crypto/dist/heimdal/lib/krb5/n-fold.c

   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 __RCSID("$Heimdal: n-fold.c 22190 2007-12-06 16:24:22Z lha $"
  36         "$NetBSD$");
  37
  38 static krb5_error_code
  39 rr13(unsigned char *buf, size_t len)
  40 {
  41     unsigned char *tmp;
  42     int bytes = (len + 7) / 8;
  43     int i;
  44     if(len == 0)
  45         return 0;
  46     {
  47         const int bits = 13 % len;
  48         const int lbit = len % 8;
  49
  50         tmp = malloc(bytes);
  51         if (tmp == NULL)
  52             return ENOMEM;
  53         memcpy(tmp, buf, bytes);
  54         if(lbit) {
  55             /* pad final byte with inital bits */
  56             tmp[bytes - 1] &= 0xff << (8 - lbit);
  57             for(i = lbit; i < 8; i += len)
  58                 tmp[bytes - 1] |= buf[0] >> i;
  59         }
  60         for(i = 0; i < bytes; i++) {
  61             int bb;
  62             int b1, s1, b2, s2;
  63             /* calculate first bit position of this byte */
  64             bb = 8 * i - bits;
  65             while(bb < 0)
  66                 bb += len;
  67             /* byte offset and shift count */
  68             b1 = bb / 8;
  69             s1 = bb % 8;
  70
  71             if(bb + 8 > bytes * 8)
  72                 /* watch for wraparound */
  73                 s2 = (len + 8 - s1) % 8;
  74             else
  75                 s2 = 8 - s1;
  76             b2 = (b1 + 1) % bytes;
  77             buf[i] = (tmp[b1] << s1) | (tmp[b2] >> s2);
  78         }
  79         free(tmp);
  80     }
  81     return 0;
  82 }
  83
  84 /* Add `b' to `a', both being one's complement numbers. */
  85 static void
  86 add1(unsigned char *a, unsigned char *b, size_t len)
  87 {
  88     int i;
  89     int carry = 0;
  90     for(i = len - 1; i >= 0; i--){
  91         int x = a[i] + b[i] + carry;
  92         carry = x > 0xff;
  93         a[i] = x & 0xff;
  94     }
  95     for(i = len - 1; carry && i >= 0; i--){
  96         int x = a[i] + carry;
  97         carry = x > 0xff;
  98         a[i] = x & 0xff;
  99     }
 100 }
 101
 102 krb5_error_code KRB5_LIB_FUNCTION
 103 _krb5_n_fold(const void *str, size_t len, void *key, size_t size)
 104 {
 105     /* if len < size we need at most N * len bytes, ie < 2 * size;
 106        if len > size we need at most 2 * len */
 107     krb5_error_code ret = 0;
 108     size_t maxlen = 2 * max(size, len);
 109     size_t l = 0;
 110     unsigned char *tmp = malloc(maxlen);
 111     unsigned char *buf = malloc(len);
 112
 113     if (tmp == NULL || buf == NULL)
 114         return ENOMEM;
 115
 116     memcpy(buf, str, len);
 117     memset(key, 0, size);
 118     do {
 119         memcpy(tmp + l, buf, len);
 120         l += len;
 121         ret = rr13(buf, len * 8);
 122         if (ret)
 123             goto out;
 124         while(l >= size) {
 125             add1(key, tmp, size);
 126             l -= size;
 127             if(l == 0)
 128                 break;
 129             memmove(tmp, tmp + size, l);
 130         }
 131     } while(l != 0);
 132 out:
 133     memset(buf, 0, len);
 134     free(buf);
 135     memset(tmp, 0, maxlen);
 136     free(tmp);
 137     return ret;
 138 }