| 1 | /*
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| 2 | * Copyright 1995-2020 The OpenSSL Project Authors. All Rights Reserved.
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| 3 | *
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| 4 | * Licensed under the Apache License 2.0 (the "License"). You may not use
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| 5 | * this file except in compliance with the License. You can obtain a copy
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| 6 | * in the file LICENSE in the source distribution or at
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| 7 | * https://www.openssl.org/source/license.html
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| 8 | */
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| 9 |
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| 10 | /*
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| 11 | * DES low level APIs are deprecated for public use, but still ok for internal
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| 12 | * use.
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| 13 | */
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| 14 | #include "internal/deprecated.h"
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| 15 |
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| 16 | #include "des_local.h"
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| 17 |
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| 18 | /*
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| 19 | * The input and output are loaded in multiples of 8 bits. What this means is
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| 20 | * that if you have numbits=12 and length=2 the first 12 bits will be
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| 21 | * retrieved from the first byte and half the second. The second 12 bits
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| 22 | * will come from the 3rd and half the 4th byte.
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| 23 | */
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| 24 | void DES_ofb_encrypt(const unsigned char *in, unsigned char *out, int numbits,
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| 25 | long length, DES_key_schedule *schedule,
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| 26 | DES_cblock *ivec)
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| 27 | {
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| 28 | register DES_LONG d0, d1, vv0, vv1, v0, v1, n = (numbits + 7) / 8;
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| 29 | register DES_LONG mask0, mask1;
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| 30 | register long l = length;
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| 31 | register int num = numbits;
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| 32 | DES_LONG ti[2];
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| 33 | unsigned char *iv;
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| 34 |
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| 35 | if (num > 64)
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| 36 | return;
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| 37 | if (num > 32) {
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| 38 | mask0 = 0xffffffffL;
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| 39 | if (num >= 64)
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| 40 | mask1 = mask0;
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| 41 | else
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| 42 | mask1 = (1L << (num - 32)) - 1;
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| 43 | } else {
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| 44 | if (num == 32)
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| 45 | mask0 = 0xffffffffL;
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| 46 | else
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| 47 | mask0 = (1L << num) - 1;
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| 48 | mask1 = 0x00000000L;
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| 49 | }
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| 50 |
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| 51 | iv = &(*ivec)[0];
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| 52 | c2l(iv, v0);
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| 53 | c2l(iv, v1);
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| 54 | ti[0] = v0;
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| 55 | ti[1] = v1;
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| 56 | while (l-- > 0) {
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| 57 | ti[0] = v0;
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| 58 | ti[1] = v1;
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| 59 | DES_encrypt1((DES_LONG *)ti, schedule, DES_ENCRYPT);
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| 60 | vv0 = ti[0];
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| 61 | vv1 = ti[1];
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| 62 | c2ln(in, d0, d1, n);
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| 63 | in += n;
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| 64 | d0 = (d0 ^ vv0) & mask0;
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| 65 | d1 = (d1 ^ vv1) & mask1;
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| 66 | l2cn(d0, d1, out, n);
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| 67 | out += n;
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| 68 |
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| 69 | if (num == 32) {
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| 70 | v0 = v1;
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| 71 | v1 = vv0;
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| 72 | } else if (num == 64) {
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| 73 | v0 = vv0;
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| 74 | v1 = vv1;
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| 75 | } else if (num > 32) { /* && num != 64 */
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| 76 | v0 = ((v1 >> (num - 32)) | (vv0 << (64 - num))) & 0xffffffffL;
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| 77 | v1 = ((vv0 >> (num - 32)) | (vv1 << (64 - num))) & 0xffffffffL;
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| 78 | } else { /* num < 32 */
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| 79 |
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| 80 | v0 = ((v0 >> num) | (v1 << (32 - num))) & 0xffffffffL;
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| 81 | v1 = ((v1 >> num) | (vv0 << (32 - num))) & 0xffffffffL;
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| 82 | }
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| 83 | }
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| 84 | iv = &(*ivec)[0];
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| 85 | l2c(v0, iv);
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| 86 | l2c(v1, iv);
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| 87 | v0 = v1 = d0 = d1 = ti[0] = ti[1] = vv0 = vv1 = 0;
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| 88 | }
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