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/*

** ********************************************************************

** md4.c -- Implementation of MD4 Message Digest Algorithm           **

** Updated: 2/16/90 by Ronald L. Rivest                              **

** (C) 1990 RSA Data Security, Inc.                                  **

** ********************************************************************

*/

/*

** To use MD4:

**   -- Include md4.h in your program

**   -- Declare an MDstruct MD to hold the state of the digest

**          computation.

**   -- Initialize MD using MDbegin(&MD)

**   -- For each full block (64 bytes) X you wish to process, call

**          MD4Update(&MD,X,512)

**      (512 is the number of bits in a full block.)

**   -- For the last block (less than 64 bytes) you wish to process,

**          MD4Update(&MD,X,n)

**      where n is the number of bits in the partial block. A partial

**      block terminates the computation, so every MD computation

**      should terminate by processing a partial block, even if it

**      has n = 0.

**   -- The message digest is available in MD.buffer[0] ...

**      MD.buffer[3].  (Least-significant byte of each word

**      should be output first.)

**   -- You can print out the digest using MDprint(&MD)

*/

/* Implementation notes:

** This implementation assumes that ints are 32-bit quantities.

*/

#define TRUE  1

#define FALSE 0

/* Compile-time includes

*/

#include <stdio.h>

#include "md4.h"

#include "pppd.h"

/* Compile-time declarations of MD4 "magic constants".

*/

#define I0  0x67452301       /* Initial values for MD buffer */

#define I1  0xefcdab89

#define I2  0x98badcfe

#define I3  0x10325476

#define C2  013240474631     /* round 2 constant = sqrt(2) in octal */

#define C3  015666365641     /* round 3 constant = sqrt(3) in octal */

/* C2 and C3 are from Knuth, The Art of Programming, Volume 2

** (Seminumerical Algorithms), Second Edition (1981), Addison-Wesley.

** Table 2, page 660.

*/

#define fs1  3               /* round 1 shift amounts */

#define fs2  7

#define fs3 11

#define fs4 19

#define gs1  3               /* round 2 shift amounts */

#define gs2  5

#define gs3  9

#define gs4 13

#define hs1  3               /* round 3 shift amounts */

#define hs2  9

#define hs3 11

#define hs4 15

/* Compile-time macro declarations for MD4.

** Note: The "rot" operator uses the variable "tmp".

** It assumes tmp is declared as unsigned int, so that the >>

** operator will shift in zeros rather than extending the sign bit.

*/

#define f(X,Y,Z)             ((X&Y) | ((~X)&Z))

#define g(X,Y,Z)             ((X&Y) | (X&Z) | (Y&Z))

#define h(X,Y,Z)             (X^Y^Z)

#define rot(X,S)             (tmp=X,(tmp<<S) | (tmp>>(32-S)))

#define ff(A,B,C,D,i,s)      A = rot((A + f(B,C,D) + X[i]),s)

#define gg(A,B,C,D,i,s)      A = rot((A + g(B,C,D) + X[i] + C2),s)

#define hh(A,B,C,D,i,s)      A = rot((A + h(B,C,D) + X[i] + C3),s)

/* MD4print(MDp)

** Print message digest buffer MDp as 32 hexadecimal digits.

** Order is from low-order byte of buffer[0] to high-order byte of

** buffer[3].

** Each byte is printed with high-order hexadecimal digit first.

** This is a user-callable routine.

*/

void

MD4Print(MDp)

MD4_CTX *MDp;

{

  int i,j;

  for (i=0;i<4;i++)

    for (j=0;j<32;j=j+8)

      printf("%02x",(MDp->buffer[i]>>j) & 0xFF);

}

/* MD4Init(MDp)

** Initialize message digest buffer MDp.

** This is a user-callable routine.

*/

void

MD4Init(MDp)

MD4_CTX *MDp;

{

  int i;

  MDp->buffer[0] = I0;

  MDp->buffer[1] = I1;

  MDp->buffer[2] = I2;

  MDp->buffer[3] = I3;

  for (i=0;i<8;i++) MDp->count[i] = 0;

  MDp->done = 0;

}

/* MDblock(MDp,X)

** Update message digest buffer MDp->buffer using 16-word data block X.

** Assumes all 16 words of X are full of data.

** Does not update MDp->count.

** This routine is not user-callable.

*/

static void

MDblock(MDp,Xb)

MD4_CTX *MDp;

unsigned char *Xb;

{

  register unsigned int tmp, A, B, C, D;

  unsigned int X[16];

  int i;

  for (i = 0; i < 16; ++i) {

    X[i] = Xb[0] + (Xb[1] << 8) + (Xb[2] << 16) + (Xb[3] << 24);

    Xb += 4;

  }

  A = MDp->buffer[0];

  B = MDp->buffer[1];

  C = MDp->buffer[2];

  D = MDp->buffer[3];

  /* Update the message digest buffer */

  ff(A , B , C , D ,  0 , fs1); /* Round 1 */

  ff(D , A , B , C ,  1 , fs2);

  ff(C , D , A , B ,  2 , fs3);

  ff(B , C , D , A ,  3 , fs4);

  ff(A , B , C , D ,  4 , fs1);

  ff(D , A , B , C ,  5 , fs2);

  ff(C , D , A , B ,  6 , fs3);

  ff(B , C , D , A ,  7 , fs4);

  ff(A , B , C , D ,  8 , fs1);

  ff(D , A , B , C ,  9 , fs2);

  ff(C , D , A , B , 10 , fs3);

  ff(B , C , D , A , 11 , fs4);

  ff(A , B , C , D , 12 , fs1);

  ff(D , A , B , C , 13 , fs2);

  ff(C , D , A , B , 14 , fs3);

  ff(B , C , D , A , 15 , fs4);

  gg(A , B , C , D ,  0 , gs1); /* Round 2 */

  gg(D , A , B , C ,  4 , gs2);

  gg(C , D , A , B ,  8 , gs3);

  gg(B , C , D , A , 12 , gs4);

  gg(A , B , C , D ,  1 , gs1);

  gg(D , A , B , C ,  5 , gs2);

  gg(C , D , A , B ,  9 , gs3);

  gg(B , C , D , A , 13 , gs4);

  gg(A , B , C , D ,  2 , gs1);

  gg(D , A , B , C ,  6 , gs2);

  gg(C , D , A , B , 10 , gs3);

  gg(B , C , D , A , 14 , gs4);

  gg(A , B , C , D ,  3 , gs1);

  gg(D , A , B , C ,  7 , gs2);

  gg(C , D , A , B , 11 , gs3);

  gg(B , C , D , A , 15 , gs4);

  hh(A , B , C , D ,  0 , hs1); /* Round 3 */

  hh(D , A , B , C ,  8 , hs2);

  hh(C , D , A , B ,  4 , hs3);

  hh(B , C , D , A , 12 , hs4);

  hh(A , B , C , D ,  2 , hs1);

  hh(D , A , B , C , 10 , hs2);

  hh(C , D , A , B ,  6 , hs3);

  hh(B , C , D , A , 14 , hs4);

  hh(A , B , C , D ,  1 , hs1);

  hh(D , A , B , C ,  9 , hs2);

  hh(C , D , A , B ,  5 , hs3);

  hh(B , C , D , A , 13 , hs4);

  hh(A , B , C , D ,  3 , hs1);

  hh(D , A , B , C , 11 , hs2);

  hh(C , D , A , B ,  7 , hs3);

  hh(B , C , D , A , 15 , hs4);

  MDp->buffer[0] += A;

  MDp->buffer[1] += B;

  MDp->buffer[2] += C;

  MDp->buffer[3] += D;

}

/* MD4Update(MDp,X,count)

** Input: X -- a pointer to an array of unsigned characters.

**        count -- the number of bits of X to use.

**          (if not a multiple of 8, uses high bits of last byte.)

** Update MDp using the number of bits of X given by count.

** This is the basic input routine for an MD4 user.

** The routine completes the MD computation when count < 512, so

** every MD computation should end with one call to MD4Update with a

** count less than 512.  A call with count 0 will be ignored if the

** MD has already been terminated (done != 0), so an extra call with

** count 0 can be given as a "courtesy close" to force termination

** if desired.

*/

void

MD4Update(MDp,X,count)

MD4_CTX *MDp;

unsigned char *X;

unsigned int count;

{

  unsigned int i, tmp, bit, byte, mask;

  unsigned char XX[64];

  unsigned char *p;

  /* return with no error if this is a courtesy close with count

  ** zero and MDp->done is true.

  */

  if (count == 0 && MDp->done) return;

  /* check to see if MD is already done and report error */

  if (MDp->done)

  { printf("\nError: MD4Update MD already done."); return; }

  /* Add count to MDp->count */

  tmp = count;

  p = MDp->count;

  while (tmp)

  { tmp += *p;

  *p++ = tmp;

  tmp = tmp >> 8;

  }

  /* Process data */

  if (count == 512)

  { /* Full block of data to handle */

    MDblock(MDp,X);

  }

  else if (count > 512) /* Check for count too large */

  {

    printf("\nError: MD4Update called with illegal count value %d.",

           count);

    return;

  }

  else /* partial block -- must be last block so finish up */

  {

    /* Find out how many bytes and residual bits there are */

    byte = count >> 3;

    bit =  count & 7;

    /* Copy X into XX since we need to modify it */

    for (i=0;i<=byte;i++)   XX[i] = X[i];

    for (i=byte+1;i<64;i++) XX[i] = 0;

    /* Add padding '1' bit and low-order zeros in last byte */

    mask = 1 << (7 - bit);

    XX[byte] = (XX[byte] | mask) & ~( mask - 1);

    /* If room for bit count, finish up with this block */

    if (byte <= 55)

    {

      for (i=0;i<8;i++) XX[56+i] = MDp->count[i];

      MDblock(MDp,XX);

    }

    else /* need to do two blocks to finish up */

    {

      MDblock(MDp,XX);

      for (i=0;i<56;i++) XX[i] = 0;

      for (i=0;i<8;i++)  XX[56+i] = MDp->count[i];

      MDblock(MDp,XX);

    }

    /* Set flag saying we're done with MD computation */

    MDp->done = 1;

  }

}

/*

** Finish up MD4 computation and return message digest.

*/

void

MD4Final(buf, MD)

unsigned char *buf;

MD4_CTX *MD;

{

  int i, j;

  unsigned int w;

  MD4Update(MD, NULL, 0);

  for (i = 0; i < 4; ++i) {

    w = MD->buffer[i];

    for (j = 0; j < 4; ++j) {

      *buf++ = w;

      w >>= 8;

    }

  }

}

/*

** End of md4.c

****************************(cut)***********************************/