Problem - Kevin Tafuro

unsigned char *next_iv, *start = out;
/* If there's not enough stuff to fit in ctbuf, dump it in there and return */
if (il < SPC_BLOCK_SZ - ctx->ix) {
while (il--) ctx->ctbuf[ctx->ix++] = *in++;
if (ol) *ol = 0;
return 1;
}
/* If there's stuff in ctbuf, fill it. */
if (ctx->ix % SPC_BLOCK_SZ) {
while (ctx->ix < SPC_BLOCK_SZ) {
ctx->ctbuf[ctx->ix++] = *in++;
--il;
}
}
if (!il) {
if (ol) *ol = 0;
return 1;
}
/* If we get here, and the ctbuf is full, it can't be padding. Spill it. */
if (ctx->ix) {
SPC_DO_DECRYPT(&(ctx->ks), ctx->ctbuf, out);
for (i = 0; i < SPC_BLOCK_SZ / sizeof(int); i++) {
((int *)out)[i] ^= ((int *)ctx->iv)[i];
((int *)ctx->iv)[i] = ((int *)ctx->ctbuf)[i];
}
out += SPC_BLOCK_SZ;
}
if (il > SPC_BLOCK_SZ) {
SPC_DO_DECRYPT(&(ctx->ks), in, out);
for (i = 0; i < SPC_BLOCK_SZ / sizeof(int); i++)
((int *)out)[i] ^= ((int *)ctx->iv)[i];
next_iv = in;
out += SPC_BLOCK_SZ;
in += SPC_BLOCK_SZ;
il -= SPC_BLOCK_SZ;
} else next_iv = ctx->iv;
while (il > SPC_BLOCK_SZ) {
SPC_DO_DECRYPT(&(ctx->ks), in, out);
for (i = 0; i < SPC_BLOCK_SZ / sizeof(int); i++)
((int *)out)[i] ^= ((int *)next_iv)[i];
next_iv = in;
out += SPC_BLOCK_SZ;
in += SPC_BLOCK_SZ;
il -= SPC_BLOCK_SZ;
}
/* Store the IV. */
for (i = 0; i < SPC_BLOCK_SZ / sizeof(int); i++)
((int *)ctx->iv)[i] = ((int *)next_iv)[i];
ctx->ix = 0;
while (il--) ctx->ctbuf[ctx->ix++] = *in++;
184 | Chapter 5: Symmetric Encryption
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