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#include "fitz_base.h"
#include "fitz_stream.h"
typedef struct fz_aesd_s fz_aesd;
struct fz_aesd_s
{
fz_filter super;
fz_aes aes;
unsigned char iv[16];
int ivcount;
};
fz_error
fz_newaesdfilter(fz_filter **fp, unsigned char *key, unsigned keylen)
{
FZ_NEWFILTER(fz_aesd, f, aesdfilter);
aes_setkey_dec(&f->aes, key, keylen * 8);
f->ivcount = 0;
return fz_okay;
}
void
fz_dropaesdfilter(fz_filter *f)
{
}
fz_error
fz_processaesdfilter(fz_filter *filter, fz_buffer *in, fz_buffer *out)
{
fz_aesd *f = (fz_aesd*)filter;
int n;
while (1)
{
if (in->rp + 16 > in->wp)
{
if (in->eof)
return fz_iodone;
return fz_ioneedin;
}
if (f->ivcount < 16)
{
f->iv[f->ivcount++] = *in->rp++;
}
else
{
if (out->wp + 16 > out->ep)
return fz_ioneedout;
n = MIN(in->wp - in->rp, out->ep - out->wp);
n = (n / 16) * 16;
aes_crypt_cbc(&f->aes, AES_DECRYPT, n, f->iv, in->rp, out->wp);
in->rp += n;
out->wp += n;
/* Remove padding bytes */
if (in->eof && in->rp == in->wp)
{
int pad = out->wp[-1];
if (pad < 1 || pad > 16)
return fz_throw("aes padding out of range: %d", pad);
out->wp -= pad;
}
}
}
}
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