Problem - Kevin Tafuro

unsigned char b[SPC_KEY_SZ];
size_t ix;
size_t tl;
} SPC_DM_CTX;
void spc_dm_init(SPC_DM_CTX *c) {
memset(c->h, 0x52, SPC_BLOCK_SZ);
c->ix = 0;
c->tl = 0;
}
static void spc_dm_once(SPC_DM_CTX *c, unsigned char b[SPC_KEY_SZ]) {
int i;
SPC_KEY_SCHED ks;
unsigned char tmp[SPC_BLOCK_SZ];
SPC_ENCRYPT_INIT(&ks, b, SPC_KEY_SZ);
SPC_DO_ENCRYPT(&ks, c->h, tmp);
for (i = 0; i < SPC_BLOCK_SZ / sizeof(int); i++)
((int *)c->h)[i] ^= ((int *)tmp)[i];
}
void spc_dm_update(SPC_DM_CTX *c, unsigned char *t, size_t l) {
c->tl += l; /* if c->tl < l: abort */
while (c->ix && l) {
c->b[c->ix++] = *t++;
l--;
if (!(c->ix %= SPC_KEY_SZ)) spc_dm_once(c, c->b);
}
while (l > SPC_KEY_SZ) {
spc_dm_once(c, t);
t += SPC_KEY_SZ;
l -= SPC_KEY_SZ;
}
c->ix = l;
for (l = 0; l < c->ix; l++) c->b[l] = *t++;
}
void spc_dm_final(SPC_DM_CTX *c, unsigned char output[SPC_BLOCK_SZ]) {
int i;
c->b[c->ix++] = 0x80;
while (c->ix < SPC_KEY_SZ) c->b[c->ix++] = 0;
spc_dm_once(c, c->b);
memset(c->b, 0, SPC_KEY_SZ - sizeof(size_t));
c->tl = htonl(c->tl);
for (i = 0; i < sizeof(size_t); i++)
c->b[SPC_KEY_SZ - sizeof(size_t) + i] = ((unsigned char *)(&c->tl))[i];
spc_dm_once(c, c->b);
memcpy(output, c->h, SPC_BLOCK_SZ);
}
Constructing a Hash Function from a Block Cipher | 293
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