1 /* crypto/des/ofb_enc.c */

     2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)

     3  * All rights reserved.

     4  *

     5  * This package is an SSL implementation written

     6  * by Eric Young (eay@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@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@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@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 EXPORT_C 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