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