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      1 /* crypto/des/ofb_enc.c */
      2 /* Copyright (C) 1995-1998 Eric Young (eay (at) cryptsoft.com)
      3  * All rights reserved.
      4  *
      5  * This package is an SSL implementation written
      6  * by Eric Young (eay (at) cryptsoft.com).
      7  * The implementation was written so as to conform with Netscapes SSL.
      8  *
      9  * This library is free for commercial and non-commercial use as long as
     10  * the following conditions are aheared to.  The following conditions
     11  * apply to all code found in this distribution, be it the RC4, RSA,
     12  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
     13  * included with this distribution is covered by the same copyright terms
     14  * except that the holder is Tim Hudson (tjh (at) cryptsoft.com).
     15  *
     16  * Copyright remains Eric Young's, and as such any Copyright notices in
     17  * the code are not to be removed.
     18  * If this package is used in a product, Eric Young should be given attribution
     19  * as the author of the parts of the library used.
     20  * This can be in the form of a textual message at program startup or
     21  * in documentation (online or textual) provided with the package.
     22  *
     23  * Redistribution and use in source and binary forms, with or without
     24  * modification, are permitted provided that the following conditions
     25  * are met:
     26  * 1. Redistributions of source code must retain the copyright
     27  *    notice, this list of conditions and the following disclaimer.
     28  * 2. Redistributions in binary form must reproduce the above copyright
     29  *    notice, this list of conditions and the following disclaimer in the
     30  *    documentation and/or other materials provided with the distribution.
     31  * 3. All advertising materials mentioning features or use of this software
     32  *    must display the following acknowledgement:
     33  *    "This product includes cryptographic software written by
     34  *     Eric Young (eay (at) cryptsoft.com)"
     35  *    The word 'cryptographic' can be left out if the rouines from the library
     36  *    being used are not cryptographic related :-).
     37  * 4. If you include any Windows specific code (or a derivative thereof) from
     38  *    the apps directory (application code) you must include an acknowledgement:
     39  *    "This product includes software written by Tim Hudson (tjh (at) cryptsoft.com)"
     40  *
     41  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
     42  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     43  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     44  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     45  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     46  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     47  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     48  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     49  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     50  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     51  * SUCH DAMAGE.
     52  *
     53  * The licence and distribution terms for any publically available version or
     54  * derivative of this code cannot be changed.  i.e. this code cannot simply be
     55  * copied and put under another distribution licence
     56  * [including the GNU Public Licence.]
     57  */
     58 
     59 #include "des_locl.h"
     60 
     61 /* The input and output are loaded in multiples of 8 bits.
     62  * What this means is that if you hame numbits=12 and length=2
     63  * the first 12 bits will be retrieved from the first byte and half
     64  * the second.  The second 12 bits will come from the 3rd and half the 4th
     65  * byte.
     66  */
     67 void DES_ofb_encrypt(const unsigned char *in, unsigned char *out, int numbits,
     68 		     long length, DES_key_schedule *schedule,
     69 		     DES_cblock *ivec)
     70 	{
     71 	register DES_LONG d0,d1,vv0,vv1,v0,v1,n=(numbits+7)/8;
     72 	register DES_LONG mask0,mask1;
     73 	register long l=length;
     74 	register int num=numbits;
     75 	DES_LONG ti[2];
     76 	unsigned char *iv;
     77 
     78 	if (num > 64) return;
     79 	if (num > 32)
     80 		{
     81 		mask0=0xffffffffL;
     82 		if (num >= 64)
     83 			mask1=mask0;
     84 		else
     85 			mask1=(1L<<(num-32))-1;
     86 		}
     87 	else
     88 		{
     89 		if (num == 32)
     90 			mask0=0xffffffffL;
     91 		else
     92 			mask0=(1L<<num)-1;
     93 		mask1=0x00000000L;
     94 		}
     95 
     96 	iv = &(*ivec)[0];
     97 	c2l(iv,v0);
     98 	c2l(iv,v1);
     99 	ti[0]=v0;
    100 	ti[1]=v1;
    101 	while (l-- > 0)
    102 		{
    103 		ti[0]=v0;
    104 		ti[1]=v1;
    105 		DES_encrypt1((DES_LONG *)ti,schedule,DES_ENCRYPT);
    106 		vv0=ti[0];
    107 		vv1=ti[1];
    108 		c2ln(in,d0,d1,n);
    109 		in+=n;
    110 		d0=(d0^vv0)&mask0;
    111 		d1=(d1^vv1)&mask1;
    112 		l2cn(d0,d1,out,n);
    113 		out+=n;
    114 
    115 		if (num == 32)
    116 			{ v0=v1; v1=vv0; }
    117 		else if (num == 64)
    118 				{ v0=vv0; v1=vv1; }
    119 		else if (num > 32) /* && num != 64 */
    120 			{
    121 			v0=((v1>>(num-32))|(vv0<<(64-num)))&0xffffffffL;
    122 			v1=((vv0>>(num-32))|(vv1<<(64-num)))&0xffffffffL;
    123 			}
    124 		else /* num < 32 */
    125 			{
    126 			v0=((v0>>num)|(v1<<(32-num)))&0xffffffffL;
    127 			v1=((v1>>num)|(vv0<<(32-num)))&0xffffffffL;
    128 			}
    129 		}
    130 	iv = &(*ivec)[0];
    131 	l2c(v0,iv);
    132 	l2c(v1,iv);
    133 	v0=v1=d0=d1=ti[0]=ti[1]=vv0=vv1=0;
    134 	}
    135 
    136