Modules/sha256module.c

/* SHA256 module */

/* This module provides an interface to NIST's SHA-256 and SHA-224 Algorithms */

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

   Andrew Kuchling (amk@amk.ca)
   Greg Stein (gstein@lyra.org)
   Trevor Perrin (trevp@trevp.net)

   Copyright (C) 2005-2007   Gregory P. Smith (greg@krypto.org)
   Licensed to PSF under a Contributor Agreement.

*/

/* SHA objects */

#include "Python.h"
#include "structmember.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  32

/* The structure for storing SHA info */

typedef struct {
    PyObject_HEAD
    SHA_INT32 digest[8];		/* 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 */
    int digestsize;
} SHAobject;

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

static void longReverse(SHA_INT32 *buffer, int byteCount, int 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(SHAobject *src, SHAobject *dest)
{
    dest->Endianness = src->Endianness;
    dest->local = src->local;
    dest->digestsize = src->digestsize;
    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-256 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.
 *
 */

/* LibTomCrypt, modular cryptographic library -- Tom St Denis
 *
 * LibTomCrypt is a library that provides various cryptographic
 * algorithms in a highly modular and flexible manner.
 *
 * The library is free for all purposes without any express
 * gurantee it works.
 *
 * Tom St Denis, tomstdenis@iahu.ca, http://libtom.org
 */


/* SHA256 by Tom St Denis */

/* Various logical functions */
#define ROR(x, y)\
( ((((unsigned long)(x)&0xFFFFFFFFUL)>>(unsigned long)((y)&31)) | \
((unsigned long)(x)<<(unsigned long)(32-((y)&31)))) & 0xFFFFFFFFUL)
#define Ch(x,y,z)       (z ^ (x & (y ^ z)))
#define Maj(x,y,z)      (((x | y) & z) | (x & y)) 
#define S(x, n)         ROR((x),(n))
#define R(x, n)         (((x)&0xFFFFFFFFUL)>>(n))
#define Sigma0(x)       (S(x, 2) ^ S(x, 13) ^ S(x, 22))
#define Sigma1(x)       (S(x, 6) ^ S(x, 11) ^ S(x, 25))
#define Gamma0(x)       (S(x, 7) ^ S(x, 18) ^ R(x, 3))
#define Gamma1(x)       (S(x, 17) ^ S(x, 19) ^ R(x, 10))


static void
sha_transform(SHAobject *sha_info)
{
    int i;
	SHA_INT32 S[8], W[64], t0, t1;

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

    for (i = 16; i < 64; ++i) {
		W[i] = Gamma1(W[i - 2]) + W[i - 7] + Gamma0(W[i - 15]) + W[i - 16];
    }
    for (i = 0; i < 8; ++i) {
        S[i] = sha_info->digest[i];
    }

    /* Compress */
#define RND(a,b,c,d,e,f,g,h,i,ki)                    \
     t0 = h + Sigma1(e) + Ch(e, f, g) + ki + W[i];   \
     t1 = Sigma0(a) + Maj(a, b, c);                  \
     d += t0;                                        \
     h  = t0 + t1;

    RND(S[0],S[1],S[2],S[3],S[4],S[5],S[6],S[7],0,0x428a2f98);
    RND(S[7],S[0],S[1],S[2],S[3],S[4],S[5],S[6],1,0x71374491);
    RND(S[6],S[7],S[0],S[1],S[2],S[3],S[4],S[5],2,0xb5c0fbcf);
    RND(S[5],S[6],S[7],S[0],S[1],S[2],S[3],S[4],3,0xe9b5dba5);
    RND(S[4],S[5],S[6],S[7],S[0],S[1],S[2],S[3],4,0x3956c25b);
    RND(S[3],S[4],S[5],S[6],S[7],S[0],S[1],S[2],5,0x59f111f1);
    RND(S[2],S[3],S[4],S[5],S[6],S[7],S[0],S[1],6,0x923f82a4);
    RND(S[1],S[2],S[3],S[4],S[5],S[6],S[7],S[0],7,0xab1c5ed5);
    RND(S[0],S[1],S[2],S[3],S[4],S[5],S[6],S[7],8,0xd807aa98);
    RND(S[7],S[0],S[1],S[2],S[3],S[4],S[5],S[6],9,0x12835b01);
    RND(S[6],S[7],S[0],S[1],S[2],S[3],S[4],S[5],10,0x243185be);
    RND(S[5],S[6],S[7],S[0],S[1],S[2],S[3],S[4],11,0x550c7dc3);
    RND(S[4],S[5],S[6],S[7],S[0],S[1],S[2],S[3],12,0x72be5d74);
    RND(S[3],S[4],S[5],S[6],S[7],S[0],S[1],S[2],13,0x80deb1fe);
    RND(S[2],S[3],S[4],S[5],S[6],S[7],S[0],S[1],14,0x9bdc06a7);
    RND(S[1],S[2],S[3],S[4],S[5],S[6],S[7],S[0],15,0xc19bf174);
    RND(S[0],S[1],S[2],S[3],S[4],S[5],S[6],S[7],16,0xe49b69c1);
    RND(S[7],S[0],S[1],S[2],S[3],S[4],S[5],S[6],17,0xefbe4786);
    RND(S[6],S[7],S[0],S[1],S[2],S[3],S[4],S[5],18,0x0fc19dc6);
    RND(S[5],S[6],S[7],S[0],S[1],S[2],S[3],S[4],19,0x240ca1cc);
    RND(S[4],S[5],S[6],S[7],S[0],S[1],S[2],S[3],20,0x2de92c6f);
    RND(S[3],S[4],S[5],S[6],S[7],S[0],S[1],S[2],21,0x4a7484aa);
    RND(S[2],S[3],S[4],S[5],S[6],S[7],S[0],S[1],22,0x5cb0a9dc);
    RND(S[1],S[2],S[3],S[4],S[5],S[6],S[7],S[0],23,0x76f988da);
    RND(S[0],S[1],S[2],S[3],S[4],S[5],S[6],S[7],24,0x983e5152);
    RND(S[7],S[0],S[1],S[2],S[3],S[4],S[5],S[6],25,0xa831c66d);
    RND(S[6],S[7],S[0],S[1],S[2],S[3],S[4],S[5],26,0xb00327c8);
    RND(S[5],S[6],S[7],S[0],S[1],S[2],S[3],S[4],27,0xbf597fc7);
    RND(S[4],S[5],S[6],S[7],S[0],S[1],S[2],S[3],28,0xc6e00bf3);
    RND(S[3],S[4],S[5],S[6],S[7],S[0],S[1],S[2],29,0xd5a79147);
    RND(S[2],S[3],S[4],S[5],S[6],S[7],S[0],S[1],30,0x06ca6351);
    RND(S[1],S[2],S[3],S[4],S[5],S[6],S[7],S[0],31,0x14292967);
    RND(S[0],S[1],S[2],S[3],S[4],S[5],S[6],S[7],32,0x27b70a85);
    RND(S[7],S[0],S[1],S[2],S[3],S[4],S[5],S[6],33,0x2e1b2138);
    RND(S[6],S[7],S[0],S[1],S[2],S[3],S[4],S[5],34,0x4d2c6dfc);
    RND(S[5],S[6],S[7],S[0],S[1],S[2],S[3],S[4],35,0x53380d13);
    RND(S[4],S[5],S[6],S[7],S[0],S[1],S[2],S[3],36,0x650a7354);
    RND(S[3],S[4],S[5],S[6],S[7],S[0],S[1],S[2],37,0x766a0abb);
    RND(S[2],S[3],S[4],S[5],S[6],S[7],S[0],S[1],38,0x81c2c92e);
    RND(S[1],S[2],S[3],S[4],S[5],S[6],S[7],S[0],39,0x92722c85);
    RND(S[0],S[1],S[2],S[3],S[4],S[5],S[6],S[7],40,0xa2bfe8a1);
    RND(S[7],S[0],S[1],S[2],S[3],S[4],S[5],S[6],41,0xa81a664b);
    RND(S[6],S[7],S[0],S[1],S[2],S[3],S[4],S[5],42,0xc24b8b70);
    RND(S[5],S[6],S[7],S[0],S[1],S[2],S[3],S[4],43,0xc76c51a3);
    RND(S[4],S[5],S[6],S[7],S[0],S[1],S[2],S[3],44,0xd192e819);
    RND(S[3],S[4],S[5],S[6],S[7],S[0],S[1],S[2],45,0xd6990624);
    RND(S[2],S[3],S[4],S[5],S[6],S[7],S[0],S[1],46,0xf40e3585);
    RND(S[1],S[2],S[3],S[4],S[5],S[6],S[7],S[0],47,0x106aa070);
    RND(S[0],S[1],S[2],S[3],S[4],S[5],S[6],S[7],48,0x19a4c116);
    RND(S[7],S[0],S[1],S[2],S[3],S[4],S[5],S[6],49,0x1e376c08);
    RND(S[6],S[7],S[0],S[1],S[2],S[3],S[4],S[5],50,0x2748774c);
    RND(S[5],S[6],S[7],S[0],S[1],S[2],S[3],S[4],51,0x34b0bcb5);
    RND(S[4],S[5],S[6],S[7],S[0],S[1],S[2],S[3],52,0x391c0cb3);
    RND(S[3],S[4],S[5],S[6],S[7],S[0],S[1],S[2],53,0x4ed8aa4a);
    RND(S[2],S[3],S[4],S[5],S[6],S[7],S[0],S[1],54,0x5b9cca4f);
    RND(S[1],S[2],S[3],S[4],S[5],S[6],S[7],S[0],55,0x682e6ff3);
    RND(S[0],S[1],S[2],S[3],S[4],S[5],S[6],S[7],56,0x748f82ee);
    RND(S[7],S[0],S[1],S[2],S[3],S[4],S[5],S[6],57,0x78a5636f);
    RND(S[6],S[7],S[0],S[1],S[2],S[3],S[4],S[5],58,0x84c87814);
    RND(S[5],S[6],S[7],S[0],S[1],S[2],S[3],S[4],59,0x8cc70208);
    RND(S[4],S[5],S[6],S[7],S[0],S[1],S[2],S[3],60,0x90befffa);
    RND(S[3],S[4],S[5],S[6],S[7],S[0],S[1],S[2],61,0xa4506ceb);
    RND(S[2],S[3],S[4],S[5],S[6],S[7],S[0],S[1],62,0xbef9a3f7);
    RND(S[1],S[2],S[3],S[4],S[5],S[6],S[7],S[0],63,0xc67178f2);

#undef RND     
    
    /* feedback */
    for (i = 0; i < 8; i++) {
        sha_info->digest[i] = sha_info->digest[i] + S[i];
    }

}



/* initialize the SHA digest */

static void
sha_init(SHAobject *sha_info)
{
    TestEndianness(sha_info->Endianness)
    sha_info->digest[0] = 0x6A09E667L;
    sha_info->digest[1] = 0xBB67AE85L;
    sha_info->digest[2] = 0x3C6EF372L;
    sha_info->digest[3] = 0xA54FF53AL;
    sha_info->digest[4] = 0x510E527FL;
    sha_info->digest[5] = 0x9B05688CL;
    sha_info->digest[6] = 0x1F83D9ABL;
    sha_info->digest[7] = 0x5BE0CD19L;
    sha_info->count_lo = 0L;
    sha_info->count_hi = 0L;
    sha_info->local = 0;
    sha_info->digestsize = 32;
}

static void
sha224_init(SHAobject *sha_info)
{
    TestEndianness(sha_info->Endianness)
    sha_info->digest[0] = 0xc1059ed8L;
    sha_info->digest[1] = 0x367cd507L;
    sha_info->digest[2] = 0x3070dd17L;
    sha_info->digest[3] = 0xf70e5939L;
    sha_info->digest[4] = 0xffc00b31L;
    sha_info->digest[5] = 0x68581511L;
    sha_info->digest[6] = 0x64f98fa7L;
    sha_info->digest[7] = 0xbefa4fa4L;
    sha_info->count_lo = 0L;
    sha_info->count_hi = 0L;
    sha_info->local = 0;
    sha_info->digestsize = 28;
}


/* update the SHA digest */

static void
sha_update(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(unsigned char digest[SHA_DIGESTSIZE], 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);
    digest[20] = (unsigned char) ((sha_info->digest[5] >> 24) & 0xff);
    digest[21] = (unsigned char) ((sha_info->digest[5] >> 16) & 0xff);
    digest[22] = (unsigned char) ((sha_info->digest[5] >>  8) & 0xff);
    digest[23] = (unsigned char) ((sha_info->digest[5]      ) & 0xff);
    digest[24] = (unsigned char) ((sha_info->digest[6] >> 24) & 0xff);
    digest[25] = (unsigned char) ((sha_info->digest[6] >> 16) & 0xff);
    digest[26] = (unsigned char) ((sha_info->digest[6] >>  8) & 0xff);
    digest[27] = (unsigned char) ((sha_info->digest[6]      ) & 0xff);
    digest[28] = (unsigned char) ((sha_info->digest[7] >> 24) & 0xff);
    digest[29] = (unsigned char) ((sha_info->digest[7] >> 16) & 0xff);
    digest[30] = (unsigned char) ((sha_info->digest[7] >>  8) & 0xff);
    digest[31] = (unsigned char) ((sha_info->digest[7]      ) & 0xff);
}

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

static PyTypeObject SHA224type;
static PyTypeObject SHA256type;


static SHAobject *
newSHA224object(void)
{
    return (SHAobject *)PyObject_New(SHAobject, &SHA224type);
}

static SHAobject *
newSHA256object(void)
{
    return (SHAobject *)PyObject_New(SHAobject, &SHA256type);
}

/* Internal methods for a hash object */

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


/* External methods for a hash object */

PyDoc_STRVAR(SHA256_copy__doc__, "Return a copy of the hash object.");

static PyObject *
SHA256_copy(SHAobject *self, PyObject *unused)
{
    SHAobject *newobj;

    if (Py_Type(self) == &SHA256type) {
        if ( (newobj = newSHA256object())==NULL)
            return NULL;
    } else {
        if ( (newobj = newSHA224object())==NULL)
            return NULL;
    }

    SHAcopy(self, newobj);
    return (PyObject *)newobj;
}

PyDoc_STRVAR(SHA256_digest__doc__,
"Return the digest value as a string of binary data.");

static PyObject *
SHA256_digest(SHAobject *self, PyObject *unused)
{
    unsigned char digest[SHA_DIGESTSIZE];
    SHAobject temp;

    SHAcopy(self, &temp);
    sha_final(digest, &temp);
    return PyBytes_FromStringAndSize((const char *)digest, self->digestsize);
}

PyDoc_STRVAR(SHA256_hexdigest__doc__,
"Return the digest value as a string of hexadecimal digits.");

static PyObject *
SHA256_hexdigest(SHAobject *self, PyObject *unused)
{
    unsigned char digest[SHA_DIGESTSIZE];
    SHAobject temp;
    PyObject *retval;
    Py_UNICODE *hex_digest;
    int i, j;

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

    /* Create a new string */
    retval = PyUnicode_FromStringAndSize(NULL, self->digestsize * 2);
    if (!retval)
	    return NULL;
    hex_digest = PyUnicode_AS_UNICODE(retval);
    if (!hex_digest) {
	    Py_DECREF(retval);
	    return NULL;
    }

    /* Make hex version of the digest */
    for(i=j=0; i<self->digestsize; i++) {
        char c;
        c = (digest[i] >> 4) & 0xf;
	c = (c>9) ? c+'a'-10 : c + '0';
        hex_digest[j++] = c;
        c = (digest[i] & 0xf);
	c = (c>9) ? c+'a'-10 : c + '0';
        hex_digest[j++] = c;
    }
    return retval;
}

PyDoc_STRVAR(SHA256_update__doc__,
"Update this hash object's state with the provided string.");

static PyObject *
SHA256_update(SHAobject *self, PyObject *args)
{
    unsigned char *cp;
    int len;

    if (!PyArg_ParseTuple(args, "s#:update", &cp, &len))
        return NULL;

    sha_update(self, cp, len);

    Py_INCREF(Py_None);
    return Py_None;
}

static PyMethodDef SHA_methods[] = {
    {"copy",	  (PyCFunction)SHA256_copy,      METH_NOARGS,  SHA256_copy__doc__},
    {"digest",	  (PyCFunction)SHA256_digest,    METH_NOARGS,  SHA256_digest__doc__},
    {"hexdigest", (PyCFunction)SHA256_hexdigest, METH_NOARGS,  SHA256_hexdigest__doc__},
    {"update",	  (PyCFunction)SHA256_update,    METH_VARARGS, SHA256_update__doc__},
    {NULL,	  NULL}		/* sentinel */
};

static PyObject *
SHA256_get_block_size(PyObject *self, void *closure)
{
    return PyInt_FromLong(SHA_BLOCKSIZE);
}

static PyObject *
SHA256_get_name(PyObject *self, void *closure)
{
    if (((SHAobject *)self)->digestsize == 32)
        return PyUnicode_FromStringAndSize("SHA256", 6);
    else
        return PyUnicode_FromStringAndSize("SHA224", 6);
}

static PyGetSetDef SHA_getseters[] = {
    {"block_size",
     (getter)SHA256_get_block_size, NULL,
     NULL,
     NULL},
    {"name",
     (getter)SHA256_get_name, NULL,
     NULL,
     NULL},
    {NULL}  /* Sentinel */
};

static PyMemberDef SHA_members[] = {
    {"digest_size", T_INT, offsetof(SHAobject, digestsize), READONLY, NULL},
    /* the old md5 and sha modules support 'digest_size' as in PEP 247.
     * the old sha module also supported 'digestsize'.  ugh. */
    {"digestsize", T_INT, offsetof(SHAobject, digestsize), READONLY, NULL},
    {NULL}  /* Sentinel */
};

static PyTypeObject SHA224type = {
    PyVarObject_HEAD_INIT(NULL, 0)
    "_sha256.sha224",	/*tp_name*/
    sizeof(SHAobject),	/*tp_size*/
    0,			/*tp_itemsize*/
    /* methods */
    SHA_dealloc,	/*tp_dealloc*/
    0,			/*tp_print*/
    0,          	/*tp_getattr*/
    0,                  /*tp_setattr*/
    0,                  /*tp_compare*/
    0,                  /*tp_repr*/
    0,                  /*tp_as_number*/
    0,                  /*tp_as_sequence*/
    0,                  /*tp_as_mapping*/
    0,                  /*tp_hash*/
    0,                  /*tp_call*/
    0,                  /*tp_str*/
    0,                  /*tp_getattro*/
    0,                  /*tp_setattro*/
    0,                  /*tp_as_buffer*/
    Py_TPFLAGS_DEFAULT, /*tp_flags*/
    0,                  /*tp_doc*/
    0,                  /*tp_traverse*/
    0,			/*tp_clear*/
    0,			/*tp_richcompare*/
    0,			/*tp_weaklistoffset*/
    0,			/*tp_iter*/
    0,			/*tp_iternext*/
    SHA_methods,	/* tp_methods */
    SHA_members,	/* tp_members */
    SHA_getseters,      /* tp_getset */
};

static PyTypeObject SHA256type = {
    PyVarObject_HEAD_INIT(NULL, 0)
    "_sha256.sha256",	/*tp_name*/
    sizeof(SHAobject),	/*tp_size*/
    0,			/*tp_itemsize*/
    /* methods */
    SHA_dealloc,	/*tp_dealloc*/
    0,			/*tp_print*/
    0,          	/*tp_getattr*/
    0,                  /*tp_setattr*/
    0,                  /*tp_compare*/
    0,                  /*tp_repr*/
    0,                  /*tp_as_number*/
    0,                  /*tp_as_sequence*/
    0,                  /*tp_as_mapping*/
    0,                  /*tp_hash*/
    0,                  /*tp_call*/
    0,                  /*tp_str*/
    0,                  /*tp_getattro*/
    0,                  /*tp_setattro*/
    0,                  /*tp_as_buffer*/
    Py_TPFLAGS_DEFAULT, /*tp_flags*/
    0,                  /*tp_doc*/
    0,                  /*tp_traverse*/
    0,			/*tp_clear*/
    0,			/*tp_richcompare*/
    0,			/*tp_weaklistoffset*/
    0,			/*tp_iter*/
    0,			/*tp_iternext*/
    SHA_methods,	/* tp_methods */
    SHA_members,	/* tp_members */
    SHA_getseters,      /* tp_getset */
};


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

PyDoc_STRVAR(SHA256_new__doc__,
"Return a new SHA-256 hash object; optionally initialized with a string.");

static PyObject *
SHA256_new(PyObject *self, PyObject *args, PyObject *kwdict)
{
    static char *kwlist[] = {"string", NULL};
    SHAobject *new;
    unsigned char *cp = NULL;
    int len;

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

    if ((new = newSHA256object()) == NULL)
        return NULL;

    sha_init(new);

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

    return (PyObject *)new;
}

PyDoc_STRVAR(SHA224_new__doc__,
"Return a new SHA-224 hash object; optionally initialized with a string.");

static PyObject *
SHA224_new(PyObject *self, PyObject *args, PyObject *kwdict)
{
    static char *kwlist[] = {"string", NULL};
    SHAobject *new;
    unsigned char *cp = NULL;
    int len;

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

    if ((new = newSHA224object()) == NULL)
        return NULL;

    sha224_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[] = {
    {"sha256", (PyCFunction)SHA256_new, METH_VARARGS|METH_KEYWORDS, SHA256_new__doc__},
    {"sha224", (PyCFunction)SHA224_new, METH_VARARGS|METH_KEYWORDS, SHA224_new__doc__},
    {NULL,	NULL}		 /* Sentinel */
};


/* Initialize this module. */

#define insint(n,v) { PyModule_AddIntConstant(m,n,v); }

PyMODINIT_FUNC
init_sha256(void)
{
    PyObject *m;

    Py_Type(&SHA224type) = &PyType_Type;
    if (PyType_Ready(&SHA224type) < 0)
        return;
    Py_Type(&SHA256type) = &PyType_Type;
    if (PyType_Ready(&SHA256type) < 0)
        return;
    m = Py_InitModule("_sha256", SHA_functions);
    if (m == NULL)
	return;
}