ofb_enc.c

/* crypto/des/ofb_enc.c */ /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) * All rights reserved. * * This package is an SSL implementation written * by Eric Young (eay@cryptsoft.com). * The implementation was written so as to conform with Netscapes SSL. * * This library is free for commercial and non-commercial use as long as * the following conditions are aheared to. The following conditions * apply to all code found in this distribution, be it the RC4, RSA, * lhash, DES, etc., code; not just the SSL code. The SSL documentation * included with this distribution is covered by the same copyright terms * except that the holder is Tim Hudson (tjh@cryptsoft.com). * * Copyright remains Eric Young's, and as such any Copyright notices in * the code are not to be removed. * If this package is used in a product, Eric Young should be given attribution * as the author of the parts of the library used. * This can be in the form of a textual message at program startup or * in documentation (online or textual) provided with the package. * * 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 copyright * notice, this list of conditions and the following disclaimer. * 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. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * "This product includes cryptographic software written by * Eric Young (eay@cryptsoft.com)" * The word 'cryptographic' can be left out if the rouines from the library * being used are not cryptographic related :-). * 4. If you include any Windows specific code (or a derivative thereof) from * the apps directory (application code) you must include an acknowledgement: * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" * * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``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 OR CONTRIBUTORS 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. * * The licence and distribution terms for any publically available version or * derivative of this code cannot be changed. i.e. this code cannot simply be * copied and put under another distribution licence * [including the GNU Public Licence.] */ #include "des_locl.h" /* The input and output are loaded in multiples of 8 bits. * What this means is that if you hame numbits=12 and length=2 * the first 12 bits will be retrieved from the first byte and half * the second. The second 12 bits will come from the 3rd and half the 4th * byte. */ void DES_ofb_encrypt(const unsigned char *in, unsigned char *out, int numbits, long length, DES_key_schedule *schedule, DES_cblock *ivec) { register DES_LONG d0,d1,vv0,vv1,v0,v1,n=(numbits+7)/8; register DES_LONG mask0,mask1; register long l=length; register int num=numbits; DES_LONG ti[2]; unsigned char *iv; if (num > 64) return; if (num > 32) { mask0=0xffffffffL; if (num >= 64) mask1=mask0; else mask1=(1L<<(num-32))-1; } else { if (num == 32) mask0=0xffffffffL; else mask0=(1L<<num)-1; mask1=0x00000000L; } iv = &(*ivec)[0]; c2l(iv,v0); c2l(iv,v1); ti[0]=v0; ti[1]=v1; while (l-- > 0) { ti[0]=v0; ti[1]=v1; DES_encrypt1((DES_LONG *)ti,schedule,DES_ENCRYPT); vv0=ti[0]; vv1=ti[1]; c2ln(in,d0,d1,n); in+=n; d0=(d0^vv0)&mask0; d1=(d1^vv1)&mask1; l2cn(d0,d1,out,n); out+=n; if (num == 32) { v0=v1; v1=vv0; } else if (num == 64) { v0=vv0; v1=vv1; } else if (num > 32) /* && num != 64 */ { v0=((v1>>(num-32))|(vv0<<(64-num)))&0xffffffffL; v1=((vv0>>(num-32))|(vv1<<(64-num)))&0xffffffffL; } else /* num < 32 */ { v0=((v0>>num)|(v1<<(32-num)))&0xffffffffL; v1=((v1>>num)|(vv0<<(32-num)))&0xffffffffL; } } iv = &(*ivec)[0]; l2c(v0,iv); l2c(v1,iv); v0=v1=d0=d1=ti[0]=ti[1]=vv0=vv1=0; }

Generated by Doxygen 1.6.0 Back to index