Pieter,
I am far from having analysed all the CurveZMQ library, but the
following change passes the tests :
src/cusrc/curvezmq_codec.c - s_encrypt :
Before :
size_t box_size = crypto_box_ZEROBYTES + size;
byte *plain = malloc (box_size);
byte *box = malloc (box_size);
.....
memcpy (target, box + crypto_box_BOXZEROBYTES, size +
crypto_box_BOXZEROBYTES);
After :
size_t plain_size = crypto_box_ZEROBYTES + size;
byte *plain = malloc (plain_size);
size_t box_size = crypto_box_BOXZEROBYTES + size;
byte *box = malloc (box_size);
.....
memcpy (target, box + crypto_box_BOXZEROBYTES, size);
Le 18/08/2013 10:07, Pieter Hintjens a écrit :
Thanks for this analysis. I'll look at it when I have an hour or two;
it's too tricky to fix in passing.
On Thu, Aug 15, 2013 at 12:30 PM, Laurent Alebarde <[email protected]> wrote:
Hi all,
I am reviewing the curvezmq code with a debugger :
Fact :
in curvezmq_codec.c (s_encrypt from s_produce_hello, line 288) :
memcpy (target, box + crypto_box_BOXZEROBYTES, size +
crypto_box_BOXZEROBYTES);
copies from (box + crypto_box_BOXZEROBYTES) (size + crypto_box_BOXZEROBYTES)
bytes
Debugger aborts (while the executable itself in a shell works well).
Consequences :
1) an amount of (crypto_box_BOXZEROBYTES) undefined bytes after the box
are copied to target, while the box is malloc-ed with a size of
(crypto_box_ZEROBYTES + size)
2) the spec "target must be nonce + box" is not fullfilled since the
first crypto_box_BOXZEROBYTES bytes of the box are not copied to target (may
be ok since they are zeros)
Possible solutions :
1) change to : memcpy (target, box + crypto_box_BOXZEROBYTES, size);
and set appropriatly the remaining (crypto_box_BOXZEROBYTES) bytes
of target
2) change to : memcpy (target, box, size + crypto_box_BOXZEROBYTES);
and adapt the size of target : hello_t.box becomes : bytes box[96]
3) change to : memcpy (target, box + crypto_box_BOXZEROBYTES, size);
and adapt the size of target : hello_t.box becomes : bytes box[64]
In addition : box should be malloc-ed with a size of
(crypto_box_BOXZEROBYTES + size) instead of (crypto_box_ZEROBYTES + size)
Cheers,
Laurent.
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