| /* 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; |
| } |