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 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 }