136 lines
4.7 KiB
C
136 lines
4.7 KiB
C
/* crypto/des/ofb_enc.c */
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/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
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* All rights reserved.
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*
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* This package is an SSL implementation written
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* by Eric Young (eay@cryptsoft.com).
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* The implementation was written so as to conform with Netscapes SSL.
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*
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* This library is free for commercial and non-commercial use as long as
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* the following conditions are aheared to. The following conditions
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* apply to all code found in this distribution, be it the RC4, RSA,
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* lhash, DES, etc., code; not just the SSL code. The SSL documentation
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* included with this distribution is covered by the same copyright terms
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* except that the holder is Tim Hudson (tjh@cryptsoft.com).
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*
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* Copyright remains Eric Young's, and as such any Copyright notices in
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* the code are not to be removed.
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* If this package is used in a product, Eric Young should be given attribution
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* as the author of the parts of the library used.
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* This can be in the form of a textual message at program startup or
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* in documentation (online or textual) provided with the package.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* "This product includes cryptographic software written by
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* Eric Young (eay@cryptsoft.com)"
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* The word 'cryptographic' can be left out if the rouines from the library
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* being used are not cryptographic related :-).
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* 4. If you include any Windows specific code (or a derivative thereof) from
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* the apps directory (application code) you must include an acknowledgement:
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* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
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*
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* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* The licence and distribution terms for any publically available version or
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* derivative of this code cannot be changed. i.e. this code cannot simply be
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* copied and put under another distribution licence
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* [including the GNU Public Licence.]
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*/
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#include "des_locl.h"
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/* The input and output are loaded in multiples of 8 bits.
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* What this means is that if you hame numbits=12 and length=2
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* the first 12 bits will be retrieved from the first byte and half
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* the second. The second 12 bits will come from the 3rd and half the 4th
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* byte.
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*/
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void DES_ofb_encrypt(const unsigned char *in, unsigned char *out, int numbits,
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long length, DES_key_schedule *schedule,
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DES_cblock *ivec)
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{
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register DES_LONG d0,d1,vv0,vv1,v0,v1,n=(numbits+7)/8;
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register DES_LONG mask0,mask1;
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register long l=length;
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register int num=numbits;
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DES_LONG ti[2];
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unsigned char *iv;
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if (num > 64) return;
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if (num > 32)
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{
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mask0=0xffffffffL;
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if (num >= 64)
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mask1=mask0;
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else
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mask1=(1L<<(num-32))-1;
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}
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else
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{
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if (num == 32)
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mask0=0xffffffffL;
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else
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mask0=(1L<<num)-1;
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mask1=0x00000000L;
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}
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iv = &(*ivec)[0];
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c2l(iv,v0);
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c2l(iv,v1);
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ti[0]=v0;
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ti[1]=v1;
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while (l-- > 0)
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{
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ti[0]=v0;
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ti[1]=v1;
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DES_encrypt1((DES_LONG *)ti,schedule,DES_ENCRYPT);
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vv0=ti[0];
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vv1=ti[1];
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c2ln(in,d0,d1,n);
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in+=n;
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d0=(d0^vv0)&mask0;
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d1=(d1^vv1)&mask1;
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l2cn(d0,d1,out,n);
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out+=n;
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if (num == 32)
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{ v0=v1; v1=vv0; }
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else if (num == 64)
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{ v0=vv0; v1=vv1; }
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else if (num > 32) /* && num != 64 */
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{
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v0=((v1>>(num-32))|(vv0<<(64-num)))&0xffffffffL;
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v1=((vv0>>(num-32))|(vv1<<(64-num)))&0xffffffffL;
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}
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else /* num < 32 */
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{
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v0=((v0>>num)|(v1<<(32-num)))&0xffffffffL;
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v1=((v1>>num)|(vv0<<(32-num)))&0xffffffffL;
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}
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}
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iv = &(*ivec)[0];
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l2c(v0,iv);
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l2c(v1,iv);
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v0=v1=d0=d1=ti[0]=ti[1]=vv0=vv1=0;
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}
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