openssl/crypto/cast/c_ofb64.c

/* crypto/cast/c_ofb64.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 <openssl/cast.h>
#include "cast_lcl.h"

/*
 * The input and output encrypted as though 64bit ofb mode is being used.
 * The extra state information to record how much of the 64bit block we have
 * used is contained in *num;
 */
void CAST_ofb64_encrypt(const unsigned char *in, unsigned char *out,
                        long length, const CAST_KEY *schedule,
                        unsigned char *ivec, int *num)
{
    register CAST_LONG v0, v1, t;
    register int n = *num;
    register long l = length;
    unsigned char d[8];
    register char *dp;
    CAST_LONG ti[2];
    unsigned char *iv;
    int save = 0;

    iv = ivec;
    n2l(iv, v0);
    n2l(iv, v1);
    ti[0] = v0;
    ti[1] = v1;
    dp = (char *)d;
    l2n(v0, dp);
    l2n(v1, dp);
    while (l--) {
        if (n == 0) {
            CAST_encrypt((CAST_LONG *)ti, schedule);
            dp = (char *)d;
            t = ti[0];
            l2n(t, dp);
            t = ti[1];
            l2n(t, dp);
            save++;
        }
        *(out++) = *(in++) ^ d[n];
        n = (n + 1) & 0x07;
    }
    if (save) {
        v0 = ti[0];
        v1 = ti[1];
        iv = ivec;
        l2n(v0, iv);
        l2n(v1, iv);
    }
    t = v0 = v1 = ti[0] = ti[1] = 0;
    *num = n;
}