + K; \
    E = D;  \
    D = C;  \
    C = S(30, B); \
    B = A;  \
    A = temp
#else                   /* Version 1: Summer '94 update */
#define r1(f, K) \
    temp = *p1++ ^ *p2++ ^ *p3++ ^ *p4++; \
    temp = S(5, A) + f(B, C, D) + E + (*p0++ = S(1,temp)) + K; \
    E = D;  \
    D = C;  \
    C = S(30, B); \
    B = A;  \
    A = temp
#endif

static void nist_guts(file_flag, stream, mem, length, buf)
int file_flag;                  /* Input from memory, or from stream? */
FILE *stream;
char *mem;
uint32 length;
uint32 *buf;
{
    int i, nread, nbits;
    union longbyte d;
    uint32 hi_length, lo_length;
    int padded;
    char *s;

    register uint32 *p0, *p1, *p2, *p3, *p4;
    uint32 A, B, C, D, E, temp;

    uint32 h0, h1, h2, h3, h4;

    h0 = 0x67452301;                            /* Accumulators */
    h1 = 0xefcdab89;
    h2 = 0x98badcfe;
    h3 = 0x10325476;
    h4 = 0xc3d2e1f0;

    padded = FALSE;
    s = mem;
    for (hi_length = lo_length = 0; ;)  /* Process 16 longs at a time */
    {
	if (file_flag)
	{
		nread = fread(d.B, 1, 64, stream);  /* Read as 64 bytes */
	}
	else
	{
		if (length < 64) nread = length;
		else             nread = 64;
		length -= nread;
		memcpy(d.B, s, nread);
		s += nread;
	}
	if (nread < 64)   /* Partial block? */
	{
		nbits = nread << 3;               /* Length: bits */
		if ((lo_length += nbits) < (unsigned int)nbits)
			hi_length++;              /* 64-bit integer */

		if (nread < 64 && ! padded)  /* Append a single bit */
		{
			d.B[nread++] = (char)0x80; /* Using up next byte */
			padded = TRUE;       /* Single bit once */
		}
		for (i = nread; i < 64; i++) /* Pad with nulls */
			d.B[i] = 0;
		if (nread <= 56)   /* Room for length in this block */
		{
			d.W[14] = hi_length;
			d.W[15] = lo_length;
#ifdef SHA_LITTLE_ENDIAN
	      byteReverse(d.W, 56 );
#endif /* SHA_LITTLE_ENDIAN */
		}
#ifdef SHA_LITTLE_ENDIAN
	   else byteReverse(d.W, 64 );
#endif /* SHA_LITTLE_ENDIAN */
	}
	else    /* Full block -- get efficient */
	{
		if ((lo_length += 512) < 512)
			hi_length++;    /* 64-bit integer */
#ifdef SHA_LITTLE_ENDIAN
	   byteReverse(d.W, 64 );
#endif /* SHA_LITTLE_ENDIAN */
	}

	p0 = d.W;
	A = h0; B = h1; C = h2; D = h3; E = h4;

	r0(f0,K0); r0(f0,K0); r0(f0,K0); r0(f0,K0); r0(f0,K0);
	r0(f0,K0); r0(f0,K0); r0(f0,K0); r0(f0,K0); r0(f0,K0);
	r0(f0,K0); r0(f0,K0); r0(f0,K0); r0(f0,K0); r0(f0,K0);
	r0(f0,K0);

	p1 = &d.W[13]; p2 = &d.W[8]; p3 = &d.W[2]; p4 = &d.W[0];

		   r1(f0,K0); r1(f0,K0); r1(f0,K0); r1(f0,K0);
	r1(f1,K1); r1(f1,K1); r1(f1,K1); r1(f1,K1); r1(f1,K1);
	r1(f1,K1); r1(f1,K1); r1(f1,K1); r1(f1,K1); r1(f1,K1);
	r1(f1,K1); r1(f1,K1); r1(f1,K1); r1(f1,K1); r1(f1,K1);
	r1(f1,K1); r1(f1,K1); r1(f1,K1); r1(f1,K1); r1(f1,K1);
	r1(f2,K2); r1(f2,K2); r1(f2,K2); r1(f2,K2); r1(f2,K2);
	r1(f2,K2); r1(f2,K2); r1(f2,K2); r1(f2,K2); r1(f2,K2);
	r1(f2,K2); r1(f2,K2); r1(f2,K2); r1(f2,K2); r1(f2,K2);
	r1(f2,K2); r1(f2,K2); r1(f2,K2); r1(f2,K2); r1(f2,K2);
	r1(f3,K3); r1(f3,K3); r1(f3,K3); r1(f3,K3); r1(f3,K3);
	r1(f3,K3); r1(f3,K3); r1(f3,K3); r1(f3,K3); r1(f3,K3);
	r1(f3,K3); r1(f3,K3); r1(f3,K3); r1(f3,K3); r1(f3,K3);
	r1(f3,K3); r1(f3,K3); r1(f3,K3); r1(f3,K3); r1(f3,K3);

	h0 += A; h1 += B; h2 += C; h3 += D; h4 += E;

	if (nread <= 56) break; /* If it's greater, length in next block */
    }
    buf[0] = h0; buf[1] = h1; buf[2] = h2; buf[3] = h3; buf[4] = h4;
}
