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

   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
  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_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
 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 }