1 /* $NetBSD: n-fold.c,v 1.1.1.2 2014/04/24 12:45:50 pettai Exp $ */
2
3 /*
4 * Copyright (c) 1999 Kungliga Tekniska Högskolan
5 * (Royal Institute of Technology, Stockholm, Sweden).
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 *
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * 3. Neither the name of KTH nor the names of its contributors may be
20 * used to endorse or promote products derived from this software without
21 * specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY KTH AND ITS CONTRIBUTORS ``AS IS'' AND ANY
24 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
26 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL KTH OR ITS CONTRIBUTORS BE
27 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
28 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
29 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
30 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
31 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
32 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
33 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */
34
35 #include "krb5_locl.h"
36
37 static krb5_error_code
rr13(unsigned char * buf,size_t len)38 rr13(unsigned char *buf, size_t len)
39 {
40 unsigned char *tmp;
41 int bytes = (len + 7) / 8;
42 int i;
43 if(len == 0)
44 return 0;
45 {
46 const int bits = 13 % len;
47 const int lbit = len % 8;
48
49 tmp = malloc(bytes);
50 if (tmp == NULL)
51 return ENOMEM;
52 memcpy(tmp, buf, bytes);
53 if(lbit) {
54 /* pad final byte with inital bits */
55 tmp[bytes - 1] &= 0xff << (8 - lbit);
56 for(i = lbit; i < 8; i += len)
57 tmp[bytes - 1] |= buf[0] >> i;
58 }
59 for(i = 0; i < bytes; i++) {
60 int bb;
61 int b1, s1, b2, s2;
62 /* calculate first bit position of this byte */
63 bb = 8 * i - bits;
64 while(bb < 0)
65 bb += len;
66 /* byte offset and shift count */
67 b1 = bb / 8;
68 s1 = bb % 8;
69
70 if(bb + 8 > bytes * 8)
71 /* watch for wraparound */
72 s2 = (len + 8 - s1) % 8;
73 else
74 s2 = 8 - s1;
75 b2 = (b1 + 1) % bytes;
76 buf[i] = (tmp[b1] << s1) | (tmp[b2] >> s2);
77 }
78 free(tmp);
79 }
80 return 0;
81 }
82
83 /* Add `b' to `a', both being one's complement numbers. */
84 static void
add1(unsigned char * a,unsigned char * b,size_t len)85 add1(unsigned char *a, unsigned char *b, size_t len)
86 {
87 int i;
88 int carry = 0;
89 for(i = len - 1; i >= 0; i--){
90 int x = a[i] + b[i] + carry;
91 carry = x > 0xff;
92 a[i] = x & 0xff;
93 }
94 for(i = len - 1; carry && i >= 0; i--){
95 int x = a[i] + carry;
96 carry = x > 0xff;
97 a[i] = x & 0xff;
98 }
99 }
100
101 KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
_krb5_n_fold(const void * str,size_t len,void * key,size_t size)102 _krb5_n_fold(const void *str, size_t len, void *key, size_t size)
103 {
104 /* if len < size we need at most N * len bytes, ie < 2 * size;
105 if len > size we need at most 2 * len */
106 krb5_error_code ret = 0;
107 size_t maxlen = 2 * max(size, len);
108 size_t l = 0;
109 unsigned char *tmp = malloc(maxlen);
110 unsigned char *buf = malloc(len);
111
112 if (tmp == NULL || buf == NULL) {
113 ret = ENOMEM;
114 goto out;
115 }
116
117 memcpy(buf, str, len);
118 memset(key, 0, size);
119 do {
120 memcpy(tmp + l, buf, len);
121 l += len;
122 ret = rr13(buf, len * 8);
123 if (ret)
124 goto out;
125 while(l >= size) {
126 add1(key, tmp, size);
127 l -= size;
128 if(l == 0)
129 break;
130 memmove(tmp, tmp + size, l);
131 }
132 } while(l != 0);
133 out:
134 if (buf) {
135 memset(buf, 0, len);
136 free(buf);
137 }
138 if (tmp) {
139 memset(tmp, 0, maxlen);
140 free(tmp);
141 }
142 return ret;
143 }
144