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Yes I understand Hemanth but the inverse key is not an output of the

Jonathan/Marcio,
I am sorry for the confusion but I have clearly stated in the tb_readme
doc that the mode for encryption or decryption has to be set in the TB
module aes_tester for generic inputs. I have for example used the default
key/inverse-key pair of:
000102030405060708090A0B0C0D0E0F
13111D7FE3944A17F307A78B4D2B30C5
in the above test bench. The enryption/decryption is selected by setting
the  "mode_tb" variable "manually" in this TB module. I have NOT devised
the TB to to run encryption-decryption back to back. You also need to copy
the encrypted output data to the file "encoded_text.txt" to run the
decryption on the same ouput to get back the original message.
To be specific, I would suggest you to run the test with the "mode_tb"
signal set to "1"(it is currently set to "0" in the project) which will
enable encryption. After running the test, copy the ouput from the file
"coded_text.txt" to the input file for decryption "encoded_text.txt" and
run the test again with the "mode_tb" set to "0" which will enable
decryption and you can see your original message in file
"decoded_text.txt".
I am assuming that you faced the problems when running the generic input
tests run the TB "aes_tester".

Thanks,
Hemanth

> Yes I understand Hemanth but the inverse key is not an output of the
> AES core, I dont know where to access it.  Everything you said makes
> perfect sense so if I could figure out how to access the inverse key I'll
> be fine.  Thanks!
>
> ----- Original Message -----
> From: Hemanth<hemanths@d...>
> To:
> Date: Wed Oct 18 13:37:36 CEST 2006
> Subject: [oc] AES128 Question
>
>> Hi Jonathan,
>> I am sorry for not being able to reply earlier, I have been
>> travelling a
>> lot and hardly have checked my mails in between. Hmm.. that was a
>> long
>> time back and dont remember exactly but if my memory is correct the
>> inverse key is the key that is output after an encryption is
>> completed. If
>> you observe, both data and key undergo a series of transformation
>> and at
>> the end there is both a garbled key and encrypted data coming out.
>> This
>> key is taken as the inverse key for decryption. Infact I have used
>> one set
>> of key pairs as default in my test bench. This information is also
>> explained in the FIPS document.
>> Hope this helps,
>> Hemanth
>> > While using the AES128 core (aes_crypto_core) I have come
>> across a
>> > problem; after encrypting data with a key and receiving an
>> output, how
>> > do I know what the inverse key is in order to decrypt the
>> output? I had
>> > an example from the fips document about AES so I was able to
>> test
>> > given their key and output key, and was successful in doing
>> so.
>> > However, making up a key wont work for me as I have no idea
>> what the
>> > inverse key is. Clearing this issue up would really help me
>> out. Thanks.
>> > _______________________________________________
>> > http://www.opencores.org/mailman/listinfo/cores
>> >
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