A local copy of OpenSSL from GitHub
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/*
* Copyright 1995-2020 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the Apache License 2.0 (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
/*
* DES low level APIs are deprecated for public use, but still ok for internal
* use.
*/
#include "internal/deprecated.h"
#include "e_os.h"
#include "des_local.h"
#include <assert.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.
*/
/*
* Until Aug 1 2003 this function did not correctly implement CFB-r, so it
* will not be compatible with any encryption prior to that date. Ben.
*/
void DES_cfb_encrypt(const unsigned char *in, unsigned char *out, int numbits,
long length, DES_key_schedule *schedule,
DES_cblock *ivec, int enc)
{
register DES_LONG d0, d1, v0, v1;
register unsigned long l = length;
register int num = numbits / 8, n = (numbits + 7) / 8, i, rem =
numbits % 8;
DES_LONG ti[2];
unsigned char *iv;
#ifndef L_ENDIAN
unsigned char ovec[16];
#else
unsigned int sh[4];
unsigned char *ovec = (unsigned char *)sh;
/* I kind of count that compiler optimizes away this assertion, */
assert(sizeof(sh[0]) == 4); /* as this holds true for all, */
/* but 16-bit platforms... */
#endif
if (numbits <= 0 || numbits > 64)
return;
iv = &(*ivec)[0];
c2l(iv, v0);
c2l(iv, v1);
if (enc) {
while (l >= (unsigned long)n) {
l -= n;
ti[0] = v0;
ti[1] = v1;
DES_encrypt1((DES_LONG *)ti, schedule, DES_ENCRYPT);
c2ln(in, d0, d1, n);
in += n;
d0 ^= ti[0];
d1 ^= ti[1];
l2cn(d0, d1, out, n);
out += n;
/*
* 30-08-94 - eay - changed because l>>32 and l<<32 are bad under
* gcc :-(
*/
if (numbits == 32) {
v0 = v1;
v1 = d0;
} else if (numbits == 64) {
v0 = d0;
v1 = d1;
} else {
#ifndef L_ENDIAN
iv = &ovec[0];
l2c(v0, iv);
l2c(v1, iv);
l2c(d0, iv);
l2c(d1, iv);
#else
sh[0] = v0, sh[1] = v1, sh[2] = d0, sh[3] = d1;
#endif
if (rem == 0)
memmove(ovec, ovec + num, 8);
else
for (i = 0; i < 8; ++i)
ovec[i] = ovec[i + num] << rem |
ovec[i + num + 1] >> (8 - rem);
#ifdef L_ENDIAN
v0 = sh[0], v1 = sh[1];
#else
iv = &ovec[0];
c2l(iv, v0);
c2l(iv, v1);
#endif
}
}
} else {
while (l >= (unsigned long)n) {
l -= n;
ti[0] = v0;
ti[1] = v1;
DES_encrypt1((DES_LONG *)ti, schedule, DES_ENCRYPT);
c2ln(in, d0, d1, n);
in += n;
/*
* 30-08-94 - eay - changed because l>>32 and l<<32 are bad under
* gcc :-(
*/
if (numbits == 32) {
v0 = v1;
v1 = d0;
} else if (numbits == 64) {
v0 = d0;
v1 = d1;
} else {
#ifndef L_ENDIAN
iv = &ovec[0];
l2c(v0, iv);
l2c(v1, iv);
l2c(d0, iv);
l2c(d1, iv);
#else
sh[0] = v0, sh[1] = v1, sh[2] = d0, sh[3] = d1;
#endif
if (rem == 0)
memmove(ovec, ovec + num, 8);
else
for (i = 0; i < 8; ++i)
ovec[i] = ovec[i + num] << rem |
ovec[i + num + 1] >> (8 - rem);
#ifdef L_ENDIAN
v0 = sh[0], v1 = sh[1];
#else
iv = &ovec[0];
c2l(iv, v0);
c2l(iv, v1);
#endif
}
d0 ^= ti[0];
d1 ^= ti[1];
l2cn(d0, d1, out, n);
out += n;
}
}
iv = &(*ivec)[0];
l2c(v0, iv);
l2c(v1, iv);
v0 = v1 = d0 = d1 = ti[0] = ti[1] = 0;
}