Modules/shamodule.c

/***********************************************************
Copyright 1999 by Stichting Mathematisch Centrum, Amsterdam,
The Netherlands.

                        All Rights Reserved

Permission to use, copy, modify, and distribute this software and its
documentation for any purpose and without fee is hereby granted,
provided that the above copyright notice appear in all copies and that
both that copyright notice and this permission notice appear in
supporting documentation, and that the names of Stichting Mathematisch
Centrum or CWI or Corporation for National Research Initiatives or
CNRI not be used in advertising or publicity pertaining to
distribution of the software without specific, written prior
permission.

While CWI is the initial source for this software, a modified version
is made available by the Corporation for National Research Initiatives
(CNRI) at the Internet address ftp://ftp.python.org.

STICHTING MATHEMATISCH CENTRUM AND CNRI DISCLAIM ALL WARRANTIES WITH
REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL STICHTING MATHEMATISCH
CENTRUM OR CNRI BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL
DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
PERFORMANCE OF THIS SOFTWARE.

******************************************************************/

/* SHA module */

/* This module provides an interface to NIST's Secure Hash Algorithm */

/* See below for information about the original code this module was
   based upon. Additional work performed by:

   Andrew Kuchling (amk1@erols.com)
   Greg Stein (gstein@lyra.org)
*/

/* SHA objects */

#include "Python.h"


/* Endianness testing and definitions */
#define TestEndianness(variable) {int i=1; variable=PCT_BIG_ENDIAN;\
	if (*((char*)&i)==1) variable=PCT_LITTLE_ENDIAN;}

#define PCT_LITTLE_ENDIAN 1
#define PCT_BIG_ENDIAN 0

/* Some useful types */

typedef unsigned char SHA_BYTE;

#if SIZEOF_INT == 4
typedef unsigned int SHA_INT32;	/* 32-bit integer */
#else
/* not defined. compilation will die. */
#endif

/* The SHA block size and message digest sizes, in bytes */

#define SHA_BLOCKSIZE    64
#define SHA_DIGESTSIZE  20

/* The structure for storing SHS info */

typedef struct {
	PyObject_HEAD
	SHA_INT32 digest[5];		/* Message digest */
	SHA_INT32 count_lo, count_hi;	/* 64-bit bit count */
	SHA_BYTE data[SHA_BLOCKSIZE];	/* SHA data buffer */
	int Endianness;
	int local;			/* unprocessed amount in data */
} SHAobject;

/* When run on a little-endian CPU we need to perform byte reversal on an
   array of longwords. */

static void longReverse(buffer, byteCount, Endianness)
    SHA_INT32 *buffer; 
    int byteCount, Endianness;
{
    SHA_INT32 value;

    if ( Endianness == PCT_BIG_ENDIAN )
	return;

    byteCount /= sizeof(*buffer);
    while( byteCount-- )
    {
        value = *buffer;
        value = ( ( value & 0xFF00FF00L ) >> 8  ) | \
                ( ( value & 0x00FF00FFL ) << 8 );
        *buffer++ = ( value << 16 ) | ( value >> 16 );
    }
}

static void SHAcopy(src, dest)
     SHAobject *src, *dest;
{
	dest->Endianness = src->Endianness;
	dest->local = src->local;
	dest->count_lo = src->count_lo;
	dest->count_hi = src->count_hi;
	memcpy(dest->digest, src->digest, sizeof(src->digest));
	memcpy(dest->data, src->data, sizeof(src->data));
}


/* ------------------------------------------------------------------------
 *
 * This code for the SHA algorithm was noted as public domain. The original
 * headers are pasted below.
 *
 * Several changes have been made to make it more compatible with the
 * Python environment and desired interface.
 *
 */

/* NIST Secure Hash Algorithm */
/* heavily modified by Uwe Hollerbach <uh@alumni.caltech edu> */
/* from Peter C. Gutmann's implementation as found in */
/* Applied Cryptography by Bruce Schneier */
/* Further modifications to include the "UNRAVEL" stuff, below */

/* This code is in the public domain */

/* UNRAVEL should be fastest & biggest */
/* UNROLL_LOOPS should be just as big, but slightly slower */
/* both undefined should be smallest and slowest */

#define UNRAVEL
/* #define UNROLL_LOOPS */

/* The SHA f()-functions.  The f1 and f3 functions can be optimized to
   save one boolean operation each - thanks to Rich Schroeppel,
   rcs@cs.arizona.edu for discovering this */

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

/* SHA constants */

#define CONST1		0x5a827999L			/* Rounds  0-19 */
#define CONST2		0x6ed9eba1L			/* Rounds 20-39 */
#define CONST3		0x8f1bbcdcL			/* Rounds 40-59 */
#define CONST4		0xca62c1d6L			/* Rounds 60-79 */

/* 32-bit rotate */

#define R32(x,n)	((x << n) | (x >> (32 - n)))

/* the generic case, for when the overall rotation is not unraveled */

#define FG(n)	\
    T = R32(A,5) + f##n(B,C,D) + E + *WP++ + CONST##n;	\
    E = D; D = C; C = R32(B,30); B = A; A = T

/* specific cases, for when the overall rotation is unraveled */

#define FA(n)	\
    T = R32(A,5) + f##n(B,C,D) + E + *WP++ + CONST##n; B = R32(B,30)

#define FB(n)	\
    E = R32(T,5) + f##n(A,B,C) + D + *WP++ + CONST##n; A = R32(A,30)

#define FC(n)	\
    D = R32(E,5) + f##n(T,A,B) + C + *WP++ + CONST##n; T = R32(T,30)

#define FD(n)	\
    C = R32(D,5) + f##n(E,T,A) + B + *WP++ + CONST##n; E = R32(E,30)

#define FE(n)	\
    B = R32(C,5) + f##n(D,E,T) + A + *WP++ + CONST##n; D = R32(D,30)

#define FT(n)	\
    A = R32(B,5) + f##n(C,D,E) + T + *WP++ + CONST##n; C = R32(C,30)

/* do SHA transformation */

static void
sha_transform(sha_info)
	SHAobject *sha_info;
{
    int i;
    SHA_INT32 T, A, B, C, D, E, W[80], *WP;

    memcpy(W, sha_info->data, sizeof(sha_info->data));
    longReverse(W, sizeof(sha_info->data), sha_info->Endianness);

    for (i = 16; i < 80; ++i) {
	W[i] = W[i-3] ^ W[i-8] ^ W[i-14] ^ W[i-16];

	/* extra rotation fix */
	W[i] = R32(W[i], 1);
    }
    A = sha_info->digest[0];
    B = sha_info->digest[1];
    C = sha_info->digest[2];
    D = sha_info->digest[3];
    E = sha_info->digest[4];
    WP = W;
#ifdef UNRAVEL
    FA(1); FB(1); FC(1); FD(1); FE(1); FT(1); FA(1); FB(1); FC(1); FD(1);
    FE(1); FT(1); FA(1); FB(1); FC(1); FD(1); FE(1); FT(1); FA(1); FB(1);
    FC(2); FD(2); FE(2); FT(2); FA(2); FB(2); FC(2); FD(2); FE(2); FT(2);
    FA(2); FB(2); FC(2); FD(2); FE(2); FT(2); FA(2); FB(2); FC(2); FD(2);
    FE(3); FT(3); FA(3); FB(3); FC(3); FD(3); FE(3); FT(3); FA(3); FB(3);
    FC(3); FD(3); FE(3); FT(3); FA(3); FB(3); FC(3); FD(3); FE(3); FT(3);
    FA(4); FB(4); FC(4); FD(4); FE(4); FT(4); FA(4); FB(4); FC(4); FD(4);
    FE(4); FT(4); FA(4); FB(4); FC(4); FD(4); FE(4); FT(4); FA(4); FB(4);
    sha_info->digest[0] += E;
    sha_info->digest[1] += T;
    sha_info->digest[2] += A;
    sha_info->digest[3] += B;
    sha_info->digest[4] += C;
#else /* !UNRAVEL */
#ifdef UNROLL_LOOPS
    FG(1); FG(1); FG(1); FG(1); FG(1); FG(1); FG(1); FG(1); FG(1); FG(1);
    FG(1); FG(1); FG(1); FG(1); FG(1); FG(1); FG(1); FG(1); FG(1); FG(1);
    FG(2); FG(2); FG(2); FG(2); FG(2); FG(2); FG(2); FG(2); FG(2); FG(2);
    FG(2); FG(2); FG(2); FG(2); FG(2); FG(2); FG(2); FG(2); FG(2); FG(2);
    FG(3); FG(3); FG(3); FG(3); FG(3); FG(3); FG(3); FG(3); FG(3); FG(3);
    FG(3); FG(3); FG(3); FG(3); FG(3); FG(3); FG(3); FG(3); FG(3); FG(3);
    FG(4); FG(4); FG(4); FG(4); FG(4); FG(4); FG(4); FG(4); FG(4); FG(4);
    FG(4); FG(4); FG(4); FG(4); FG(4); FG(4); FG(4); FG(4); FG(4); FG(4);
#else /* !UNROLL_LOOPS */
    for (i =  0; i < 20; ++i) { FG(1); }
    for (i = 20; i < 40; ++i) { FG(2); }
    for (i = 40; i < 60; ++i) { FG(3); }
    for (i = 60; i < 80; ++i) { FG(4); }
#endif /* !UNROLL_LOOPS */
    sha_info->digest[0] += A;
    sha_info->digest[1] += B;
    sha_info->digest[2] += C;
    sha_info->digest[3] += D;
    sha_info->digest[4] += E;
#endif /* !UNRAVEL */
}

/* initialize the SHA digest */

static void
sha_init(sha_info)
    SHAobject *sha_info;
{
    TestEndianness(sha_info->Endianness)

    sha_info->digest[0] = 0x67452301L;
    sha_info->digest[1] = 0xefcdab89L;
    sha_info->digest[2] = 0x98badcfeL;
    sha_info->digest[3] = 0x10325476L;
    sha_info->digest[4] = 0xc3d2e1f0L;
    sha_info->count_lo = 0L;
    sha_info->count_hi = 0L;
    sha_info->local = 0;
}

/* update the SHA digest */

static void
sha_update(sha_info, buffer, count)
    SHAobject *sha_info;
    SHA_BYTE *buffer;
    int count;
{
    int i;
    SHA_INT32 clo;

    clo = sha_info->count_lo + ((SHA_INT32) count << 3);
    if (clo < sha_info->count_lo) {
		++sha_info->count_hi;
    }
    sha_info->count_lo = clo;
    sha_info->count_hi += (SHA_INT32) count >> 29;
    if (sha_info->local) {
		i = SHA_BLOCKSIZE - sha_info->local;
		if (i > count) {
			i = count;
		}
		memcpy(((SHA_BYTE *) sha_info->data) + sha_info->local,
		       buffer, i);
		count -= i;
		buffer += i;
		sha_info->local += i;
		if (sha_info->local == SHA_BLOCKSIZE) {
			sha_transform(sha_info);
		} else {
			return;
		}
    }
    while (count >= SHA_BLOCKSIZE) {
		memcpy(sha_info->data, buffer, SHA_BLOCKSIZE);
		buffer += SHA_BLOCKSIZE;
		count -= SHA_BLOCKSIZE;
		sha_transform(sha_info);
    }
    memcpy(sha_info->data, buffer, count);
    sha_info->local = count;
}

/* finish computing the SHA digest */

static void
sha_final(digest, sha_info)
    unsigned char digest[20];
    SHAobject *sha_info;
{
    int count;
    SHA_INT32 lo_bit_count, hi_bit_count;

    lo_bit_count = sha_info->count_lo;
    hi_bit_count = sha_info->count_hi;
    count = (int) ((lo_bit_count >> 3) & 0x3f);
    ((SHA_BYTE *) sha_info->data)[count++] = 0x80;
    if (count > SHA_BLOCKSIZE - 8)
    {
	memset(((SHA_BYTE *) sha_info->data) + count, 0,
	       SHA_BLOCKSIZE - count);
	sha_transform(sha_info);
	memset((SHA_BYTE *) sha_info->data, 0, SHA_BLOCKSIZE - 8);
    }
    else
    {
	memset(((SHA_BYTE *) sha_info->data) + count, 0,
	       SHA_BLOCKSIZE - 8 - count);
    }

    /* GJS: note that we add the hi/lo in big-endian. sha_transform will
       swap these values into host-order. */
    sha_info->data[56] = (hi_bit_count >> 24) & 0xff;
    sha_info->data[57] = (hi_bit_count >> 16) & 0xff;
    sha_info->data[58] = (hi_bit_count >>  8) & 0xff;
    sha_info->data[59] = (hi_bit_count >>  0) & 0xff;
    sha_info->data[60] = (lo_bit_count >> 24) & 0xff;
    sha_info->data[61] = (lo_bit_count >> 16) & 0xff;
    sha_info->data[62] = (lo_bit_count >>  8) & 0xff;
    sha_info->data[63] = (lo_bit_count >>  0) & 0xff;
    sha_transform(sha_info);
    digest[ 0] = (unsigned char) ((sha_info->digest[0] >> 24) & 0xff);
    digest[ 1] = (unsigned char) ((sha_info->digest[0] >> 16) & 0xff);
    digest[ 2] = (unsigned char) ((sha_info->digest[0] >>  8) & 0xff);
    digest[ 3] = (unsigned char) ((sha_info->digest[0]      ) & 0xff);
    digest[ 4] = (unsigned char) ((sha_info->digest[1] >> 24) & 0xff);
    digest[ 5] = (unsigned char) ((sha_info->digest[1] >> 16) & 0xff);
    digest[ 6] = (unsigned char) ((sha_info->digest[1] >>  8) & 0xff);
    digest[ 7] = (unsigned char) ((sha_info->digest[1]      ) & 0xff);
    digest[ 8] = (unsigned char) ((sha_info->digest[2] >> 24) & 0xff);
    digest[ 9] = (unsigned char) ((sha_info->digest[2] >> 16) & 0xff);
    digest[10] = (unsigned char) ((sha_info->digest[2] >>  8) & 0xff);
    digest[11] = (unsigned char) ((sha_info->digest[2]      ) & 0xff);
    digest[12] = (unsigned char) ((sha_info->digest[3] >> 24) & 0xff);
    digest[13] = (unsigned char) ((sha_info->digest[3] >> 16) & 0xff);
    digest[14] = (unsigned char) ((sha_info->digest[3] >>  8) & 0xff);
    digest[15] = (unsigned char) ((sha_info->digest[3]      ) & 0xff);
    digest[16] = (unsigned char) ((sha_info->digest[4] >> 24) & 0xff);
    digest[17] = (unsigned char) ((sha_info->digest[4] >> 16) & 0xff);
    digest[18] = (unsigned char) ((sha_info->digest[4] >>  8) & 0xff);
    digest[19] = (unsigned char) ((sha_info->digest[4]      ) & 0xff);
}

/*
 * End of copied SHA code.
 *
 * ------------------------------------------------------------------------
 */

staticforward PyTypeObject SHAtype;


static SHAobject *
newSHAobject()
{
	return (SHAobject *)PyObject_NEW(SHAobject, &SHAtype);
}

/* Internal methods for a hashing object */

static void
SHA_dealloc(ptr)
	PyObject *ptr;
{
	PyMem_DEL(ptr);
}


/* External methods for a hashing object */

static char SHA_copy__doc__[] = 
"Return a copy of the hashing object.";

static PyObject *
SHA_copy(self, args)
	SHAobject *self;
	PyObject *args;
{
	SHAobject *newobj;

	if (!PyArg_NoArgs(args)) {
		return NULL;
	}

	if ( (newobj = newSHAobject())==NULL)
		return NULL;
	
	SHAcopy(self, newobj);
	return (PyObject *)newobj;
}

static char SHA_digest__doc__[] = 
"Return the digest value as a string of binary data.";

static PyObject *
SHA_digest(self, args)
	SHAobject *self;
	PyObject *args;
{
	unsigned char digest[SHA_DIGESTSIZE];
	SHAobject temp;

	if (!PyArg_NoArgs(args))
		return NULL;

	SHAcopy(self, &temp);
	sha_final(digest, &temp);
	return PyString_FromStringAndSize((const char *)digest, sizeof(digest));
}

static char SHA_hexdigest__doc__[] = 
"Return the digest value as a string of hexadecimal digits.";

static PyObject *
SHA_hexdigest(self, args)
	SHAobject *self;
	PyObject *args;
{
	unsigned char digest[SHA_DIGESTSIZE];
	SHAobject temp;
	PyObject *retval;
	char *hex_digest;
	int i, j;

	if (!PyArg_NoArgs(args))
		return NULL;

	/* Get the raw (binary) digest value */
	SHAcopy(self, &temp);
	sha_final(digest, &temp);

	/* Create a new string */
	retval = PyString_FromStringAndSize(NULL, sizeof(digest) * 2);
	hex_digest = PyString_AsString(retval);

	/* Make hex version of the digest */
	for(i=j=0; i<sizeof(digest); i++)	
	{
		char c;
		c = digest[i] / 16; c = (c>9) ? c+'a'-10 : c + '0';
		hex_digest[j++] = c;
		c = digest[i] % 16; c = (c>9) ? c+'a'-10 : c + '0';
		hex_digest[j++] = c;
	}

	return retval;
}

static char SHA_update__doc__[] = 
"Update this hashing object's state with the provided string.";

static PyObject *
SHA_update(self, args)
	SHAobject *self;
	PyObject *args;
{
	unsigned char *cp;
	int len;

	if (!PyArg_Parse(args, "s#", &cp, &len))
		return NULL;

	sha_update(self, cp, len);

	Py_INCREF(Py_None);
	return Py_None;
}

static PyMethodDef SHA_methods[] = {
	{"copy",	(PyCFunction)SHA_copy, 0, SHA_copy__doc__},
	{"digest",	(PyCFunction)SHA_digest, 0, SHA_digest__doc__},
	{"hexdigest",	(PyCFunction)SHA_hexdigest, 0, SHA_hexdigest__doc__},
	{"update",	(PyCFunction)SHA_update, 0, SHA_update__doc__},
	{NULL,		NULL}		/* sentinel */
};

static PyObject *
SHA_getattr(self, name)
	PyObject *self;
	char *name;
{
	if (strcmp(name, "blocksize")==0)
		return PyInt_FromLong(1);
	if (strcmp(name, "digestsize")==0)
		return PyInt_FromLong(20);
	
	return Py_FindMethod(SHA_methods, self, name);
}

static PyTypeObject SHAtype = {
	PyObject_HEAD_INIT(NULL)
	0,			/*ob_size*/
	"SHA",			/*tp_name*/
	sizeof(SHAobject),	/*tp_size*/
	0,			/*tp_itemsize*/
	/* methods */
	SHA_dealloc,		/*tp_dealloc*/
	0,			/*tp_print*/
	SHA_getattr,		/*tp_getattr*/
};


/* The single module-level function: new() */

static char SHA_new__doc__[] =
 "Return a new SHA hashing object.  An optional string "
 "argument may be provided; if present, this string will be "
 " automatically hashed."; 

static PyObject *
SHA_new(self, args, kwdict)
	PyObject *self;
	PyObject *args;
	PyObject *kwdict;
{
	static char *kwlist[] = {"string", NULL};
	SHAobject *new;
	unsigned char *cp = NULL;
	int len;
	
	if ((new = newSHAobject()) == NULL)
		return NULL;

	if (!PyArg_ParseTupleAndKeywords(args, kwdict, "|s#", kwlist,
					 &cp, &len)) {
	        Py_DECREF(new);
		return NULL;
	}

        sha_init(new);

	if (PyErr_Occurred()) {
		Py_DECREF(new);
		return NULL;
	}
	if (cp)
		sha_update(new, cp, len);

	return (PyObject *)new;
}


/* List of functions exported by this module */

static struct PyMethodDef SHA_functions[] = {
	{"new", (PyCFunction)SHA_new, METH_VARARGS|METH_KEYWORDS, SHA_new__doc__},
	{"sha",	(PyCFunction)SHA_new, METH_VARARGS|METH_KEYWORDS, SHA_new__doc__},
	{NULL,	NULL}		 /* Sentinel */
};


/* Initialize this module. */

#define insint(n,v) { PyObject *o=PyInt_FromLong(v); \
	if (o!=NULL) PyDict_SetItemString(d,n,o); \
	Py_XDECREF(o); }

void
initsha()
{
	PyObject *d, *m;

	SHAtype.ob_type = &PyType_Type;
	m = Py_InitModule("sha", SHA_functions);

	/* Add some symbolic constants to the module */
	d = PyModule_GetDict(m);
	insint("blocksize", 1);  /* For future use, in case some hash
				    functions require an integral number of
				    blocks */ 
	insint("digestsize", 20);

	/* Check for errors */
	if (PyErr_Occurred())
		Py_FatalError("can't initialize module SHA");
}