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/*

 * random.c -- A strong random number generator

 *

 * Version 1.00, last modified 26-May-96

 *

 * Copyright Theodore Ts'o, 1994, 1995, 1996.  All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the above copyright

 *    notice, and the entire permission notice in its entirety,

 *    including the disclaimer of warranties.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 * 3. The name of the author may not be used to endorse or promote

 *    products derived from this software without specific prior

 *    written permission.

 *

 * ALTERNATIVELY, this product may be distributed under the terms of

 * the GNU Public License, in which case the provisions of the GPL are

 * required INSTEAD OF the above restrictions.  (This clause is

 * necessary due to a potential bad interaction between the GPL and

 * the restrictions contained in a BSD-style copyright.)

 *

 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED

 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES

 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE

 * DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,

 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES

 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR

 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,

 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED

 * OF THE POSSIBILITY OF SUCH DAMAGE.

 */

/*

 * (now, with legal B.S. out of the way.....)

 *

 * This routine gathers environmental noise from device drivers, etc.,

 * and returns good random numbers, suitable for cryptographic use.

 * Besides the obvious cryptographic uses, these numbers are also good

 * for seeding TCP sequence numbers, and other places where it is

 * desirable to have numbers which are not only random, but hard to

 * predict by an attacker.

 *

 * Theory of operation

 * ===================

 *

 * Computers are very predictable devices.  Hence it is extremely hard

 * to produce truly random numbers on a computer --- as opposed to

 * pseudo-random numbers, which can easily generated by using a

 * algorithm.  Unfortunately, it is very easy for attackers to guess

 * the sequence of pseudo-random number generators, and for some

 * applications this is not acceptable.  So instead, we must try to

 * gather "environmental noise" from the computer's environment, which

 * must be hard for outside attackers to observe, and use that to

 * generate random numbers.  In a Unix environment, this is best done

 * from inside the kernel.

 *

 * Sources of randomness from the environment include inter-keyboard

 * timings, inter-interrupt timings from some interrupts, and other

 * events which are both (a) non-deterministic and (b) hard for an

 * outside observer to measure.  Randomness from these sources are

 * added to an "entropy pool", which is mixed using a CRC-like function.

 * This is not cryptographically strong, but it is adequate assuming

 * the randomness is not chosen maliciously, and it is fast enough that

 * the overhead of doing it on every interrupt is very reasonable.

 * As random bytes are mixed into the entropy pool, the routines keep

 * an *estimate* of how many bits of randomness have been stored into

 * the random number generator's internal state.

 *

 * When random bytes are desired, they are obtained by taking the MD5

 * hash of the contents of the "entropy pool".  The MD5 hash avoids

 * exposing the internal state of the entropy pool.  It is believed to

 * be computationally infeasible to derive any useful information

 * about the input of MD5 from its output.  Even if it is possible to

 * analyze MD5 in some clever way, as long as the amount of data

 * returned from the generator is less than the inherent entropy in

 * the pool, the output data is totally unpredictable.  For this

 * reason, the routine decreases its internal estimate of how many

 * bits of "true randomness" are contained in the entropy pool as it

 * outputs random numbers.

 *

 * If this estimate goes to zero, the routine can still generate

 * random numbers; however, an attacker may (at least in theory) be

 * able to infer the future output of the generator from prior

 * outputs.  This requires successful cryptanalysis of MD5, which is

 * not believed to be feasible, but there is a remote possibility.

 * Nonetheless, these numbers should be useful for the vast majority

 * of purposes.

 *

 * Exported interfaces ---- output

 * ===============================

 *

 * There are three exported interfaces; the first is one designed to

 * be used from within the kernel:

 *

 *      void get_random_bytes(void *buf, int nbytes);

 *

 * This interface will return the requested number of random bytes,

 * and place it in the requested buffer.

 *

 * The two other interfaces are two character devices /dev/random and

 * /dev/urandom.  /dev/random is suitable for use when very high

 * quality randomness is desired (for example, for key generation or

 * one-time pads), as it will only return a maximum of the number of

 * bits of randomness (as estimated by the random number generator)

 * contained in the entropy pool.

 *

 * The /dev/urandom device does not have this limit, and will return

 * as many bytes as are requested.  As more and more random bytes are

 * requested without giving time for the entropy pool to recharge,

 * this will result in random numbers that are merely cryptographically

 * strong.  For many applications, however, this is acceptable.

 *

 * Exported interfaces ---- input

 * ==============================

 *

 * The current exported interfaces for gathering environmental noise

 * from the devices are:

 *

 *      void add_keyboard_randomness(unsigned char scancode);

 *      void add_mouse_randomness(__u32 mouse_data);

 *      void add_interrupt_randomness(int irq);

 *      void add_blkdev_randomness(int irq);

 *

 * add_keyboard_randomness() uses the inter-keypress timing, as well as the

 * scancode as random inputs into the "entropy pool".

 *

 * add_mouse_randomness() uses the mouse interrupt timing, as well as

 * the reported position of the mouse from the hardware.

 *

 * add_interrupt_randomness() uses the inter-interrupt timing as random

 * inputs to the entropy pool.  Note that not all interrupts are good

 * sources of randomness!  For example, the timer interrupts is not a

 * good choice, because the periodicity of the interrupts is to

 * regular, and hence predictable to an attacker.  Disk interrupts are

 * a better measure, since the timing of the disk interrupts are more

 * unpredictable.

 *

 * add_blkdev_randomness() times the finishing time of block requests.

 *

 * All of these routines try to estimate how many bits of randomness a

 * particular randomness source.  They do this by keeping track of the

 * first and second order deltas of the event timings.

 *

 * Ensuring unpredictability at system startup

 * ============================================

 *

 * When any operating system starts up, it will go through a sequence

 * of actions that are fairly predictable by an adversary, especially

 * if the start-up does not involve interaction with a human operator.

 * This reduces the actual number of bits of unpredictability in the

 * entropy pool below the value in entropy_count.  In order to

 * counteract this effect, it helps to carry information in the

 * entropy pool across shut-downs and start-ups.  To do this, put the

 * following lines an appropriate script which is run during the boot

 * sequence:

 *

 *      echo "Initializing random number generator..."

 *      # Carry a random seed from start-up to start-up

 *      # Load and then save 512 bytes, which is the size of the entropy pool

 *      if [ -f /etc/random-seed ]; then

 *              cat /etc/random-seed >/dev/urandom

 *      fi

 *      dd if=/dev/urandom of=/etc/random-seed count=1

 *

 * and the following lines in an appropriate script which is run as

 * the system is shutdown:

 *

 *      # Carry a random seed from shut-down to start-up

 *      # Save 512 bytes, which is the size of the entropy pool

 *      echo "Saving random seed..."

 *      dd if=/dev/urandom of=/etc/random-seed count=1

 *

 * For example, on many Linux systems, the appropriate scripts are

 * usually /etc/rc.d/rc.local and /etc/rc.d/rc.0, respectively.

 *

 * Effectively, these commands cause the contents of the entropy pool

 * to be saved at shut-down time and reloaded into the entropy pool at

 * start-up.  (The 'dd' in the addition to the bootup script is to

 * make sure that /etc/random-seed is different for every start-up,

 * even if the system crashes without executing rc.0.)  Even with

 * complete knowledge of the start-up activities, predicting the state

 * of the entropy pool requires knowledge of the previous history of

 * the system.

 *

 * Configuring the /dev/random driver under Linux

 * ==============================================

 *

 * The /dev/random driver under Linux uses minor numbers 8 and 9 of

 * the /dev/mem major number (#1).  So if your system does not have

 * /dev/random and /dev/urandom created already, they can be created

 * by using the commands:

 *

 *      mknod /dev/random c 1 8

 *      mknod /dev/urandom c 1 9

 *

 * Acknowledgements:

 * =================

 *

 * Ideas for constructing this random number generator were derived

 * from the Pretty Good Privacy's random number generator, and from

 * private discussions with Phil Karn.  Colin Plumb provided a faster

 * random number generator, which speed up the mixing function of the

 * entropy pool, taken from PGP 3.0 (under development).  It has since

 * been modified by myself to provide better mixing in the case where

 * the input values to add_entropy_word() are mostly small numbers.

 * Dale Worley has also contributed many useful ideas and suggestions

 * to improve this driver.

 *

 * Any flaws in the design are solely my responsibility, and should

 * not be attributed to the Phil, Colin, or any of authors of PGP.

 *

 * The code for MD5 transform was taken from Colin Plumb's

 * implementation, which has been placed in the public domain.  The

 * MD5 cryptographic checksum was devised by Ronald Rivest, and is

 * documented in RFC 1321, "The MD5 Message Digest Algorithm".

 *

 * Further background information on this topic may be obtained from

 * RFC 1750, "Randomness Recommendations for Security", by Donald

 * Eastlake, Steve Crocker, and Jeff Schiller.

 */

#include <linux/config.h> /* CONFIG_RST_COOKIES and CONFIG_SYN_COOKIES */

#include <linux/utsname.h>

#include <linux/kernel.h>

#include <linux/major.h>

#include <linux/string.h>

#include <linux/fcntl.h>

#include <linux/malloc.h>

#include <linux/random.h>

#include <asm/segment.h>

#include <asm/irq.h>

#include <asm/io.h>

/*

 * Configuration information

 */

#undef RANDOM_BENCHMARK

#undef BENCHMARK_NOINT

/*

 * The pool is stirred with a primitive polynomial of degree 128

 * over GF(2), namely x^128 + x^99 + x^59 + x^31 + x^9 + x^7 + 1.

 * For a pool of size 64, try x^64+x^62+x^38+x^10+x^6+x+1.

 */

#define POOLWORDS 128    /* Power of 2 - note that this is 32-bit words */

#define POOLBITS (POOLWORDS*32)

#if POOLWORDS == 128

#define TAP1    99     /* The polynomial taps */

#define TAP2    59

#define TAP3    31

#define TAP4    9

#define TAP5    7

#elif POOLWORDS == 64

#define TAP1    62      /* The polynomial taps */

#define TAP2    38

#define TAP3    10

#define TAP4    6

#define TAP5    1

#else

#error No primitive polynomial available for chosen POOLWORDS

#endif

/*

 * The minimum number of bits to release a "wait on input".  Should

 * probably always be 8, since a /dev/random read can return a single

 * byte.

 */

#define WAIT_INPUT_BITS 8

/*

 * The limit number of bits under which to release a "wait on

 * output".  Should probably always be the same as WAIT_INPUT_BITS, so

 * that an output wait releases when and only when a wait on input

 * would block.

 */

#define WAIT_OUTPUT_BITS WAIT_INPUT_BITS

/* There is actually only one of these, globally. */

struct random_bucket {

        unsigned add_ptr;

        unsigned entropy_count;

        int input_rotate;

        __u32 *pool;

};

#ifdef RANDOM_BENCHMARK

/* For benchmarking only */

struct random_benchmark {

        unsigned long long      start_time;

        int                     times;          /* # of samples */

        unsigned long           min;

        unsigned long           max;

        unsigned long           accum;          /* accumulator for average */

        const char              *descr;

        int                     unit;

        unsigned long           flags;

};

#define BENCHMARK_INTERVAL 500

static void initialize_benchmark(struct random_benchmark *bench,

                                 const char *descr, int unit);

static void begin_benchmark(struct random_benchmark *bench);

static void end_benchmark(struct random_benchmark *bench);

struct random_benchmark timer_benchmark;

#endif

/* There is one of these per entropy source */

struct timer_rand_state {

        unsigned long   last_time;

        int             last_delta,last_delta2;

        int             dont_count_entropy:1;

};

static struct random_bucket random_state;

static __u32 random_pool[POOLWORDS];

static struct timer_rand_state keyboard_timer_state;

static struct timer_rand_state mouse_timer_state;

static struct timer_rand_state extract_timer_state;

static struct timer_rand_state *irq_timer_state[NR_IRQS];

static struct timer_rand_state *blkdev_timer_state[MAX_BLKDEV];

static struct wait_queue *random_wait;

static int random_read(struct inode * inode, struct file * file,

                       char * buf, int nbytes);

static int random_read_unlimited(struct inode * inode, struct file * file,

                                 char * buf, int nbytes);

static int random_select(struct inode *inode, struct file *file,

                         int sel_type, select_table * wait);

static int random_write(struct inode * inode, struct file * file,

                        const char * buffer, int count);

static int random_ioctl(struct inode * inode, struct file * file,

                        unsigned int cmd, unsigned long arg);

static inline void fast_add_entropy_word(struct random_bucket *r,

                                         const __u32 input);

static void add_entropy_word(struct random_bucket *r,

                                    const __u32 input);

#ifndef MIN

#define MIN(a,b) (((a) < (b)) ? (a) : (b))

#endif

/*

 * Unfortunately, while the GCC optimizer for the i386 understands how

 * to optimize a static rotate left of x bits, it doesn't know how to

 * deal with a variable rotate of x bits.  So we use a bit of asm magic.

 */

#if (!defined (__i386__))

extern inline __u32 rotate_left(int i, __u32 word)

{

        return (word << i) | (word >> (32 - i));

}

#else

extern inline __u32 rotate_left(int i, __u32 word)

{

        __asm__("roll %%cl,%0"

                :"=r" (word)

                :"0" (word),"c" (i));

        return word;

}

#endif

/*

 * More asm magic....

 *

 * For entropy estimation, we need to do an integral base 2

 * logarithm.  By default, use an open-coded C version, although we do

 * have a version which takes advantage of the Intel's x86's "bsr"

 * instruction.

 */

#if (!defined (__i386__))

static inline __u32 int_ln(__u32 word)

{

        __u32 nbits = 0;

        while (1) {

                word >>= 1;

                if (!word)

                        break;

                nbits++;

        }

        return nbits;

}

#else

static inline __u32 int_ln(__u32 word)

{

        __asm__("bsrl %1,%0\n\t"

                "jnz 1f\n\t"

                "movl $0,%0\n"

                "1:"

                :"=r" (word)

                :"r" (word));

        return word;

}

#endif

/*

 * Initialize the random pool with standard stuff.

 *

 * NOTE: This is an OS-dependent function.

 */

static void init_std_data(struct random_bucket *r)

{

        __u32 word, *p;

        int i;

        struct timeval  tv;

        do_gettimeofday(&tv);

        add_entropy_word(r, tv.tv_sec);

        add_entropy_word(r, tv.tv_usec);

        for (p = (__u32 *) &system_utsname,

             i = sizeof(system_utsname) / sizeof(__u32);

             i ; i--, p++) {

                memcpy(&word, p, sizeof(__u32));

                add_entropy_word(r, word);

        }

}

/* Clear the entropy pool and associated counters. */

static void rand_clear_pool(void)

{

        random_state.add_ptr = 0;

        random_state.entropy_count = 0;

        random_state.pool = random_pool;

        random_state.input_rotate = 0;

        memset(random_pool, 0, sizeof(random_pool));

        init_std_data(&random_state);

}

void rand_initialize(void)

{

        int i;

        rand_clear_pool();

        for (i = 0; i < NR_IRQS; i++)

                irq_timer_state[i] = NULL;

        for (i = 0; i < MAX_BLKDEV; i++)

                blkdev_timer_state[i] = NULL;

        memset(&keyboard_timer_state, 0, sizeof(struct timer_rand_state));

        memset(&mouse_timer_state, 0, sizeof(struct timer_rand_state));

        memset(&extract_timer_state, 0, sizeof(struct timer_rand_state));

#ifdef RANDOM_BENCHMARK

        initialize_benchmark(&timer_benchmark, "timer", 0);

#endif

        extract_timer_state.dont_count_entropy = 1;

        random_wait = NULL;

}

void rand_initialize_irq(int irq)

{

        struct timer_rand_state *state;

        if (irq >= NR_IRQS || irq_timer_state[irq])

                return;

        /*

         * If kmalloc returns null, we just won't use that entropy

         * source.

         */

        state = kmalloc(sizeof(struct timer_rand_state), GFP_KERNEL);

        if (state) {

                irq_timer_state[irq] = state;

                memset(state, 0, sizeof(struct timer_rand_state));

        }

}

void rand_initialize_blkdev(int major, int mode)

{

        struct timer_rand_state *state;

        if (major >= MAX_BLKDEV || blkdev_timer_state[major])

                return;

        /*

         * If kmalloc returns null, we just won't use that entropy

         * source.

         */

        state = kmalloc(sizeof(struct timer_rand_state), mode);

        if (state) {

                blkdev_timer_state[major] = state;

                memset(state, 0, sizeof(struct timer_rand_state));

        }

}

/*

 * This function adds a byte into the entropy "pool".  It does not

 * update the entropy estimate.  The caller must do this if appropriate.

 *

 * The pool is stirred with a primitive polynomial of degree 128

 * over GF(2), namely x^128 + x^99 + x^59 + x^31 + x^9 + x^7 + 1.

 * For a pool of size 64, try x^64+x^62+x^38+x^10+x^6+x+1.

 *

 * We rotate the input word by a changing number of bits, to help

 * assure that all bits in the entropy get toggled.  Otherwise, if we

 * consistently feed the entropy pool small numbers (like jiffies and

 * scancodes, for example), the upper bits of the entropy pool don't

 * get affected. --- TYT, 10/11/95

 */

static inline void fast_add_entropy_word(struct random_bucket *r,

                                         const __u32 input)

{

        unsigned i;

        int new_rotate;

        __u32 w;

        w = rotate_left(r->input_rotate, input);

        i = r->add_ptr = (r->add_ptr - 1) & (POOLWORDS-1);

        /*

         * Normally, we add 7 bits of rotation to the pool.  At the

         * beginning of the pool, add an extra 7 bits rotation, so

         * that successive passes spread the input bits across the

         * pool evenly.

         */

        new_rotate = r->input_rotate + 14;

        if (i)

                new_rotate = r->input_rotate + 7;

        r->input_rotate = new_rotate & 31;

        /* XOR in the various taps */

        w ^= r->pool[(i+TAP1)&(POOLWORDS-1)];

        w ^= r->pool[(i+TAP2)&(POOLWORDS-1)];

        w ^= r->pool[(i+TAP3)&(POOLWORDS-1)];

        w ^= r->pool[(i+TAP4)&(POOLWORDS-1)];

        w ^= r->pool[(i+TAP5)&(POOLWORDS-1)];

        w ^= r->pool[i];

        /* Rotate w left 1 bit (stolen from SHA) and store */

        r->pool[i] = (w << 1) | (w >> 31);

}

/*

 * For places where we don't need the inlined version

 */

static void add_entropy_word(struct random_bucket *r,

                                    const __u32 input)

{

        fast_add_entropy_word(r, input);

}

/*

 * This function adds entropy to the entropy "pool" by using timing

 * delays.  It uses the timer_rand_state structure to make an estimate

 * of how many bits of entropy this call has added to the pool.

 *

 * The number "num" is also added to the pool - it should somehow describe

 * the type of event which just happened.  This is currently 0-255 for

 * keyboard scan codes, and 256 upwards for interrupts.

 * On the i386, this is assumed to be at most 16 bits, and the high bits

 * are used for a high-resolution timer.

 *

 */

static void add_timer_randomness(struct random_bucket *r,

                                 struct timer_rand_state *state, unsigned num)

{

        int     delta, delta2, delta3;

        __u32           time;

#ifdef RANDOM_BENCHMARK

        begin_benchmark(&timer_benchmark);

#endif

#if defined (__i386__)

        if (x86_capability & 16) {

                unsigned long low, high;

                __asm__(".byte 0x0f,0x31"

                        :"=a" (low), "=d" (high));

                time = (__u32) low;

                num ^= (__u32) high;

        } else {

                time = jiffies;

        }

#else

        time = jiffies;

#endif

        fast_add_entropy_word(r, (__u32) num);

        fast_add_entropy_word(r, time);

        /*

         * Calculate number of bits of randomness we probably

         * added.  We take into account the first and second order

         * deltas in order to make our estimate.

         */

        if (!state->dont_count_entropy &&

            (r->entropy_count < POOLBITS)) {

                delta = time - state->last_time;

                state->last_time = time;

                if (delta < 0) delta = -delta;

                delta2 = delta - state->last_delta;

                state->last_delta = delta;

                if (delta2 < 0) delta2 = -delta2;

                delta3 = delta2 - state->last_delta2;

                state->last_delta2 = delta2;

                if (delta3 < 0) delta3 = -delta3;

                delta = MIN(MIN(delta, delta2), delta3) >> 1;

                /* Limit entropy estimate to 12 bits */

                delta &= (1 << 12) - 1;

                r->entropy_count += int_ln(delta);

                /* Prevent overflow */

                if (r->entropy_count > POOLBITS)

                        r->entropy_count = POOLBITS;

        }

        /* Wake up waiting processes, if we have enough entropy. */

        if (r->entropy_count >= WAIT_INPUT_BITS)

                wake_up_interruptible(&random_wait);

#ifdef RANDOM_BENCHMARK

        end_benchmark(&timer_benchmark);

#endif

}

void add_keyboard_randomness(unsigned char scancode)

{

        add_timer_randomness(&random_state, &keyboard_timer_state, scancode);

}

void add_mouse_randomness(__u32 mouse_data)

{

        add_timer_randomness(&random_state, &mouse_timer_state, mouse_data);

}

void add_interrupt_randomness(int irq)

{

        if (irq >= NR_IRQS || irq_timer_state[irq] == 0)

                return;

        add_timer_randomness(&random_state, irq_timer_state[irq], 0x100+irq);

}

void add_blkdev_randomness(int major)

{

        if (major >= MAX_BLKDEV)

                return;

        if (blkdev_timer_state[major] == 0) {

                rand_initialize_blkdev(major, GFP_ATOMIC);

                if (blkdev_timer_state[major] == 0)

                        return;

        }

        add_timer_randomness(&random_state, blkdev_timer_state[major],

                             0x200+major);

}

#define USE_SHA

#ifdef USE_SHA

#define HASH_BUFFER_SIZE 5

#define HASH_TRANSFORM SHATransform

/*

 * SHA transform algorithm, taken from code written by Peter Gutman,

 * and apparently in the public domain.

 */

/* The SHA f()-functions.  */

#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 ) | ( z & ( x | y ) ) )   /* Rounds 40-59 */

#define f4(x,y,z)   ( x ^ y ^ z )                       /* Rounds 60-79 */

/* The SHA Mysterious Constants */

#define K1  0x5A827999L                                 /* Rounds  0-19 */

#define K2  0x6ED9EBA1L                                 /* Rounds 20-39 */

#define K3  0x8F1BBCDCL                                 /* Rounds 40-59 */

#define K4  0xCA62C1D6L                                 /* Rounds 60-79 */

#define ROTL(n,X)  ( ( ( X ) << n ) | ( ( X ) >> ( 32 - n ) ) )

#define expand(W,i) ( W[ i & 15 ] = \

                     ROTL( 1, ( W[ i & 15 ] ^ W[ (i - 14) & 15 ] ^ \

                                W[ (i - 8) & 15 ] ^ W[ (i - 3) & 15 ] ) ) )

#define subRound(a, b, c, d, e, f, k, data) \

    ( e += ROTL( 5, a ) + f( b, c, d ) + k + data, b = ROTL( 30, b ) )

void SHATransform(__u32 *digest, __u32 *data)

    {

    __u32 A, B, C, D, E;     /* Local vars */

    __u32 eData[ 16 ];       /* Expanded data */

    /* Set up first buffer and local data buffer */

    A = digest[ 0 ];

    B = digest[ 1 ];

    C = digest[ 2 ];

    D = digest[ 3 ];

    E = digest[ 4 ];

    memcpy( eData, data, 16*sizeof(__u32));

    /* Heavy mangling, in 4 sub-rounds of 20 iterations each. */

    subRound( A, B, C, D, E, f1, K1, eData[  0 ] );

    subRound( E, A, B, C, D, f1, K1, eData[  1 ] );

    subRound( D, E, A, B, C, f1, K1, eData[  2 ] );

    subRound( C, D, E, A, B, f1, K1, eData[  3 ] );

    subRound( B, C, D, E, A, f1, K1, eData[  4 ] );

    subRound( A, B, C, D, E, f1, K1, eData[  5 ] );

    subRound( E, A, B, C, D, f1, K1, eData[  6 ] );

    subRound( D, E, A, B, C, f1, K1, eData[  7 ] );

    subRound( C, D, E, A, B, f1, K1, eData[  8 ] );

    subRound( B, C, D, E, A, f1, K1, eData[  9 ] );

    subRound( A, B, C, D, E, f1, K1, eData[ 10 ] );

    subRound( E, A, B, C, D, f1, K1, eData[ 11 ] );

    subRound( D, E, A, B, C, f1, K1, eData[ 12 ] );

    subRound( C, D, E, A, B, f1, K1, eData[ 13 ] );

    subRound( B, C, D, E, A, f1, K1, eData[ 14 ] );

    subRound( A, B, C, D, E, f1, K1, eData[ 15 ] );

    subRound( E, A, B, C, D, f1, K1, expand( eData, 16 ) );

    subRound( D, E, A, B, C, f1, K1, expand( eData, 17 ) );

    subRound( C, D, E, A, B, f1, K1, expand( eData, 18 ) );