aaae186ab9
git-svn-id: svn://svn.h5l.se/heimdal/trunk/heimdal@5332 ec53bebd-3082-4978-b11e-865c3cabbd6b
89 lines
1.9 KiB
C
89 lines
1.9 KiB
C
#include "krb5_locl.h"
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static void
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rr13(unsigned char *buf, size_t len)
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{
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unsigned char *tmp;
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int bytes = (len + 7) / 8;
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int i;
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const int bits = 13 % len;
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const int lbit = len % 8;
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tmp = malloc(bytes);
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memcpy(tmp, buf, bytes);
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if(lbit) {
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/* pad final byte with inital bits */
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tmp[bytes - 1] &= 0xff << (8 - lbit);
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for(i = lbit; i < 8; i += len)
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tmp[bytes - 1] |= buf[0] >> i;
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}
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for(i = 0; i < bytes; i++) {
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int bb;
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int b1, s1, b2, s2;
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/* calculate first bit position of this byte */
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bb = 8 * i - bits;
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while(bb < 0)
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bb += len;
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/* byte offset and shift count */
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b1 = bb / 8;
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s1 = bb % 8;
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if(bb + 8 > bytes * 8)
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/* watch for wraparound */
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s2 = (len + 8 - s1) % 8;
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else
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s2 = 8 - s1;
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b2 = (b1 + 1) % bytes;
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buf[i] = (tmp[b1] << s1) | (tmp[b2] >> s2);
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}
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free(tmp);
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}
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/* Add `b' to `a', both beeing one's complement numbers. */
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static void
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add1(unsigned char *a, unsigned char *b, size_t len)
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{
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int i;
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int carry = 0;
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for(i = len - 1; i >= 0; i--){
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int x = a[i] + b[i] + carry;
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carry = x > 0xff;
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a[i] = x & 0xff;
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}
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for(i = len - 1; carry && i >= 0; i--){
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int x = a[i] + carry;
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carry = x > 0xff;
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a[i] = carry & 0xff;
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}
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}
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void
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n_fold(const void *str, size_t len, void *key, size_t size)
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{
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/* if len < size we need at most N * len bytes, ie < 2 * size;
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if len > size we need at most 2 * len */
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size_t maxlen = 2 * max(size, len);
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size_t l = 0;
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unsigned char *tmp = malloc(maxlen);
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unsigned char *buf = malloc(len);
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memcpy(buf, str, len);
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memset(key, 0, size);
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do {
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memcpy(tmp + l, buf, len);
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l += len;
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rr13(buf, len * 8);
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while(l >= size) {
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add1(key, tmp, size);
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l -= size;
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if(l == 0)
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break;
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memmove(tmp, tmp + size, l);
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}
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} while(l != 0);
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memset(buf, 0, len);
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free(buf);
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memset(tmp, 0, maxlen);
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free(tmp);
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}
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