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,v 1.6 1999/08/27 09:03:41 joda Exp $"); 36 37 static void 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; 45 { 46 const int bits = 13 % len; 47 const int lbit = len % 8; 48 49 tmp = malloc(bytes); 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 } 79 80 /* Add `b' to `a', both beeing one's complement numbers. */ 81 static void 82 add1(unsigned char *a, unsigned char *b, size_t len) 83 { 84 int i; 85 int carry = 0; 86 for(i = len - 1; i >= 0; i--){ 87 int x = a[i] + b[i] + carry; 88 carry = x > 0xff; 89 a[i] = x & 0xff; 90 } 91 for(i = len - 1; carry && i >= 0; i--){ 92 int x = a[i] + carry; 93 carry = x > 0xff; 94 a[i] = x & 0xff; 95 } 96 } 97 98 void 99 _krb5_n_fold(const void *str, size_t len, void *key, size_t size) 100 { 101 /* if len < size we need at most N * len bytes, ie < 2 * size; 102 if len > size we need at most 2 * len */ 103 size_t maxlen = 2 * max(size, len); 104 size_t l = 0; 105 unsigned char *tmp = malloc(maxlen); 106 unsigned char *buf = malloc(len); 107 108 memcpy(buf, str, len); 109 memset(key, 0, size); 110 do { 111 memcpy(tmp + l, buf, len); 112 l += len; 113 rr13(buf, len * 8); 114 while(l >= size) { 115 add1(key, tmp, size); 116 l -= size; 117 if(l == 0) 118 break; 119 memmove(tmp, tmp + size, l); 120 } 121 } while(l != 0); 122 memset(buf, 0, len); 123 free(buf); 124 memset(tmp, 0, maxlen); 125 free(tmp); 126 } 127