Modules/shamodule.c

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

                        All Rights Reserved

Copyright (c) 2000, BeOpen.com.
Copyright (c) 1995-2000, Corporation for National Research Initiatives.
Copyright (c) 1990-1995, Stichting Mathematisch Centrum.
All rights reserved.

See the file "Misc/COPYRIGHT" for information on usage and
redistribution of this file, and for a DISCLAIMER OF ALL WARRANTIES.

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

/* 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, (int)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;
{
	PyObject_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#:new", 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");
}