| 1 | /*
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| 2 | * Copyright (c) 1999 Kungliga Tekniska Högskolan
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| 3 | * (Royal Institute of Technology, Stockholm, Sweden).
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| 4 | * All rights reserved.
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| 5 | *
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| 6 | * Redistribution and use in source and binary forms, with or without
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| 7 | * modification, are permitted provided that the following conditions
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| 8 | * are met:
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| 9 | *
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| 10 | * 1. Redistributions of source code must retain the above copyright
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| 11 | * notice, this list of conditions and the following disclaimer.
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| 12 | *
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| 13 | * 2. Redistributions in binary form must reproduce the above copyright
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| 14 | * notice, this list of conditions and the following disclaimer in the
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| 15 | * documentation and/or other materials provided with the distribution.
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| 16 | *
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| 17 | * 3. Neither the name of KTH nor the names of its contributors may be
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| 18 | * used to endorse or promote products derived from this software without
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| 19 | * specific prior written permission.
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| 20 | *
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| 21 | * THIS SOFTWARE IS PROVIDED BY KTH AND ITS CONTRIBUTORS ``AS IS'' AND ANY
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| 22 | * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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| 23 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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| 24 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL KTH OR ITS CONTRIBUTORS BE
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| 25 | * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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| 26 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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| 27 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
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| 28 | * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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| 29 | * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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| 30 | * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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| 31 | * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */
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| 32 |
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| 33 | #include "krb5_locl.h"
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| 34 |
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| 35 | static krb5_error_code
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| 36 | rr13(unsigned char *buf, size_t len)
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| 37 | {
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| 38 | unsigned char *tmp;
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| 39 | int bytes = (len + 7) / 8;
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| 40 | int i;
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| 41 | if(len == 0)
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| 42 | return 0;
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| 43 | {
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| 44 | const int bits = 13 % len;
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| 45 | const int lbit = len % 8;
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| 46 |
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| 47 | tmp = malloc(bytes);
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| 48 | if (tmp == NULL)
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| 49 | return ENOMEM;
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| 50 | memcpy(tmp, buf, bytes);
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| 51 | if(lbit) {
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| 52 | /* pad final byte with inital bits */
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| 53 | tmp[bytes - 1] &= 0xff << (8 - lbit);
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| 54 | for(i = lbit; i < 8; i += len)
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| 55 | tmp[bytes - 1] |= buf[0] >> i;
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| 56 | }
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| 57 | for(i = 0; i < bytes; i++) {
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| 58 | int bb;
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| 59 | int b1, s1, b2, s2;
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| 60 | /* calculate first bit position of this byte */
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| 61 | bb = 8 * i - bits;
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| 62 | while(bb < 0)
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| 63 | bb += len;
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| 64 | /* byte offset and shift count */
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| 65 | b1 = bb / 8;
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| 66 | s1 = bb % 8;
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| 67 |
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| 68 | if(bb + 8 > bytes * 8)
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| 69 | /* watch for wraparound */
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| 70 | s2 = (len + 8 - s1) % 8;
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| 71 | else
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| 72 | s2 = 8 - s1;
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| 73 | b2 = (b1 + 1) % bytes;
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| 74 | buf[i] = (tmp[b1] << s1) | (tmp[b2] >> s2);
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| 75 | }
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| 76 | free(tmp);
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| 77 | }
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| 78 | return 0;
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| 79 | }
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| 80 |
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| 81 | /* Add `b' to `a', both being one's complement numbers. */
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| 82 | static void
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| 83 | add1(unsigned char *a, unsigned char *b, size_t len)
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| 84 | {
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| 85 | int i;
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| 86 | int carry = 0;
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| 87 | for(i = len - 1; i >= 0; i--){
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| 88 | int x = a[i] + b[i] + carry;
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| 89 | carry = x > 0xff;
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| 90 | a[i] = x & 0xff;
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| 91 | }
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| 92 | for(i = len - 1; carry && i >= 0; i--){
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| 93 | int x = a[i] + carry;
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| 94 | carry = x > 0xff;
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| 95 | a[i] = x & 0xff;
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| 96 | }
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| 97 | }
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| 98 |
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| 99 | krb5_error_code KRB5_LIB_FUNCTION
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| 100 | _krb5_n_fold(const void *str, size_t len, void *key, size_t size)
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| 101 | {
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| 102 | /* if len < size we need at most N * len bytes, ie < 2 * size;
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| 103 | if len > size we need at most 2 * len */
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| 104 | krb5_error_code ret = 0;
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| 105 | size_t maxlen = 2 * max(size, len);
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| 106 | size_t l = 0;
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| 107 | unsigned char *tmp = malloc(maxlen);
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| 108 | unsigned char *buf = malloc(len);
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| 109 |
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| 110 | if (tmp == NULL || buf == NULL) {
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| 111 | ret = ENOMEM;
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| 112 | goto out;
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| 113 | }
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| 114 |
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| 115 | memcpy(buf, str, len);
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| 116 | memset(key, 0, size);
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| 117 | do {
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| 118 | memcpy(tmp + l, buf, len);
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| 119 | l += len;
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| 120 | ret = rr13(buf, len * 8);
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| 121 | if (ret)
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| 122 | goto out;
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| 123 | while(l >= size) {
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| 124 | add1(key, tmp, size);
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| 125 | l -= size;
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| 126 | if(l == 0)
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| 127 | break;
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| 128 | memmove(tmp, tmp + size, l);
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| 129 | }
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| 130 | } while(l != 0);
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| 131 | out:
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| 132 | if (buf) {
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| 133 | memset(buf, 0, len);
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| 134 | free(buf);
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| 135 | }
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| 136 | if (tmp) {
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| 137 | memset(tmp, 0, maxlen);
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| 138 | free(tmp);
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| 139 | }
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| 140 | return ret;
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| 141 | }
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