1 /* 2 * Copyright (c) 1999 Kungliga Tekniska H�gskolan 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 RCSID("$Id: n-fold.c 22190 2007-12-06 16:24:22Z lha $"); 36 37 static krb5_error_code 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 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_error_code KRB5_LIB_FUNCTION 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 return ENOMEM; 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 memset(buf, 0, len); 133 free(buf); 134 memset(tmp, 0, maxlen); 135 free(tmp); 136 return ret; 137 } 138