On 6/19/2014 11:19 AM, Jeffrey Walton wrote:
...
CCM is probably the oldest of the three, its more complicated, and its
offline (you have to have all data beforehand - you cannot stream data
into it).
Personally, I don't care about GCM's parallelizability because I
require all data to be authent
Hey, thanks Jeff !
I also inadvertently found an interresting article of a certain M. J. W. ...
;-)
I should have read more carefully :
http://www.codeproject.com/Articles/34380/Authenticated-Encryption
particularly when it states : "It is up to the receiver to determine
whether to accept a tag
On Thu, Jun 19, 2014 at 4:48 AM, Michel wrote:
> Ok, I have missed that point (and probably many others...)
> I need to go deeper to better understand things,
> and I am grateful for your explanations.
If AEAD schemes are your thing, then you might take a look at David
Wagner's http://www.cs.berke
Ok, I have missed that point (and probably many others...)
I need to go deeper to better understand things,
and I am grateful for your explanations.
Le 18/06/2014 20:25, Thulasi Goriparthi a écrit :
In the test program, you are feeding a fixed ccm_tag to decryption
process. This will not work fo
One more thing to correct myself.
2 as tag length is not allowed. only 4, 6, 8, 10, 12, 14, 16 are allowed.
On Wed, Jun 18, 2014 at 11:55 PM, Thulasi Goriparthi <
thulasi.goripar...@gmail.com> wrote:
> In the test program, you are feeding a fixed ccm_tag to decryption
> process. This will not w
In the test program, you are feeding a fixed ccm_tag to decryption process.
This will not work for CCM, as tag length itself will also be an input for
tag generation. Change in tag length, will change the tag produced. I
modified the decryption api(aes_ccm_decrypt) to take the tag generated by
encr
I tried all of 2, 4, 6, 8, 10, 12, 14, 16 values, and always got a
"Plaintext not available: tag verify failed".
Even when tag length of decryption was equal to tag length of encryption.
:-(
It just works for : tag length of decryption = tag length of encryption
= 16.
Thanks again for your hel
Truncate-able tags gave a way to truncated hmac extension.
Haven't gone through CCM RFC 3610 completely.
I can see the restriction of possible M values(Tag lengths) to 2, 4, 6, 8,
10, 12, 14, 16. Can you try reducing the tag size accordingly and see if it
succeeds.
On Wed, Jun 18, 2014 at 6:52
Thank for your answer.
But isn't this strategy very hazardous ?
And why just for GCM and not CCM ?
Le 18/06/2014 14:37, Thulasi Goriparthi a écrit :
EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_SET_TAG, sizeof(gcm_tag), gcm_tag);
When you change tag length with the above statement, you are tellin
EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_SET_TAG, sizeof(gcm_tag), gcm_tag);
When you change tag length with the above statement, you are telling
the decrypt context to consider only those many number of bytes
for tag comparision.
On Wed, Jun 18, 2014 at 4:52 PM, Michel wrote:
> Hi all,
>
> I w
Hi all,
I was surprised that decryption succeeded in GCM mode althought the tag
was shorter than the one produced when encrypting,
as it is not the case in CCM. Is it the intended behaviour ?
In order to rule out a possible bug in my program, I finally used the
example code at :
https://gith
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