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Hmm..,

Thanks Hemanth.  What is the easiest way to "spy" on the key during 
the key's transformation?  Much of the AES code is rather complicated 
for me.

----- Original Message ----- 
From: Hemanth<hemanths@d...> 
To: 
Date: Mon Oct 23 08:15:29 CEST 2006 
Subject: [oc] AES128 Question 

> Hmm.., 
> I got where you are pointing at, I think I missed answering this in 
> my 
> previous post. You are right the RTL does'nt ouput the inverse key. 
> I 
> think my assumption was that the RTL need'nt take the burden of it. 
> So 
> looks like you have to record the inverse key by looking at the 
> waveform 
> or better still adding a piece of code to the TB to spy on the 
> interior 
> signals of the key expander module at the end of its 
> encryption/decryption 
> phase or even better you could have an excel spread sheet or some 
> program 
> do that. 
> Hope this answers your doubts, 
> 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 at 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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