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 } 144